11da177e4SLinus Torvalds /* 2c54fce6eSTejun Heo * kernel/workqueue.c - generic async execution with shared worker pool 31da177e4SLinus Torvalds * 4c54fce6eSTejun Heo * Copyright (C) 2002 Ingo Molnar 51da177e4SLinus Torvalds * 61da177e4SLinus Torvalds * Derived from the taskqueue/keventd code by: 71da177e4SLinus Torvalds * David Woodhouse <dwmw2@infradead.org> 8e1f8e874SFrancois Cami * Andrew Morton 91da177e4SLinus Torvalds * Kai Petzke <wpp@marie.physik.tu-berlin.de> 101da177e4SLinus Torvalds * Theodore Ts'o <tytso@mit.edu> 1189ada679SChristoph Lameter * 12cde53535SChristoph Lameter * Made to use alloc_percpu by Christoph Lameter. 13c54fce6eSTejun Heo * 14c54fce6eSTejun Heo * Copyright (C) 2010 SUSE Linux Products GmbH 15c54fce6eSTejun Heo * Copyright (C) 2010 Tejun Heo <tj@kernel.org> 16c54fce6eSTejun Heo * 17c54fce6eSTejun Heo * This is the generic async execution mechanism. Work items as are 18c54fce6eSTejun Heo * executed in process context. The worker pool is shared and 19c54fce6eSTejun Heo * automatically managed. There is one worker pool for each CPU and 20c54fce6eSTejun Heo * one extra for works which are better served by workers which are 21c54fce6eSTejun Heo * not bound to any specific CPU. 22c54fce6eSTejun Heo * 23c54fce6eSTejun Heo * Please read Documentation/workqueue.txt for details. 241da177e4SLinus Torvalds */ 251da177e4SLinus Torvalds 269984de1aSPaul Gortmaker #include <linux/export.h> 271da177e4SLinus Torvalds #include <linux/kernel.h> 281da177e4SLinus Torvalds #include <linux/sched.h> 291da177e4SLinus Torvalds #include <linux/init.h> 301da177e4SLinus Torvalds #include <linux/signal.h> 311da177e4SLinus Torvalds #include <linux/completion.h> 321da177e4SLinus Torvalds #include <linux/workqueue.h> 331da177e4SLinus Torvalds #include <linux/slab.h> 341da177e4SLinus Torvalds #include <linux/cpu.h> 351da177e4SLinus Torvalds #include <linux/notifier.h> 361da177e4SLinus Torvalds #include <linux/kthread.h> 371fa44ecaSJames Bottomley #include <linux/hardirq.h> 3846934023SChristoph Lameter #include <linux/mempolicy.h> 39341a5958SRafael J. Wysocki #include <linux/freezer.h> 40d5abe669SPeter Zijlstra #include <linux/kallsyms.h> 41d5abe669SPeter Zijlstra #include <linux/debug_locks.h> 424e6045f1SJohannes Berg #include <linux/lockdep.h> 43c34056a3STejun Heo #include <linux/idr.h> 4429c91e99STejun Heo #include <linux/jhash.h> 4542f8570fSSasha Levin #include <linux/hashtable.h> 4676af4d93STejun Heo #include <linux/rculist.h> 47bce90380STejun Heo #include <linux/nodemask.h> 484c16bd32STejun Heo #include <linux/moduleparam.h> 493d1cb205STejun Heo #include <linux/uaccess.h> 50e22bee78STejun Heo 51ea138446STejun Heo #include "workqueue_internal.h" 521da177e4SLinus Torvalds 53c8e55f36STejun Heo enum { 54bc2ae0f5STejun Heo /* 5524647570STejun Heo * worker_pool flags 56bc2ae0f5STejun Heo * 5724647570STejun Heo * A bound pool is either associated or disassociated with its CPU. 58bc2ae0f5STejun Heo * While associated (!DISASSOCIATED), all workers are bound to the 59bc2ae0f5STejun Heo * CPU and none has %WORKER_UNBOUND set and concurrency management 60bc2ae0f5STejun Heo * is in effect. 61bc2ae0f5STejun Heo * 62bc2ae0f5STejun Heo * While DISASSOCIATED, the cpu may be offline and all workers have 63bc2ae0f5STejun Heo * %WORKER_UNBOUND set and concurrency management disabled, and may 6424647570STejun Heo * be executing on any CPU. The pool behaves as an unbound one. 65bc2ae0f5STejun Heo * 66bc3a1afcSTejun Heo * Note that DISASSOCIATED should be flipped only while holding 67bc3a1afcSTejun Heo * manager_mutex to avoid changing binding state while 6824647570STejun Heo * create_worker() is in progress. 69bc2ae0f5STejun Heo */ 7011ebea50STejun Heo POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ 7124647570STejun Heo POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ 7235b6bb63STejun Heo POOL_FREEZING = 1 << 3, /* freeze in progress */ 73db7bccf4STejun Heo 74c8e55f36STejun Heo /* worker flags */ 75c8e55f36STejun Heo WORKER_STARTED = 1 << 0, /* started */ 76c8e55f36STejun Heo WORKER_DIE = 1 << 1, /* die die die */ 77c8e55f36STejun Heo WORKER_IDLE = 1 << 2, /* is idle */ 78e22bee78STejun Heo WORKER_PREP = 1 << 3, /* preparing to run works */ 79fb0e7bebSTejun Heo WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ 80f3421797STejun Heo WORKER_UNBOUND = 1 << 7, /* worker is unbound */ 81a9ab775bSTejun Heo WORKER_REBOUND = 1 << 8, /* worker was rebound */ 82e22bee78STejun Heo 83a9ab775bSTejun Heo WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | 84a9ab775bSTejun Heo WORKER_UNBOUND | WORKER_REBOUND, 85db7bccf4STejun Heo 86e34cdddbSTejun Heo NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ 874ce62e9eSTejun Heo 8829c91e99STejun Heo UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ 89c8e55f36STejun Heo BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ 90db7bccf4STejun Heo 91e22bee78STejun Heo MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ 92e22bee78STejun Heo IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ 93e22bee78STejun Heo 943233cdbdSTejun Heo MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, 953233cdbdSTejun Heo /* call for help after 10ms 963233cdbdSTejun Heo (min two ticks) */ 97e22bee78STejun Heo MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ 98e22bee78STejun Heo CREATE_COOLDOWN = HZ, /* time to breath after fail */ 991da177e4SLinus Torvalds 1001da177e4SLinus Torvalds /* 101e22bee78STejun Heo * Rescue workers are used only on emergencies and shared by 102e22bee78STejun Heo * all cpus. Give -20. 103e22bee78STejun Heo */ 104e22bee78STejun Heo RESCUER_NICE_LEVEL = -20, 1053270476aSTejun Heo HIGHPRI_NICE_LEVEL = -20, 106ecf6881fSTejun Heo 107ecf6881fSTejun Heo WQ_NAME_LEN = 24, 108c8e55f36STejun Heo }; 109c8e55f36STejun Heo 1101da177e4SLinus Torvalds /* 1114690c4abSTejun Heo * Structure fields follow one of the following exclusion rules. 1124690c4abSTejun Heo * 113e41e704bSTejun Heo * I: Modifiable by initialization/destruction paths and read-only for 114e41e704bSTejun Heo * everyone else. 1154690c4abSTejun Heo * 116e22bee78STejun Heo * P: Preemption protected. Disabling preemption is enough and should 117e22bee78STejun Heo * only be modified and accessed from the local cpu. 118e22bee78STejun Heo * 119d565ed63STejun Heo * L: pool->lock protected. Access with pool->lock held. 1204690c4abSTejun Heo * 121d565ed63STejun Heo * X: During normal operation, modification requires pool->lock and should 122d565ed63STejun Heo * be done only from local cpu. Either disabling preemption on local 123d565ed63STejun Heo * cpu or grabbing pool->lock is enough for read access. If 124d565ed63STejun Heo * POOL_DISASSOCIATED is set, it's identical to L. 125e22bee78STejun Heo * 126822d8405STejun Heo * MG: pool->manager_mutex and pool->lock protected. Writes require both 127822d8405STejun Heo * locks. Reads can happen under either lock. 128822d8405STejun Heo * 12968e13a67SLai Jiangshan * PL: wq_pool_mutex protected. 13076af4d93STejun Heo * 13168e13a67SLai Jiangshan * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads. 1325bcab335STejun Heo * 1333c25a55dSLai Jiangshan * WQ: wq->mutex protected. 1343c25a55dSLai Jiangshan * 135b5927605SLai Jiangshan * WR: wq->mutex protected for writes. Sched-RCU protected for reads. 1362e109a28STejun Heo * 1372e109a28STejun Heo * MD: wq_mayday_lock protected. 1384690c4abSTejun Heo */ 1394690c4abSTejun Heo 1402eaebdb3STejun Heo /* struct worker is defined in workqueue_internal.h */ 141c34056a3STejun Heo 142bd7bdd43STejun Heo struct worker_pool { 143d565ed63STejun Heo spinlock_t lock; /* the pool lock */ 144d84ff051STejun Heo int cpu; /* I: the associated cpu */ 145f3f90ad4STejun Heo int node; /* I: the associated node ID */ 1469daf9e67STejun Heo int id; /* I: pool ID */ 14711ebea50STejun Heo unsigned int flags; /* X: flags */ 148bd7bdd43STejun Heo 149bd7bdd43STejun Heo struct list_head worklist; /* L: list of pending works */ 150bd7bdd43STejun Heo int nr_workers; /* L: total number of workers */ 151ea1abd61SLai Jiangshan 152ea1abd61SLai Jiangshan /* nr_idle includes the ones off idle_list for rebinding */ 153bd7bdd43STejun Heo int nr_idle; /* L: currently idle ones */ 154bd7bdd43STejun Heo 155bd7bdd43STejun Heo struct list_head idle_list; /* X: list of idle workers */ 156bd7bdd43STejun Heo struct timer_list idle_timer; /* L: worker idle timeout */ 157bd7bdd43STejun Heo struct timer_list mayday_timer; /* L: SOS timer for workers */ 158bd7bdd43STejun Heo 159c5aa87bbSTejun Heo /* a workers is either on busy_hash or idle_list, or the manager */ 160c9e7cf27STejun Heo DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); 161c9e7cf27STejun Heo /* L: hash of busy workers */ 162c9e7cf27STejun Heo 163bc3a1afcSTejun Heo /* see manage_workers() for details on the two manager mutexes */ 16434a06bd6STejun Heo struct mutex manager_arb; /* manager arbitration */ 165bc3a1afcSTejun Heo struct mutex manager_mutex; /* manager exclusion */ 166822d8405STejun Heo struct idr worker_idr; /* MG: worker IDs and iteration */ 167e19e397aSTejun Heo 1687a4e344cSTejun Heo struct workqueue_attrs *attrs; /* I: worker attributes */ 16968e13a67SLai Jiangshan struct hlist_node hash_node; /* PL: unbound_pool_hash node */ 17068e13a67SLai Jiangshan int refcnt; /* PL: refcnt for unbound pools */ 1717a4e344cSTejun Heo 172e19e397aSTejun Heo /* 173e19e397aSTejun Heo * The current concurrency level. As it's likely to be accessed 174e19e397aSTejun Heo * from other CPUs during try_to_wake_up(), put it in a separate 175e19e397aSTejun Heo * cacheline. 176e19e397aSTejun Heo */ 177e19e397aSTejun Heo atomic_t nr_running ____cacheline_aligned_in_smp; 17829c91e99STejun Heo 17929c91e99STejun Heo /* 18029c91e99STejun Heo * Destruction of pool is sched-RCU protected to allow dereferences 18129c91e99STejun Heo * from get_work_pool(). 18229c91e99STejun Heo */ 18329c91e99STejun Heo struct rcu_head rcu; 1848b03ae3cSTejun Heo } ____cacheline_aligned_in_smp; 1858b03ae3cSTejun Heo 1868b03ae3cSTejun Heo /* 187112202d9STejun Heo * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS 188112202d9STejun Heo * of work_struct->data are used for flags and the remaining high bits 189112202d9STejun Heo * point to the pwq; thus, pwqs need to be aligned at two's power of the 190112202d9STejun Heo * number of flag bits. 1911da177e4SLinus Torvalds */ 192112202d9STejun Heo struct pool_workqueue { 193bd7bdd43STejun Heo struct worker_pool *pool; /* I: the associated pool */ 1944690c4abSTejun Heo struct workqueue_struct *wq; /* I: the owning workqueue */ 19573f53c4aSTejun Heo int work_color; /* L: current color */ 19673f53c4aSTejun Heo int flush_color; /* L: flushing color */ 1978864b4e5STejun Heo int refcnt; /* L: reference count */ 19873f53c4aSTejun Heo int nr_in_flight[WORK_NR_COLORS]; 19973f53c4aSTejun Heo /* L: nr of in_flight works */ 2001e19ffc6STejun Heo int nr_active; /* L: nr of active works */ 201a0a1a5fdSTejun Heo int max_active; /* L: max active works */ 2021e19ffc6STejun Heo struct list_head delayed_works; /* L: delayed works */ 2033c25a55dSLai Jiangshan struct list_head pwqs_node; /* WR: node on wq->pwqs */ 2042e109a28STejun Heo struct list_head mayday_node; /* MD: node on wq->maydays */ 2058864b4e5STejun Heo 2068864b4e5STejun Heo /* 2078864b4e5STejun Heo * Release of unbound pwq is punted to system_wq. See put_pwq() 2088864b4e5STejun Heo * and pwq_unbound_release_workfn() for details. pool_workqueue 2098864b4e5STejun Heo * itself is also sched-RCU protected so that the first pwq can be 210b09f4fd3SLai Jiangshan * determined without grabbing wq->mutex. 2118864b4e5STejun Heo */ 2128864b4e5STejun Heo struct work_struct unbound_release_work; 2138864b4e5STejun Heo struct rcu_head rcu; 214e904e6c2STejun Heo } __aligned(1 << WORK_STRUCT_FLAG_BITS); 2151da177e4SLinus Torvalds 2161da177e4SLinus Torvalds /* 21773f53c4aSTejun Heo * Structure used to wait for workqueue flush. 21873f53c4aSTejun Heo */ 21973f53c4aSTejun Heo struct wq_flusher { 2203c25a55dSLai Jiangshan struct list_head list; /* WQ: list of flushers */ 2213c25a55dSLai Jiangshan int flush_color; /* WQ: flush color waiting for */ 22273f53c4aSTejun Heo struct completion done; /* flush completion */ 22373f53c4aSTejun Heo }; 2241da177e4SLinus Torvalds 225226223abSTejun Heo struct wq_device; 226226223abSTejun Heo 22773f53c4aSTejun Heo /* 228c5aa87bbSTejun Heo * The externally visible workqueue. It relays the issued work items to 229c5aa87bbSTejun Heo * the appropriate worker_pool through its pool_workqueues. 2301da177e4SLinus Torvalds */ 2311da177e4SLinus Torvalds struct workqueue_struct { 2323c25a55dSLai Jiangshan struct list_head pwqs; /* WR: all pwqs of this wq */ 23368e13a67SLai Jiangshan struct list_head list; /* PL: list of all workqueues */ 23473f53c4aSTejun Heo 2353c25a55dSLai Jiangshan struct mutex mutex; /* protects this wq */ 2363c25a55dSLai Jiangshan int work_color; /* WQ: current work color */ 2373c25a55dSLai Jiangshan int flush_color; /* WQ: current flush color */ 238112202d9STejun Heo atomic_t nr_pwqs_to_flush; /* flush in progress */ 2393c25a55dSLai Jiangshan struct wq_flusher *first_flusher; /* WQ: first flusher */ 2403c25a55dSLai Jiangshan struct list_head flusher_queue; /* WQ: flush waiters */ 2413c25a55dSLai Jiangshan struct list_head flusher_overflow; /* WQ: flush overflow list */ 24273f53c4aSTejun Heo 2432e109a28STejun Heo struct list_head maydays; /* MD: pwqs requesting rescue */ 244e22bee78STejun Heo struct worker *rescuer; /* I: rescue worker */ 245e22bee78STejun Heo 24687fc741eSLai Jiangshan int nr_drainers; /* WQ: drain in progress */ 247a357fc03SLai Jiangshan int saved_max_active; /* WQ: saved pwq max_active */ 248226223abSTejun Heo 2496029a918STejun Heo struct workqueue_attrs *unbound_attrs; /* WQ: only for unbound wqs */ 2504c16bd32STejun Heo struct pool_workqueue *dfl_pwq; /* WQ: only for unbound wqs */ 2516029a918STejun Heo 252226223abSTejun Heo #ifdef CONFIG_SYSFS 253226223abSTejun Heo struct wq_device *wq_dev; /* I: for sysfs interface */ 254226223abSTejun Heo #endif 2554e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 2564e6045f1SJohannes Berg struct lockdep_map lockdep_map; 2574e6045f1SJohannes Berg #endif 258ecf6881fSTejun Heo char name[WQ_NAME_LEN]; /* I: workqueue name */ 2592728fd2fSTejun Heo 2602728fd2fSTejun Heo /* hot fields used during command issue, aligned to cacheline */ 2612728fd2fSTejun Heo unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ 2622728fd2fSTejun Heo struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ 263df2d5ae4STejun Heo struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */ 2641da177e4SLinus Torvalds }; 2651da177e4SLinus Torvalds 266e904e6c2STejun Heo static struct kmem_cache *pwq_cache; 267e904e6c2STejun Heo 268bce90380STejun Heo static int wq_numa_tbl_len; /* highest possible NUMA node id + 1 */ 269bce90380STejun Heo static cpumask_var_t *wq_numa_possible_cpumask; 270bce90380STejun Heo /* possible CPUs of each node */ 271bce90380STejun Heo 272d55262c4STejun Heo static bool wq_disable_numa; 273d55262c4STejun Heo module_param_named(disable_numa, wq_disable_numa, bool, 0444); 274d55262c4STejun Heo 275cee22a15SViresh Kumar /* see the comment above the definition of WQ_POWER_EFFICIENT */ 276cee22a15SViresh Kumar #ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT 277cee22a15SViresh Kumar static bool wq_power_efficient = true; 278cee22a15SViresh Kumar #else 279cee22a15SViresh Kumar static bool wq_power_efficient; 280cee22a15SViresh Kumar #endif 281cee22a15SViresh Kumar 282cee22a15SViresh Kumar module_param_named(power_efficient, wq_power_efficient, bool, 0444); 283cee22a15SViresh Kumar 284bce90380STejun Heo static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ 285bce90380STejun Heo 2864c16bd32STejun Heo /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ 2874c16bd32STejun Heo static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; 2884c16bd32STejun Heo 28968e13a67SLai Jiangshan static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ 2902e109a28STejun Heo static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ 2915bcab335STejun Heo 29268e13a67SLai Jiangshan static LIST_HEAD(workqueues); /* PL: list of all workqueues */ 29368e13a67SLai Jiangshan static bool workqueue_freezing; /* PL: have wqs started freezing? */ 2947d19c5ceSTejun Heo 2957d19c5ceSTejun Heo /* the per-cpu worker pools */ 2967d19c5ceSTejun Heo static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], 2977d19c5ceSTejun Heo cpu_worker_pools); 2987d19c5ceSTejun Heo 29968e13a67SLai Jiangshan static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ 3007d19c5ceSTejun Heo 30168e13a67SLai Jiangshan /* PL: hash of all unbound pools keyed by pool->attrs */ 30229c91e99STejun Heo static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); 30329c91e99STejun Heo 304c5aa87bbSTejun Heo /* I: attributes used when instantiating standard unbound pools on demand */ 30529c91e99STejun Heo static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; 30629c91e99STejun Heo 307d320c038STejun Heo struct workqueue_struct *system_wq __read_mostly; 308ad7b1f84SMarc Dionne EXPORT_SYMBOL(system_wq); 309044c782cSValentin Ilie struct workqueue_struct *system_highpri_wq __read_mostly; 3101aabe902SJoonsoo Kim EXPORT_SYMBOL_GPL(system_highpri_wq); 311044c782cSValentin Ilie struct workqueue_struct *system_long_wq __read_mostly; 312d320c038STejun Heo EXPORT_SYMBOL_GPL(system_long_wq); 313044c782cSValentin Ilie struct workqueue_struct *system_unbound_wq __read_mostly; 314f3421797STejun Heo EXPORT_SYMBOL_GPL(system_unbound_wq); 315044c782cSValentin Ilie struct workqueue_struct *system_freezable_wq __read_mostly; 31624d51addSTejun Heo EXPORT_SYMBOL_GPL(system_freezable_wq); 3170668106cSViresh Kumar struct workqueue_struct *system_power_efficient_wq __read_mostly; 3180668106cSViresh Kumar EXPORT_SYMBOL_GPL(system_power_efficient_wq); 3190668106cSViresh Kumar struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; 3200668106cSViresh Kumar EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); 321d320c038STejun Heo 3227d19c5ceSTejun Heo static int worker_thread(void *__worker); 3237d19c5ceSTejun Heo static void copy_workqueue_attrs(struct workqueue_attrs *to, 3247d19c5ceSTejun Heo const struct workqueue_attrs *from); 3257d19c5ceSTejun Heo 32697bd2347STejun Heo #define CREATE_TRACE_POINTS 32797bd2347STejun Heo #include <trace/events/workqueue.h> 32897bd2347STejun Heo 32968e13a67SLai Jiangshan #define assert_rcu_or_pool_mutex() \ 3305bcab335STejun Heo rcu_lockdep_assert(rcu_read_lock_sched_held() || \ 33168e13a67SLai Jiangshan lockdep_is_held(&wq_pool_mutex), \ 33268e13a67SLai Jiangshan "sched RCU or wq_pool_mutex should be held") 3335bcab335STejun Heo 334b09f4fd3SLai Jiangshan #define assert_rcu_or_wq_mutex(wq) \ 33576af4d93STejun Heo rcu_lockdep_assert(rcu_read_lock_sched_held() || \ 336b5927605SLai Jiangshan lockdep_is_held(&wq->mutex), \ 337b09f4fd3SLai Jiangshan "sched RCU or wq->mutex should be held") 33876af4d93STejun Heo 339822d8405STejun Heo #ifdef CONFIG_LOCKDEP 340822d8405STejun Heo #define assert_manager_or_pool_lock(pool) \ 341519e3c11SLai Jiangshan WARN_ONCE(debug_locks && \ 342519e3c11SLai Jiangshan !lockdep_is_held(&(pool)->manager_mutex) && \ 343822d8405STejun Heo !lockdep_is_held(&(pool)->lock), \ 344822d8405STejun Heo "pool->manager_mutex or ->lock should be held") 345822d8405STejun Heo #else 346822d8405STejun Heo #define assert_manager_or_pool_lock(pool) do { } while (0) 347822d8405STejun Heo #endif 348822d8405STejun Heo 349f02ae73aSTejun Heo #define for_each_cpu_worker_pool(pool, cpu) \ 350f02ae73aSTejun Heo for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ 351f02ae73aSTejun Heo (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ 3527a62c2c8STejun Heo (pool)++) 3534ce62e9eSTejun Heo 35449e3cf44STejun Heo /** 35517116969STejun Heo * for_each_pool - iterate through all worker_pools in the system 35617116969STejun Heo * @pool: iteration cursor 357611c92a0STejun Heo * @pi: integer used for iteration 358fa1b54e6STejun Heo * 35968e13a67SLai Jiangshan * This must be called either with wq_pool_mutex held or sched RCU read 36068e13a67SLai Jiangshan * locked. If the pool needs to be used beyond the locking in effect, the 36168e13a67SLai Jiangshan * caller is responsible for guaranteeing that the pool stays online. 362fa1b54e6STejun Heo * 363fa1b54e6STejun Heo * The if/else clause exists only for the lockdep assertion and can be 364fa1b54e6STejun Heo * ignored. 36517116969STejun Heo */ 366611c92a0STejun Heo #define for_each_pool(pool, pi) \ 367611c92a0STejun Heo idr_for_each_entry(&worker_pool_idr, pool, pi) \ 36868e13a67SLai Jiangshan if (({ assert_rcu_or_pool_mutex(); false; })) { } \ 369fa1b54e6STejun Heo else 37017116969STejun Heo 37117116969STejun Heo /** 372822d8405STejun Heo * for_each_pool_worker - iterate through all workers of a worker_pool 373822d8405STejun Heo * @worker: iteration cursor 374822d8405STejun Heo * @wi: integer used for iteration 375822d8405STejun Heo * @pool: worker_pool to iterate workers of 376822d8405STejun Heo * 377822d8405STejun Heo * This must be called with either @pool->manager_mutex or ->lock held. 378822d8405STejun Heo * 379822d8405STejun Heo * The if/else clause exists only for the lockdep assertion and can be 380822d8405STejun Heo * ignored. 381822d8405STejun Heo */ 382822d8405STejun Heo #define for_each_pool_worker(worker, wi, pool) \ 383822d8405STejun Heo idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \ 384822d8405STejun Heo if (({ assert_manager_or_pool_lock((pool)); false; })) { } \ 385822d8405STejun Heo else 386822d8405STejun Heo 387822d8405STejun Heo /** 38849e3cf44STejun Heo * for_each_pwq - iterate through all pool_workqueues of the specified workqueue 38949e3cf44STejun Heo * @pwq: iteration cursor 39049e3cf44STejun Heo * @wq: the target workqueue 39176af4d93STejun Heo * 392b09f4fd3SLai Jiangshan * This must be called either with wq->mutex held or sched RCU read locked. 393794b18bcSTejun Heo * If the pwq needs to be used beyond the locking in effect, the caller is 394794b18bcSTejun Heo * responsible for guaranteeing that the pwq stays online. 39576af4d93STejun Heo * 39676af4d93STejun Heo * The if/else clause exists only for the lockdep assertion and can be 39776af4d93STejun Heo * ignored. 39849e3cf44STejun Heo */ 39949e3cf44STejun Heo #define for_each_pwq(pwq, wq) \ 40076af4d93STejun Heo list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \ 401b09f4fd3SLai Jiangshan if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \ 40276af4d93STejun Heo else 403f3421797STejun Heo 404dc186ad7SThomas Gleixner #ifdef CONFIG_DEBUG_OBJECTS_WORK 405dc186ad7SThomas Gleixner 406dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr; 407dc186ad7SThomas Gleixner 40899777288SStanislaw Gruszka static void *work_debug_hint(void *addr) 40999777288SStanislaw Gruszka { 41099777288SStanislaw Gruszka return ((struct work_struct *) addr)->func; 41199777288SStanislaw Gruszka } 41299777288SStanislaw Gruszka 413dc186ad7SThomas Gleixner /* 414dc186ad7SThomas Gleixner * fixup_init is called when: 415dc186ad7SThomas Gleixner * - an active object is initialized 416dc186ad7SThomas Gleixner */ 417dc186ad7SThomas Gleixner static int work_fixup_init(void *addr, enum debug_obj_state state) 418dc186ad7SThomas Gleixner { 419dc186ad7SThomas Gleixner struct work_struct *work = addr; 420dc186ad7SThomas Gleixner 421dc186ad7SThomas Gleixner switch (state) { 422dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 423dc186ad7SThomas Gleixner cancel_work_sync(work); 424dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 425dc186ad7SThomas Gleixner return 1; 426dc186ad7SThomas Gleixner default: 427dc186ad7SThomas Gleixner return 0; 428dc186ad7SThomas Gleixner } 429dc186ad7SThomas Gleixner } 430dc186ad7SThomas Gleixner 431dc186ad7SThomas Gleixner /* 432dc186ad7SThomas Gleixner * fixup_activate is called when: 433dc186ad7SThomas Gleixner * - an active object is activated 434dc186ad7SThomas Gleixner * - an unknown object is activated (might be a statically initialized object) 435dc186ad7SThomas Gleixner */ 436dc186ad7SThomas Gleixner static int work_fixup_activate(void *addr, enum debug_obj_state state) 437dc186ad7SThomas Gleixner { 438dc186ad7SThomas Gleixner struct work_struct *work = addr; 439dc186ad7SThomas Gleixner 440dc186ad7SThomas Gleixner switch (state) { 441dc186ad7SThomas Gleixner 442dc186ad7SThomas Gleixner case ODEBUG_STATE_NOTAVAILABLE: 443dc186ad7SThomas Gleixner /* 444dc186ad7SThomas Gleixner * This is not really a fixup. The work struct was 445dc186ad7SThomas Gleixner * statically initialized. We just make sure that it 446dc186ad7SThomas Gleixner * is tracked in the object tracker. 447dc186ad7SThomas Gleixner */ 44822df02bbSTejun Heo if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { 449dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 450dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 451dc186ad7SThomas Gleixner return 0; 452dc186ad7SThomas Gleixner } 453dc186ad7SThomas Gleixner WARN_ON_ONCE(1); 454dc186ad7SThomas Gleixner return 0; 455dc186ad7SThomas Gleixner 456dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 457dc186ad7SThomas Gleixner WARN_ON(1); 458dc186ad7SThomas Gleixner 459dc186ad7SThomas Gleixner default: 460dc186ad7SThomas Gleixner return 0; 461dc186ad7SThomas Gleixner } 462dc186ad7SThomas Gleixner } 463dc186ad7SThomas Gleixner 464dc186ad7SThomas Gleixner /* 465dc186ad7SThomas Gleixner * fixup_free is called when: 466dc186ad7SThomas Gleixner * - an active object is freed 467dc186ad7SThomas Gleixner */ 468dc186ad7SThomas Gleixner static int work_fixup_free(void *addr, enum debug_obj_state state) 469dc186ad7SThomas Gleixner { 470dc186ad7SThomas Gleixner struct work_struct *work = addr; 471dc186ad7SThomas Gleixner 472dc186ad7SThomas Gleixner switch (state) { 473dc186ad7SThomas Gleixner case ODEBUG_STATE_ACTIVE: 474dc186ad7SThomas Gleixner cancel_work_sync(work); 475dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 476dc186ad7SThomas Gleixner return 1; 477dc186ad7SThomas Gleixner default: 478dc186ad7SThomas Gleixner return 0; 479dc186ad7SThomas Gleixner } 480dc186ad7SThomas Gleixner } 481dc186ad7SThomas Gleixner 482dc186ad7SThomas Gleixner static struct debug_obj_descr work_debug_descr = { 483dc186ad7SThomas Gleixner .name = "work_struct", 48499777288SStanislaw Gruszka .debug_hint = work_debug_hint, 485dc186ad7SThomas Gleixner .fixup_init = work_fixup_init, 486dc186ad7SThomas Gleixner .fixup_activate = work_fixup_activate, 487dc186ad7SThomas Gleixner .fixup_free = work_fixup_free, 488dc186ad7SThomas Gleixner }; 489dc186ad7SThomas Gleixner 490dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) 491dc186ad7SThomas Gleixner { 492dc186ad7SThomas Gleixner debug_object_activate(work, &work_debug_descr); 493dc186ad7SThomas Gleixner } 494dc186ad7SThomas Gleixner 495dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) 496dc186ad7SThomas Gleixner { 497dc186ad7SThomas Gleixner debug_object_deactivate(work, &work_debug_descr); 498dc186ad7SThomas Gleixner } 499dc186ad7SThomas Gleixner 500dc186ad7SThomas Gleixner void __init_work(struct work_struct *work, int onstack) 501dc186ad7SThomas Gleixner { 502dc186ad7SThomas Gleixner if (onstack) 503dc186ad7SThomas Gleixner debug_object_init_on_stack(work, &work_debug_descr); 504dc186ad7SThomas Gleixner else 505dc186ad7SThomas Gleixner debug_object_init(work, &work_debug_descr); 506dc186ad7SThomas Gleixner } 507dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(__init_work); 508dc186ad7SThomas Gleixner 509dc186ad7SThomas Gleixner void destroy_work_on_stack(struct work_struct *work) 510dc186ad7SThomas Gleixner { 511dc186ad7SThomas Gleixner debug_object_free(work, &work_debug_descr); 512dc186ad7SThomas Gleixner } 513dc186ad7SThomas Gleixner EXPORT_SYMBOL_GPL(destroy_work_on_stack); 514dc186ad7SThomas Gleixner 515dc186ad7SThomas Gleixner #else 516dc186ad7SThomas Gleixner static inline void debug_work_activate(struct work_struct *work) { } 517dc186ad7SThomas Gleixner static inline void debug_work_deactivate(struct work_struct *work) { } 518dc186ad7SThomas Gleixner #endif 519dc186ad7SThomas Gleixner 5209daf9e67STejun Heo /* allocate ID and assign it to @pool */ 5219daf9e67STejun Heo static int worker_pool_assign_id(struct worker_pool *pool) 5229daf9e67STejun Heo { 5239daf9e67STejun Heo int ret; 5249daf9e67STejun Heo 52568e13a67SLai Jiangshan lockdep_assert_held(&wq_pool_mutex); 5265bcab335STejun Heo 527e68035fbSTejun Heo ret = idr_alloc(&worker_pool_idr, pool, 0, 0, GFP_KERNEL); 528229641a6STejun Heo if (ret >= 0) { 529e68035fbSTejun Heo pool->id = ret; 530229641a6STejun Heo return 0; 531229641a6STejun Heo } 5329daf9e67STejun Heo return ret; 5339daf9e67STejun Heo } 5349daf9e67STejun Heo 53576af4d93STejun Heo /** 536df2d5ae4STejun Heo * unbound_pwq_by_node - return the unbound pool_workqueue for the given node 537df2d5ae4STejun Heo * @wq: the target workqueue 538df2d5ae4STejun Heo * @node: the node ID 539df2d5ae4STejun Heo * 540df2d5ae4STejun Heo * This must be called either with pwq_lock held or sched RCU read locked. 541df2d5ae4STejun Heo * If the pwq needs to be used beyond the locking in effect, the caller is 542df2d5ae4STejun Heo * responsible for guaranteeing that the pwq stays online. 543df2d5ae4STejun Heo */ 544df2d5ae4STejun Heo static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, 545df2d5ae4STejun Heo int node) 546df2d5ae4STejun Heo { 547df2d5ae4STejun Heo assert_rcu_or_wq_mutex(wq); 548df2d5ae4STejun Heo return rcu_dereference_raw(wq->numa_pwq_tbl[node]); 549df2d5ae4STejun Heo } 550df2d5ae4STejun Heo 55173f53c4aSTejun Heo static unsigned int work_color_to_flags(int color) 55273f53c4aSTejun Heo { 55373f53c4aSTejun Heo return color << WORK_STRUCT_COLOR_SHIFT; 55473f53c4aSTejun Heo } 55573f53c4aSTejun Heo 55673f53c4aSTejun Heo static int get_work_color(struct work_struct *work) 55773f53c4aSTejun Heo { 55873f53c4aSTejun Heo return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & 55973f53c4aSTejun Heo ((1 << WORK_STRUCT_COLOR_BITS) - 1); 56073f53c4aSTejun Heo } 56173f53c4aSTejun Heo 56273f53c4aSTejun Heo static int work_next_color(int color) 56373f53c4aSTejun Heo { 56473f53c4aSTejun Heo return (color + 1) % WORK_NR_COLORS; 565a848e3b6SOleg Nesterov } 566a848e3b6SOleg Nesterov 5674594bf15SDavid Howells /* 568112202d9STejun Heo * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data 569112202d9STejun Heo * contain the pointer to the queued pwq. Once execution starts, the flag 5707c3eed5cSTejun Heo * is cleared and the high bits contain OFFQ flags and pool ID. 5717a22ad75STejun Heo * 572112202d9STejun Heo * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() 573112202d9STejun Heo * and clear_work_data() can be used to set the pwq, pool or clear 574bbb68dfaSTejun Heo * work->data. These functions should only be called while the work is 575bbb68dfaSTejun Heo * owned - ie. while the PENDING bit is set. 5767a22ad75STejun Heo * 577112202d9STejun Heo * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq 5787c3eed5cSTejun Heo * corresponding to a work. Pool is available once the work has been 579112202d9STejun Heo * queued anywhere after initialization until it is sync canceled. pwq is 5807c3eed5cSTejun Heo * available only while the work item is queued. 581bbb68dfaSTejun Heo * 582bbb68dfaSTejun Heo * %WORK_OFFQ_CANCELING is used to mark a work item which is being 583bbb68dfaSTejun Heo * canceled. While being canceled, a work item may have its PENDING set 584bbb68dfaSTejun Heo * but stay off timer and worklist for arbitrarily long and nobody should 585bbb68dfaSTejun Heo * try to steal the PENDING bit. 5864594bf15SDavid Howells */ 5877a22ad75STejun Heo static inline void set_work_data(struct work_struct *work, unsigned long data, 5887a22ad75STejun Heo unsigned long flags) 5897a22ad75STejun Heo { 5906183c009STejun Heo WARN_ON_ONCE(!work_pending(work)); 5917a22ad75STejun Heo atomic_long_set(&work->data, data | flags | work_static(work)); 5927a22ad75STejun Heo } 5937a22ad75STejun Heo 594112202d9STejun Heo static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, 5954690c4abSTejun Heo unsigned long extra_flags) 596365970a1SDavid Howells { 597112202d9STejun Heo set_work_data(work, (unsigned long)pwq, 598112202d9STejun Heo WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); 599365970a1SDavid Howells } 600365970a1SDavid Howells 6014468a00fSLai Jiangshan static void set_work_pool_and_keep_pending(struct work_struct *work, 6024468a00fSLai Jiangshan int pool_id) 6034468a00fSLai Jiangshan { 6044468a00fSLai Jiangshan set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 6054468a00fSLai Jiangshan WORK_STRUCT_PENDING); 6064468a00fSLai Jiangshan } 6074468a00fSLai Jiangshan 6087c3eed5cSTejun Heo static void set_work_pool_and_clear_pending(struct work_struct *work, 6097c3eed5cSTejun Heo int pool_id) 6104d707b9fSOleg Nesterov { 61123657bb1STejun Heo /* 61223657bb1STejun Heo * The following wmb is paired with the implied mb in 61323657bb1STejun Heo * test_and_set_bit(PENDING) and ensures all updates to @work made 61423657bb1STejun Heo * here are visible to and precede any updates by the next PENDING 61523657bb1STejun Heo * owner. 61623657bb1STejun Heo */ 61723657bb1STejun Heo smp_wmb(); 6187c3eed5cSTejun Heo set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); 6194d707b9fSOleg Nesterov } 6204d707b9fSOleg Nesterov 6217a22ad75STejun Heo static void clear_work_data(struct work_struct *work) 622365970a1SDavid Howells { 6237c3eed5cSTejun Heo smp_wmb(); /* see set_work_pool_and_clear_pending() */ 6247c3eed5cSTejun Heo set_work_data(work, WORK_STRUCT_NO_POOL, 0); 6257a22ad75STejun Heo } 6267a22ad75STejun Heo 627112202d9STejun Heo static struct pool_workqueue *get_work_pwq(struct work_struct *work) 6287a22ad75STejun Heo { 629e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 6307a22ad75STejun Heo 631112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 632e120153dSTejun Heo return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); 633e120153dSTejun Heo else 634e120153dSTejun Heo return NULL; 6357a22ad75STejun Heo } 6367a22ad75STejun Heo 6377c3eed5cSTejun Heo /** 6387c3eed5cSTejun Heo * get_work_pool - return the worker_pool a given work was associated with 6397c3eed5cSTejun Heo * @work: the work item of interest 6407c3eed5cSTejun Heo * 6417c3eed5cSTejun Heo * Return the worker_pool @work was last associated with. %NULL if none. 642fa1b54e6STejun Heo * 64368e13a67SLai Jiangshan * Pools are created and destroyed under wq_pool_mutex, and allows read 64468e13a67SLai Jiangshan * access under sched-RCU read lock. As such, this function should be 64568e13a67SLai Jiangshan * called under wq_pool_mutex or with preemption disabled. 646fa1b54e6STejun Heo * 647fa1b54e6STejun Heo * All fields of the returned pool are accessible as long as the above 648fa1b54e6STejun Heo * mentioned locking is in effect. If the returned pool needs to be used 649fa1b54e6STejun Heo * beyond the critical section, the caller is responsible for ensuring the 650fa1b54e6STejun Heo * returned pool is and stays online. 6517c3eed5cSTejun Heo */ 6527c3eed5cSTejun Heo static struct worker_pool *get_work_pool(struct work_struct *work) 6537a22ad75STejun Heo { 654e120153dSTejun Heo unsigned long data = atomic_long_read(&work->data); 6557c3eed5cSTejun Heo int pool_id; 6567a22ad75STejun Heo 65768e13a67SLai Jiangshan assert_rcu_or_pool_mutex(); 658fa1b54e6STejun Heo 659112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 660112202d9STejun Heo return ((struct pool_workqueue *) 6617c3eed5cSTejun Heo (data & WORK_STRUCT_WQ_DATA_MASK))->pool; 6627a22ad75STejun Heo 6637c3eed5cSTejun Heo pool_id = data >> WORK_OFFQ_POOL_SHIFT; 6647c3eed5cSTejun Heo if (pool_id == WORK_OFFQ_POOL_NONE) 6657a22ad75STejun Heo return NULL; 6667a22ad75STejun Heo 667fa1b54e6STejun Heo return idr_find(&worker_pool_idr, pool_id); 6687c3eed5cSTejun Heo } 6697c3eed5cSTejun Heo 6707c3eed5cSTejun Heo /** 6717c3eed5cSTejun Heo * get_work_pool_id - return the worker pool ID a given work is associated with 6727c3eed5cSTejun Heo * @work: the work item of interest 6737c3eed5cSTejun Heo * 6747c3eed5cSTejun Heo * Return the worker_pool ID @work was last associated with. 6757c3eed5cSTejun Heo * %WORK_OFFQ_POOL_NONE if none. 6767c3eed5cSTejun Heo */ 6777c3eed5cSTejun Heo static int get_work_pool_id(struct work_struct *work) 6787c3eed5cSTejun Heo { 67954d5b7d0SLai Jiangshan unsigned long data = atomic_long_read(&work->data); 6807c3eed5cSTejun Heo 681112202d9STejun Heo if (data & WORK_STRUCT_PWQ) 682112202d9STejun Heo return ((struct pool_workqueue *) 68354d5b7d0SLai Jiangshan (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; 68454d5b7d0SLai Jiangshan 68554d5b7d0SLai Jiangshan return data >> WORK_OFFQ_POOL_SHIFT; 6867c3eed5cSTejun Heo } 6877c3eed5cSTejun Heo 688bbb68dfaSTejun Heo static void mark_work_canceling(struct work_struct *work) 689bbb68dfaSTejun Heo { 6907c3eed5cSTejun Heo unsigned long pool_id = get_work_pool_id(work); 691bbb68dfaSTejun Heo 6927c3eed5cSTejun Heo pool_id <<= WORK_OFFQ_POOL_SHIFT; 6937c3eed5cSTejun Heo set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); 694bbb68dfaSTejun Heo } 695bbb68dfaSTejun Heo 696bbb68dfaSTejun Heo static bool work_is_canceling(struct work_struct *work) 697bbb68dfaSTejun Heo { 698bbb68dfaSTejun Heo unsigned long data = atomic_long_read(&work->data); 699bbb68dfaSTejun Heo 700112202d9STejun Heo return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); 701bbb68dfaSTejun Heo } 702bbb68dfaSTejun Heo 703e22bee78STejun Heo /* 7043270476aSTejun Heo * Policy functions. These define the policies on how the global worker 7053270476aSTejun Heo * pools are managed. Unless noted otherwise, these functions assume that 706d565ed63STejun Heo * they're being called with pool->lock held. 707e22bee78STejun Heo */ 708e22bee78STejun Heo 70963d95a91STejun Heo static bool __need_more_worker(struct worker_pool *pool) 710649027d7STejun Heo { 711e19e397aSTejun Heo return !atomic_read(&pool->nr_running); 712649027d7STejun Heo } 713649027d7STejun Heo 714e22bee78STejun Heo /* 715e22bee78STejun Heo * Need to wake up a worker? Called from anything but currently 716e22bee78STejun Heo * running workers. 717974271c4STejun Heo * 718974271c4STejun Heo * Note that, because unbound workers never contribute to nr_running, this 719706026c2STejun Heo * function will always return %true for unbound pools as long as the 720974271c4STejun Heo * worklist isn't empty. 721e22bee78STejun Heo */ 72263d95a91STejun Heo static bool need_more_worker(struct worker_pool *pool) 723e22bee78STejun Heo { 72463d95a91STejun Heo return !list_empty(&pool->worklist) && __need_more_worker(pool); 725e22bee78STejun Heo } 726e22bee78STejun Heo 727e22bee78STejun Heo /* Can I start working? Called from busy but !running workers. */ 72863d95a91STejun Heo static bool may_start_working(struct worker_pool *pool) 729e22bee78STejun Heo { 73063d95a91STejun Heo return pool->nr_idle; 731e22bee78STejun Heo } 732e22bee78STejun Heo 733e22bee78STejun Heo /* Do I need to keep working? Called from currently running workers. */ 73463d95a91STejun Heo static bool keep_working(struct worker_pool *pool) 735e22bee78STejun Heo { 736e19e397aSTejun Heo return !list_empty(&pool->worklist) && 737e19e397aSTejun Heo atomic_read(&pool->nr_running) <= 1; 738e22bee78STejun Heo } 739e22bee78STejun Heo 740e22bee78STejun Heo /* Do we need a new worker? Called from manager. */ 74163d95a91STejun Heo static bool need_to_create_worker(struct worker_pool *pool) 742e22bee78STejun Heo { 74363d95a91STejun Heo return need_more_worker(pool) && !may_start_working(pool); 744e22bee78STejun Heo } 745e22bee78STejun Heo 746e22bee78STejun Heo /* Do I need to be the manager? */ 74763d95a91STejun Heo static bool need_to_manage_workers(struct worker_pool *pool) 748e22bee78STejun Heo { 74963d95a91STejun Heo return need_to_create_worker(pool) || 75011ebea50STejun Heo (pool->flags & POOL_MANAGE_WORKERS); 751e22bee78STejun Heo } 752e22bee78STejun Heo 753e22bee78STejun Heo /* Do we have too many workers and should some go away? */ 75463d95a91STejun Heo static bool too_many_workers(struct worker_pool *pool) 755e22bee78STejun Heo { 75634a06bd6STejun Heo bool managing = mutex_is_locked(&pool->manager_arb); 75763d95a91STejun Heo int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ 75863d95a91STejun Heo int nr_busy = pool->nr_workers - nr_idle; 759e22bee78STejun Heo 760ea1abd61SLai Jiangshan /* 761ea1abd61SLai Jiangshan * nr_idle and idle_list may disagree if idle rebinding is in 762ea1abd61SLai Jiangshan * progress. Never return %true if idle_list is empty. 763ea1abd61SLai Jiangshan */ 764ea1abd61SLai Jiangshan if (list_empty(&pool->idle_list)) 765ea1abd61SLai Jiangshan return false; 766ea1abd61SLai Jiangshan 767e22bee78STejun Heo return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; 768e22bee78STejun Heo } 769e22bee78STejun Heo 770e22bee78STejun Heo /* 771e22bee78STejun Heo * Wake up functions. 772e22bee78STejun Heo */ 773e22bee78STejun Heo 7747e11629dSTejun Heo /* Return the first worker. Safe with preemption disabled */ 77563d95a91STejun Heo static struct worker *first_worker(struct worker_pool *pool) 7767e11629dSTejun Heo { 77763d95a91STejun Heo if (unlikely(list_empty(&pool->idle_list))) 7787e11629dSTejun Heo return NULL; 7797e11629dSTejun Heo 78063d95a91STejun Heo return list_first_entry(&pool->idle_list, struct worker, entry); 7817e11629dSTejun Heo } 7827e11629dSTejun Heo 7837e11629dSTejun Heo /** 7847e11629dSTejun Heo * wake_up_worker - wake up an idle worker 78563d95a91STejun Heo * @pool: worker pool to wake worker from 7867e11629dSTejun Heo * 78763d95a91STejun Heo * Wake up the first idle worker of @pool. 7887e11629dSTejun Heo * 7897e11629dSTejun Heo * CONTEXT: 790d565ed63STejun Heo * spin_lock_irq(pool->lock). 7917e11629dSTejun Heo */ 79263d95a91STejun Heo static void wake_up_worker(struct worker_pool *pool) 7937e11629dSTejun Heo { 79463d95a91STejun Heo struct worker *worker = first_worker(pool); 7957e11629dSTejun Heo 7967e11629dSTejun Heo if (likely(worker)) 7977e11629dSTejun Heo wake_up_process(worker->task); 7987e11629dSTejun Heo } 7997e11629dSTejun Heo 8004690c4abSTejun Heo /** 801e22bee78STejun Heo * wq_worker_waking_up - a worker is waking up 802e22bee78STejun Heo * @task: task waking up 803e22bee78STejun Heo * @cpu: CPU @task is waking up to 804e22bee78STejun Heo * 805e22bee78STejun Heo * This function is called during try_to_wake_up() when a worker is 806e22bee78STejun Heo * being awoken. 807e22bee78STejun Heo * 808e22bee78STejun Heo * CONTEXT: 809e22bee78STejun Heo * spin_lock_irq(rq->lock) 810e22bee78STejun Heo */ 811d84ff051STejun Heo void wq_worker_waking_up(struct task_struct *task, int cpu) 812e22bee78STejun Heo { 813e22bee78STejun Heo struct worker *worker = kthread_data(task); 814e22bee78STejun Heo 81536576000SJoonsoo Kim if (!(worker->flags & WORKER_NOT_RUNNING)) { 816ec22ca5eSTejun Heo WARN_ON_ONCE(worker->pool->cpu != cpu); 817e19e397aSTejun Heo atomic_inc(&worker->pool->nr_running); 818e22bee78STejun Heo } 81936576000SJoonsoo Kim } 820e22bee78STejun Heo 821e22bee78STejun Heo /** 822e22bee78STejun Heo * wq_worker_sleeping - a worker is going to sleep 823e22bee78STejun Heo * @task: task going to sleep 824e22bee78STejun Heo * @cpu: CPU in question, must be the current CPU number 825e22bee78STejun Heo * 826e22bee78STejun Heo * This function is called during schedule() when a busy worker is 827e22bee78STejun Heo * going to sleep. Worker on the same cpu can be woken up by 828e22bee78STejun Heo * returning pointer to its task. 829e22bee78STejun Heo * 830e22bee78STejun Heo * CONTEXT: 831e22bee78STejun Heo * spin_lock_irq(rq->lock) 832e22bee78STejun Heo * 833e22bee78STejun Heo * RETURNS: 834e22bee78STejun Heo * Worker task on @cpu to wake up, %NULL if none. 835e22bee78STejun Heo */ 836d84ff051STejun Heo struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu) 837e22bee78STejun Heo { 838e22bee78STejun Heo struct worker *worker = kthread_data(task), *to_wakeup = NULL; 839111c225aSTejun Heo struct worker_pool *pool; 840e22bee78STejun Heo 841111c225aSTejun Heo /* 842111c225aSTejun Heo * Rescuers, which may not have all the fields set up like normal 843111c225aSTejun Heo * workers, also reach here, let's not access anything before 844111c225aSTejun Heo * checking NOT_RUNNING. 845111c225aSTejun Heo */ 8462d64672eSSteven Rostedt if (worker->flags & WORKER_NOT_RUNNING) 847e22bee78STejun Heo return NULL; 848e22bee78STejun Heo 849111c225aSTejun Heo pool = worker->pool; 850111c225aSTejun Heo 851e22bee78STejun Heo /* this can only happen on the local cpu */ 8526183c009STejun Heo if (WARN_ON_ONCE(cpu != raw_smp_processor_id())) 8536183c009STejun Heo return NULL; 854e22bee78STejun Heo 855e22bee78STejun Heo /* 856e22bee78STejun Heo * The counterpart of the following dec_and_test, implied mb, 857e22bee78STejun Heo * worklist not empty test sequence is in insert_work(). 858e22bee78STejun Heo * Please read comment there. 859e22bee78STejun Heo * 860628c78e7STejun Heo * NOT_RUNNING is clear. This means that we're bound to and 861628c78e7STejun Heo * running on the local cpu w/ rq lock held and preemption 862628c78e7STejun Heo * disabled, which in turn means that none else could be 863d565ed63STejun Heo * manipulating idle_list, so dereferencing idle_list without pool 864628c78e7STejun Heo * lock is safe. 865e22bee78STejun Heo */ 866e19e397aSTejun Heo if (atomic_dec_and_test(&pool->nr_running) && 867e19e397aSTejun Heo !list_empty(&pool->worklist)) 86863d95a91STejun Heo to_wakeup = first_worker(pool); 869e22bee78STejun Heo return to_wakeup ? to_wakeup->task : NULL; 870e22bee78STejun Heo } 871e22bee78STejun Heo 872e22bee78STejun Heo /** 873e22bee78STejun Heo * worker_set_flags - set worker flags and adjust nr_running accordingly 874cb444766STejun Heo * @worker: self 875d302f017STejun Heo * @flags: flags to set 876d302f017STejun Heo * @wakeup: wakeup an idle worker if necessary 877d302f017STejun Heo * 878e22bee78STejun Heo * Set @flags in @worker->flags and adjust nr_running accordingly. If 879e22bee78STejun Heo * nr_running becomes zero and @wakeup is %true, an idle worker is 880e22bee78STejun Heo * woken up. 881d302f017STejun Heo * 882cb444766STejun Heo * CONTEXT: 883d565ed63STejun Heo * spin_lock_irq(pool->lock) 884d302f017STejun Heo */ 885d302f017STejun Heo static inline void worker_set_flags(struct worker *worker, unsigned int flags, 886d302f017STejun Heo bool wakeup) 887d302f017STejun Heo { 888bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 889e22bee78STejun Heo 890cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 891cb444766STejun Heo 892e22bee78STejun Heo /* 893e22bee78STejun Heo * If transitioning into NOT_RUNNING, adjust nr_running and 894e22bee78STejun Heo * wake up an idle worker as necessary if requested by 895e22bee78STejun Heo * @wakeup. 896e22bee78STejun Heo */ 897e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && 898e22bee78STejun Heo !(worker->flags & WORKER_NOT_RUNNING)) { 899e22bee78STejun Heo if (wakeup) { 900e19e397aSTejun Heo if (atomic_dec_and_test(&pool->nr_running) && 901bd7bdd43STejun Heo !list_empty(&pool->worklist)) 90263d95a91STejun Heo wake_up_worker(pool); 903e22bee78STejun Heo } else 904e19e397aSTejun Heo atomic_dec(&pool->nr_running); 905e22bee78STejun Heo } 906e22bee78STejun Heo 907d302f017STejun Heo worker->flags |= flags; 908d302f017STejun Heo } 909d302f017STejun Heo 910d302f017STejun Heo /** 911e22bee78STejun Heo * worker_clr_flags - clear worker flags and adjust nr_running accordingly 912cb444766STejun Heo * @worker: self 913d302f017STejun Heo * @flags: flags to clear 914d302f017STejun Heo * 915e22bee78STejun Heo * Clear @flags in @worker->flags and adjust nr_running accordingly. 916d302f017STejun Heo * 917cb444766STejun Heo * CONTEXT: 918d565ed63STejun Heo * spin_lock_irq(pool->lock) 919d302f017STejun Heo */ 920d302f017STejun Heo static inline void worker_clr_flags(struct worker *worker, unsigned int flags) 921d302f017STejun Heo { 92263d95a91STejun Heo struct worker_pool *pool = worker->pool; 923e22bee78STejun Heo unsigned int oflags = worker->flags; 924e22bee78STejun Heo 925cb444766STejun Heo WARN_ON_ONCE(worker->task != current); 926cb444766STejun Heo 927d302f017STejun Heo worker->flags &= ~flags; 928e22bee78STejun Heo 92942c025f3STejun Heo /* 93042c025f3STejun Heo * If transitioning out of NOT_RUNNING, increment nr_running. Note 93142c025f3STejun Heo * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask 93242c025f3STejun Heo * of multiple flags, not a single flag. 93342c025f3STejun Heo */ 934e22bee78STejun Heo if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) 935e22bee78STejun Heo if (!(worker->flags & WORKER_NOT_RUNNING)) 936e19e397aSTejun Heo atomic_inc(&pool->nr_running); 937d302f017STejun Heo } 938d302f017STejun Heo 939d302f017STejun Heo /** 9408cca0eeaSTejun Heo * find_worker_executing_work - find worker which is executing a work 941c9e7cf27STejun Heo * @pool: pool of interest 9428cca0eeaSTejun Heo * @work: work to find worker for 9438cca0eeaSTejun Heo * 944c9e7cf27STejun Heo * Find a worker which is executing @work on @pool by searching 945c9e7cf27STejun Heo * @pool->busy_hash which is keyed by the address of @work. For a worker 946a2c1c57bSTejun Heo * to match, its current execution should match the address of @work and 947a2c1c57bSTejun Heo * its work function. This is to avoid unwanted dependency between 948a2c1c57bSTejun Heo * unrelated work executions through a work item being recycled while still 949a2c1c57bSTejun Heo * being executed. 950a2c1c57bSTejun Heo * 951a2c1c57bSTejun Heo * This is a bit tricky. A work item may be freed once its execution 952a2c1c57bSTejun Heo * starts and nothing prevents the freed area from being recycled for 953a2c1c57bSTejun Heo * another work item. If the same work item address ends up being reused 954a2c1c57bSTejun Heo * before the original execution finishes, workqueue will identify the 955a2c1c57bSTejun Heo * recycled work item as currently executing and make it wait until the 956a2c1c57bSTejun Heo * current execution finishes, introducing an unwanted dependency. 957a2c1c57bSTejun Heo * 958c5aa87bbSTejun Heo * This function checks the work item address and work function to avoid 959c5aa87bbSTejun Heo * false positives. Note that this isn't complete as one may construct a 960c5aa87bbSTejun Heo * work function which can introduce dependency onto itself through a 961c5aa87bbSTejun Heo * recycled work item. Well, if somebody wants to shoot oneself in the 962c5aa87bbSTejun Heo * foot that badly, there's only so much we can do, and if such deadlock 963c5aa87bbSTejun Heo * actually occurs, it should be easy to locate the culprit work function. 9648cca0eeaSTejun Heo * 9658cca0eeaSTejun Heo * CONTEXT: 966d565ed63STejun Heo * spin_lock_irq(pool->lock). 9678cca0eeaSTejun Heo * 9688cca0eeaSTejun Heo * RETURNS: 9698cca0eeaSTejun Heo * Pointer to worker which is executing @work if found, NULL 9708cca0eeaSTejun Heo * otherwise. 9718cca0eeaSTejun Heo */ 972c9e7cf27STejun Heo static struct worker *find_worker_executing_work(struct worker_pool *pool, 9738cca0eeaSTejun Heo struct work_struct *work) 9748cca0eeaSTejun Heo { 97542f8570fSSasha Levin struct worker *worker; 97642f8570fSSasha Levin 977b67bfe0dSSasha Levin hash_for_each_possible(pool->busy_hash, worker, hentry, 978a2c1c57bSTejun Heo (unsigned long)work) 979a2c1c57bSTejun Heo if (worker->current_work == work && 980a2c1c57bSTejun Heo worker->current_func == work->func) 98142f8570fSSasha Levin return worker; 98242f8570fSSasha Levin 98342f8570fSSasha Levin return NULL; 9848cca0eeaSTejun Heo } 9858cca0eeaSTejun Heo 9868cca0eeaSTejun Heo /** 987bf4ede01STejun Heo * move_linked_works - move linked works to a list 988bf4ede01STejun Heo * @work: start of series of works to be scheduled 989bf4ede01STejun Heo * @head: target list to append @work to 990bf4ede01STejun Heo * @nextp: out paramter for nested worklist walking 991bf4ede01STejun Heo * 992bf4ede01STejun Heo * Schedule linked works starting from @work to @head. Work series to 993bf4ede01STejun Heo * be scheduled starts at @work and includes any consecutive work with 994bf4ede01STejun Heo * WORK_STRUCT_LINKED set in its predecessor. 995bf4ede01STejun Heo * 996bf4ede01STejun Heo * If @nextp is not NULL, it's updated to point to the next work of 997bf4ede01STejun Heo * the last scheduled work. This allows move_linked_works() to be 998bf4ede01STejun Heo * nested inside outer list_for_each_entry_safe(). 999bf4ede01STejun Heo * 1000bf4ede01STejun Heo * CONTEXT: 1001d565ed63STejun Heo * spin_lock_irq(pool->lock). 1002bf4ede01STejun Heo */ 1003bf4ede01STejun Heo static void move_linked_works(struct work_struct *work, struct list_head *head, 1004bf4ede01STejun Heo struct work_struct **nextp) 1005bf4ede01STejun Heo { 1006bf4ede01STejun Heo struct work_struct *n; 1007bf4ede01STejun Heo 1008bf4ede01STejun Heo /* 1009bf4ede01STejun Heo * Linked worklist will always end before the end of the list, 1010bf4ede01STejun Heo * use NULL for list head. 1011bf4ede01STejun Heo */ 1012bf4ede01STejun Heo list_for_each_entry_safe_from(work, n, NULL, entry) { 1013bf4ede01STejun Heo list_move_tail(&work->entry, head); 1014bf4ede01STejun Heo if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) 1015bf4ede01STejun Heo break; 1016bf4ede01STejun Heo } 1017bf4ede01STejun Heo 1018bf4ede01STejun Heo /* 1019bf4ede01STejun Heo * If we're already inside safe list traversal and have moved 1020bf4ede01STejun Heo * multiple works to the scheduled queue, the next position 1021bf4ede01STejun Heo * needs to be updated. 1022bf4ede01STejun Heo */ 1023bf4ede01STejun Heo if (nextp) 1024bf4ede01STejun Heo *nextp = n; 1025bf4ede01STejun Heo } 1026bf4ede01STejun Heo 10278864b4e5STejun Heo /** 10288864b4e5STejun Heo * get_pwq - get an extra reference on the specified pool_workqueue 10298864b4e5STejun Heo * @pwq: pool_workqueue to get 10308864b4e5STejun Heo * 10318864b4e5STejun Heo * Obtain an extra reference on @pwq. The caller should guarantee that 10328864b4e5STejun Heo * @pwq has positive refcnt and be holding the matching pool->lock. 10338864b4e5STejun Heo */ 10348864b4e5STejun Heo static void get_pwq(struct pool_workqueue *pwq) 10358864b4e5STejun Heo { 10368864b4e5STejun Heo lockdep_assert_held(&pwq->pool->lock); 10378864b4e5STejun Heo WARN_ON_ONCE(pwq->refcnt <= 0); 10388864b4e5STejun Heo pwq->refcnt++; 10398864b4e5STejun Heo } 10408864b4e5STejun Heo 10418864b4e5STejun Heo /** 10428864b4e5STejun Heo * put_pwq - put a pool_workqueue reference 10438864b4e5STejun Heo * @pwq: pool_workqueue to put 10448864b4e5STejun Heo * 10458864b4e5STejun Heo * Drop a reference of @pwq. If its refcnt reaches zero, schedule its 10468864b4e5STejun Heo * destruction. The caller should be holding the matching pool->lock. 10478864b4e5STejun Heo */ 10488864b4e5STejun Heo static void put_pwq(struct pool_workqueue *pwq) 10498864b4e5STejun Heo { 10508864b4e5STejun Heo lockdep_assert_held(&pwq->pool->lock); 10518864b4e5STejun Heo if (likely(--pwq->refcnt)) 10528864b4e5STejun Heo return; 10538864b4e5STejun Heo if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) 10548864b4e5STejun Heo return; 10558864b4e5STejun Heo /* 10568864b4e5STejun Heo * @pwq can't be released under pool->lock, bounce to 10578864b4e5STejun Heo * pwq_unbound_release_workfn(). This never recurses on the same 10588864b4e5STejun Heo * pool->lock as this path is taken only for unbound workqueues and 10598864b4e5STejun Heo * the release work item is scheduled on a per-cpu workqueue. To 10608864b4e5STejun Heo * avoid lockdep warning, unbound pool->locks are given lockdep 10618864b4e5STejun Heo * subclass of 1 in get_unbound_pool(). 10628864b4e5STejun Heo */ 10638864b4e5STejun Heo schedule_work(&pwq->unbound_release_work); 10648864b4e5STejun Heo } 10658864b4e5STejun Heo 1066dce90d47STejun Heo /** 1067dce90d47STejun Heo * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock 1068dce90d47STejun Heo * @pwq: pool_workqueue to put (can be %NULL) 1069dce90d47STejun Heo * 1070dce90d47STejun Heo * put_pwq() with locking. This function also allows %NULL @pwq. 1071dce90d47STejun Heo */ 1072dce90d47STejun Heo static void put_pwq_unlocked(struct pool_workqueue *pwq) 1073dce90d47STejun Heo { 1074dce90d47STejun Heo if (pwq) { 1075dce90d47STejun Heo /* 1076dce90d47STejun Heo * As both pwqs and pools are sched-RCU protected, the 1077dce90d47STejun Heo * following lock operations are safe. 1078dce90d47STejun Heo */ 1079dce90d47STejun Heo spin_lock_irq(&pwq->pool->lock); 1080dce90d47STejun Heo put_pwq(pwq); 1081dce90d47STejun Heo spin_unlock_irq(&pwq->pool->lock); 1082dce90d47STejun Heo } 1083dce90d47STejun Heo } 1084dce90d47STejun Heo 1085112202d9STejun Heo static void pwq_activate_delayed_work(struct work_struct *work) 1086bf4ede01STejun Heo { 1087112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 1088bf4ede01STejun Heo 1089bf4ede01STejun Heo trace_workqueue_activate_work(work); 1090112202d9STejun Heo move_linked_works(work, &pwq->pool->worklist, NULL); 1091bf4ede01STejun Heo __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); 1092112202d9STejun Heo pwq->nr_active++; 1093bf4ede01STejun Heo } 1094bf4ede01STejun Heo 1095112202d9STejun Heo static void pwq_activate_first_delayed(struct pool_workqueue *pwq) 10963aa62497SLai Jiangshan { 1097112202d9STejun Heo struct work_struct *work = list_first_entry(&pwq->delayed_works, 10983aa62497SLai Jiangshan struct work_struct, entry); 10993aa62497SLai Jiangshan 1100112202d9STejun Heo pwq_activate_delayed_work(work); 11013aa62497SLai Jiangshan } 11023aa62497SLai Jiangshan 1103bf4ede01STejun Heo /** 1104112202d9STejun Heo * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight 1105112202d9STejun Heo * @pwq: pwq of interest 1106bf4ede01STejun Heo * @color: color of work which left the queue 1107bf4ede01STejun Heo * 1108bf4ede01STejun Heo * A work either has completed or is removed from pending queue, 1109112202d9STejun Heo * decrement nr_in_flight of its pwq and handle workqueue flushing. 1110bf4ede01STejun Heo * 1111bf4ede01STejun Heo * CONTEXT: 1112d565ed63STejun Heo * spin_lock_irq(pool->lock). 1113bf4ede01STejun Heo */ 1114112202d9STejun Heo static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) 1115bf4ede01STejun Heo { 11168864b4e5STejun Heo /* uncolored work items don't participate in flushing or nr_active */ 1117bf4ede01STejun Heo if (color == WORK_NO_COLOR) 11188864b4e5STejun Heo goto out_put; 1119bf4ede01STejun Heo 1120112202d9STejun Heo pwq->nr_in_flight[color]--; 1121bf4ede01STejun Heo 1122112202d9STejun Heo pwq->nr_active--; 1123112202d9STejun Heo if (!list_empty(&pwq->delayed_works)) { 1124bf4ede01STejun Heo /* one down, submit a delayed one */ 1125112202d9STejun Heo if (pwq->nr_active < pwq->max_active) 1126112202d9STejun Heo pwq_activate_first_delayed(pwq); 1127bf4ede01STejun Heo } 1128bf4ede01STejun Heo 1129bf4ede01STejun Heo /* is flush in progress and are we at the flushing tip? */ 1130112202d9STejun Heo if (likely(pwq->flush_color != color)) 11318864b4e5STejun Heo goto out_put; 1132bf4ede01STejun Heo 1133bf4ede01STejun Heo /* are there still in-flight works? */ 1134112202d9STejun Heo if (pwq->nr_in_flight[color]) 11358864b4e5STejun Heo goto out_put; 1136bf4ede01STejun Heo 1137112202d9STejun Heo /* this pwq is done, clear flush_color */ 1138112202d9STejun Heo pwq->flush_color = -1; 1139bf4ede01STejun Heo 1140bf4ede01STejun Heo /* 1141112202d9STejun Heo * If this was the last pwq, wake up the first flusher. It 1142bf4ede01STejun Heo * will handle the rest. 1143bf4ede01STejun Heo */ 1144112202d9STejun Heo if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) 1145112202d9STejun Heo complete(&pwq->wq->first_flusher->done); 11468864b4e5STejun Heo out_put: 11478864b4e5STejun Heo put_pwq(pwq); 1148bf4ede01STejun Heo } 1149bf4ede01STejun Heo 115036e227d2STejun Heo /** 1151bbb68dfaSTejun Heo * try_to_grab_pending - steal work item from worklist and disable irq 115236e227d2STejun Heo * @work: work item to steal 115336e227d2STejun Heo * @is_dwork: @work is a delayed_work 1154bbb68dfaSTejun Heo * @flags: place to store irq state 115536e227d2STejun Heo * 115636e227d2STejun Heo * Try to grab PENDING bit of @work. This function can handle @work in any 115736e227d2STejun Heo * stable state - idle, on timer or on worklist. Return values are 115836e227d2STejun Heo * 115936e227d2STejun Heo * 1 if @work was pending and we successfully stole PENDING 116036e227d2STejun Heo * 0 if @work was idle and we claimed PENDING 116136e227d2STejun Heo * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry 1162bbb68dfaSTejun Heo * -ENOENT if someone else is canceling @work, this state may persist 1163bbb68dfaSTejun Heo * for arbitrarily long 116436e227d2STejun Heo * 1165bbb68dfaSTejun Heo * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting 1166e0aecdd8STejun Heo * interrupted while holding PENDING and @work off queue, irq must be 1167e0aecdd8STejun Heo * disabled on entry. This, combined with delayed_work->timer being 1168e0aecdd8STejun Heo * irqsafe, ensures that we return -EAGAIN for finite short period of time. 1169bbb68dfaSTejun Heo * 1170bbb68dfaSTejun Heo * On successful return, >= 0, irq is disabled and the caller is 1171bbb68dfaSTejun Heo * responsible for releasing it using local_irq_restore(*@flags). 1172bbb68dfaSTejun Heo * 1173e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 1174bf4ede01STejun Heo */ 1175bbb68dfaSTejun Heo static int try_to_grab_pending(struct work_struct *work, bool is_dwork, 1176bbb68dfaSTejun Heo unsigned long *flags) 1177bf4ede01STejun Heo { 1178d565ed63STejun Heo struct worker_pool *pool; 1179112202d9STejun Heo struct pool_workqueue *pwq; 1180bf4ede01STejun Heo 1181bbb68dfaSTejun Heo local_irq_save(*flags); 1182bbb68dfaSTejun Heo 118336e227d2STejun Heo /* try to steal the timer if it exists */ 118436e227d2STejun Heo if (is_dwork) { 118536e227d2STejun Heo struct delayed_work *dwork = to_delayed_work(work); 118636e227d2STejun Heo 1187e0aecdd8STejun Heo /* 1188e0aecdd8STejun Heo * dwork->timer is irqsafe. If del_timer() fails, it's 1189e0aecdd8STejun Heo * guaranteed that the timer is not queued anywhere and not 1190e0aecdd8STejun Heo * running on the local CPU. 1191e0aecdd8STejun Heo */ 119236e227d2STejun Heo if (likely(del_timer(&dwork->timer))) 119336e227d2STejun Heo return 1; 119436e227d2STejun Heo } 119536e227d2STejun Heo 119636e227d2STejun Heo /* try to claim PENDING the normal way */ 1197bf4ede01STejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) 1198bf4ede01STejun Heo return 0; 1199bf4ede01STejun Heo 1200bf4ede01STejun Heo /* 1201bf4ede01STejun Heo * The queueing is in progress, or it is already queued. Try to 1202bf4ede01STejun Heo * steal it from ->worklist without clearing WORK_STRUCT_PENDING. 1203bf4ede01STejun Heo */ 1204d565ed63STejun Heo pool = get_work_pool(work); 1205d565ed63STejun Heo if (!pool) 1206bbb68dfaSTejun Heo goto fail; 1207bf4ede01STejun Heo 1208d565ed63STejun Heo spin_lock(&pool->lock); 1209bf4ede01STejun Heo /* 1210112202d9STejun Heo * work->data is guaranteed to point to pwq only while the work 1211112202d9STejun Heo * item is queued on pwq->wq, and both updating work->data to point 1212112202d9STejun Heo * to pwq on queueing and to pool on dequeueing are done under 1213112202d9STejun Heo * pwq->pool->lock. This in turn guarantees that, if work->data 1214112202d9STejun Heo * points to pwq which is associated with a locked pool, the work 12150b3dae68SLai Jiangshan * item is currently queued on that pool. 1216bf4ede01STejun Heo */ 1217112202d9STejun Heo pwq = get_work_pwq(work); 1218112202d9STejun Heo if (pwq && pwq->pool == pool) { 1219bf4ede01STejun Heo debug_work_deactivate(work); 12203aa62497SLai Jiangshan 12213aa62497SLai Jiangshan /* 122216062836STejun Heo * A delayed work item cannot be grabbed directly because 122316062836STejun Heo * it might have linked NO_COLOR work items which, if left 1224112202d9STejun Heo * on the delayed_list, will confuse pwq->nr_active 122516062836STejun Heo * management later on and cause stall. Make sure the work 122616062836STejun Heo * item is activated before grabbing. 12273aa62497SLai Jiangshan */ 12283aa62497SLai Jiangshan if (*work_data_bits(work) & WORK_STRUCT_DELAYED) 1229112202d9STejun Heo pwq_activate_delayed_work(work); 12303aa62497SLai Jiangshan 1231bf4ede01STejun Heo list_del_init(&work->entry); 1232112202d9STejun Heo pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work)); 123336e227d2STejun Heo 1234112202d9STejun Heo /* work->data points to pwq iff queued, point to pool */ 12354468a00fSLai Jiangshan set_work_pool_and_keep_pending(work, pool->id); 12364468a00fSLai Jiangshan 1237d565ed63STejun Heo spin_unlock(&pool->lock); 123836e227d2STejun Heo return 1; 1239bf4ede01STejun Heo } 1240d565ed63STejun Heo spin_unlock(&pool->lock); 1241bbb68dfaSTejun Heo fail: 1242bbb68dfaSTejun Heo local_irq_restore(*flags); 1243bbb68dfaSTejun Heo if (work_is_canceling(work)) 1244bbb68dfaSTejun Heo return -ENOENT; 1245bbb68dfaSTejun Heo cpu_relax(); 124636e227d2STejun Heo return -EAGAIN; 1247bf4ede01STejun Heo } 1248bf4ede01STejun Heo 1249bf4ede01STejun Heo /** 1250706026c2STejun Heo * insert_work - insert a work into a pool 1251112202d9STejun Heo * @pwq: pwq @work belongs to 12524690c4abSTejun Heo * @work: work to insert 12534690c4abSTejun Heo * @head: insertion point 12544690c4abSTejun Heo * @extra_flags: extra WORK_STRUCT_* flags to set 12554690c4abSTejun Heo * 1256112202d9STejun Heo * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to 1257706026c2STejun Heo * work_struct flags. 12584690c4abSTejun Heo * 12594690c4abSTejun Heo * CONTEXT: 1260d565ed63STejun Heo * spin_lock_irq(pool->lock). 1261365970a1SDavid Howells */ 1262112202d9STejun Heo static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, 1263112202d9STejun Heo struct list_head *head, unsigned int extra_flags) 1264b89deed3SOleg Nesterov { 1265112202d9STejun Heo struct worker_pool *pool = pwq->pool; 1266e1d8aa9fSFrederic Weisbecker 12674690c4abSTejun Heo /* we own @work, set data and link */ 1268112202d9STejun Heo set_work_pwq(work, pwq, extra_flags); 12691a4d9b0aSOleg Nesterov list_add_tail(&work->entry, head); 12708864b4e5STejun Heo get_pwq(pwq); 1271e22bee78STejun Heo 1272e22bee78STejun Heo /* 1273c5aa87bbSTejun Heo * Ensure either wq_worker_sleeping() sees the above 1274c5aa87bbSTejun Heo * list_add_tail() or we see zero nr_running to avoid workers lying 1275c5aa87bbSTejun Heo * around lazily while there are works to be processed. 1276e22bee78STejun Heo */ 1277e22bee78STejun Heo smp_mb(); 1278e22bee78STejun Heo 127963d95a91STejun Heo if (__need_more_worker(pool)) 128063d95a91STejun Heo wake_up_worker(pool); 1281b89deed3SOleg Nesterov } 1282b89deed3SOleg Nesterov 1283c8efcc25STejun Heo /* 1284c8efcc25STejun Heo * Test whether @work is being queued from another work executing on the 12858d03ecfeSTejun Heo * same workqueue. 1286c8efcc25STejun Heo */ 1287c8efcc25STejun Heo static bool is_chained_work(struct workqueue_struct *wq) 1288c8efcc25STejun Heo { 1289c8efcc25STejun Heo struct worker *worker; 1290c8efcc25STejun Heo 12918d03ecfeSTejun Heo worker = current_wq_worker(); 1292c8efcc25STejun Heo /* 12938d03ecfeSTejun Heo * Return %true iff I'm a worker execuing a work item on @wq. If 12948d03ecfeSTejun Heo * I'm @worker, it's safe to dereference it without locking. 1295c8efcc25STejun Heo */ 1296112202d9STejun Heo return worker && worker->current_pwq->wq == wq; 1297c8efcc25STejun Heo } 1298c8efcc25STejun Heo 1299d84ff051STejun Heo static void __queue_work(int cpu, struct workqueue_struct *wq, 13001da177e4SLinus Torvalds struct work_struct *work) 13011da177e4SLinus Torvalds { 1302112202d9STejun Heo struct pool_workqueue *pwq; 1303c9178087STejun Heo struct worker_pool *last_pool; 13041e19ffc6STejun Heo struct list_head *worklist; 13058a2e8e5dSTejun Heo unsigned int work_flags; 1306b75cac93SJoonsoo Kim unsigned int req_cpu = cpu; 13078930cabaSTejun Heo 13088930cabaSTejun Heo /* 13098930cabaSTejun Heo * While a work item is PENDING && off queue, a task trying to 13108930cabaSTejun Heo * steal the PENDING will busy-loop waiting for it to either get 13118930cabaSTejun Heo * queued or lose PENDING. Grabbing PENDING and queueing should 13128930cabaSTejun Heo * happen with IRQ disabled. 13138930cabaSTejun Heo */ 13148930cabaSTejun Heo WARN_ON_ONCE(!irqs_disabled()); 13151da177e4SLinus Torvalds 1316dc186ad7SThomas Gleixner debug_work_activate(work); 13171e19ffc6STejun Heo 1318c8efcc25STejun Heo /* if dying, only works from the same workqueue are allowed */ 1319618b01ebSTejun Heo if (unlikely(wq->flags & __WQ_DRAINING) && 1320c8efcc25STejun Heo WARN_ON_ONCE(!is_chained_work(wq))) 1321e41e704bSTejun Heo return; 13229e8cd2f5STejun Heo retry: 1323df2d5ae4STejun Heo if (req_cpu == WORK_CPU_UNBOUND) 1324f3421797STejun Heo cpu = raw_smp_processor_id(); 1325df2d5ae4STejun Heo 1326df2d5ae4STejun Heo /* pwq which will be used unless @work is executing elsewhere */ 1327df2d5ae4STejun Heo if (!(wq->flags & WQ_UNBOUND)) 1328c9178087STejun Heo pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); 1329df2d5ae4STejun Heo else 1330df2d5ae4STejun Heo pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); 1331f3421797STejun Heo 133218aa9effSTejun Heo /* 1333c9178087STejun Heo * If @work was previously on a different pool, it might still be 1334c9178087STejun Heo * running there, in which case the work needs to be queued on that 1335c9178087STejun Heo * pool to guarantee non-reentrancy. 133618aa9effSTejun Heo */ 1337c9e7cf27STejun Heo last_pool = get_work_pool(work); 1338112202d9STejun Heo if (last_pool && last_pool != pwq->pool) { 133918aa9effSTejun Heo struct worker *worker; 134018aa9effSTejun Heo 1341d565ed63STejun Heo spin_lock(&last_pool->lock); 134218aa9effSTejun Heo 1343c9e7cf27STejun Heo worker = find_worker_executing_work(last_pool, work); 134418aa9effSTejun Heo 1345112202d9STejun Heo if (worker && worker->current_pwq->wq == wq) { 1346c9178087STejun Heo pwq = worker->current_pwq; 13478594fadeSLai Jiangshan } else { 134818aa9effSTejun Heo /* meh... not running there, queue here */ 1349d565ed63STejun Heo spin_unlock(&last_pool->lock); 1350112202d9STejun Heo spin_lock(&pwq->pool->lock); 135118aa9effSTejun Heo } 13528930cabaSTejun Heo } else { 1353112202d9STejun Heo spin_lock(&pwq->pool->lock); 13548930cabaSTejun Heo } 1355502ca9d8STejun Heo 13569e8cd2f5STejun Heo /* 13579e8cd2f5STejun Heo * pwq is determined and locked. For unbound pools, we could have 13589e8cd2f5STejun Heo * raced with pwq release and it could already be dead. If its 13599e8cd2f5STejun Heo * refcnt is zero, repeat pwq selection. Note that pwqs never die 1360df2d5ae4STejun Heo * without another pwq replacing it in the numa_pwq_tbl or while 1361df2d5ae4STejun Heo * work items are executing on it, so the retrying is guaranteed to 13629e8cd2f5STejun Heo * make forward-progress. 13639e8cd2f5STejun Heo */ 13649e8cd2f5STejun Heo if (unlikely(!pwq->refcnt)) { 13659e8cd2f5STejun Heo if (wq->flags & WQ_UNBOUND) { 13669e8cd2f5STejun Heo spin_unlock(&pwq->pool->lock); 13679e8cd2f5STejun Heo cpu_relax(); 13689e8cd2f5STejun Heo goto retry; 13699e8cd2f5STejun Heo } 13709e8cd2f5STejun Heo /* oops */ 13719e8cd2f5STejun Heo WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", 13729e8cd2f5STejun Heo wq->name, cpu); 13739e8cd2f5STejun Heo } 13749e8cd2f5STejun Heo 1375112202d9STejun Heo /* pwq determined, queue */ 1376112202d9STejun Heo trace_workqueue_queue_work(req_cpu, pwq, work); 1377502ca9d8STejun Heo 1378f5b2552bSDan Carpenter if (WARN_ON(!list_empty(&work->entry))) { 1379112202d9STejun Heo spin_unlock(&pwq->pool->lock); 1380f5b2552bSDan Carpenter return; 1381f5b2552bSDan Carpenter } 13821e19ffc6STejun Heo 1383112202d9STejun Heo pwq->nr_in_flight[pwq->work_color]++; 1384112202d9STejun Heo work_flags = work_color_to_flags(pwq->work_color); 13851e19ffc6STejun Heo 1386112202d9STejun Heo if (likely(pwq->nr_active < pwq->max_active)) { 1387cdadf009STejun Heo trace_workqueue_activate_work(work); 1388112202d9STejun Heo pwq->nr_active++; 1389112202d9STejun Heo worklist = &pwq->pool->worklist; 13908a2e8e5dSTejun Heo } else { 13918a2e8e5dSTejun Heo work_flags |= WORK_STRUCT_DELAYED; 1392112202d9STejun Heo worklist = &pwq->delayed_works; 13938a2e8e5dSTejun Heo } 13941e19ffc6STejun Heo 1395112202d9STejun Heo insert_work(pwq, work, worklist, work_flags); 13961e19ffc6STejun Heo 1397112202d9STejun Heo spin_unlock(&pwq->pool->lock); 13981da177e4SLinus Torvalds } 13991da177e4SLinus Torvalds 14000fcb78c2SRolf Eike Beer /** 1401c1a220e7SZhang Rui * queue_work_on - queue work on specific cpu 1402c1a220e7SZhang Rui * @cpu: CPU number to execute work on 1403c1a220e7SZhang Rui * @wq: workqueue to use 1404c1a220e7SZhang Rui * @work: work to queue 1405c1a220e7SZhang Rui * 1406d4283e93STejun Heo * Returns %false if @work was already on a queue, %true otherwise. 1407c1a220e7SZhang Rui * 1408c1a220e7SZhang Rui * We queue the work to a specific CPU, the caller must ensure it 1409c1a220e7SZhang Rui * can't go away. 1410c1a220e7SZhang Rui */ 1411d4283e93STejun Heo bool queue_work_on(int cpu, struct workqueue_struct *wq, 1412d4283e93STejun Heo struct work_struct *work) 1413c1a220e7SZhang Rui { 1414d4283e93STejun Heo bool ret = false; 14158930cabaSTejun Heo unsigned long flags; 14168930cabaSTejun Heo 14178930cabaSTejun Heo local_irq_save(flags); 1418c1a220e7SZhang Rui 141922df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 14204690c4abSTejun Heo __queue_work(cpu, wq, work); 1421d4283e93STejun Heo ret = true; 1422c1a220e7SZhang Rui } 14238930cabaSTejun Heo 14248930cabaSTejun Heo local_irq_restore(flags); 1425c1a220e7SZhang Rui return ret; 1426c1a220e7SZhang Rui } 1427ad7b1f84SMarc Dionne EXPORT_SYMBOL(queue_work_on); 1428c1a220e7SZhang Rui 1429d8e794dfSTejun Heo void delayed_work_timer_fn(unsigned long __data) 14301da177e4SLinus Torvalds { 143152bad64dSDavid Howells struct delayed_work *dwork = (struct delayed_work *)__data; 14321da177e4SLinus Torvalds 1433e0aecdd8STejun Heo /* should have been called from irqsafe timer with irq already off */ 143460c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 14351da177e4SLinus Torvalds } 14361438ade5SKonstantin Khlebnikov EXPORT_SYMBOL(delayed_work_timer_fn); 14371da177e4SLinus Torvalds 14387beb2edfSTejun Heo static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, 143952bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 14401da177e4SLinus Torvalds { 14417beb2edfSTejun Heo struct timer_list *timer = &dwork->timer; 14427beb2edfSTejun Heo struct work_struct *work = &dwork->work; 14431da177e4SLinus Torvalds 14447beb2edfSTejun Heo WARN_ON_ONCE(timer->function != delayed_work_timer_fn || 14457beb2edfSTejun Heo timer->data != (unsigned long)dwork); 1446fc4b514fSTejun Heo WARN_ON_ONCE(timer_pending(timer)); 1447fc4b514fSTejun Heo WARN_ON_ONCE(!list_empty(&work->entry)); 14487beb2edfSTejun Heo 14498852aac2STejun Heo /* 14508852aac2STejun Heo * If @delay is 0, queue @dwork->work immediately. This is for 14518852aac2STejun Heo * both optimization and correctness. The earliest @timer can 14528852aac2STejun Heo * expire is on the closest next tick and delayed_work users depend 14538852aac2STejun Heo * on that there's no such delay when @delay is 0. 14548852aac2STejun Heo */ 14558852aac2STejun Heo if (!delay) { 14568852aac2STejun Heo __queue_work(cpu, wq, &dwork->work); 14578852aac2STejun Heo return; 14588852aac2STejun Heo } 14598852aac2STejun Heo 14607beb2edfSTejun Heo timer_stats_timer_set_start_info(&dwork->timer); 14617beb2edfSTejun Heo 146260c057bcSLai Jiangshan dwork->wq = wq; 14631265057fSTejun Heo dwork->cpu = cpu; 14647beb2edfSTejun Heo timer->expires = jiffies + delay; 14657beb2edfSTejun Heo 14667beb2edfSTejun Heo if (unlikely(cpu != WORK_CPU_UNBOUND)) 14677beb2edfSTejun Heo add_timer_on(timer, cpu); 14687beb2edfSTejun Heo else 14697beb2edfSTejun Heo add_timer(timer); 14707beb2edfSTejun Heo } 14711da177e4SLinus Torvalds 14720fcb78c2SRolf Eike Beer /** 14730fcb78c2SRolf Eike Beer * queue_delayed_work_on - queue work on specific CPU after delay 14740fcb78c2SRolf Eike Beer * @cpu: CPU number to execute work on 14750fcb78c2SRolf Eike Beer * @wq: workqueue to use 1476af9997e4SRandy Dunlap * @dwork: work to queue 14770fcb78c2SRolf Eike Beer * @delay: number of jiffies to wait before queueing 14780fcb78c2SRolf Eike Beer * 1479715f1300STejun Heo * Returns %false if @work was already on a queue, %true otherwise. If 1480715f1300STejun Heo * @delay is zero and @dwork is idle, it will be scheduled for immediate 1481715f1300STejun Heo * execution. 14820fcb78c2SRolf Eike Beer */ 1483d4283e93STejun Heo bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, 148452bad64dSDavid Howells struct delayed_work *dwork, unsigned long delay) 14857a6bc1cdSVenkatesh Pallipadi { 148652bad64dSDavid Howells struct work_struct *work = &dwork->work; 1487d4283e93STejun Heo bool ret = false; 14888930cabaSTejun Heo unsigned long flags; 14898930cabaSTejun Heo 14908930cabaSTejun Heo /* read the comment in __queue_work() */ 14918930cabaSTejun Heo local_irq_save(flags); 14927a6bc1cdSVenkatesh Pallipadi 149322df02bbSTejun Heo if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { 14947beb2edfSTejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 1495d4283e93STejun Heo ret = true; 14967a6bc1cdSVenkatesh Pallipadi } 14978930cabaSTejun Heo 14988930cabaSTejun Heo local_irq_restore(flags); 14997a6bc1cdSVenkatesh Pallipadi return ret; 15007a6bc1cdSVenkatesh Pallipadi } 1501ad7b1f84SMarc Dionne EXPORT_SYMBOL(queue_delayed_work_on); 15021da177e4SLinus Torvalds 1503c8e55f36STejun Heo /** 15048376fe22STejun Heo * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU 15058376fe22STejun Heo * @cpu: CPU number to execute work on 15068376fe22STejun Heo * @wq: workqueue to use 15078376fe22STejun Heo * @dwork: work to queue 15088376fe22STejun Heo * @delay: number of jiffies to wait before queueing 15098376fe22STejun Heo * 15108376fe22STejun Heo * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, 15118376fe22STejun Heo * modify @dwork's timer so that it expires after @delay. If @delay is 15128376fe22STejun Heo * zero, @work is guaranteed to be scheduled immediately regardless of its 15138376fe22STejun Heo * current state. 15148376fe22STejun Heo * 15158376fe22STejun Heo * Returns %false if @dwork was idle and queued, %true if @dwork was 15168376fe22STejun Heo * pending and its timer was modified. 15178376fe22STejun Heo * 1518e0aecdd8STejun Heo * This function is safe to call from any context including IRQ handler. 15198376fe22STejun Heo * See try_to_grab_pending() for details. 15208376fe22STejun Heo */ 15218376fe22STejun Heo bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, 15228376fe22STejun Heo struct delayed_work *dwork, unsigned long delay) 15238376fe22STejun Heo { 15248376fe22STejun Heo unsigned long flags; 15258376fe22STejun Heo int ret; 15268376fe22STejun Heo 15278376fe22STejun Heo do { 15288376fe22STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 15298376fe22STejun Heo } while (unlikely(ret == -EAGAIN)); 15308376fe22STejun Heo 15318376fe22STejun Heo if (likely(ret >= 0)) { 15328376fe22STejun Heo __queue_delayed_work(cpu, wq, dwork, delay); 15338376fe22STejun Heo local_irq_restore(flags); 15348376fe22STejun Heo } 15358376fe22STejun Heo 15368376fe22STejun Heo /* -ENOENT from try_to_grab_pending() becomes %true */ 15378376fe22STejun Heo return ret; 15388376fe22STejun Heo } 15398376fe22STejun Heo EXPORT_SYMBOL_GPL(mod_delayed_work_on); 15408376fe22STejun Heo 15418376fe22STejun Heo /** 1542c8e55f36STejun Heo * worker_enter_idle - enter idle state 1543c8e55f36STejun Heo * @worker: worker which is entering idle state 1544c8e55f36STejun Heo * 1545c8e55f36STejun Heo * @worker is entering idle state. Update stats and idle timer if 1546c8e55f36STejun Heo * necessary. 1547c8e55f36STejun Heo * 1548c8e55f36STejun Heo * LOCKING: 1549d565ed63STejun Heo * spin_lock_irq(pool->lock). 1550c8e55f36STejun Heo */ 1551c8e55f36STejun Heo static void worker_enter_idle(struct worker *worker) 15521da177e4SLinus Torvalds { 1553bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1554c8e55f36STejun Heo 15556183c009STejun Heo if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || 15566183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->entry) && 15576183c009STejun Heo (worker->hentry.next || worker->hentry.pprev))) 15586183c009STejun Heo return; 1559c8e55f36STejun Heo 1560cb444766STejun Heo /* can't use worker_set_flags(), also called from start_worker() */ 1561cb444766STejun Heo worker->flags |= WORKER_IDLE; 1562bd7bdd43STejun Heo pool->nr_idle++; 1563e22bee78STejun Heo worker->last_active = jiffies; 1564c8e55f36STejun Heo 1565c8e55f36STejun Heo /* idle_list is LIFO */ 1566bd7bdd43STejun Heo list_add(&worker->entry, &pool->idle_list); 1567db7bccf4STejun Heo 156863d95a91STejun Heo if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) 1569628c78e7STejun Heo mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); 1570cb444766STejun Heo 1571544ecf31STejun Heo /* 1572706026c2STejun Heo * Sanity check nr_running. Because wq_unbind_fn() releases 1573d565ed63STejun Heo * pool->lock between setting %WORKER_UNBOUND and zapping 1574628c78e7STejun Heo * nr_running, the warning may trigger spuriously. Check iff 1575628c78e7STejun Heo * unbind is not in progress. 1576544ecf31STejun Heo */ 157724647570STejun Heo WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && 1578bd7bdd43STejun Heo pool->nr_workers == pool->nr_idle && 1579e19e397aSTejun Heo atomic_read(&pool->nr_running)); 1580c8e55f36STejun Heo } 1581c8e55f36STejun Heo 1582c8e55f36STejun Heo /** 1583c8e55f36STejun Heo * worker_leave_idle - leave idle state 1584c8e55f36STejun Heo * @worker: worker which is leaving idle state 1585c8e55f36STejun Heo * 1586c8e55f36STejun Heo * @worker is leaving idle state. Update stats. 1587c8e55f36STejun Heo * 1588c8e55f36STejun Heo * LOCKING: 1589d565ed63STejun Heo * spin_lock_irq(pool->lock). 1590c8e55f36STejun Heo */ 1591c8e55f36STejun Heo static void worker_leave_idle(struct worker *worker) 1592c8e55f36STejun Heo { 1593bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1594c8e55f36STejun Heo 15956183c009STejun Heo if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) 15966183c009STejun Heo return; 1597d302f017STejun Heo worker_clr_flags(worker, WORKER_IDLE); 1598bd7bdd43STejun Heo pool->nr_idle--; 1599c8e55f36STejun Heo list_del_init(&worker->entry); 1600c8e55f36STejun Heo } 1601c8e55f36STejun Heo 1602e22bee78STejun Heo /** 1603f36dc67bSLai Jiangshan * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it 1604f36dc67bSLai Jiangshan * @pool: target worker_pool 1605f36dc67bSLai Jiangshan * 1606f36dc67bSLai Jiangshan * Bind %current to the cpu of @pool if it is associated and lock @pool. 1607e22bee78STejun Heo * 1608e22bee78STejun Heo * Works which are scheduled while the cpu is online must at least be 1609e22bee78STejun Heo * scheduled to a worker which is bound to the cpu so that if they are 1610e22bee78STejun Heo * flushed from cpu callbacks while cpu is going down, they are 1611e22bee78STejun Heo * guaranteed to execute on the cpu. 1612e22bee78STejun Heo * 1613f5faa077SLai Jiangshan * This function is to be used by unbound workers and rescuers to bind 1614e22bee78STejun Heo * themselves to the target cpu and may race with cpu going down or 1615e22bee78STejun Heo * coming online. kthread_bind() can't be used because it may put the 1616e22bee78STejun Heo * worker to already dead cpu and set_cpus_allowed_ptr() can't be used 1617706026c2STejun Heo * verbatim as it's best effort and blocking and pool may be 1618e22bee78STejun Heo * [dis]associated in the meantime. 1619e22bee78STejun Heo * 1620706026c2STejun Heo * This function tries set_cpus_allowed() and locks pool and verifies the 162124647570STejun Heo * binding against %POOL_DISASSOCIATED which is set during 1622f2d5a0eeSTejun Heo * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker 1623f2d5a0eeSTejun Heo * enters idle state or fetches works without dropping lock, it can 1624f2d5a0eeSTejun Heo * guarantee the scheduling requirement described in the first paragraph. 1625e22bee78STejun Heo * 1626e22bee78STejun Heo * CONTEXT: 1627d565ed63STejun Heo * Might sleep. Called without any lock but returns with pool->lock 1628e22bee78STejun Heo * held. 1629e22bee78STejun Heo * 1630e22bee78STejun Heo * RETURNS: 1631706026c2STejun Heo * %true if the associated pool is online (@worker is successfully 1632e22bee78STejun Heo * bound), %false if offline. 1633e22bee78STejun Heo */ 1634f36dc67bSLai Jiangshan static bool worker_maybe_bind_and_lock(struct worker_pool *pool) 1635d565ed63STejun Heo __acquires(&pool->lock) 1636e22bee78STejun Heo { 1637e22bee78STejun Heo while (true) { 1638e22bee78STejun Heo /* 1639e22bee78STejun Heo * The following call may fail, succeed or succeed 1640e22bee78STejun Heo * without actually migrating the task to the cpu if 1641e22bee78STejun Heo * it races with cpu hotunplug operation. Verify 164224647570STejun Heo * against POOL_DISASSOCIATED. 1643e22bee78STejun Heo */ 164424647570STejun Heo if (!(pool->flags & POOL_DISASSOCIATED)) 16457a4e344cSTejun Heo set_cpus_allowed_ptr(current, pool->attrs->cpumask); 1646e22bee78STejun Heo 1647d565ed63STejun Heo spin_lock_irq(&pool->lock); 164824647570STejun Heo if (pool->flags & POOL_DISASSOCIATED) 1649e22bee78STejun Heo return false; 1650f5faa077SLai Jiangshan if (task_cpu(current) == pool->cpu && 16517a4e344cSTejun Heo cpumask_equal(¤t->cpus_allowed, pool->attrs->cpumask)) 1652e22bee78STejun Heo return true; 1653d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1654e22bee78STejun Heo 16555035b20fSTejun Heo /* 16565035b20fSTejun Heo * We've raced with CPU hot[un]plug. Give it a breather 16575035b20fSTejun Heo * and retry migration. cond_resched() is required here; 16585035b20fSTejun Heo * otherwise, we might deadlock against cpu_stop trying to 16595035b20fSTejun Heo * bring down the CPU on non-preemptive kernel. 16605035b20fSTejun Heo */ 1661e22bee78STejun Heo cpu_relax(); 16625035b20fSTejun Heo cond_resched(); 1663e22bee78STejun Heo } 1664e22bee78STejun Heo } 1665e22bee78STejun Heo 1666c34056a3STejun Heo static struct worker *alloc_worker(void) 1667c34056a3STejun Heo { 1668c34056a3STejun Heo struct worker *worker; 1669c34056a3STejun Heo 1670c34056a3STejun Heo worker = kzalloc(sizeof(*worker), GFP_KERNEL); 1671c8e55f36STejun Heo if (worker) { 1672c8e55f36STejun Heo INIT_LIST_HEAD(&worker->entry); 1673affee4b2STejun Heo INIT_LIST_HEAD(&worker->scheduled); 1674e22bee78STejun Heo /* on creation a worker is in !idle && prep state */ 1675e22bee78STejun Heo worker->flags = WORKER_PREP; 1676c8e55f36STejun Heo } 1677c34056a3STejun Heo return worker; 1678c34056a3STejun Heo } 1679c34056a3STejun Heo 1680c34056a3STejun Heo /** 1681c34056a3STejun Heo * create_worker - create a new workqueue worker 168263d95a91STejun Heo * @pool: pool the new worker will belong to 1683c34056a3STejun Heo * 168463d95a91STejun Heo * Create a new worker which is bound to @pool. The returned worker 1685c34056a3STejun Heo * can be started by calling start_worker() or destroyed using 1686c34056a3STejun Heo * destroy_worker(). 1687c34056a3STejun Heo * 1688c34056a3STejun Heo * CONTEXT: 1689c34056a3STejun Heo * Might sleep. Does GFP_KERNEL allocations. 1690c34056a3STejun Heo * 1691c34056a3STejun Heo * RETURNS: 1692c34056a3STejun Heo * Pointer to the newly created worker. 1693c34056a3STejun Heo */ 1694bc2ae0f5STejun Heo static struct worker *create_worker(struct worker_pool *pool) 1695c34056a3STejun Heo { 1696c34056a3STejun Heo struct worker *worker = NULL; 1697f3421797STejun Heo int id = -1; 1698e3c916a4STejun Heo char id_buf[16]; 1699c34056a3STejun Heo 1700cd549687STejun Heo lockdep_assert_held(&pool->manager_mutex); 1701cd549687STejun Heo 1702822d8405STejun Heo /* 1703822d8405STejun Heo * ID is needed to determine kthread name. Allocate ID first 1704822d8405STejun Heo * without installing the pointer. 1705822d8405STejun Heo */ 1706822d8405STejun Heo idr_preload(GFP_KERNEL); 1707d565ed63STejun Heo spin_lock_irq(&pool->lock); 1708822d8405STejun Heo 1709822d8405STejun Heo id = idr_alloc(&pool->worker_idr, NULL, 0, 0, GFP_NOWAIT); 1710822d8405STejun Heo 1711d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1712822d8405STejun Heo idr_preload_end(); 1713822d8405STejun Heo if (id < 0) 1714c34056a3STejun Heo goto fail; 1715c34056a3STejun Heo 1716c34056a3STejun Heo worker = alloc_worker(); 1717c34056a3STejun Heo if (!worker) 1718c34056a3STejun Heo goto fail; 1719c34056a3STejun Heo 1720bd7bdd43STejun Heo worker->pool = pool; 1721c34056a3STejun Heo worker->id = id; 1722c34056a3STejun Heo 172329c91e99STejun Heo if (pool->cpu >= 0) 1724e3c916a4STejun Heo snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, 1725e3c916a4STejun Heo pool->attrs->nice < 0 ? "H" : ""); 1726f3421797STejun Heo else 1727e3c916a4STejun Heo snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); 1728e3c916a4STejun Heo 1729f3f90ad4STejun Heo worker->task = kthread_create_on_node(worker_thread, worker, pool->node, 1730e3c916a4STejun Heo "kworker/%s", id_buf); 1731c34056a3STejun Heo if (IS_ERR(worker->task)) 1732c34056a3STejun Heo goto fail; 1733c34056a3STejun Heo 1734c5aa87bbSTejun Heo /* 1735c5aa87bbSTejun Heo * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any 1736c5aa87bbSTejun Heo * online CPUs. It'll be re-applied when any of the CPUs come up. 1737c5aa87bbSTejun Heo */ 17387a4e344cSTejun Heo set_user_nice(worker->task, pool->attrs->nice); 17397a4e344cSTejun Heo set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); 17403270476aSTejun Heo 174114a40ffcSTejun Heo /* prevent userland from meddling with cpumask of workqueue workers */ 174214a40ffcSTejun Heo worker->task->flags |= PF_NO_SETAFFINITY; 17437a4e344cSTejun Heo 17447a4e344cSTejun Heo /* 17457a4e344cSTejun Heo * The caller is responsible for ensuring %POOL_DISASSOCIATED 17467a4e344cSTejun Heo * remains stable across this function. See the comments above the 17477a4e344cSTejun Heo * flag definition for details. 17487a4e344cSTejun Heo */ 17497a4e344cSTejun Heo if (pool->flags & POOL_DISASSOCIATED) 1750f3421797STejun Heo worker->flags |= WORKER_UNBOUND; 1751c34056a3STejun Heo 1752822d8405STejun Heo /* successful, commit the pointer to idr */ 1753822d8405STejun Heo spin_lock_irq(&pool->lock); 1754822d8405STejun Heo idr_replace(&pool->worker_idr, worker, worker->id); 1755822d8405STejun Heo spin_unlock_irq(&pool->lock); 1756822d8405STejun Heo 1757c34056a3STejun Heo return worker; 1758822d8405STejun Heo 1759c34056a3STejun Heo fail: 1760c34056a3STejun Heo if (id >= 0) { 1761d565ed63STejun Heo spin_lock_irq(&pool->lock); 1762822d8405STejun Heo idr_remove(&pool->worker_idr, id); 1763d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1764c34056a3STejun Heo } 1765c34056a3STejun Heo kfree(worker); 1766c34056a3STejun Heo return NULL; 1767c34056a3STejun Heo } 1768c34056a3STejun Heo 1769c34056a3STejun Heo /** 1770c34056a3STejun Heo * start_worker - start a newly created worker 1771c34056a3STejun Heo * @worker: worker to start 1772c34056a3STejun Heo * 1773706026c2STejun Heo * Make the pool aware of @worker and start it. 1774c34056a3STejun Heo * 1775c34056a3STejun Heo * CONTEXT: 1776d565ed63STejun Heo * spin_lock_irq(pool->lock). 1777c34056a3STejun Heo */ 1778c34056a3STejun Heo static void start_worker(struct worker *worker) 1779c34056a3STejun Heo { 1780cb444766STejun Heo worker->flags |= WORKER_STARTED; 1781bd7bdd43STejun Heo worker->pool->nr_workers++; 1782c8e55f36STejun Heo worker_enter_idle(worker); 1783c34056a3STejun Heo wake_up_process(worker->task); 1784c34056a3STejun Heo } 1785c34056a3STejun Heo 1786c34056a3STejun Heo /** 1787ebf44d16STejun Heo * create_and_start_worker - create and start a worker for a pool 1788ebf44d16STejun Heo * @pool: the target pool 1789ebf44d16STejun Heo * 1790cd549687STejun Heo * Grab the managership of @pool and create and start a new worker for it. 1791ebf44d16STejun Heo */ 1792ebf44d16STejun Heo static int create_and_start_worker(struct worker_pool *pool) 1793ebf44d16STejun Heo { 1794ebf44d16STejun Heo struct worker *worker; 1795ebf44d16STejun Heo 1796cd549687STejun Heo mutex_lock(&pool->manager_mutex); 1797cd549687STejun Heo 1798ebf44d16STejun Heo worker = create_worker(pool); 1799ebf44d16STejun Heo if (worker) { 1800ebf44d16STejun Heo spin_lock_irq(&pool->lock); 1801ebf44d16STejun Heo start_worker(worker); 1802ebf44d16STejun Heo spin_unlock_irq(&pool->lock); 1803ebf44d16STejun Heo } 1804ebf44d16STejun Heo 1805cd549687STejun Heo mutex_unlock(&pool->manager_mutex); 1806cd549687STejun Heo 1807ebf44d16STejun Heo return worker ? 0 : -ENOMEM; 1808ebf44d16STejun Heo } 1809ebf44d16STejun Heo 1810ebf44d16STejun Heo /** 1811c34056a3STejun Heo * destroy_worker - destroy a workqueue worker 1812c34056a3STejun Heo * @worker: worker to be destroyed 1813c34056a3STejun Heo * 1814706026c2STejun Heo * Destroy @worker and adjust @pool stats accordingly. 1815c8e55f36STejun Heo * 1816c8e55f36STejun Heo * CONTEXT: 1817d565ed63STejun Heo * spin_lock_irq(pool->lock) which is released and regrabbed. 1818c34056a3STejun Heo */ 1819c34056a3STejun Heo static void destroy_worker(struct worker *worker) 1820c34056a3STejun Heo { 1821bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 1822c34056a3STejun Heo 1823cd549687STejun Heo lockdep_assert_held(&pool->manager_mutex); 1824cd549687STejun Heo lockdep_assert_held(&pool->lock); 1825cd549687STejun Heo 1826c34056a3STejun Heo /* sanity check frenzy */ 18276183c009STejun Heo if (WARN_ON(worker->current_work) || 18286183c009STejun Heo WARN_ON(!list_empty(&worker->scheduled))) 18296183c009STejun Heo return; 1830c34056a3STejun Heo 1831c8e55f36STejun Heo if (worker->flags & WORKER_STARTED) 1832bd7bdd43STejun Heo pool->nr_workers--; 1833c8e55f36STejun Heo if (worker->flags & WORKER_IDLE) 1834bd7bdd43STejun Heo pool->nr_idle--; 1835c8e55f36STejun Heo 1836c8e55f36STejun Heo list_del_init(&worker->entry); 1837cb444766STejun Heo worker->flags |= WORKER_DIE; 1838c8e55f36STejun Heo 1839822d8405STejun Heo idr_remove(&pool->worker_idr, worker->id); 1840822d8405STejun Heo 1841d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1842c8e55f36STejun Heo 1843c34056a3STejun Heo kthread_stop(worker->task); 1844c34056a3STejun Heo kfree(worker); 1845c34056a3STejun Heo 1846d565ed63STejun Heo spin_lock_irq(&pool->lock); 1847c34056a3STejun Heo } 1848c34056a3STejun Heo 184963d95a91STejun Heo static void idle_worker_timeout(unsigned long __pool) 1850e22bee78STejun Heo { 185163d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 1852e22bee78STejun Heo 1853d565ed63STejun Heo spin_lock_irq(&pool->lock); 1854e22bee78STejun Heo 185563d95a91STejun Heo if (too_many_workers(pool)) { 1856e22bee78STejun Heo struct worker *worker; 1857e22bee78STejun Heo unsigned long expires; 1858e22bee78STejun Heo 1859e22bee78STejun Heo /* idle_list is kept in LIFO order, check the last one */ 186063d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 1861e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 1862e22bee78STejun Heo 1863e22bee78STejun Heo if (time_before(jiffies, expires)) 186463d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 1865e22bee78STejun Heo else { 1866e22bee78STejun Heo /* it's been idle for too long, wake up manager */ 186711ebea50STejun Heo pool->flags |= POOL_MANAGE_WORKERS; 186863d95a91STejun Heo wake_up_worker(pool); 1869e22bee78STejun Heo } 1870e22bee78STejun Heo } 1871e22bee78STejun Heo 1872d565ed63STejun Heo spin_unlock_irq(&pool->lock); 1873e22bee78STejun Heo } 1874e22bee78STejun Heo 1875493a1724STejun Heo static void send_mayday(struct work_struct *work) 1876e22bee78STejun Heo { 1877112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 1878112202d9STejun Heo struct workqueue_struct *wq = pwq->wq; 1879493a1724STejun Heo 18802e109a28STejun Heo lockdep_assert_held(&wq_mayday_lock); 1881e22bee78STejun Heo 1882493008a8STejun Heo if (!wq->rescuer) 1883493a1724STejun Heo return; 1884e22bee78STejun Heo 1885e22bee78STejun Heo /* mayday mayday mayday */ 1886493a1724STejun Heo if (list_empty(&pwq->mayday_node)) { 1887493a1724STejun Heo list_add_tail(&pwq->mayday_node, &wq->maydays); 1888e22bee78STejun Heo wake_up_process(wq->rescuer->task); 1889493a1724STejun Heo } 1890e22bee78STejun Heo } 1891e22bee78STejun Heo 1892706026c2STejun Heo static void pool_mayday_timeout(unsigned long __pool) 1893e22bee78STejun Heo { 189463d95a91STejun Heo struct worker_pool *pool = (void *)__pool; 1895e22bee78STejun Heo struct work_struct *work; 1896e22bee78STejun Heo 18972e109a28STejun Heo spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */ 1898493a1724STejun Heo spin_lock(&pool->lock); 1899e22bee78STejun Heo 190063d95a91STejun Heo if (need_to_create_worker(pool)) { 1901e22bee78STejun Heo /* 1902e22bee78STejun Heo * We've been trying to create a new worker but 1903e22bee78STejun Heo * haven't been successful. We might be hitting an 1904e22bee78STejun Heo * allocation deadlock. Send distress signals to 1905e22bee78STejun Heo * rescuers. 1906e22bee78STejun Heo */ 190763d95a91STejun Heo list_for_each_entry(work, &pool->worklist, entry) 1908e22bee78STejun Heo send_mayday(work); 1909e22bee78STejun Heo } 1910e22bee78STejun Heo 1911493a1724STejun Heo spin_unlock(&pool->lock); 19122e109a28STejun Heo spin_unlock_irq(&wq_mayday_lock); 1913e22bee78STejun Heo 191463d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); 1915e22bee78STejun Heo } 1916e22bee78STejun Heo 1917e22bee78STejun Heo /** 1918e22bee78STejun Heo * maybe_create_worker - create a new worker if necessary 191963d95a91STejun Heo * @pool: pool to create a new worker for 1920e22bee78STejun Heo * 192163d95a91STejun Heo * Create a new worker for @pool if necessary. @pool is guaranteed to 1922e22bee78STejun Heo * have at least one idle worker on return from this function. If 1923e22bee78STejun Heo * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is 192463d95a91STejun Heo * sent to all rescuers with works scheduled on @pool to resolve 1925e22bee78STejun Heo * possible allocation deadlock. 1926e22bee78STejun Heo * 1927c5aa87bbSTejun Heo * On return, need_to_create_worker() is guaranteed to be %false and 1928c5aa87bbSTejun Heo * may_start_working() %true. 1929e22bee78STejun Heo * 1930e22bee78STejun Heo * LOCKING: 1931d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 1932e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. Called only from 1933e22bee78STejun Heo * manager. 1934e22bee78STejun Heo * 1935e22bee78STejun Heo * RETURNS: 1936c5aa87bbSTejun Heo * %false if no action was taken and pool->lock stayed locked, %true 1937e22bee78STejun Heo * otherwise. 1938e22bee78STejun Heo */ 193963d95a91STejun Heo static bool maybe_create_worker(struct worker_pool *pool) 1940d565ed63STejun Heo __releases(&pool->lock) 1941d565ed63STejun Heo __acquires(&pool->lock) 1942e22bee78STejun Heo { 194363d95a91STejun Heo if (!need_to_create_worker(pool)) 1944e22bee78STejun Heo return false; 1945e22bee78STejun Heo restart: 1946d565ed63STejun Heo spin_unlock_irq(&pool->lock); 19479f9c2364STejun Heo 1948e22bee78STejun Heo /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ 194963d95a91STejun Heo mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); 1950e22bee78STejun Heo 1951e22bee78STejun Heo while (true) { 1952e22bee78STejun Heo struct worker *worker; 1953e22bee78STejun Heo 1954bc2ae0f5STejun Heo worker = create_worker(pool); 1955e22bee78STejun Heo if (worker) { 195663d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 1957d565ed63STejun Heo spin_lock_irq(&pool->lock); 1958e22bee78STejun Heo start_worker(worker); 19596183c009STejun Heo if (WARN_ON_ONCE(need_to_create_worker(pool))) 19606183c009STejun Heo goto restart; 1961e22bee78STejun Heo return true; 1962e22bee78STejun Heo } 1963e22bee78STejun Heo 196463d95a91STejun Heo if (!need_to_create_worker(pool)) 1965e22bee78STejun Heo break; 1966e22bee78STejun Heo 1967e22bee78STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 1968e22bee78STejun Heo schedule_timeout(CREATE_COOLDOWN); 19699f9c2364STejun Heo 197063d95a91STejun Heo if (!need_to_create_worker(pool)) 1971e22bee78STejun Heo break; 1972e22bee78STejun Heo } 1973e22bee78STejun Heo 197463d95a91STejun Heo del_timer_sync(&pool->mayday_timer); 1975d565ed63STejun Heo spin_lock_irq(&pool->lock); 197663d95a91STejun Heo if (need_to_create_worker(pool)) 1977e22bee78STejun Heo goto restart; 1978e22bee78STejun Heo return true; 1979e22bee78STejun Heo } 1980e22bee78STejun Heo 1981e22bee78STejun Heo /** 1982e22bee78STejun Heo * maybe_destroy_worker - destroy workers which have been idle for a while 198363d95a91STejun Heo * @pool: pool to destroy workers for 1984e22bee78STejun Heo * 198563d95a91STejun Heo * Destroy @pool workers which have been idle for longer than 1986e22bee78STejun Heo * IDLE_WORKER_TIMEOUT. 1987e22bee78STejun Heo * 1988e22bee78STejun Heo * LOCKING: 1989d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 1990e22bee78STejun Heo * multiple times. Called only from manager. 1991e22bee78STejun Heo * 1992e22bee78STejun Heo * RETURNS: 1993c5aa87bbSTejun Heo * %false if no action was taken and pool->lock stayed locked, %true 1994e22bee78STejun Heo * otherwise. 1995e22bee78STejun Heo */ 199663d95a91STejun Heo static bool maybe_destroy_workers(struct worker_pool *pool) 1997e22bee78STejun Heo { 1998e22bee78STejun Heo bool ret = false; 1999e22bee78STejun Heo 200063d95a91STejun Heo while (too_many_workers(pool)) { 2001e22bee78STejun Heo struct worker *worker; 2002e22bee78STejun Heo unsigned long expires; 2003e22bee78STejun Heo 200463d95a91STejun Heo worker = list_entry(pool->idle_list.prev, struct worker, entry); 2005e22bee78STejun Heo expires = worker->last_active + IDLE_WORKER_TIMEOUT; 2006e22bee78STejun Heo 2007e22bee78STejun Heo if (time_before(jiffies, expires)) { 200863d95a91STejun Heo mod_timer(&pool->idle_timer, expires); 2009e22bee78STejun Heo break; 2010e22bee78STejun Heo } 2011e22bee78STejun Heo 2012e22bee78STejun Heo destroy_worker(worker); 2013e22bee78STejun Heo ret = true; 2014e22bee78STejun Heo } 2015e22bee78STejun Heo 2016e22bee78STejun Heo return ret; 2017e22bee78STejun Heo } 2018e22bee78STejun Heo 2019e22bee78STejun Heo /** 2020e22bee78STejun Heo * manage_workers - manage worker pool 2021e22bee78STejun Heo * @worker: self 2022e22bee78STejun Heo * 2023706026c2STejun Heo * Assume the manager role and manage the worker pool @worker belongs 2024e22bee78STejun Heo * to. At any given time, there can be only zero or one manager per 2025706026c2STejun Heo * pool. The exclusion is handled automatically by this function. 2026e22bee78STejun Heo * 2027e22bee78STejun Heo * The caller can safely start processing works on false return. On 2028e22bee78STejun Heo * true return, it's guaranteed that need_to_create_worker() is false 2029e22bee78STejun Heo * and may_start_working() is true. 2030e22bee78STejun Heo * 2031e22bee78STejun Heo * CONTEXT: 2032d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2033e22bee78STejun Heo * multiple times. Does GFP_KERNEL allocations. 2034e22bee78STejun Heo * 2035e22bee78STejun Heo * RETURNS: 2036d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2037d565ed63STejun Heo * multiple times. Does GFP_KERNEL allocations. 2038e22bee78STejun Heo */ 2039e22bee78STejun Heo static bool manage_workers(struct worker *worker) 2040e22bee78STejun Heo { 204163d95a91STejun Heo struct worker_pool *pool = worker->pool; 2042e22bee78STejun Heo bool ret = false; 2043e22bee78STejun Heo 2044bc3a1afcSTejun Heo /* 2045bc3a1afcSTejun Heo * Managership is governed by two mutexes - manager_arb and 2046bc3a1afcSTejun Heo * manager_mutex. manager_arb handles arbitration of manager role. 2047bc3a1afcSTejun Heo * Anyone who successfully grabs manager_arb wins the arbitration 2048bc3a1afcSTejun Heo * and becomes the manager. mutex_trylock() on pool->manager_arb 2049bc3a1afcSTejun Heo * failure while holding pool->lock reliably indicates that someone 2050bc3a1afcSTejun Heo * else is managing the pool and the worker which failed trylock 2051bc3a1afcSTejun Heo * can proceed to executing work items. This means that anyone 2052bc3a1afcSTejun Heo * grabbing manager_arb is responsible for actually performing 2053bc3a1afcSTejun Heo * manager duties. If manager_arb is grabbed and released without 2054bc3a1afcSTejun Heo * actual management, the pool may stall indefinitely. 2055bc3a1afcSTejun Heo * 2056bc3a1afcSTejun Heo * manager_mutex is used for exclusion of actual management 2057bc3a1afcSTejun Heo * operations. The holder of manager_mutex can be sure that none 2058bc3a1afcSTejun Heo * of management operations, including creation and destruction of 2059bc3a1afcSTejun Heo * workers, won't take place until the mutex is released. Because 2060bc3a1afcSTejun Heo * manager_mutex doesn't interfere with manager role arbitration, 2061bc3a1afcSTejun Heo * it is guaranteed that the pool's management, while may be 2062bc3a1afcSTejun Heo * delayed, won't be disturbed by someone else grabbing 2063bc3a1afcSTejun Heo * manager_mutex. 2064bc3a1afcSTejun Heo */ 206534a06bd6STejun Heo if (!mutex_trylock(&pool->manager_arb)) 2066e22bee78STejun Heo return ret; 2067e22bee78STejun Heo 2068ee378aa4SLai Jiangshan /* 2069bc3a1afcSTejun Heo * With manager arbitration won, manager_mutex would be free in 2070bc3a1afcSTejun Heo * most cases. trylock first without dropping @pool->lock. 2071ee378aa4SLai Jiangshan */ 2072bc3a1afcSTejun Heo if (unlikely(!mutex_trylock(&pool->manager_mutex))) { 2073d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2074bc3a1afcSTejun Heo mutex_lock(&pool->manager_mutex); 20758f174b11SJoonsoo Kim spin_lock_irq(&pool->lock); 2076ee378aa4SLai Jiangshan ret = true; 2077ee378aa4SLai Jiangshan } 2078ee378aa4SLai Jiangshan 207911ebea50STejun Heo pool->flags &= ~POOL_MANAGE_WORKERS; 2080e22bee78STejun Heo 2081e22bee78STejun Heo /* 2082e22bee78STejun Heo * Destroy and then create so that may_start_working() is true 2083e22bee78STejun Heo * on return. 2084e22bee78STejun Heo */ 208563d95a91STejun Heo ret |= maybe_destroy_workers(pool); 208663d95a91STejun Heo ret |= maybe_create_worker(pool); 2087e22bee78STejun Heo 2088bc3a1afcSTejun Heo mutex_unlock(&pool->manager_mutex); 208934a06bd6STejun Heo mutex_unlock(&pool->manager_arb); 2090e22bee78STejun Heo return ret; 2091e22bee78STejun Heo } 2092e22bee78STejun Heo 2093a62428c0STejun Heo /** 2094a62428c0STejun Heo * process_one_work - process single work 2095c34056a3STejun Heo * @worker: self 2096a62428c0STejun Heo * @work: work to process 2097a62428c0STejun Heo * 2098a62428c0STejun Heo * Process @work. This function contains all the logics necessary to 2099a62428c0STejun Heo * process a single work including synchronization against and 2100a62428c0STejun Heo * interaction with other workers on the same cpu, queueing and 2101a62428c0STejun Heo * flushing. As long as context requirement is met, any worker can 2102a62428c0STejun Heo * call this function to process a work. 2103a62428c0STejun Heo * 2104a62428c0STejun Heo * CONTEXT: 2105d565ed63STejun Heo * spin_lock_irq(pool->lock) which is released and regrabbed. 2106a62428c0STejun Heo */ 2107c34056a3STejun Heo static void process_one_work(struct worker *worker, struct work_struct *work) 2108d565ed63STejun Heo __releases(&pool->lock) 2109d565ed63STejun Heo __acquires(&pool->lock) 21101da177e4SLinus Torvalds { 2111112202d9STejun Heo struct pool_workqueue *pwq = get_work_pwq(work); 2112bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 2113112202d9STejun Heo bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; 211473f53c4aSTejun Heo int work_color; 21157e11629dSTejun Heo struct worker *collision; 21164e6045f1SJohannes Berg #ifdef CONFIG_LOCKDEP 21174e6045f1SJohannes Berg /* 2118a62428c0STejun Heo * It is permissible to free the struct work_struct from 2119a62428c0STejun Heo * inside the function that is called from it, this we need to 2120a62428c0STejun Heo * take into account for lockdep too. To avoid bogus "held 2121a62428c0STejun Heo * lock freed" warnings as well as problems when looking into 2122a62428c0STejun Heo * work->lockdep_map, make a copy and use that here. 21234e6045f1SJohannes Berg */ 21244d82a1deSPeter Zijlstra struct lockdep_map lockdep_map; 21254d82a1deSPeter Zijlstra 21264d82a1deSPeter Zijlstra lockdep_copy_map(&lockdep_map, &work->lockdep_map); 21274e6045f1SJohannes Berg #endif 21286fec10a1STejun Heo /* 21296fec10a1STejun Heo * Ensure we're on the correct CPU. DISASSOCIATED test is 21306fec10a1STejun Heo * necessary to avoid spurious warnings from rescuers servicing the 213124647570STejun Heo * unbound or a disassociated pool. 21326fec10a1STejun Heo */ 21335f7dabfdSLai Jiangshan WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && 213424647570STejun Heo !(pool->flags & POOL_DISASSOCIATED) && 2135ec22ca5eSTejun Heo raw_smp_processor_id() != pool->cpu); 213625511a47STejun Heo 21377e11629dSTejun Heo /* 21387e11629dSTejun Heo * A single work shouldn't be executed concurrently by 21397e11629dSTejun Heo * multiple workers on a single cpu. Check whether anyone is 21407e11629dSTejun Heo * already processing the work. If so, defer the work to the 21417e11629dSTejun Heo * currently executing one. 21427e11629dSTejun Heo */ 2143c9e7cf27STejun Heo collision = find_worker_executing_work(pool, work); 21447e11629dSTejun Heo if (unlikely(collision)) { 21457e11629dSTejun Heo move_linked_works(work, &collision->scheduled, NULL); 21467e11629dSTejun Heo return; 21477e11629dSTejun Heo } 21481da177e4SLinus Torvalds 21498930cabaSTejun Heo /* claim and dequeue */ 21501da177e4SLinus Torvalds debug_work_deactivate(work); 2151c9e7cf27STejun Heo hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); 2152c34056a3STejun Heo worker->current_work = work; 2153a2c1c57bSTejun Heo worker->current_func = work->func; 2154112202d9STejun Heo worker->current_pwq = pwq; 215573f53c4aSTejun Heo work_color = get_work_color(work); 21567a22ad75STejun Heo 2157a62428c0STejun Heo list_del_init(&work->entry); 2158a62428c0STejun Heo 2159649027d7STejun Heo /* 2160fb0e7bebSTejun Heo * CPU intensive works don't participate in concurrency 2161fb0e7bebSTejun Heo * management. They're the scheduler's responsibility. 2162fb0e7bebSTejun Heo */ 2163fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2164fb0e7bebSTejun Heo worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); 2165fb0e7bebSTejun Heo 2166974271c4STejun Heo /* 2167d565ed63STejun Heo * Unbound pool isn't concurrency managed and work items should be 2168974271c4STejun Heo * executed ASAP. Wake up another worker if necessary. 2169974271c4STejun Heo */ 217063d95a91STejun Heo if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) 217163d95a91STejun Heo wake_up_worker(pool); 2172974271c4STejun Heo 21738930cabaSTejun Heo /* 21747c3eed5cSTejun Heo * Record the last pool and clear PENDING which should be the last 2175d565ed63STejun Heo * update to @work. Also, do this inside @pool->lock so that 217623657bb1STejun Heo * PENDING and queued state changes happen together while IRQ is 217723657bb1STejun Heo * disabled. 21788930cabaSTejun Heo */ 21797c3eed5cSTejun Heo set_work_pool_and_clear_pending(work, pool->id); 21801da177e4SLinus Torvalds 2181d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2182365970a1SDavid Howells 2183112202d9STejun Heo lock_map_acquire_read(&pwq->wq->lockdep_map); 21843295f0efSIngo Molnar lock_map_acquire(&lockdep_map); 2185e36c886aSArjan van de Ven trace_workqueue_execute_start(work); 2186a2c1c57bSTejun Heo worker->current_func(work); 2187e36c886aSArjan van de Ven /* 2188e36c886aSArjan van de Ven * While we must be careful to not use "work" after this, the trace 2189e36c886aSArjan van de Ven * point will only record its address. 2190e36c886aSArjan van de Ven */ 2191e36c886aSArjan van de Ven trace_workqueue_execute_end(work); 21923295f0efSIngo Molnar lock_map_release(&lockdep_map); 2193112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 21941da177e4SLinus Torvalds 2195d5abe669SPeter Zijlstra if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { 2196044c782cSValentin Ilie pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" 2197044c782cSValentin Ilie " last function: %pf\n", 2198a2c1c57bSTejun Heo current->comm, preempt_count(), task_pid_nr(current), 2199a2c1c57bSTejun Heo worker->current_func); 2200d5abe669SPeter Zijlstra debug_show_held_locks(current); 2201d5abe669SPeter Zijlstra dump_stack(); 2202d5abe669SPeter Zijlstra } 2203d5abe669SPeter Zijlstra 2204d565ed63STejun Heo spin_lock_irq(&pool->lock); 2205a62428c0STejun Heo 2206fb0e7bebSTejun Heo /* clear cpu intensive status */ 2207fb0e7bebSTejun Heo if (unlikely(cpu_intensive)) 2208fb0e7bebSTejun Heo worker_clr_flags(worker, WORKER_CPU_INTENSIVE); 2209fb0e7bebSTejun Heo 2210a62428c0STejun Heo /* we're done with it, release */ 221142f8570fSSasha Levin hash_del(&worker->hentry); 2212c34056a3STejun Heo worker->current_work = NULL; 2213a2c1c57bSTejun Heo worker->current_func = NULL; 2214112202d9STejun Heo worker->current_pwq = NULL; 22153d1cb205STejun Heo worker->desc_valid = false; 2216112202d9STejun Heo pwq_dec_nr_in_flight(pwq, work_color); 22171da177e4SLinus Torvalds } 22181da177e4SLinus Torvalds 2219affee4b2STejun Heo /** 2220affee4b2STejun Heo * process_scheduled_works - process scheduled works 2221affee4b2STejun Heo * @worker: self 2222affee4b2STejun Heo * 2223affee4b2STejun Heo * Process all scheduled works. Please note that the scheduled list 2224affee4b2STejun Heo * may change while processing a work, so this function repeatedly 2225affee4b2STejun Heo * fetches a work from the top and executes it. 2226affee4b2STejun Heo * 2227affee4b2STejun Heo * CONTEXT: 2228d565ed63STejun Heo * spin_lock_irq(pool->lock) which may be released and regrabbed 2229affee4b2STejun Heo * multiple times. 2230affee4b2STejun Heo */ 2231affee4b2STejun Heo static void process_scheduled_works(struct worker *worker) 22321da177e4SLinus Torvalds { 2233affee4b2STejun Heo while (!list_empty(&worker->scheduled)) { 2234affee4b2STejun Heo struct work_struct *work = list_first_entry(&worker->scheduled, 2235a62428c0STejun Heo struct work_struct, entry); 2236c34056a3STejun Heo process_one_work(worker, work); 2237a62428c0STejun Heo } 22381da177e4SLinus Torvalds } 22391da177e4SLinus Torvalds 22404690c4abSTejun Heo /** 22414690c4abSTejun Heo * worker_thread - the worker thread function 2242c34056a3STejun Heo * @__worker: self 22434690c4abSTejun Heo * 2244c5aa87bbSTejun Heo * The worker thread function. All workers belong to a worker_pool - 2245c5aa87bbSTejun Heo * either a per-cpu one or dynamic unbound one. These workers process all 2246c5aa87bbSTejun Heo * work items regardless of their specific target workqueue. The only 2247c5aa87bbSTejun Heo * exception is work items which belong to workqueues with a rescuer which 2248c5aa87bbSTejun Heo * will be explained in rescuer_thread(). 22494690c4abSTejun Heo */ 2250c34056a3STejun Heo static int worker_thread(void *__worker) 22511da177e4SLinus Torvalds { 2252c34056a3STejun Heo struct worker *worker = __worker; 2253bd7bdd43STejun Heo struct worker_pool *pool = worker->pool; 22541da177e4SLinus Torvalds 2255e22bee78STejun Heo /* tell the scheduler that this is a workqueue worker */ 2256e22bee78STejun Heo worker->task->flags |= PF_WQ_WORKER; 2257c8e55f36STejun Heo woke_up: 2258d565ed63STejun Heo spin_lock_irq(&pool->lock); 2259affee4b2STejun Heo 2260a9ab775bSTejun Heo /* am I supposed to die? */ 2261a9ab775bSTejun Heo if (unlikely(worker->flags & WORKER_DIE)) { 2262d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2263a9ab775bSTejun Heo WARN_ON_ONCE(!list_empty(&worker->entry)); 2264e22bee78STejun Heo worker->task->flags &= ~PF_WQ_WORKER; 2265c8e55f36STejun Heo return 0; 2266c8e55f36STejun Heo } 2267c8e55f36STejun Heo 2268c8e55f36STejun Heo worker_leave_idle(worker); 2269db7bccf4STejun Heo recheck: 2270e22bee78STejun Heo /* no more worker necessary? */ 227163d95a91STejun Heo if (!need_more_worker(pool)) 2272e22bee78STejun Heo goto sleep; 2273e22bee78STejun Heo 2274e22bee78STejun Heo /* do we need to manage? */ 227563d95a91STejun Heo if (unlikely(!may_start_working(pool)) && manage_workers(worker)) 2276e22bee78STejun Heo goto recheck; 2277e22bee78STejun Heo 2278c8e55f36STejun Heo /* 2279c8e55f36STejun Heo * ->scheduled list can only be filled while a worker is 2280c8e55f36STejun Heo * preparing to process a work or actually processing it. 2281c8e55f36STejun Heo * Make sure nobody diddled with it while I was sleeping. 2282c8e55f36STejun Heo */ 22836183c009STejun Heo WARN_ON_ONCE(!list_empty(&worker->scheduled)); 2284c8e55f36STejun Heo 2285e22bee78STejun Heo /* 2286a9ab775bSTejun Heo * Finish PREP stage. We're guaranteed to have at least one idle 2287a9ab775bSTejun Heo * worker or that someone else has already assumed the manager 2288a9ab775bSTejun Heo * role. This is where @worker starts participating in concurrency 2289a9ab775bSTejun Heo * management if applicable and concurrency management is restored 2290a9ab775bSTejun Heo * after being rebound. See rebind_workers() for details. 2291e22bee78STejun Heo */ 2292a9ab775bSTejun Heo worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); 2293e22bee78STejun Heo 2294e22bee78STejun Heo do { 2295affee4b2STejun Heo struct work_struct *work = 2296bd7bdd43STejun Heo list_first_entry(&pool->worklist, 2297affee4b2STejun Heo struct work_struct, entry); 2298affee4b2STejun Heo 2299c8e55f36STejun Heo if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { 2300affee4b2STejun Heo /* optimization path, not strictly necessary */ 2301affee4b2STejun Heo process_one_work(worker, work); 2302affee4b2STejun Heo if (unlikely(!list_empty(&worker->scheduled))) 2303affee4b2STejun Heo process_scheduled_works(worker); 2304affee4b2STejun Heo } else { 2305c8e55f36STejun Heo move_linked_works(work, &worker->scheduled, NULL); 2306affee4b2STejun Heo process_scheduled_works(worker); 2307affee4b2STejun Heo } 230863d95a91STejun Heo } while (keep_working(pool)); 2309affee4b2STejun Heo 2310e22bee78STejun Heo worker_set_flags(worker, WORKER_PREP, false); 2311d313dd85STejun Heo sleep: 231263d95a91STejun Heo if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) 2313e22bee78STejun Heo goto recheck; 2314d313dd85STejun Heo 2315c8e55f36STejun Heo /* 2316d565ed63STejun Heo * pool->lock is held and there's no work to process and no need to 2317d565ed63STejun Heo * manage, sleep. Workers are woken up only while holding 2318d565ed63STejun Heo * pool->lock or from local cpu, so setting the current state 2319d565ed63STejun Heo * before releasing pool->lock is enough to prevent losing any 2320d565ed63STejun Heo * event. 2321c8e55f36STejun Heo */ 2322c8e55f36STejun Heo worker_enter_idle(worker); 2323c8e55f36STejun Heo __set_current_state(TASK_INTERRUPTIBLE); 2324d565ed63STejun Heo spin_unlock_irq(&pool->lock); 23251da177e4SLinus Torvalds schedule(); 2326c8e55f36STejun Heo goto woke_up; 23271da177e4SLinus Torvalds } 23281da177e4SLinus Torvalds 2329e22bee78STejun Heo /** 2330e22bee78STejun Heo * rescuer_thread - the rescuer thread function 2331111c225aSTejun Heo * @__rescuer: self 2332e22bee78STejun Heo * 2333e22bee78STejun Heo * Workqueue rescuer thread function. There's one rescuer for each 2334493008a8STejun Heo * workqueue which has WQ_MEM_RECLAIM set. 2335e22bee78STejun Heo * 2336706026c2STejun Heo * Regular work processing on a pool may block trying to create a new 2337e22bee78STejun Heo * worker which uses GFP_KERNEL allocation which has slight chance of 2338e22bee78STejun Heo * developing into deadlock if some works currently on the same queue 2339e22bee78STejun Heo * need to be processed to satisfy the GFP_KERNEL allocation. This is 2340e22bee78STejun Heo * the problem rescuer solves. 2341e22bee78STejun Heo * 2342706026c2STejun Heo * When such condition is possible, the pool summons rescuers of all 2343706026c2STejun Heo * workqueues which have works queued on the pool and let them process 2344e22bee78STejun Heo * those works so that forward progress can be guaranteed. 2345e22bee78STejun Heo * 2346e22bee78STejun Heo * This should happen rarely. 2347e22bee78STejun Heo */ 2348111c225aSTejun Heo static int rescuer_thread(void *__rescuer) 2349e22bee78STejun Heo { 2350111c225aSTejun Heo struct worker *rescuer = __rescuer; 2351111c225aSTejun Heo struct workqueue_struct *wq = rescuer->rescue_wq; 2352e22bee78STejun Heo struct list_head *scheduled = &rescuer->scheduled; 2353e22bee78STejun Heo 2354e22bee78STejun Heo set_user_nice(current, RESCUER_NICE_LEVEL); 2355111c225aSTejun Heo 2356111c225aSTejun Heo /* 2357111c225aSTejun Heo * Mark rescuer as worker too. As WORKER_PREP is never cleared, it 2358111c225aSTejun Heo * doesn't participate in concurrency management. 2359111c225aSTejun Heo */ 2360111c225aSTejun Heo rescuer->task->flags |= PF_WQ_WORKER; 2361e22bee78STejun Heo repeat: 2362e22bee78STejun Heo set_current_state(TASK_INTERRUPTIBLE); 23631da177e4SLinus Torvalds 2364412d32e6SMike Galbraith if (kthread_should_stop()) { 2365412d32e6SMike Galbraith __set_current_state(TASK_RUNNING); 2366111c225aSTejun Heo rescuer->task->flags &= ~PF_WQ_WORKER; 2367e22bee78STejun Heo return 0; 2368412d32e6SMike Galbraith } 23691da177e4SLinus Torvalds 2370493a1724STejun Heo /* see whether any pwq is asking for help */ 23712e109a28STejun Heo spin_lock_irq(&wq_mayday_lock); 2372493a1724STejun Heo 2373493a1724STejun Heo while (!list_empty(&wq->maydays)) { 2374493a1724STejun Heo struct pool_workqueue *pwq = list_first_entry(&wq->maydays, 2375493a1724STejun Heo struct pool_workqueue, mayday_node); 2376112202d9STejun Heo struct worker_pool *pool = pwq->pool; 2377e22bee78STejun Heo struct work_struct *work, *n; 2378e22bee78STejun Heo 2379e22bee78STejun Heo __set_current_state(TASK_RUNNING); 2380493a1724STejun Heo list_del_init(&pwq->mayday_node); 2381493a1724STejun Heo 23822e109a28STejun Heo spin_unlock_irq(&wq_mayday_lock); 2383e22bee78STejun Heo 2384e22bee78STejun Heo /* migrate to the target cpu if possible */ 2385f36dc67bSLai Jiangshan worker_maybe_bind_and_lock(pool); 2386b3104104SLai Jiangshan rescuer->pool = pool; 2387e22bee78STejun Heo 2388e22bee78STejun Heo /* 2389e22bee78STejun Heo * Slurp in all works issued via this workqueue and 2390e22bee78STejun Heo * process'em. 2391e22bee78STejun Heo */ 23926183c009STejun Heo WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); 2393bd7bdd43STejun Heo list_for_each_entry_safe(work, n, &pool->worklist, entry) 2394112202d9STejun Heo if (get_work_pwq(work) == pwq) 2395e22bee78STejun Heo move_linked_works(work, scheduled, &n); 2396e22bee78STejun Heo 2397e22bee78STejun Heo process_scheduled_works(rescuer); 23987576958aSTejun Heo 23997576958aSTejun Heo /* 2400d565ed63STejun Heo * Leave this pool. If keep_working() is %true, notify a 24017576958aSTejun Heo * regular worker; otherwise, we end up with 0 concurrency 24027576958aSTejun Heo * and stalling the execution. 24037576958aSTejun Heo */ 240463d95a91STejun Heo if (keep_working(pool)) 240563d95a91STejun Heo wake_up_worker(pool); 24067576958aSTejun Heo 2407b3104104SLai Jiangshan rescuer->pool = NULL; 2408493a1724STejun Heo spin_unlock(&pool->lock); 24092e109a28STejun Heo spin_lock(&wq_mayday_lock); 24101da177e4SLinus Torvalds } 24111da177e4SLinus Torvalds 24122e109a28STejun Heo spin_unlock_irq(&wq_mayday_lock); 2413493a1724STejun Heo 2414111c225aSTejun Heo /* rescuers should never participate in concurrency management */ 2415111c225aSTejun Heo WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); 2416e22bee78STejun Heo schedule(); 2417e22bee78STejun Heo goto repeat; 24181da177e4SLinus Torvalds } 24191da177e4SLinus Torvalds 2420fc2e4d70SOleg Nesterov struct wq_barrier { 2421fc2e4d70SOleg Nesterov struct work_struct work; 2422fc2e4d70SOleg Nesterov struct completion done; 2423fc2e4d70SOleg Nesterov }; 2424fc2e4d70SOleg Nesterov 2425fc2e4d70SOleg Nesterov static void wq_barrier_func(struct work_struct *work) 2426fc2e4d70SOleg Nesterov { 2427fc2e4d70SOleg Nesterov struct wq_barrier *barr = container_of(work, struct wq_barrier, work); 2428fc2e4d70SOleg Nesterov complete(&barr->done); 2429fc2e4d70SOleg Nesterov } 2430fc2e4d70SOleg Nesterov 24314690c4abSTejun Heo /** 24324690c4abSTejun Heo * insert_wq_barrier - insert a barrier work 2433112202d9STejun Heo * @pwq: pwq to insert barrier into 24344690c4abSTejun Heo * @barr: wq_barrier to insert 2435affee4b2STejun Heo * @target: target work to attach @barr to 2436affee4b2STejun Heo * @worker: worker currently executing @target, NULL if @target is not executing 24374690c4abSTejun Heo * 2438affee4b2STejun Heo * @barr is linked to @target such that @barr is completed only after 2439affee4b2STejun Heo * @target finishes execution. Please note that the ordering 2440affee4b2STejun Heo * guarantee is observed only with respect to @target and on the local 2441affee4b2STejun Heo * cpu. 2442affee4b2STejun Heo * 2443affee4b2STejun Heo * Currently, a queued barrier can't be canceled. This is because 2444affee4b2STejun Heo * try_to_grab_pending() can't determine whether the work to be 2445affee4b2STejun Heo * grabbed is at the head of the queue and thus can't clear LINKED 2446affee4b2STejun Heo * flag of the previous work while there must be a valid next work 2447affee4b2STejun Heo * after a work with LINKED flag set. 2448affee4b2STejun Heo * 2449affee4b2STejun Heo * Note that when @worker is non-NULL, @target may be modified 2450112202d9STejun Heo * underneath us, so we can't reliably determine pwq from @target. 24514690c4abSTejun Heo * 24524690c4abSTejun Heo * CONTEXT: 2453d565ed63STejun Heo * spin_lock_irq(pool->lock). 24544690c4abSTejun Heo */ 2455112202d9STejun Heo static void insert_wq_barrier(struct pool_workqueue *pwq, 2456affee4b2STejun Heo struct wq_barrier *barr, 2457affee4b2STejun Heo struct work_struct *target, struct worker *worker) 2458fc2e4d70SOleg Nesterov { 2459affee4b2STejun Heo struct list_head *head; 2460affee4b2STejun Heo unsigned int linked = 0; 2461affee4b2STejun Heo 2462dc186ad7SThomas Gleixner /* 2463d565ed63STejun Heo * debugobject calls are safe here even with pool->lock locked 2464dc186ad7SThomas Gleixner * as we know for sure that this will not trigger any of the 2465dc186ad7SThomas Gleixner * checks and call back into the fixup functions where we 2466dc186ad7SThomas Gleixner * might deadlock. 2467dc186ad7SThomas Gleixner */ 2468ca1cab37SAndrew Morton INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); 246922df02bbSTejun Heo __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); 2470fc2e4d70SOleg Nesterov init_completion(&barr->done); 247183c22520SOleg Nesterov 2472affee4b2STejun Heo /* 2473affee4b2STejun Heo * If @target is currently being executed, schedule the 2474affee4b2STejun Heo * barrier to the worker; otherwise, put it after @target. 2475affee4b2STejun Heo */ 2476affee4b2STejun Heo if (worker) 2477affee4b2STejun Heo head = worker->scheduled.next; 2478affee4b2STejun Heo else { 2479affee4b2STejun Heo unsigned long *bits = work_data_bits(target); 2480affee4b2STejun Heo 2481affee4b2STejun Heo head = target->entry.next; 2482affee4b2STejun Heo /* there can already be other linked works, inherit and set */ 2483affee4b2STejun Heo linked = *bits & WORK_STRUCT_LINKED; 2484affee4b2STejun Heo __set_bit(WORK_STRUCT_LINKED_BIT, bits); 2485affee4b2STejun Heo } 2486affee4b2STejun Heo 2487dc186ad7SThomas Gleixner debug_work_activate(&barr->work); 2488112202d9STejun Heo insert_work(pwq, &barr->work, head, 2489affee4b2STejun Heo work_color_to_flags(WORK_NO_COLOR) | linked); 2490fc2e4d70SOleg Nesterov } 2491fc2e4d70SOleg Nesterov 249273f53c4aSTejun Heo /** 2493112202d9STejun Heo * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing 249473f53c4aSTejun Heo * @wq: workqueue being flushed 249573f53c4aSTejun Heo * @flush_color: new flush color, < 0 for no-op 249673f53c4aSTejun Heo * @work_color: new work color, < 0 for no-op 249773f53c4aSTejun Heo * 2498112202d9STejun Heo * Prepare pwqs for workqueue flushing. 249973f53c4aSTejun Heo * 2500112202d9STejun Heo * If @flush_color is non-negative, flush_color on all pwqs should be 2501112202d9STejun Heo * -1. If no pwq has in-flight commands at the specified color, all 2502112202d9STejun Heo * pwq->flush_color's stay at -1 and %false is returned. If any pwq 2503112202d9STejun Heo * has in flight commands, its pwq->flush_color is set to 2504112202d9STejun Heo * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq 250573f53c4aSTejun Heo * wakeup logic is armed and %true is returned. 250673f53c4aSTejun Heo * 250773f53c4aSTejun Heo * The caller should have initialized @wq->first_flusher prior to 250873f53c4aSTejun Heo * calling this function with non-negative @flush_color. If 250973f53c4aSTejun Heo * @flush_color is negative, no flush color update is done and %false 251073f53c4aSTejun Heo * is returned. 251173f53c4aSTejun Heo * 2512112202d9STejun Heo * If @work_color is non-negative, all pwqs should have the same 251373f53c4aSTejun Heo * work_color which is previous to @work_color and all will be 251473f53c4aSTejun Heo * advanced to @work_color. 251573f53c4aSTejun Heo * 251673f53c4aSTejun Heo * CONTEXT: 25173c25a55dSLai Jiangshan * mutex_lock(wq->mutex). 251873f53c4aSTejun Heo * 251973f53c4aSTejun Heo * RETURNS: 252073f53c4aSTejun Heo * %true if @flush_color >= 0 and there's something to flush. %false 252173f53c4aSTejun Heo * otherwise. 252273f53c4aSTejun Heo */ 2523112202d9STejun Heo static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, 252473f53c4aSTejun Heo int flush_color, int work_color) 25251da177e4SLinus Torvalds { 252673f53c4aSTejun Heo bool wait = false; 252749e3cf44STejun Heo struct pool_workqueue *pwq; 25281da177e4SLinus Torvalds 252973f53c4aSTejun Heo if (flush_color >= 0) { 25306183c009STejun Heo WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); 2531112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 1); 2532dc186ad7SThomas Gleixner } 253314441960SOleg Nesterov 253449e3cf44STejun Heo for_each_pwq(pwq, wq) { 2535112202d9STejun Heo struct worker_pool *pool = pwq->pool; 25361da177e4SLinus Torvalds 2537b09f4fd3SLai Jiangshan spin_lock_irq(&pool->lock); 253873f53c4aSTejun Heo 253973f53c4aSTejun Heo if (flush_color >= 0) { 25406183c009STejun Heo WARN_ON_ONCE(pwq->flush_color != -1); 254173f53c4aSTejun Heo 2542112202d9STejun Heo if (pwq->nr_in_flight[flush_color]) { 2543112202d9STejun Heo pwq->flush_color = flush_color; 2544112202d9STejun Heo atomic_inc(&wq->nr_pwqs_to_flush); 254573f53c4aSTejun Heo wait = true; 25461da177e4SLinus Torvalds } 254773f53c4aSTejun Heo } 254873f53c4aSTejun Heo 254973f53c4aSTejun Heo if (work_color >= 0) { 25506183c009STejun Heo WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); 2551112202d9STejun Heo pwq->work_color = work_color; 255273f53c4aSTejun Heo } 255373f53c4aSTejun Heo 2554b09f4fd3SLai Jiangshan spin_unlock_irq(&pool->lock); 25551da177e4SLinus Torvalds } 25561da177e4SLinus Torvalds 2557112202d9STejun Heo if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) 255873f53c4aSTejun Heo complete(&wq->first_flusher->done); 255973f53c4aSTejun Heo 256073f53c4aSTejun Heo return wait; 256183c22520SOleg Nesterov } 25621da177e4SLinus Torvalds 25630fcb78c2SRolf Eike Beer /** 25641da177e4SLinus Torvalds * flush_workqueue - ensure that any scheduled work has run to completion. 25650fcb78c2SRolf Eike Beer * @wq: workqueue to flush 25661da177e4SLinus Torvalds * 2567c5aa87bbSTejun Heo * This function sleeps until all work items which were queued on entry 2568c5aa87bbSTejun Heo * have finished execution, but it is not livelocked by new incoming ones. 25691da177e4SLinus Torvalds */ 25707ad5b3a5SHarvey Harrison void flush_workqueue(struct workqueue_struct *wq) 25711da177e4SLinus Torvalds { 257273f53c4aSTejun Heo struct wq_flusher this_flusher = { 257373f53c4aSTejun Heo .list = LIST_HEAD_INIT(this_flusher.list), 257473f53c4aSTejun Heo .flush_color = -1, 257573f53c4aSTejun Heo .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), 257673f53c4aSTejun Heo }; 257773f53c4aSTejun Heo int next_color; 2578b1f4ec17SOleg Nesterov 25793295f0efSIngo Molnar lock_map_acquire(&wq->lockdep_map); 25803295f0efSIngo Molnar lock_map_release(&wq->lockdep_map); 258173f53c4aSTejun Heo 25823c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 258373f53c4aSTejun Heo 258473f53c4aSTejun Heo /* 258573f53c4aSTejun Heo * Start-to-wait phase 258673f53c4aSTejun Heo */ 258773f53c4aSTejun Heo next_color = work_next_color(wq->work_color); 258873f53c4aSTejun Heo 258973f53c4aSTejun Heo if (next_color != wq->flush_color) { 259073f53c4aSTejun Heo /* 259173f53c4aSTejun Heo * Color space is not full. The current work_color 259273f53c4aSTejun Heo * becomes our flush_color and work_color is advanced 259373f53c4aSTejun Heo * by one. 259473f53c4aSTejun Heo */ 25956183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); 259673f53c4aSTejun Heo this_flusher.flush_color = wq->work_color; 259773f53c4aSTejun Heo wq->work_color = next_color; 259873f53c4aSTejun Heo 259973f53c4aSTejun Heo if (!wq->first_flusher) { 260073f53c4aSTejun Heo /* no flush in progress, become the first flusher */ 26016183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 260273f53c4aSTejun Heo 260373f53c4aSTejun Heo wq->first_flusher = &this_flusher; 260473f53c4aSTejun Heo 2605112202d9STejun Heo if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, 260673f53c4aSTejun Heo wq->work_color)) { 260773f53c4aSTejun Heo /* nothing to flush, done */ 260873f53c4aSTejun Heo wq->flush_color = next_color; 260973f53c4aSTejun Heo wq->first_flusher = NULL; 261073f53c4aSTejun Heo goto out_unlock; 261173f53c4aSTejun Heo } 261273f53c4aSTejun Heo } else { 261373f53c4aSTejun Heo /* wait in queue */ 26146183c009STejun Heo WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); 261573f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_queue); 2616112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 261773f53c4aSTejun Heo } 261873f53c4aSTejun Heo } else { 261973f53c4aSTejun Heo /* 262073f53c4aSTejun Heo * Oops, color space is full, wait on overflow queue. 262173f53c4aSTejun Heo * The next flush completion will assign us 262273f53c4aSTejun Heo * flush_color and transfer to flusher_queue. 262373f53c4aSTejun Heo */ 262473f53c4aSTejun Heo list_add_tail(&this_flusher.list, &wq->flusher_overflow); 262573f53c4aSTejun Heo } 262673f53c4aSTejun Heo 26273c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 262873f53c4aSTejun Heo 262973f53c4aSTejun Heo wait_for_completion(&this_flusher.done); 263073f53c4aSTejun Heo 263173f53c4aSTejun Heo /* 263273f53c4aSTejun Heo * Wake-up-and-cascade phase 263373f53c4aSTejun Heo * 263473f53c4aSTejun Heo * First flushers are responsible for cascading flushes and 263573f53c4aSTejun Heo * handling overflow. Non-first flushers can simply return. 263673f53c4aSTejun Heo */ 263773f53c4aSTejun Heo if (wq->first_flusher != &this_flusher) 263873f53c4aSTejun Heo return; 263973f53c4aSTejun Heo 26403c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 264173f53c4aSTejun Heo 26424ce48b37STejun Heo /* we might have raced, check again with mutex held */ 26434ce48b37STejun Heo if (wq->first_flusher != &this_flusher) 26444ce48b37STejun Heo goto out_unlock; 26454ce48b37STejun Heo 264673f53c4aSTejun Heo wq->first_flusher = NULL; 264773f53c4aSTejun Heo 26486183c009STejun Heo WARN_ON_ONCE(!list_empty(&this_flusher.list)); 26496183c009STejun Heo WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); 265073f53c4aSTejun Heo 265173f53c4aSTejun Heo while (true) { 265273f53c4aSTejun Heo struct wq_flusher *next, *tmp; 265373f53c4aSTejun Heo 265473f53c4aSTejun Heo /* complete all the flushers sharing the current flush color */ 265573f53c4aSTejun Heo list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { 265673f53c4aSTejun Heo if (next->flush_color != wq->flush_color) 265773f53c4aSTejun Heo break; 265873f53c4aSTejun Heo list_del_init(&next->list); 265973f53c4aSTejun Heo complete(&next->done); 266073f53c4aSTejun Heo } 266173f53c4aSTejun Heo 26626183c009STejun Heo WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && 266373f53c4aSTejun Heo wq->flush_color != work_next_color(wq->work_color)); 266473f53c4aSTejun Heo 266573f53c4aSTejun Heo /* this flush_color is finished, advance by one */ 266673f53c4aSTejun Heo wq->flush_color = work_next_color(wq->flush_color); 266773f53c4aSTejun Heo 266873f53c4aSTejun Heo /* one color has been freed, handle overflow queue */ 266973f53c4aSTejun Heo if (!list_empty(&wq->flusher_overflow)) { 267073f53c4aSTejun Heo /* 267173f53c4aSTejun Heo * Assign the same color to all overflowed 267273f53c4aSTejun Heo * flushers, advance work_color and append to 267373f53c4aSTejun Heo * flusher_queue. This is the start-to-wait 267473f53c4aSTejun Heo * phase for these overflowed flushers. 267573f53c4aSTejun Heo */ 267673f53c4aSTejun Heo list_for_each_entry(tmp, &wq->flusher_overflow, list) 267773f53c4aSTejun Heo tmp->flush_color = wq->work_color; 267873f53c4aSTejun Heo 267973f53c4aSTejun Heo wq->work_color = work_next_color(wq->work_color); 268073f53c4aSTejun Heo 268173f53c4aSTejun Heo list_splice_tail_init(&wq->flusher_overflow, 268273f53c4aSTejun Heo &wq->flusher_queue); 2683112202d9STejun Heo flush_workqueue_prep_pwqs(wq, -1, wq->work_color); 268473f53c4aSTejun Heo } 268573f53c4aSTejun Heo 268673f53c4aSTejun Heo if (list_empty(&wq->flusher_queue)) { 26876183c009STejun Heo WARN_ON_ONCE(wq->flush_color != wq->work_color); 268873f53c4aSTejun Heo break; 268973f53c4aSTejun Heo } 269073f53c4aSTejun Heo 269173f53c4aSTejun Heo /* 269273f53c4aSTejun Heo * Need to flush more colors. Make the next flusher 2693112202d9STejun Heo * the new first flusher and arm pwqs. 269473f53c4aSTejun Heo */ 26956183c009STejun Heo WARN_ON_ONCE(wq->flush_color == wq->work_color); 26966183c009STejun Heo WARN_ON_ONCE(wq->flush_color != next->flush_color); 269773f53c4aSTejun Heo 269873f53c4aSTejun Heo list_del_init(&next->list); 269973f53c4aSTejun Heo wq->first_flusher = next; 270073f53c4aSTejun Heo 2701112202d9STejun Heo if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) 270273f53c4aSTejun Heo break; 270373f53c4aSTejun Heo 270473f53c4aSTejun Heo /* 270573f53c4aSTejun Heo * Meh... this color is already done, clear first 270673f53c4aSTejun Heo * flusher and repeat cascading. 270773f53c4aSTejun Heo */ 270873f53c4aSTejun Heo wq->first_flusher = NULL; 270973f53c4aSTejun Heo } 271073f53c4aSTejun Heo 271173f53c4aSTejun Heo out_unlock: 27123c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 27131da177e4SLinus Torvalds } 2714ae90dd5dSDave Jones EXPORT_SYMBOL_GPL(flush_workqueue); 27151da177e4SLinus Torvalds 27169c5a2ba7STejun Heo /** 27179c5a2ba7STejun Heo * drain_workqueue - drain a workqueue 27189c5a2ba7STejun Heo * @wq: workqueue to drain 27199c5a2ba7STejun Heo * 27209c5a2ba7STejun Heo * Wait until the workqueue becomes empty. While draining is in progress, 27219c5a2ba7STejun Heo * only chain queueing is allowed. IOW, only currently pending or running 27229c5a2ba7STejun Heo * work items on @wq can queue further work items on it. @wq is flushed 27239c5a2ba7STejun Heo * repeatedly until it becomes empty. The number of flushing is detemined 27249c5a2ba7STejun Heo * by the depth of chaining and should be relatively short. Whine if it 27259c5a2ba7STejun Heo * takes too long. 27269c5a2ba7STejun Heo */ 27279c5a2ba7STejun Heo void drain_workqueue(struct workqueue_struct *wq) 27289c5a2ba7STejun Heo { 27299c5a2ba7STejun Heo unsigned int flush_cnt = 0; 273049e3cf44STejun Heo struct pool_workqueue *pwq; 27319c5a2ba7STejun Heo 27329c5a2ba7STejun Heo /* 27339c5a2ba7STejun Heo * __queue_work() needs to test whether there are drainers, is much 27349c5a2ba7STejun Heo * hotter than drain_workqueue() and already looks at @wq->flags. 2735618b01ebSTejun Heo * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. 27369c5a2ba7STejun Heo */ 273787fc741eSLai Jiangshan mutex_lock(&wq->mutex); 27389c5a2ba7STejun Heo if (!wq->nr_drainers++) 2739618b01ebSTejun Heo wq->flags |= __WQ_DRAINING; 274087fc741eSLai Jiangshan mutex_unlock(&wq->mutex); 27419c5a2ba7STejun Heo reflush: 27429c5a2ba7STejun Heo flush_workqueue(wq); 27439c5a2ba7STejun Heo 2744b09f4fd3SLai Jiangshan mutex_lock(&wq->mutex); 274576af4d93STejun Heo 274649e3cf44STejun Heo for_each_pwq(pwq, wq) { 2747fa2563e4SThomas Tuttle bool drained; 27489c5a2ba7STejun Heo 2749b09f4fd3SLai Jiangshan spin_lock_irq(&pwq->pool->lock); 2750112202d9STejun Heo drained = !pwq->nr_active && list_empty(&pwq->delayed_works); 2751b09f4fd3SLai Jiangshan spin_unlock_irq(&pwq->pool->lock); 2752fa2563e4SThomas Tuttle 2753fa2563e4SThomas Tuttle if (drained) 27549c5a2ba7STejun Heo continue; 27559c5a2ba7STejun Heo 27569c5a2ba7STejun Heo if (++flush_cnt == 10 || 27579c5a2ba7STejun Heo (flush_cnt % 100 == 0 && flush_cnt <= 1000)) 2758c5aa87bbSTejun Heo pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n", 27599c5a2ba7STejun Heo wq->name, flush_cnt); 276076af4d93STejun Heo 2761b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 27629c5a2ba7STejun Heo goto reflush; 27639c5a2ba7STejun Heo } 27649c5a2ba7STejun Heo 27659c5a2ba7STejun Heo if (!--wq->nr_drainers) 2766618b01ebSTejun Heo wq->flags &= ~__WQ_DRAINING; 276787fc741eSLai Jiangshan mutex_unlock(&wq->mutex); 27689c5a2ba7STejun Heo } 27699c5a2ba7STejun Heo EXPORT_SYMBOL_GPL(drain_workqueue); 27709c5a2ba7STejun Heo 2771606a5020STejun Heo static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) 2772baf59022STejun Heo { 2773baf59022STejun Heo struct worker *worker = NULL; 2774c9e7cf27STejun Heo struct worker_pool *pool; 2775112202d9STejun Heo struct pool_workqueue *pwq; 2776baf59022STejun Heo 2777baf59022STejun Heo might_sleep(); 2778baf59022STejun Heo 2779fa1b54e6STejun Heo local_irq_disable(); 2780fa1b54e6STejun Heo pool = get_work_pool(work); 2781fa1b54e6STejun Heo if (!pool) { 2782fa1b54e6STejun Heo local_irq_enable(); 2783fa1b54e6STejun Heo return false; 2784fa1b54e6STejun Heo } 2785fa1b54e6STejun Heo 2786fa1b54e6STejun Heo spin_lock(&pool->lock); 27870b3dae68SLai Jiangshan /* see the comment in try_to_grab_pending() with the same code */ 2788112202d9STejun Heo pwq = get_work_pwq(work); 2789112202d9STejun Heo if (pwq) { 2790112202d9STejun Heo if (unlikely(pwq->pool != pool)) 2791baf59022STejun Heo goto already_gone; 2792606a5020STejun Heo } else { 2793c9e7cf27STejun Heo worker = find_worker_executing_work(pool, work); 2794baf59022STejun Heo if (!worker) 2795baf59022STejun Heo goto already_gone; 2796112202d9STejun Heo pwq = worker->current_pwq; 2797606a5020STejun Heo } 2798baf59022STejun Heo 2799112202d9STejun Heo insert_wq_barrier(pwq, barr, work, worker); 2800d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2801baf59022STejun Heo 2802e159489bSTejun Heo /* 2803e159489bSTejun Heo * If @max_active is 1 or rescuer is in use, flushing another work 2804e159489bSTejun Heo * item on the same workqueue may lead to deadlock. Make sure the 2805e159489bSTejun Heo * flusher is not running on the same workqueue by verifying write 2806e159489bSTejun Heo * access. 2807e159489bSTejun Heo */ 2808493008a8STejun Heo if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer) 2809112202d9STejun Heo lock_map_acquire(&pwq->wq->lockdep_map); 2810e159489bSTejun Heo else 2811112202d9STejun Heo lock_map_acquire_read(&pwq->wq->lockdep_map); 2812112202d9STejun Heo lock_map_release(&pwq->wq->lockdep_map); 2813e159489bSTejun Heo 2814baf59022STejun Heo return true; 2815baf59022STejun Heo already_gone: 2816d565ed63STejun Heo spin_unlock_irq(&pool->lock); 2817baf59022STejun Heo return false; 2818baf59022STejun Heo } 2819baf59022STejun Heo 2820c2fda509SLai Jiangshan static bool __flush_work(struct work_struct *work) 2821c2fda509SLai Jiangshan { 2822c2fda509SLai Jiangshan struct wq_barrier barr; 2823c2fda509SLai Jiangshan 2824c2fda509SLai Jiangshan if (start_flush_work(work, &barr)) { 2825c2fda509SLai Jiangshan wait_for_completion(&barr.done); 2826c2fda509SLai Jiangshan destroy_work_on_stack(&barr.work); 2827c2fda509SLai Jiangshan return true; 2828c2fda509SLai Jiangshan } else { 2829c2fda509SLai Jiangshan return false; 2830c2fda509SLai Jiangshan } 2831c2fda509SLai Jiangshan } 2832c2fda509SLai Jiangshan 2833db700897SOleg Nesterov /** 2834401a8d04STejun Heo * flush_work - wait for a work to finish executing the last queueing instance 2835401a8d04STejun Heo * @work: the work to flush 2836db700897SOleg Nesterov * 2837606a5020STejun Heo * Wait until @work has finished execution. @work is guaranteed to be idle 2838606a5020STejun Heo * on return if it hasn't been requeued since flush started. 2839401a8d04STejun Heo * 2840401a8d04STejun Heo * RETURNS: 2841401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2842401a8d04STejun Heo * %false if it was already idle. 2843db700897SOleg Nesterov */ 2844401a8d04STejun Heo bool flush_work(struct work_struct *work) 2845db700897SOleg Nesterov { 28460976dfc1SStephen Boyd lock_map_acquire(&work->lockdep_map); 28470976dfc1SStephen Boyd lock_map_release(&work->lockdep_map); 28480976dfc1SStephen Boyd 2849c2fda509SLai Jiangshan return __flush_work(work); 2850606a5020STejun Heo } 2851db700897SOleg Nesterov EXPORT_SYMBOL_GPL(flush_work); 2852db700897SOleg Nesterov 285336e227d2STejun Heo static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) 2854401a8d04STejun Heo { 2855bbb68dfaSTejun Heo unsigned long flags; 28561f1f642eSOleg Nesterov int ret; 28571f1f642eSOleg Nesterov 28581f1f642eSOleg Nesterov do { 2859bbb68dfaSTejun Heo ret = try_to_grab_pending(work, is_dwork, &flags); 2860bbb68dfaSTejun Heo /* 2861bbb68dfaSTejun Heo * If someone else is canceling, wait for the same event it 2862bbb68dfaSTejun Heo * would be waiting for before retrying. 2863bbb68dfaSTejun Heo */ 2864bbb68dfaSTejun Heo if (unlikely(ret == -ENOENT)) 2865606a5020STejun Heo flush_work(work); 28661f1f642eSOleg Nesterov } while (unlikely(ret < 0)); 28671f1f642eSOleg Nesterov 2868bbb68dfaSTejun Heo /* tell other tasks trying to grab @work to back off */ 2869bbb68dfaSTejun Heo mark_work_canceling(work); 2870bbb68dfaSTejun Heo local_irq_restore(flags); 2871bbb68dfaSTejun Heo 2872606a5020STejun Heo flush_work(work); 28737a22ad75STejun Heo clear_work_data(work); 28741f1f642eSOleg Nesterov return ret; 28751f1f642eSOleg Nesterov } 28761f1f642eSOleg Nesterov 28776e84d644SOleg Nesterov /** 2878401a8d04STejun Heo * cancel_work_sync - cancel a work and wait for it to finish 2879401a8d04STejun Heo * @work: the work to cancel 28806e84d644SOleg Nesterov * 2881401a8d04STejun Heo * Cancel @work and wait for its execution to finish. This function 2882401a8d04STejun Heo * can be used even if the work re-queues itself or migrates to 2883401a8d04STejun Heo * another workqueue. On return from this function, @work is 2884401a8d04STejun Heo * guaranteed to be not pending or executing on any CPU. 28851f1f642eSOleg Nesterov * 2886401a8d04STejun Heo * cancel_work_sync(&delayed_work->work) must not be used for 2887401a8d04STejun Heo * delayed_work's. Use cancel_delayed_work_sync() instead. 28886e84d644SOleg Nesterov * 2889401a8d04STejun Heo * The caller must ensure that the workqueue on which @work was last 28906e84d644SOleg Nesterov * queued can't be destroyed before this function returns. 2891401a8d04STejun Heo * 2892401a8d04STejun Heo * RETURNS: 2893401a8d04STejun Heo * %true if @work was pending, %false otherwise. 28946e84d644SOleg Nesterov */ 2895401a8d04STejun Heo bool cancel_work_sync(struct work_struct *work) 28966e84d644SOleg Nesterov { 289736e227d2STejun Heo return __cancel_work_timer(work, false); 2898b89deed3SOleg Nesterov } 289928e53bddSOleg Nesterov EXPORT_SYMBOL_GPL(cancel_work_sync); 2900b89deed3SOleg Nesterov 29016e84d644SOleg Nesterov /** 2902401a8d04STejun Heo * flush_delayed_work - wait for a dwork to finish executing the last queueing 2903401a8d04STejun Heo * @dwork: the delayed work to flush 29046e84d644SOleg Nesterov * 2905401a8d04STejun Heo * Delayed timer is cancelled and the pending work is queued for 2906401a8d04STejun Heo * immediate execution. Like flush_work(), this function only 2907401a8d04STejun Heo * considers the last queueing instance of @dwork. 29081f1f642eSOleg Nesterov * 2909401a8d04STejun Heo * RETURNS: 2910401a8d04STejun Heo * %true if flush_work() waited for the work to finish execution, 2911401a8d04STejun Heo * %false if it was already idle. 29126e84d644SOleg Nesterov */ 2913401a8d04STejun Heo bool flush_delayed_work(struct delayed_work *dwork) 2914401a8d04STejun Heo { 29158930cabaSTejun Heo local_irq_disable(); 2916401a8d04STejun Heo if (del_timer_sync(&dwork->timer)) 291760c057bcSLai Jiangshan __queue_work(dwork->cpu, dwork->wq, &dwork->work); 29188930cabaSTejun Heo local_irq_enable(); 2919401a8d04STejun Heo return flush_work(&dwork->work); 2920401a8d04STejun Heo } 2921401a8d04STejun Heo EXPORT_SYMBOL(flush_delayed_work); 2922401a8d04STejun Heo 2923401a8d04STejun Heo /** 292457b30ae7STejun Heo * cancel_delayed_work - cancel a delayed work 292557b30ae7STejun Heo * @dwork: delayed_work to cancel 292609383498STejun Heo * 292757b30ae7STejun Heo * Kill off a pending delayed_work. Returns %true if @dwork was pending 292857b30ae7STejun Heo * and canceled; %false if wasn't pending. Note that the work callback 292957b30ae7STejun Heo * function may still be running on return, unless it returns %true and the 293057b30ae7STejun Heo * work doesn't re-arm itself. Explicitly flush or use 293157b30ae7STejun Heo * cancel_delayed_work_sync() to wait on it. 293209383498STejun Heo * 293357b30ae7STejun Heo * This function is safe to call from any context including IRQ handler. 293409383498STejun Heo */ 293557b30ae7STejun Heo bool cancel_delayed_work(struct delayed_work *dwork) 293609383498STejun Heo { 293757b30ae7STejun Heo unsigned long flags; 293857b30ae7STejun Heo int ret; 293957b30ae7STejun Heo 294057b30ae7STejun Heo do { 294157b30ae7STejun Heo ret = try_to_grab_pending(&dwork->work, true, &flags); 294257b30ae7STejun Heo } while (unlikely(ret == -EAGAIN)); 294357b30ae7STejun Heo 294457b30ae7STejun Heo if (unlikely(ret < 0)) 294557b30ae7STejun Heo return false; 294657b30ae7STejun Heo 29477c3eed5cSTejun Heo set_work_pool_and_clear_pending(&dwork->work, 29487c3eed5cSTejun Heo get_work_pool_id(&dwork->work)); 294957b30ae7STejun Heo local_irq_restore(flags); 2950c0158ca6SDan Magenheimer return ret; 295109383498STejun Heo } 295257b30ae7STejun Heo EXPORT_SYMBOL(cancel_delayed_work); 295309383498STejun Heo 295409383498STejun Heo /** 2955401a8d04STejun Heo * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish 2956401a8d04STejun Heo * @dwork: the delayed work cancel 2957401a8d04STejun Heo * 2958401a8d04STejun Heo * This is cancel_work_sync() for delayed works. 2959401a8d04STejun Heo * 2960401a8d04STejun Heo * RETURNS: 2961401a8d04STejun Heo * %true if @dwork was pending, %false otherwise. 2962401a8d04STejun Heo */ 2963401a8d04STejun Heo bool cancel_delayed_work_sync(struct delayed_work *dwork) 29646e84d644SOleg Nesterov { 296536e227d2STejun Heo return __cancel_work_timer(&dwork->work, true); 29666e84d644SOleg Nesterov } 2967f5a421a4SOleg Nesterov EXPORT_SYMBOL(cancel_delayed_work_sync); 29681da177e4SLinus Torvalds 29690fcb78c2SRolf Eike Beer /** 297031ddd871STejun Heo * schedule_on_each_cpu - execute a function synchronously on each online CPU 2971b6136773SAndrew Morton * @func: the function to call 2972b6136773SAndrew Morton * 297331ddd871STejun Heo * schedule_on_each_cpu() executes @func on each online CPU using the 297431ddd871STejun Heo * system workqueue and blocks until all CPUs have completed. 2975b6136773SAndrew Morton * schedule_on_each_cpu() is very slow. 297631ddd871STejun Heo * 297731ddd871STejun Heo * RETURNS: 297831ddd871STejun Heo * 0 on success, -errno on failure. 2979b6136773SAndrew Morton */ 298065f27f38SDavid Howells int schedule_on_each_cpu(work_func_t func) 298115316ba8SChristoph Lameter { 298215316ba8SChristoph Lameter int cpu; 298338f51568SNamhyung Kim struct work_struct __percpu *works; 298415316ba8SChristoph Lameter 2985b6136773SAndrew Morton works = alloc_percpu(struct work_struct); 2986b6136773SAndrew Morton if (!works) 298715316ba8SChristoph Lameter return -ENOMEM; 2988b6136773SAndrew Morton 298995402b38SGautham R Shenoy get_online_cpus(); 299093981800STejun Heo 299115316ba8SChristoph Lameter for_each_online_cpu(cpu) { 29929bfb1839SIngo Molnar struct work_struct *work = per_cpu_ptr(works, cpu); 29939bfb1839SIngo Molnar 29949bfb1839SIngo Molnar INIT_WORK(work, func); 29958de6d308SOleg Nesterov schedule_work_on(cpu, work); 299615316ba8SChristoph Lameter } 299793981800STejun Heo 299893981800STejun Heo for_each_online_cpu(cpu) 29998616a89aSOleg Nesterov flush_work(per_cpu_ptr(works, cpu)); 300093981800STejun Heo 300195402b38SGautham R Shenoy put_online_cpus(); 3002b6136773SAndrew Morton free_percpu(works); 300315316ba8SChristoph Lameter return 0; 300415316ba8SChristoph Lameter } 300515316ba8SChristoph Lameter 3006eef6a7d5SAlan Stern /** 3007eef6a7d5SAlan Stern * flush_scheduled_work - ensure that any scheduled work has run to completion. 3008eef6a7d5SAlan Stern * 3009eef6a7d5SAlan Stern * Forces execution of the kernel-global workqueue and blocks until its 3010eef6a7d5SAlan Stern * completion. 3011eef6a7d5SAlan Stern * 3012eef6a7d5SAlan Stern * Think twice before calling this function! It's very easy to get into 3013eef6a7d5SAlan Stern * trouble if you don't take great care. Either of the following situations 3014eef6a7d5SAlan Stern * will lead to deadlock: 3015eef6a7d5SAlan Stern * 3016eef6a7d5SAlan Stern * One of the work items currently on the workqueue needs to acquire 3017eef6a7d5SAlan Stern * a lock held by your code or its caller. 3018eef6a7d5SAlan Stern * 3019eef6a7d5SAlan Stern * Your code is running in the context of a work routine. 3020eef6a7d5SAlan Stern * 3021eef6a7d5SAlan Stern * They will be detected by lockdep when they occur, but the first might not 3022eef6a7d5SAlan Stern * occur very often. It depends on what work items are on the workqueue and 3023eef6a7d5SAlan Stern * what locks they need, which you have no control over. 3024eef6a7d5SAlan Stern * 3025eef6a7d5SAlan Stern * In most situations flushing the entire workqueue is overkill; you merely 3026eef6a7d5SAlan Stern * need to know that a particular work item isn't queued and isn't running. 3027eef6a7d5SAlan Stern * In such cases you should use cancel_delayed_work_sync() or 3028eef6a7d5SAlan Stern * cancel_work_sync() instead. 3029eef6a7d5SAlan Stern */ 30301da177e4SLinus Torvalds void flush_scheduled_work(void) 30311da177e4SLinus Torvalds { 3032d320c038STejun Heo flush_workqueue(system_wq); 30331da177e4SLinus Torvalds } 3034ae90dd5dSDave Jones EXPORT_SYMBOL(flush_scheduled_work); 30351da177e4SLinus Torvalds 30361da177e4SLinus Torvalds /** 30371fa44ecaSJames Bottomley * execute_in_process_context - reliably execute the routine with user context 30381fa44ecaSJames Bottomley * @fn: the function to execute 30391fa44ecaSJames Bottomley * @ew: guaranteed storage for the execute work structure (must 30401fa44ecaSJames Bottomley * be available when the work executes) 30411fa44ecaSJames Bottomley * 30421fa44ecaSJames Bottomley * Executes the function immediately if process context is available, 30431fa44ecaSJames Bottomley * otherwise schedules the function for delayed execution. 30441fa44ecaSJames Bottomley * 30451fa44ecaSJames Bottomley * Returns: 0 - function was executed 30461fa44ecaSJames Bottomley * 1 - function was scheduled for execution 30471fa44ecaSJames Bottomley */ 304865f27f38SDavid Howells int execute_in_process_context(work_func_t fn, struct execute_work *ew) 30491fa44ecaSJames Bottomley { 30501fa44ecaSJames Bottomley if (!in_interrupt()) { 305165f27f38SDavid Howells fn(&ew->work); 30521fa44ecaSJames Bottomley return 0; 30531fa44ecaSJames Bottomley } 30541fa44ecaSJames Bottomley 305565f27f38SDavid Howells INIT_WORK(&ew->work, fn); 30561fa44ecaSJames Bottomley schedule_work(&ew->work); 30571fa44ecaSJames Bottomley 30581fa44ecaSJames Bottomley return 1; 30591fa44ecaSJames Bottomley } 30601fa44ecaSJames Bottomley EXPORT_SYMBOL_GPL(execute_in_process_context); 30611fa44ecaSJames Bottomley 3062226223abSTejun Heo #ifdef CONFIG_SYSFS 3063226223abSTejun Heo /* 3064226223abSTejun Heo * Workqueues with WQ_SYSFS flag set is visible to userland via 3065226223abSTejun Heo * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the 3066226223abSTejun Heo * following attributes. 3067226223abSTejun Heo * 3068226223abSTejun Heo * per_cpu RO bool : whether the workqueue is per-cpu or unbound 3069226223abSTejun Heo * max_active RW int : maximum number of in-flight work items 3070226223abSTejun Heo * 3071226223abSTejun Heo * Unbound workqueues have the following extra attributes. 3072226223abSTejun Heo * 3073226223abSTejun Heo * id RO int : the associated pool ID 3074226223abSTejun Heo * nice RW int : nice value of the workers 3075226223abSTejun Heo * cpumask RW mask : bitmask of allowed CPUs for the workers 3076226223abSTejun Heo */ 3077226223abSTejun Heo struct wq_device { 3078226223abSTejun Heo struct workqueue_struct *wq; 3079226223abSTejun Heo struct device dev; 3080226223abSTejun Heo }; 3081226223abSTejun Heo 3082226223abSTejun Heo static struct workqueue_struct *dev_to_wq(struct device *dev) 3083226223abSTejun Heo { 3084226223abSTejun Heo struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 3085226223abSTejun Heo 3086226223abSTejun Heo return wq_dev->wq; 3087226223abSTejun Heo } 3088226223abSTejun Heo 3089226223abSTejun Heo static ssize_t wq_per_cpu_show(struct device *dev, 3090226223abSTejun Heo struct device_attribute *attr, char *buf) 3091226223abSTejun Heo { 3092226223abSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3093226223abSTejun Heo 3094226223abSTejun Heo return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); 3095226223abSTejun Heo } 3096226223abSTejun Heo 3097226223abSTejun Heo static ssize_t wq_max_active_show(struct device *dev, 3098226223abSTejun Heo struct device_attribute *attr, char *buf) 3099226223abSTejun Heo { 3100226223abSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3101226223abSTejun Heo 3102226223abSTejun Heo return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); 3103226223abSTejun Heo } 3104226223abSTejun Heo 3105226223abSTejun Heo static ssize_t wq_max_active_store(struct device *dev, 3106226223abSTejun Heo struct device_attribute *attr, 3107226223abSTejun Heo const char *buf, size_t count) 3108226223abSTejun Heo { 3109226223abSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3110226223abSTejun Heo int val; 3111226223abSTejun Heo 3112226223abSTejun Heo if (sscanf(buf, "%d", &val) != 1 || val <= 0) 3113226223abSTejun Heo return -EINVAL; 3114226223abSTejun Heo 3115226223abSTejun Heo workqueue_set_max_active(wq, val); 3116226223abSTejun Heo return count; 3117226223abSTejun Heo } 3118226223abSTejun Heo 3119226223abSTejun Heo static struct device_attribute wq_sysfs_attrs[] = { 3120226223abSTejun Heo __ATTR(per_cpu, 0444, wq_per_cpu_show, NULL), 3121226223abSTejun Heo __ATTR(max_active, 0644, wq_max_active_show, wq_max_active_store), 3122226223abSTejun Heo __ATTR_NULL, 3123226223abSTejun Heo }; 3124226223abSTejun Heo 3125d55262c4STejun Heo static ssize_t wq_pool_ids_show(struct device *dev, 3126226223abSTejun Heo struct device_attribute *attr, char *buf) 3127226223abSTejun Heo { 3128226223abSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3129d55262c4STejun Heo const char *delim = ""; 3130d55262c4STejun Heo int node, written = 0; 3131226223abSTejun Heo 3132226223abSTejun Heo rcu_read_lock_sched(); 3133d55262c4STejun Heo for_each_node(node) { 3134d55262c4STejun Heo written += scnprintf(buf + written, PAGE_SIZE - written, 3135d55262c4STejun Heo "%s%d:%d", delim, node, 3136d55262c4STejun Heo unbound_pwq_by_node(wq, node)->pool->id); 3137d55262c4STejun Heo delim = " "; 3138d55262c4STejun Heo } 3139d55262c4STejun Heo written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); 3140226223abSTejun Heo rcu_read_unlock_sched(); 3141226223abSTejun Heo 3142226223abSTejun Heo return written; 3143226223abSTejun Heo } 3144226223abSTejun Heo 3145226223abSTejun Heo static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, 3146226223abSTejun Heo char *buf) 3147226223abSTejun Heo { 3148226223abSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3149226223abSTejun Heo int written; 3150226223abSTejun Heo 31516029a918STejun Heo mutex_lock(&wq->mutex); 31526029a918STejun Heo written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); 31536029a918STejun Heo mutex_unlock(&wq->mutex); 3154226223abSTejun Heo 3155226223abSTejun Heo return written; 3156226223abSTejun Heo } 3157226223abSTejun Heo 3158226223abSTejun Heo /* prepare workqueue_attrs for sysfs store operations */ 3159226223abSTejun Heo static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) 3160226223abSTejun Heo { 3161226223abSTejun Heo struct workqueue_attrs *attrs; 3162226223abSTejun Heo 3163226223abSTejun Heo attrs = alloc_workqueue_attrs(GFP_KERNEL); 3164226223abSTejun Heo if (!attrs) 3165226223abSTejun Heo return NULL; 3166226223abSTejun Heo 31676029a918STejun Heo mutex_lock(&wq->mutex); 31686029a918STejun Heo copy_workqueue_attrs(attrs, wq->unbound_attrs); 31696029a918STejun Heo mutex_unlock(&wq->mutex); 3170226223abSTejun Heo return attrs; 3171226223abSTejun Heo } 3172226223abSTejun Heo 3173226223abSTejun Heo static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, 3174226223abSTejun Heo const char *buf, size_t count) 3175226223abSTejun Heo { 3176226223abSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3177226223abSTejun Heo struct workqueue_attrs *attrs; 3178226223abSTejun Heo int ret; 3179226223abSTejun Heo 3180226223abSTejun Heo attrs = wq_sysfs_prep_attrs(wq); 3181226223abSTejun Heo if (!attrs) 3182226223abSTejun Heo return -ENOMEM; 3183226223abSTejun Heo 3184226223abSTejun Heo if (sscanf(buf, "%d", &attrs->nice) == 1 && 3185226223abSTejun Heo attrs->nice >= -20 && attrs->nice <= 19) 3186226223abSTejun Heo ret = apply_workqueue_attrs(wq, attrs); 3187226223abSTejun Heo else 3188226223abSTejun Heo ret = -EINVAL; 3189226223abSTejun Heo 3190226223abSTejun Heo free_workqueue_attrs(attrs); 3191226223abSTejun Heo return ret ?: count; 3192226223abSTejun Heo } 3193226223abSTejun Heo 3194226223abSTejun Heo static ssize_t wq_cpumask_show(struct device *dev, 3195226223abSTejun Heo struct device_attribute *attr, char *buf) 3196226223abSTejun Heo { 3197226223abSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3198226223abSTejun Heo int written; 3199226223abSTejun Heo 32006029a918STejun Heo mutex_lock(&wq->mutex); 32016029a918STejun Heo written = cpumask_scnprintf(buf, PAGE_SIZE, wq->unbound_attrs->cpumask); 32026029a918STejun Heo mutex_unlock(&wq->mutex); 3203226223abSTejun Heo 3204226223abSTejun Heo written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); 3205226223abSTejun Heo return written; 3206226223abSTejun Heo } 3207226223abSTejun Heo 3208226223abSTejun Heo static ssize_t wq_cpumask_store(struct device *dev, 3209226223abSTejun Heo struct device_attribute *attr, 3210226223abSTejun Heo const char *buf, size_t count) 3211226223abSTejun Heo { 3212226223abSTejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3213226223abSTejun Heo struct workqueue_attrs *attrs; 3214226223abSTejun Heo int ret; 3215226223abSTejun Heo 3216226223abSTejun Heo attrs = wq_sysfs_prep_attrs(wq); 3217226223abSTejun Heo if (!attrs) 3218226223abSTejun Heo return -ENOMEM; 3219226223abSTejun Heo 3220226223abSTejun Heo ret = cpumask_parse(buf, attrs->cpumask); 3221226223abSTejun Heo if (!ret) 3222226223abSTejun Heo ret = apply_workqueue_attrs(wq, attrs); 3223226223abSTejun Heo 3224226223abSTejun Heo free_workqueue_attrs(attrs); 3225226223abSTejun Heo return ret ?: count; 3226226223abSTejun Heo } 3227226223abSTejun Heo 3228d55262c4STejun Heo static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr, 3229d55262c4STejun Heo char *buf) 3230d55262c4STejun Heo { 3231d55262c4STejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3232d55262c4STejun Heo int written; 3233d55262c4STejun Heo 3234d55262c4STejun Heo mutex_lock(&wq->mutex); 3235d55262c4STejun Heo written = scnprintf(buf, PAGE_SIZE, "%d\n", 3236d55262c4STejun Heo !wq->unbound_attrs->no_numa); 3237d55262c4STejun Heo mutex_unlock(&wq->mutex); 3238d55262c4STejun Heo 3239d55262c4STejun Heo return written; 3240d55262c4STejun Heo } 3241d55262c4STejun Heo 3242d55262c4STejun Heo static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, 3243d55262c4STejun Heo const char *buf, size_t count) 3244d55262c4STejun Heo { 3245d55262c4STejun Heo struct workqueue_struct *wq = dev_to_wq(dev); 3246d55262c4STejun Heo struct workqueue_attrs *attrs; 3247d55262c4STejun Heo int v, ret; 3248d55262c4STejun Heo 3249d55262c4STejun Heo attrs = wq_sysfs_prep_attrs(wq); 3250d55262c4STejun Heo if (!attrs) 3251d55262c4STejun Heo return -ENOMEM; 3252d55262c4STejun Heo 3253d55262c4STejun Heo ret = -EINVAL; 3254d55262c4STejun Heo if (sscanf(buf, "%d", &v) == 1) { 3255d55262c4STejun Heo attrs->no_numa = !v; 3256d55262c4STejun Heo ret = apply_workqueue_attrs(wq, attrs); 3257d55262c4STejun Heo } 3258d55262c4STejun Heo 3259d55262c4STejun Heo free_workqueue_attrs(attrs); 3260d55262c4STejun Heo return ret ?: count; 3261d55262c4STejun Heo } 3262d55262c4STejun Heo 3263226223abSTejun Heo static struct device_attribute wq_sysfs_unbound_attrs[] = { 3264d55262c4STejun Heo __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL), 3265226223abSTejun Heo __ATTR(nice, 0644, wq_nice_show, wq_nice_store), 3266226223abSTejun Heo __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), 3267d55262c4STejun Heo __ATTR(numa, 0644, wq_numa_show, wq_numa_store), 3268226223abSTejun Heo __ATTR_NULL, 3269226223abSTejun Heo }; 3270226223abSTejun Heo 3271226223abSTejun Heo static struct bus_type wq_subsys = { 3272226223abSTejun Heo .name = "workqueue", 3273226223abSTejun Heo .dev_attrs = wq_sysfs_attrs, 3274226223abSTejun Heo }; 3275226223abSTejun Heo 3276226223abSTejun Heo static int __init wq_sysfs_init(void) 3277226223abSTejun Heo { 3278226223abSTejun Heo return subsys_virtual_register(&wq_subsys, NULL); 3279226223abSTejun Heo } 3280226223abSTejun Heo core_initcall(wq_sysfs_init); 3281226223abSTejun Heo 3282226223abSTejun Heo static void wq_device_release(struct device *dev) 3283226223abSTejun Heo { 3284226223abSTejun Heo struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); 3285226223abSTejun Heo 3286226223abSTejun Heo kfree(wq_dev); 3287226223abSTejun Heo } 3288226223abSTejun Heo 3289226223abSTejun Heo /** 3290226223abSTejun Heo * workqueue_sysfs_register - make a workqueue visible in sysfs 3291226223abSTejun Heo * @wq: the workqueue to register 3292226223abSTejun Heo * 3293226223abSTejun Heo * Expose @wq in sysfs under /sys/bus/workqueue/devices. 3294226223abSTejun Heo * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set 3295226223abSTejun Heo * which is the preferred method. 3296226223abSTejun Heo * 3297226223abSTejun Heo * Workqueue user should use this function directly iff it wants to apply 3298226223abSTejun Heo * workqueue_attrs before making the workqueue visible in sysfs; otherwise, 3299226223abSTejun Heo * apply_workqueue_attrs() may race against userland updating the 3300226223abSTejun Heo * attributes. 3301226223abSTejun Heo * 3302226223abSTejun Heo * Returns 0 on success, -errno on failure. 3303226223abSTejun Heo */ 3304226223abSTejun Heo int workqueue_sysfs_register(struct workqueue_struct *wq) 3305226223abSTejun Heo { 3306226223abSTejun Heo struct wq_device *wq_dev; 3307226223abSTejun Heo int ret; 3308226223abSTejun Heo 3309226223abSTejun Heo /* 3310226223abSTejun Heo * Adjusting max_active or creating new pwqs by applyting 3311226223abSTejun Heo * attributes breaks ordering guarantee. Disallow exposing ordered 3312226223abSTejun Heo * workqueues. 3313226223abSTejun Heo */ 3314226223abSTejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED)) 3315226223abSTejun Heo return -EINVAL; 3316226223abSTejun Heo 3317226223abSTejun Heo wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); 3318226223abSTejun Heo if (!wq_dev) 3319226223abSTejun Heo return -ENOMEM; 3320226223abSTejun Heo 3321226223abSTejun Heo wq_dev->wq = wq; 3322226223abSTejun Heo wq_dev->dev.bus = &wq_subsys; 3323226223abSTejun Heo wq_dev->dev.init_name = wq->name; 3324226223abSTejun Heo wq_dev->dev.release = wq_device_release; 3325226223abSTejun Heo 3326226223abSTejun Heo /* 3327226223abSTejun Heo * unbound_attrs are created separately. Suppress uevent until 3328226223abSTejun Heo * everything is ready. 3329226223abSTejun Heo */ 3330226223abSTejun Heo dev_set_uevent_suppress(&wq_dev->dev, true); 3331226223abSTejun Heo 3332226223abSTejun Heo ret = device_register(&wq_dev->dev); 3333226223abSTejun Heo if (ret) { 3334226223abSTejun Heo kfree(wq_dev); 3335226223abSTejun Heo wq->wq_dev = NULL; 3336226223abSTejun Heo return ret; 3337226223abSTejun Heo } 3338226223abSTejun Heo 3339226223abSTejun Heo if (wq->flags & WQ_UNBOUND) { 3340226223abSTejun Heo struct device_attribute *attr; 3341226223abSTejun Heo 3342226223abSTejun Heo for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { 3343226223abSTejun Heo ret = device_create_file(&wq_dev->dev, attr); 3344226223abSTejun Heo if (ret) { 3345226223abSTejun Heo device_unregister(&wq_dev->dev); 3346226223abSTejun Heo wq->wq_dev = NULL; 3347226223abSTejun Heo return ret; 3348226223abSTejun Heo } 3349226223abSTejun Heo } 3350226223abSTejun Heo } 3351226223abSTejun Heo 3352226223abSTejun Heo kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); 3353226223abSTejun Heo return 0; 3354226223abSTejun Heo } 3355226223abSTejun Heo 3356226223abSTejun Heo /** 3357226223abSTejun Heo * workqueue_sysfs_unregister - undo workqueue_sysfs_register() 3358226223abSTejun Heo * @wq: the workqueue to unregister 3359226223abSTejun Heo * 3360226223abSTejun Heo * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. 3361226223abSTejun Heo */ 3362226223abSTejun Heo static void workqueue_sysfs_unregister(struct workqueue_struct *wq) 3363226223abSTejun Heo { 3364226223abSTejun Heo struct wq_device *wq_dev = wq->wq_dev; 3365226223abSTejun Heo 3366226223abSTejun Heo if (!wq->wq_dev) 3367226223abSTejun Heo return; 3368226223abSTejun Heo 3369226223abSTejun Heo wq->wq_dev = NULL; 3370226223abSTejun Heo device_unregister(&wq_dev->dev); 3371226223abSTejun Heo } 3372226223abSTejun Heo #else /* CONFIG_SYSFS */ 3373226223abSTejun Heo static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } 3374226223abSTejun Heo #endif /* CONFIG_SYSFS */ 3375226223abSTejun Heo 33767a4e344cSTejun Heo /** 33777a4e344cSTejun Heo * free_workqueue_attrs - free a workqueue_attrs 33787a4e344cSTejun Heo * @attrs: workqueue_attrs to free 33797a4e344cSTejun Heo * 33807a4e344cSTejun Heo * Undo alloc_workqueue_attrs(). 33817a4e344cSTejun Heo */ 33827a4e344cSTejun Heo void free_workqueue_attrs(struct workqueue_attrs *attrs) 33837a4e344cSTejun Heo { 33847a4e344cSTejun Heo if (attrs) { 33857a4e344cSTejun Heo free_cpumask_var(attrs->cpumask); 33867a4e344cSTejun Heo kfree(attrs); 33877a4e344cSTejun Heo } 33887a4e344cSTejun Heo } 33897a4e344cSTejun Heo 33907a4e344cSTejun Heo /** 33917a4e344cSTejun Heo * alloc_workqueue_attrs - allocate a workqueue_attrs 33927a4e344cSTejun Heo * @gfp_mask: allocation mask to use 33937a4e344cSTejun Heo * 33947a4e344cSTejun Heo * Allocate a new workqueue_attrs, initialize with default settings and 33957a4e344cSTejun Heo * return it. Returns NULL on failure. 33967a4e344cSTejun Heo */ 33977a4e344cSTejun Heo struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask) 33987a4e344cSTejun Heo { 33997a4e344cSTejun Heo struct workqueue_attrs *attrs; 34007a4e344cSTejun Heo 34017a4e344cSTejun Heo attrs = kzalloc(sizeof(*attrs), gfp_mask); 34027a4e344cSTejun Heo if (!attrs) 34037a4e344cSTejun Heo goto fail; 34047a4e344cSTejun Heo if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask)) 34057a4e344cSTejun Heo goto fail; 34067a4e344cSTejun Heo 340713e2e556STejun Heo cpumask_copy(attrs->cpumask, cpu_possible_mask); 34087a4e344cSTejun Heo return attrs; 34097a4e344cSTejun Heo fail: 34107a4e344cSTejun Heo free_workqueue_attrs(attrs); 34117a4e344cSTejun Heo return NULL; 34127a4e344cSTejun Heo } 34137a4e344cSTejun Heo 341429c91e99STejun Heo static void copy_workqueue_attrs(struct workqueue_attrs *to, 341529c91e99STejun Heo const struct workqueue_attrs *from) 341629c91e99STejun Heo { 341729c91e99STejun Heo to->nice = from->nice; 341829c91e99STejun Heo cpumask_copy(to->cpumask, from->cpumask); 34192865a8fbSShaohua Li /* 34202865a8fbSShaohua Li * Unlike hash and equality test, this function doesn't ignore 34212865a8fbSShaohua Li * ->no_numa as it is used for both pool and wq attrs. Instead, 34222865a8fbSShaohua Li * get_unbound_pool() explicitly clears ->no_numa after copying. 34232865a8fbSShaohua Li */ 34242865a8fbSShaohua Li to->no_numa = from->no_numa; 342529c91e99STejun Heo } 342629c91e99STejun Heo 342729c91e99STejun Heo /* hash value of the content of @attr */ 342829c91e99STejun Heo static u32 wqattrs_hash(const struct workqueue_attrs *attrs) 342929c91e99STejun Heo { 343029c91e99STejun Heo u32 hash = 0; 343129c91e99STejun Heo 343229c91e99STejun Heo hash = jhash_1word(attrs->nice, hash); 343313e2e556STejun Heo hash = jhash(cpumask_bits(attrs->cpumask), 343413e2e556STejun Heo BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); 343529c91e99STejun Heo return hash; 343629c91e99STejun Heo } 343729c91e99STejun Heo 343829c91e99STejun Heo /* content equality test */ 343929c91e99STejun Heo static bool wqattrs_equal(const struct workqueue_attrs *a, 344029c91e99STejun Heo const struct workqueue_attrs *b) 344129c91e99STejun Heo { 344229c91e99STejun Heo if (a->nice != b->nice) 344329c91e99STejun Heo return false; 344429c91e99STejun Heo if (!cpumask_equal(a->cpumask, b->cpumask)) 344529c91e99STejun Heo return false; 344629c91e99STejun Heo return true; 344729c91e99STejun Heo } 344829c91e99STejun Heo 34497a4e344cSTejun Heo /** 34507a4e344cSTejun Heo * init_worker_pool - initialize a newly zalloc'd worker_pool 34517a4e344cSTejun Heo * @pool: worker_pool to initialize 34527a4e344cSTejun Heo * 34537a4e344cSTejun Heo * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs. 345429c91e99STejun Heo * Returns 0 on success, -errno on failure. Even on failure, all fields 345529c91e99STejun Heo * inside @pool proper are initialized and put_unbound_pool() can be called 345629c91e99STejun Heo * on @pool safely to release it. 34577a4e344cSTejun Heo */ 34587a4e344cSTejun Heo static int init_worker_pool(struct worker_pool *pool) 34594e1a1f9aSTejun Heo { 34604e1a1f9aSTejun Heo spin_lock_init(&pool->lock); 346129c91e99STejun Heo pool->id = -1; 346229c91e99STejun Heo pool->cpu = -1; 3463f3f90ad4STejun Heo pool->node = NUMA_NO_NODE; 34644e1a1f9aSTejun Heo pool->flags |= POOL_DISASSOCIATED; 34654e1a1f9aSTejun Heo INIT_LIST_HEAD(&pool->worklist); 34664e1a1f9aSTejun Heo INIT_LIST_HEAD(&pool->idle_list); 34674e1a1f9aSTejun Heo hash_init(pool->busy_hash); 34684e1a1f9aSTejun Heo 34694e1a1f9aSTejun Heo init_timer_deferrable(&pool->idle_timer); 34704e1a1f9aSTejun Heo pool->idle_timer.function = idle_worker_timeout; 34714e1a1f9aSTejun Heo pool->idle_timer.data = (unsigned long)pool; 34724e1a1f9aSTejun Heo 34734e1a1f9aSTejun Heo setup_timer(&pool->mayday_timer, pool_mayday_timeout, 34744e1a1f9aSTejun Heo (unsigned long)pool); 34754e1a1f9aSTejun Heo 34764e1a1f9aSTejun Heo mutex_init(&pool->manager_arb); 3477bc3a1afcSTejun Heo mutex_init(&pool->manager_mutex); 3478822d8405STejun Heo idr_init(&pool->worker_idr); 34797a4e344cSTejun Heo 348029c91e99STejun Heo INIT_HLIST_NODE(&pool->hash_node); 348129c91e99STejun Heo pool->refcnt = 1; 348229c91e99STejun Heo 348329c91e99STejun Heo /* shouldn't fail above this point */ 34847a4e344cSTejun Heo pool->attrs = alloc_workqueue_attrs(GFP_KERNEL); 34857a4e344cSTejun Heo if (!pool->attrs) 34867a4e344cSTejun Heo return -ENOMEM; 34877a4e344cSTejun Heo return 0; 34884e1a1f9aSTejun Heo } 34894e1a1f9aSTejun Heo 349029c91e99STejun Heo static void rcu_free_pool(struct rcu_head *rcu) 349129c91e99STejun Heo { 349229c91e99STejun Heo struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); 349329c91e99STejun Heo 3494822d8405STejun Heo idr_destroy(&pool->worker_idr); 349529c91e99STejun Heo free_workqueue_attrs(pool->attrs); 349629c91e99STejun Heo kfree(pool); 349729c91e99STejun Heo } 349829c91e99STejun Heo 349929c91e99STejun Heo /** 350029c91e99STejun Heo * put_unbound_pool - put a worker_pool 350129c91e99STejun Heo * @pool: worker_pool to put 350229c91e99STejun Heo * 350329c91e99STejun Heo * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU 3504c5aa87bbSTejun Heo * safe manner. get_unbound_pool() calls this function on its failure path 3505c5aa87bbSTejun Heo * and this function should be able to release pools which went through, 3506c5aa87bbSTejun Heo * successfully or not, init_worker_pool(). 3507a892caccSTejun Heo * 3508a892caccSTejun Heo * Should be called with wq_pool_mutex held. 350929c91e99STejun Heo */ 351029c91e99STejun Heo static void put_unbound_pool(struct worker_pool *pool) 351129c91e99STejun Heo { 351229c91e99STejun Heo struct worker *worker; 351329c91e99STejun Heo 3514a892caccSTejun Heo lockdep_assert_held(&wq_pool_mutex); 3515a892caccSTejun Heo 3516a892caccSTejun Heo if (--pool->refcnt) 351729c91e99STejun Heo return; 351829c91e99STejun Heo 351929c91e99STejun Heo /* sanity checks */ 352029c91e99STejun Heo if (WARN_ON(!(pool->flags & POOL_DISASSOCIATED)) || 3521a892caccSTejun Heo WARN_ON(!list_empty(&pool->worklist))) 352229c91e99STejun Heo return; 352329c91e99STejun Heo 352429c91e99STejun Heo /* release id and unhash */ 352529c91e99STejun Heo if (pool->id >= 0) 352629c91e99STejun Heo idr_remove(&worker_pool_idr, pool->id); 352729c91e99STejun Heo hash_del(&pool->hash_node); 352829c91e99STejun Heo 3529c5aa87bbSTejun Heo /* 3530c5aa87bbSTejun Heo * Become the manager and destroy all workers. Grabbing 3531c5aa87bbSTejun Heo * manager_arb prevents @pool's workers from blocking on 3532c5aa87bbSTejun Heo * manager_mutex. 3533c5aa87bbSTejun Heo */ 353429c91e99STejun Heo mutex_lock(&pool->manager_arb); 3535cd549687STejun Heo mutex_lock(&pool->manager_mutex); 353629c91e99STejun Heo spin_lock_irq(&pool->lock); 353729c91e99STejun Heo 353829c91e99STejun Heo while ((worker = first_worker(pool))) 353929c91e99STejun Heo destroy_worker(worker); 354029c91e99STejun Heo WARN_ON(pool->nr_workers || pool->nr_idle); 354129c91e99STejun Heo 354229c91e99STejun Heo spin_unlock_irq(&pool->lock); 3543cd549687STejun Heo mutex_unlock(&pool->manager_mutex); 354429c91e99STejun Heo mutex_unlock(&pool->manager_arb); 354529c91e99STejun Heo 354629c91e99STejun Heo /* shut down the timers */ 354729c91e99STejun Heo del_timer_sync(&pool->idle_timer); 354829c91e99STejun Heo del_timer_sync(&pool->mayday_timer); 354929c91e99STejun Heo 355029c91e99STejun Heo /* sched-RCU protected to allow dereferences from get_work_pool() */ 355129c91e99STejun Heo call_rcu_sched(&pool->rcu, rcu_free_pool); 355229c91e99STejun Heo } 355329c91e99STejun Heo 355429c91e99STejun Heo /** 355529c91e99STejun Heo * get_unbound_pool - get a worker_pool with the specified attributes 355629c91e99STejun Heo * @attrs: the attributes of the worker_pool to get 355729c91e99STejun Heo * 355829c91e99STejun Heo * Obtain a worker_pool which has the same attributes as @attrs, bump the 355929c91e99STejun Heo * reference count and return it. If there already is a matching 356029c91e99STejun Heo * worker_pool, it will be used; otherwise, this function attempts to 356129c91e99STejun Heo * create a new one. On failure, returns NULL. 3562a892caccSTejun Heo * 3563a892caccSTejun Heo * Should be called with wq_pool_mutex held. 356429c91e99STejun Heo */ 356529c91e99STejun Heo static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) 356629c91e99STejun Heo { 356729c91e99STejun Heo u32 hash = wqattrs_hash(attrs); 356829c91e99STejun Heo struct worker_pool *pool; 3569f3f90ad4STejun Heo int node; 357029c91e99STejun Heo 3571a892caccSTejun Heo lockdep_assert_held(&wq_pool_mutex); 357229c91e99STejun Heo 357329c91e99STejun Heo /* do we already have a matching pool? */ 357429c91e99STejun Heo hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { 357529c91e99STejun Heo if (wqattrs_equal(pool->attrs, attrs)) { 357629c91e99STejun Heo pool->refcnt++; 357729c91e99STejun Heo goto out_unlock; 357829c91e99STejun Heo } 357929c91e99STejun Heo } 358029c91e99STejun Heo 358129c91e99STejun Heo /* nope, create a new one */ 358229c91e99STejun Heo pool = kzalloc(sizeof(*pool), GFP_KERNEL); 358329c91e99STejun Heo if (!pool || init_worker_pool(pool) < 0) 358429c91e99STejun Heo goto fail; 358529c91e99STejun Heo 358612ee4fc6SLai Jiangshan if (workqueue_freezing) 358712ee4fc6SLai Jiangshan pool->flags |= POOL_FREEZING; 358812ee4fc6SLai Jiangshan 35898864b4e5STejun Heo lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ 359029c91e99STejun Heo copy_workqueue_attrs(pool->attrs, attrs); 359129c91e99STejun Heo 35922865a8fbSShaohua Li /* 35932865a8fbSShaohua Li * no_numa isn't a worker_pool attribute, always clear it. See 35942865a8fbSShaohua Li * 'struct workqueue_attrs' comments for detail. 35952865a8fbSShaohua Li */ 35962865a8fbSShaohua Li pool->attrs->no_numa = false; 35972865a8fbSShaohua Li 3598f3f90ad4STejun Heo /* if cpumask is contained inside a NUMA node, we belong to that node */ 3599f3f90ad4STejun Heo if (wq_numa_enabled) { 3600f3f90ad4STejun Heo for_each_node(node) { 3601f3f90ad4STejun Heo if (cpumask_subset(pool->attrs->cpumask, 3602f3f90ad4STejun Heo wq_numa_possible_cpumask[node])) { 3603f3f90ad4STejun Heo pool->node = node; 3604f3f90ad4STejun Heo break; 3605f3f90ad4STejun Heo } 3606f3f90ad4STejun Heo } 3607f3f90ad4STejun Heo } 3608f3f90ad4STejun Heo 360929c91e99STejun Heo if (worker_pool_assign_id(pool) < 0) 361029c91e99STejun Heo goto fail; 361129c91e99STejun Heo 361229c91e99STejun Heo /* create and start the initial worker */ 3613ebf44d16STejun Heo if (create_and_start_worker(pool) < 0) 361429c91e99STejun Heo goto fail; 361529c91e99STejun Heo 361629c91e99STejun Heo /* install */ 361729c91e99STejun Heo hash_add(unbound_pool_hash, &pool->hash_node, hash); 361829c91e99STejun Heo out_unlock: 361929c91e99STejun Heo return pool; 362029c91e99STejun Heo fail: 362129c91e99STejun Heo if (pool) 362229c91e99STejun Heo put_unbound_pool(pool); 362329c91e99STejun Heo return NULL; 362429c91e99STejun Heo } 362529c91e99STejun Heo 36268864b4e5STejun Heo static void rcu_free_pwq(struct rcu_head *rcu) 36278864b4e5STejun Heo { 36288864b4e5STejun Heo kmem_cache_free(pwq_cache, 36298864b4e5STejun Heo container_of(rcu, struct pool_workqueue, rcu)); 36308864b4e5STejun Heo } 36318864b4e5STejun Heo 36328864b4e5STejun Heo /* 36338864b4e5STejun Heo * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt 36348864b4e5STejun Heo * and needs to be destroyed. 36358864b4e5STejun Heo */ 36368864b4e5STejun Heo static void pwq_unbound_release_workfn(struct work_struct *work) 36378864b4e5STejun Heo { 36388864b4e5STejun Heo struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, 36398864b4e5STejun Heo unbound_release_work); 36408864b4e5STejun Heo struct workqueue_struct *wq = pwq->wq; 36418864b4e5STejun Heo struct worker_pool *pool = pwq->pool; 3642bc0caf09STejun Heo bool is_last; 36438864b4e5STejun Heo 36448864b4e5STejun Heo if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) 36458864b4e5STejun Heo return; 36468864b4e5STejun Heo 364775ccf595STejun Heo /* 36483c25a55dSLai Jiangshan * Unlink @pwq. Synchronization against wq->mutex isn't strictly 364975ccf595STejun Heo * necessary on release but do it anyway. It's easier to verify 365075ccf595STejun Heo * and consistent with the linking path. 365175ccf595STejun Heo */ 36523c25a55dSLai Jiangshan mutex_lock(&wq->mutex); 36538864b4e5STejun Heo list_del_rcu(&pwq->pwqs_node); 3654bc0caf09STejun Heo is_last = list_empty(&wq->pwqs); 36553c25a55dSLai Jiangshan mutex_unlock(&wq->mutex); 36568864b4e5STejun Heo 3657a892caccSTejun Heo mutex_lock(&wq_pool_mutex); 36588864b4e5STejun Heo put_unbound_pool(pool); 3659a892caccSTejun Heo mutex_unlock(&wq_pool_mutex); 3660a892caccSTejun Heo 36618864b4e5STejun Heo call_rcu_sched(&pwq->rcu, rcu_free_pwq); 36628864b4e5STejun Heo 36638864b4e5STejun Heo /* 36648864b4e5STejun Heo * If we're the last pwq going away, @wq is already dead and no one 36658864b4e5STejun Heo * is gonna access it anymore. Free it. 36668864b4e5STejun Heo */ 36676029a918STejun Heo if (is_last) { 36686029a918STejun Heo free_workqueue_attrs(wq->unbound_attrs); 36698864b4e5STejun Heo kfree(wq); 36708864b4e5STejun Heo } 36716029a918STejun Heo } 36728864b4e5STejun Heo 36730fbd95aaSTejun Heo /** 3674699ce097STejun Heo * pwq_adjust_max_active - update a pwq's max_active to the current setting 36750fbd95aaSTejun Heo * @pwq: target pool_workqueue 36760fbd95aaSTejun Heo * 3677699ce097STejun Heo * If @pwq isn't freezing, set @pwq->max_active to the associated 3678699ce097STejun Heo * workqueue's saved_max_active and activate delayed work items 3679699ce097STejun Heo * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. 36800fbd95aaSTejun Heo */ 3681699ce097STejun Heo static void pwq_adjust_max_active(struct pool_workqueue *pwq) 36820fbd95aaSTejun Heo { 3683699ce097STejun Heo struct workqueue_struct *wq = pwq->wq; 3684699ce097STejun Heo bool freezable = wq->flags & WQ_FREEZABLE; 3685699ce097STejun Heo 3686699ce097STejun Heo /* for @wq->saved_max_active */ 3687a357fc03SLai Jiangshan lockdep_assert_held(&wq->mutex); 3688699ce097STejun Heo 3689699ce097STejun Heo /* fast exit for non-freezable wqs */ 3690699ce097STejun Heo if (!freezable && pwq->max_active == wq->saved_max_active) 3691699ce097STejun Heo return; 3692699ce097STejun Heo 3693a357fc03SLai Jiangshan spin_lock_irq(&pwq->pool->lock); 3694699ce097STejun Heo 3695699ce097STejun Heo if (!freezable || !(pwq->pool->flags & POOL_FREEZING)) { 3696699ce097STejun Heo pwq->max_active = wq->saved_max_active; 36970fbd95aaSTejun Heo 36980fbd95aaSTejun Heo while (!list_empty(&pwq->delayed_works) && 36990fbd95aaSTejun Heo pwq->nr_active < pwq->max_active) 37000fbd95aaSTejun Heo pwq_activate_first_delayed(pwq); 3701951a078aSLai Jiangshan 3702951a078aSLai Jiangshan /* 3703951a078aSLai Jiangshan * Need to kick a worker after thawed or an unbound wq's 3704951a078aSLai Jiangshan * max_active is bumped. It's a slow path. Do it always. 3705951a078aSLai Jiangshan */ 3706951a078aSLai Jiangshan wake_up_worker(pwq->pool); 3707699ce097STejun Heo } else { 3708699ce097STejun Heo pwq->max_active = 0; 3709699ce097STejun Heo } 3710699ce097STejun Heo 3711a357fc03SLai Jiangshan spin_unlock_irq(&pwq->pool->lock); 37120fbd95aaSTejun Heo } 37130fbd95aaSTejun Heo 3714e50aba9aSTejun Heo /* initialize newly alloced @pwq which is associated with @wq and @pool */ 3715f147f29eSTejun Heo static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, 3716f147f29eSTejun Heo struct worker_pool *pool) 3717d2c1d404STejun Heo { 3718d2c1d404STejun Heo BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); 3719d2c1d404STejun Heo 3720e50aba9aSTejun Heo memset(pwq, 0, sizeof(*pwq)); 3721e50aba9aSTejun Heo 3722d2c1d404STejun Heo pwq->pool = pool; 3723d2c1d404STejun Heo pwq->wq = wq; 3724d2c1d404STejun Heo pwq->flush_color = -1; 37258864b4e5STejun Heo pwq->refcnt = 1; 3726d2c1d404STejun Heo INIT_LIST_HEAD(&pwq->delayed_works); 37271befcf30STejun Heo INIT_LIST_HEAD(&pwq->pwqs_node); 3728d2c1d404STejun Heo INIT_LIST_HEAD(&pwq->mayday_node); 37298864b4e5STejun Heo INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn); 3730f147f29eSTejun Heo } 3731d2c1d404STejun Heo 3732f147f29eSTejun Heo /* sync @pwq with the current state of its associated wq and link it */ 37331befcf30STejun Heo static void link_pwq(struct pool_workqueue *pwq) 3734f147f29eSTejun Heo { 3735f147f29eSTejun Heo struct workqueue_struct *wq = pwq->wq; 3736f147f29eSTejun Heo 3737f147f29eSTejun Heo lockdep_assert_held(&wq->mutex); 373875ccf595STejun Heo 37391befcf30STejun Heo /* may be called multiple times, ignore if already linked */ 37401befcf30STejun Heo if (!list_empty(&pwq->pwqs_node)) 37411befcf30STejun Heo return; 37421befcf30STejun Heo 3743983ca25eSTejun Heo /* 3744983ca25eSTejun Heo * Set the matching work_color. This is synchronized with 37453c25a55dSLai Jiangshan * wq->mutex to avoid confusing flush_workqueue(). 3746983ca25eSTejun Heo */ 374775ccf595STejun Heo pwq->work_color = wq->work_color; 3748983ca25eSTejun Heo 3749983ca25eSTejun Heo /* sync max_active to the current setting */ 3750983ca25eSTejun Heo pwq_adjust_max_active(pwq); 3751983ca25eSTejun Heo 3752983ca25eSTejun Heo /* link in @pwq */ 37539e8cd2f5STejun Heo list_add_rcu(&pwq->pwqs_node, &wq->pwqs); 3754df2d5ae4STejun Heo } 37556029a918STejun Heo 3756f147f29eSTejun Heo /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ 3757f147f29eSTejun Heo static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, 3758f147f29eSTejun Heo const struct workqueue_attrs *attrs) 3759f147f29eSTejun Heo { 3760f147f29eSTejun Heo struct worker_pool *pool; 3761f147f29eSTejun Heo struct pool_workqueue *pwq; 3762f147f29eSTejun Heo 3763f147f29eSTejun Heo lockdep_assert_held(&wq_pool_mutex); 3764f147f29eSTejun Heo 3765f147f29eSTejun Heo pool = get_unbound_pool(attrs); 3766f147f29eSTejun Heo if (!pool) 3767f147f29eSTejun Heo return NULL; 3768f147f29eSTejun Heo 3769e50aba9aSTejun Heo pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); 3770f147f29eSTejun Heo if (!pwq) { 3771f147f29eSTejun Heo put_unbound_pool(pool); 3772f147f29eSTejun Heo return NULL; 3773f147f29eSTejun Heo } 3774f147f29eSTejun Heo 3775f147f29eSTejun Heo init_pwq(pwq, wq, pool); 3776f147f29eSTejun Heo return pwq; 3777d2c1d404STejun Heo } 3778d2c1d404STejun Heo 37794c16bd32STejun Heo /* undo alloc_unbound_pwq(), used only in the error path */ 37804c16bd32STejun Heo static void free_unbound_pwq(struct pool_workqueue *pwq) 37814c16bd32STejun Heo { 37824c16bd32STejun Heo lockdep_assert_held(&wq_pool_mutex); 37834c16bd32STejun Heo 37844c16bd32STejun Heo if (pwq) { 37854c16bd32STejun Heo put_unbound_pool(pwq->pool); 3786cece95dfSWei Yongjun kmem_cache_free(pwq_cache, pwq); 37874c16bd32STejun Heo } 37884c16bd32STejun Heo } 37894c16bd32STejun Heo 37904c16bd32STejun Heo /** 37914c16bd32STejun Heo * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node 37924c16bd32STejun Heo * @attrs: the wq_attrs of interest 37934c16bd32STejun Heo * @node: the target NUMA node 37944c16bd32STejun Heo * @cpu_going_down: if >= 0, the CPU to consider as offline 37954c16bd32STejun Heo * @cpumask: outarg, the resulting cpumask 37964c16bd32STejun Heo * 37974c16bd32STejun Heo * Calculate the cpumask a workqueue with @attrs should use on @node. If 37984c16bd32STejun Heo * @cpu_going_down is >= 0, that cpu is considered offline during 37994c16bd32STejun Heo * calculation. The result is stored in @cpumask. This function returns 38004c16bd32STejun Heo * %true if the resulting @cpumask is different from @attrs->cpumask, 38014c16bd32STejun Heo * %false if equal. 38024c16bd32STejun Heo * 38034c16bd32STejun Heo * If NUMA affinity is not enabled, @attrs->cpumask is always used. If 38044c16bd32STejun Heo * enabled and @node has online CPUs requested by @attrs, the returned 38054c16bd32STejun Heo * cpumask is the intersection of the possible CPUs of @node and 38064c16bd32STejun Heo * @attrs->cpumask. 38074c16bd32STejun Heo * 38084c16bd32STejun Heo * The caller is responsible for ensuring that the cpumask of @node stays 38094c16bd32STejun Heo * stable. 38104c16bd32STejun Heo */ 38114c16bd32STejun Heo static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, 38124c16bd32STejun Heo int cpu_going_down, cpumask_t *cpumask) 38134c16bd32STejun Heo { 3814d55262c4STejun Heo if (!wq_numa_enabled || attrs->no_numa) 38154c16bd32STejun Heo goto use_dfl; 38164c16bd32STejun Heo 38174c16bd32STejun Heo /* does @node have any online CPUs @attrs wants? */ 38184c16bd32STejun Heo cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask); 38194c16bd32STejun Heo if (cpu_going_down >= 0) 38204c16bd32STejun Heo cpumask_clear_cpu(cpu_going_down, cpumask); 38214c16bd32STejun Heo 38224c16bd32STejun Heo if (cpumask_empty(cpumask)) 38234c16bd32STejun Heo goto use_dfl; 38244c16bd32STejun Heo 38254c16bd32STejun Heo /* yeap, return possible CPUs in @node that @attrs wants */ 38264c16bd32STejun Heo cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); 38274c16bd32STejun Heo return !cpumask_equal(cpumask, attrs->cpumask); 38284c16bd32STejun Heo 38294c16bd32STejun Heo use_dfl: 38304c16bd32STejun Heo cpumask_copy(cpumask, attrs->cpumask); 38314c16bd32STejun Heo return false; 38324c16bd32STejun Heo } 38334c16bd32STejun Heo 38341befcf30STejun Heo /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */ 38351befcf30STejun Heo static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq, 38361befcf30STejun Heo int node, 38371befcf30STejun Heo struct pool_workqueue *pwq) 38381befcf30STejun Heo { 38391befcf30STejun Heo struct pool_workqueue *old_pwq; 38401befcf30STejun Heo 38411befcf30STejun Heo lockdep_assert_held(&wq->mutex); 38421befcf30STejun Heo 38431befcf30STejun Heo /* link_pwq() can handle duplicate calls */ 38441befcf30STejun Heo link_pwq(pwq); 38451befcf30STejun Heo 38461befcf30STejun Heo old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); 38471befcf30STejun Heo rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); 38481befcf30STejun Heo return old_pwq; 38491befcf30STejun Heo } 38501befcf30STejun Heo 38519e8cd2f5STejun Heo /** 38529e8cd2f5STejun Heo * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue 38539e8cd2f5STejun Heo * @wq: the target workqueue 38549e8cd2f5STejun Heo * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() 38559e8cd2f5STejun Heo * 38564c16bd32STejun Heo * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA 38574c16bd32STejun Heo * machines, this function maps a separate pwq to each NUMA node with 38584c16bd32STejun Heo * possibles CPUs in @attrs->cpumask so that work items are affine to the 38594c16bd32STejun Heo * NUMA node it was issued on. Older pwqs are released as in-flight work 38604c16bd32STejun Heo * items finish. Note that a work item which repeatedly requeues itself 38614c16bd32STejun Heo * back-to-back will stay on its current pwq. 38629e8cd2f5STejun Heo * 38639e8cd2f5STejun Heo * Performs GFP_KERNEL allocations. Returns 0 on success and -errno on 38649e8cd2f5STejun Heo * failure. 38659e8cd2f5STejun Heo */ 38669e8cd2f5STejun Heo int apply_workqueue_attrs(struct workqueue_struct *wq, 38679e8cd2f5STejun Heo const struct workqueue_attrs *attrs) 38689e8cd2f5STejun Heo { 38694c16bd32STejun Heo struct workqueue_attrs *new_attrs, *tmp_attrs; 38704c16bd32STejun Heo struct pool_workqueue **pwq_tbl, *dfl_pwq; 3871f147f29eSTejun Heo int node, ret; 38729e8cd2f5STejun Heo 38738719dceaSTejun Heo /* only unbound workqueues can change attributes */ 38749e8cd2f5STejun Heo if (WARN_ON(!(wq->flags & WQ_UNBOUND))) 38759e8cd2f5STejun Heo return -EINVAL; 38769e8cd2f5STejun Heo 38778719dceaSTejun Heo /* creating multiple pwqs breaks ordering guarantee */ 38788719dceaSTejun Heo if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs))) 38798719dceaSTejun Heo return -EINVAL; 38808719dceaSTejun Heo 38814c16bd32STejun Heo pwq_tbl = kzalloc(wq_numa_tbl_len * sizeof(pwq_tbl[0]), GFP_KERNEL); 388213e2e556STejun Heo new_attrs = alloc_workqueue_attrs(GFP_KERNEL); 38834c16bd32STejun Heo tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL); 38844c16bd32STejun Heo if (!pwq_tbl || !new_attrs || !tmp_attrs) 388513e2e556STejun Heo goto enomem; 388613e2e556STejun Heo 38874c16bd32STejun Heo /* make a copy of @attrs and sanitize it */ 388813e2e556STejun Heo copy_workqueue_attrs(new_attrs, attrs); 388913e2e556STejun Heo cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); 389013e2e556STejun Heo 38914c16bd32STejun Heo /* 38924c16bd32STejun Heo * We may create multiple pwqs with differing cpumasks. Make a 38934c16bd32STejun Heo * copy of @new_attrs which will be modified and used to obtain 38944c16bd32STejun Heo * pools. 38954c16bd32STejun Heo */ 38964c16bd32STejun Heo copy_workqueue_attrs(tmp_attrs, new_attrs); 38979e8cd2f5STejun Heo 38984c16bd32STejun Heo /* 38994c16bd32STejun Heo * CPUs should stay stable across pwq creations and installations. 39004c16bd32STejun Heo * Pin CPUs, determine the target cpumask for each node and create 39014c16bd32STejun Heo * pwqs accordingly. 39024c16bd32STejun Heo */ 39034c16bd32STejun Heo get_online_cpus(); 39044c16bd32STejun Heo 39054c16bd32STejun Heo mutex_lock(&wq_pool_mutex); 39064c16bd32STejun Heo 39074c16bd32STejun Heo /* 39084c16bd32STejun Heo * If something goes wrong during CPU up/down, we'll fall back to 39094c16bd32STejun Heo * the default pwq covering whole @attrs->cpumask. Always create 39104c16bd32STejun Heo * it even if we don't use it immediately. 39114c16bd32STejun Heo */ 39124c16bd32STejun Heo dfl_pwq = alloc_unbound_pwq(wq, new_attrs); 39134c16bd32STejun Heo if (!dfl_pwq) 39144c16bd32STejun Heo goto enomem_pwq; 39154c16bd32STejun Heo 39164c16bd32STejun Heo for_each_node(node) { 39174c16bd32STejun Heo if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) { 39184c16bd32STejun Heo pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs); 39194c16bd32STejun Heo if (!pwq_tbl[node]) 39204c16bd32STejun Heo goto enomem_pwq; 39214c16bd32STejun Heo } else { 39224c16bd32STejun Heo dfl_pwq->refcnt++; 39234c16bd32STejun Heo pwq_tbl[node] = dfl_pwq; 39244c16bd32STejun Heo } 39254c16bd32STejun Heo } 39264c16bd32STejun Heo 39274c16bd32STejun Heo mutex_unlock(&wq_pool_mutex); 39284c16bd32STejun Heo 39294c16bd32STejun Heo /* all pwqs have been created successfully, let's install'em */ 3930f147f29eSTejun Heo mutex_lock(&wq->mutex); 3931a892caccSTejun Heo 3932f147f29eSTejun Heo copy_workqueue_attrs(wq->unbound_attrs, new_attrs); 39334c16bd32STejun Heo 39344c16bd32STejun Heo /* save the previous pwq and install the new one */ 3935f147f29eSTejun Heo for_each_node(node) 39364c16bd32STejun Heo pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]); 39374c16bd32STejun Heo 39384c16bd32STejun Heo /* @dfl_pwq might not have been used, ensure it's linked */ 39394c16bd32STejun Heo link_pwq(dfl_pwq); 39404c16bd32STejun Heo swap(wq->dfl_pwq, dfl_pwq); 3941f147f29eSTejun Heo 3942f147f29eSTejun Heo mutex_unlock(&wq->mutex); 3943f147f29eSTejun Heo 39444c16bd32STejun Heo /* put the old pwqs */ 39454c16bd32STejun Heo for_each_node(node) 39464c16bd32STejun Heo put_pwq_unlocked(pwq_tbl[node]); 39474c16bd32STejun Heo put_pwq_unlocked(dfl_pwq); 39484c16bd32STejun Heo 39494c16bd32STejun Heo put_online_cpus(); 39504862125bSTejun Heo ret = 0; 39514862125bSTejun Heo /* fall through */ 39524862125bSTejun Heo out_free: 39534c16bd32STejun Heo free_workqueue_attrs(tmp_attrs); 39544862125bSTejun Heo free_workqueue_attrs(new_attrs); 39554c16bd32STejun Heo kfree(pwq_tbl); 39564862125bSTejun Heo return ret; 395713e2e556STejun Heo 39584c16bd32STejun Heo enomem_pwq: 39594c16bd32STejun Heo free_unbound_pwq(dfl_pwq); 39604c16bd32STejun Heo for_each_node(node) 39614c16bd32STejun Heo if (pwq_tbl && pwq_tbl[node] != dfl_pwq) 39624c16bd32STejun Heo free_unbound_pwq(pwq_tbl[node]); 39634c16bd32STejun Heo mutex_unlock(&wq_pool_mutex); 39644c16bd32STejun Heo put_online_cpus(); 396513e2e556STejun Heo enomem: 39664862125bSTejun Heo ret = -ENOMEM; 39674862125bSTejun Heo goto out_free; 39689e8cd2f5STejun Heo } 39699e8cd2f5STejun Heo 39704c16bd32STejun Heo /** 39714c16bd32STejun Heo * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug 39724c16bd32STejun Heo * @wq: the target workqueue 39734c16bd32STejun Heo * @cpu: the CPU coming up or going down 39744c16bd32STejun Heo * @online: whether @cpu is coming up or going down 39754c16bd32STejun Heo * 39764c16bd32STejun Heo * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and 39774c16bd32STejun Heo * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of 39784c16bd32STejun Heo * @wq accordingly. 39794c16bd32STejun Heo * 39804c16bd32STejun Heo * If NUMA affinity can't be adjusted due to memory allocation failure, it 39814c16bd32STejun Heo * falls back to @wq->dfl_pwq which may not be optimal but is always 39824c16bd32STejun Heo * correct. 39834c16bd32STejun Heo * 39844c16bd32STejun Heo * Note that when the last allowed CPU of a NUMA node goes offline for a 39854c16bd32STejun Heo * workqueue with a cpumask spanning multiple nodes, the workers which were 39864c16bd32STejun Heo * already executing the work items for the workqueue will lose their CPU 39874c16bd32STejun Heo * affinity and may execute on any CPU. This is similar to how per-cpu 39884c16bd32STejun Heo * workqueues behave on CPU_DOWN. If a workqueue user wants strict 39894c16bd32STejun Heo * affinity, it's the user's responsibility to flush the work item from 39904c16bd32STejun Heo * CPU_DOWN_PREPARE. 39914c16bd32STejun Heo */ 39924c16bd32STejun Heo static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, 39934c16bd32STejun Heo bool online) 39944c16bd32STejun Heo { 39954c16bd32STejun Heo int node = cpu_to_node(cpu); 39964c16bd32STejun Heo int cpu_off = online ? -1 : cpu; 39974c16bd32STejun Heo struct pool_workqueue *old_pwq = NULL, *pwq; 39984c16bd32STejun Heo struct workqueue_attrs *target_attrs; 39994c16bd32STejun Heo cpumask_t *cpumask; 40004c16bd32STejun Heo 40014c16bd32STejun Heo lockdep_assert_held(&wq_pool_mutex); 40024c16bd32STejun Heo 40034c16bd32STejun Heo if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND)) 40044c16bd32STejun Heo return; 40054c16bd32STejun Heo 40064c16bd32STejun Heo /* 40074c16bd32STejun Heo * We don't wanna alloc/free wq_attrs for each wq for each CPU. 40084c16bd32STejun Heo * Let's use a preallocated one. The following buf is protected by 40094c16bd32STejun Heo * CPU hotplug exclusion. 40104c16bd32STejun Heo */ 40114c16bd32STejun Heo target_attrs = wq_update_unbound_numa_attrs_buf; 40124c16bd32STejun Heo cpumask = target_attrs->cpumask; 40134c16bd32STejun Heo 40144c16bd32STejun Heo mutex_lock(&wq->mutex); 4015d55262c4STejun Heo if (wq->unbound_attrs->no_numa) 4016d55262c4STejun Heo goto out_unlock; 40174c16bd32STejun Heo 40184c16bd32STejun Heo copy_workqueue_attrs(target_attrs, wq->unbound_attrs); 40194c16bd32STejun Heo pwq = unbound_pwq_by_node(wq, node); 40204c16bd32STejun Heo 40214c16bd32STejun Heo /* 40224c16bd32STejun Heo * Let's determine what needs to be done. If the target cpumask is 40234c16bd32STejun Heo * different from wq's, we need to compare it to @pwq's and create 40244c16bd32STejun Heo * a new one if they don't match. If the target cpumask equals 40254c16bd32STejun Heo * wq's, the default pwq should be used. If @pwq is already the 40264c16bd32STejun Heo * default one, nothing to do; otherwise, install the default one. 40274c16bd32STejun Heo */ 40284c16bd32STejun Heo if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) { 40294c16bd32STejun Heo if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask)) 40304c16bd32STejun Heo goto out_unlock; 40314c16bd32STejun Heo } else { 40324c16bd32STejun Heo if (pwq == wq->dfl_pwq) 40334c16bd32STejun Heo goto out_unlock; 40344c16bd32STejun Heo else 40354c16bd32STejun Heo goto use_dfl_pwq; 40364c16bd32STejun Heo } 40374c16bd32STejun Heo 40384c16bd32STejun Heo mutex_unlock(&wq->mutex); 40394c16bd32STejun Heo 40404c16bd32STejun Heo /* create a new pwq */ 40414c16bd32STejun Heo pwq = alloc_unbound_pwq(wq, target_attrs); 40424c16bd32STejun Heo if (!pwq) { 40434c16bd32STejun Heo pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", 40444c16bd32STejun Heo wq->name); 40454c16bd32STejun Heo goto out_unlock; 40464c16bd32STejun Heo } 40474c16bd32STejun Heo 40484c16bd32STejun Heo /* 40494c16bd32STejun Heo * Install the new pwq. As this function is called only from CPU 40504c16bd32STejun Heo * hotplug callbacks and applying a new attrs is wrapped with 40514c16bd32STejun Heo * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed 40524c16bd32STejun Heo * inbetween. 40534c16bd32STejun Heo */ 40544c16bd32STejun Heo mutex_lock(&wq->mutex); 40554c16bd32STejun Heo old_pwq = numa_pwq_tbl_install(wq, node, pwq); 40564c16bd32STejun Heo goto out_unlock; 40574c16bd32STejun Heo 40584c16bd32STejun Heo use_dfl_pwq: 40594c16bd32STejun Heo spin_lock_irq(&wq->dfl_pwq->pool->lock); 40604c16bd32STejun Heo get_pwq(wq->dfl_pwq); 40614c16bd32STejun Heo spin_unlock_irq(&wq->dfl_pwq->pool->lock); 40624c16bd32STejun Heo old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq); 40634c16bd32STejun Heo out_unlock: 40644c16bd32STejun Heo mutex_unlock(&wq->mutex); 40654c16bd32STejun Heo put_pwq_unlocked(old_pwq); 40664c16bd32STejun Heo } 40674c16bd32STejun Heo 406830cdf249STejun Heo static int alloc_and_link_pwqs(struct workqueue_struct *wq) 40691da177e4SLinus Torvalds { 407049e3cf44STejun Heo bool highpri = wq->flags & WQ_HIGHPRI; 407130cdf249STejun Heo int cpu; 4072e1d8aa9fSFrederic Weisbecker 407330cdf249STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 4074420c0ddbSTejun Heo wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); 4075420c0ddbSTejun Heo if (!wq->cpu_pwqs) 407630cdf249STejun Heo return -ENOMEM; 407730cdf249STejun Heo 407830cdf249STejun Heo for_each_possible_cpu(cpu) { 40797fb98ea7STejun Heo struct pool_workqueue *pwq = 40807fb98ea7STejun Heo per_cpu_ptr(wq->cpu_pwqs, cpu); 40817a62c2c8STejun Heo struct worker_pool *cpu_pools = 4082f02ae73aSTejun Heo per_cpu(cpu_worker_pools, cpu); 408330cdf249STejun Heo 4084f147f29eSTejun Heo init_pwq(pwq, wq, &cpu_pools[highpri]); 4085f147f29eSTejun Heo 4086f147f29eSTejun Heo mutex_lock(&wq->mutex); 40871befcf30STejun Heo link_pwq(pwq); 4088f147f29eSTejun Heo mutex_unlock(&wq->mutex); 408930cdf249STejun Heo } 409030cdf249STejun Heo return 0; 40919e8cd2f5STejun Heo } else { 40929e8cd2f5STejun Heo return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); 40939e8cd2f5STejun Heo } 40940f900049STejun Heo } 40950f900049STejun Heo 4096f3421797STejun Heo static int wq_clamp_max_active(int max_active, unsigned int flags, 4097f3421797STejun Heo const char *name) 4098b71ab8c2STejun Heo { 4099f3421797STejun Heo int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; 4100f3421797STejun Heo 4101f3421797STejun Heo if (max_active < 1 || max_active > lim) 4102044c782cSValentin Ilie pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", 4103f3421797STejun Heo max_active, name, 1, lim); 4104b71ab8c2STejun Heo 4105f3421797STejun Heo return clamp_val(max_active, 1, lim); 4106b71ab8c2STejun Heo } 4107b71ab8c2STejun Heo 4108b196be89STejun Heo struct workqueue_struct *__alloc_workqueue_key(const char *fmt, 410997e37d7bSTejun Heo unsigned int flags, 41101e19ffc6STejun Heo int max_active, 4111eb13ba87SJohannes Berg struct lock_class_key *key, 4112b196be89STejun Heo const char *lock_name, ...) 41133af24433SOleg Nesterov { 4114df2d5ae4STejun Heo size_t tbl_size = 0; 4115ecf6881fSTejun Heo va_list args; 41163af24433SOleg Nesterov struct workqueue_struct *wq; 411749e3cf44STejun Heo struct pool_workqueue *pwq; 4118b196be89STejun Heo 4119cee22a15SViresh Kumar /* see the comment above the definition of WQ_POWER_EFFICIENT */ 4120cee22a15SViresh Kumar if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) 4121cee22a15SViresh Kumar flags |= WQ_UNBOUND; 4122cee22a15SViresh Kumar 4123ecf6881fSTejun Heo /* allocate wq and format name */ 4124df2d5ae4STejun Heo if (flags & WQ_UNBOUND) 4125df2d5ae4STejun Heo tbl_size = wq_numa_tbl_len * sizeof(wq->numa_pwq_tbl[0]); 4126df2d5ae4STejun Heo 4127df2d5ae4STejun Heo wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); 4128b196be89STejun Heo if (!wq) 4129d2c1d404STejun Heo return NULL; 4130b196be89STejun Heo 41316029a918STejun Heo if (flags & WQ_UNBOUND) { 41326029a918STejun Heo wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL); 41336029a918STejun Heo if (!wq->unbound_attrs) 41346029a918STejun Heo goto err_free_wq; 41356029a918STejun Heo } 41366029a918STejun Heo 4137ecf6881fSTejun Heo va_start(args, lock_name); 4138ecf6881fSTejun Heo vsnprintf(wq->name, sizeof(wq->name), fmt, args); 4139b196be89STejun Heo va_end(args); 41403af24433SOleg Nesterov 4141d320c038STejun Heo max_active = max_active ?: WQ_DFL_ACTIVE; 4142b196be89STejun Heo max_active = wq_clamp_max_active(max_active, flags, wq->name); 41433af24433SOleg Nesterov 4144b196be89STejun Heo /* init wq */ 414597e37d7bSTejun Heo wq->flags = flags; 4146a0a1a5fdSTejun Heo wq->saved_max_active = max_active; 41473c25a55dSLai Jiangshan mutex_init(&wq->mutex); 4148112202d9STejun Heo atomic_set(&wq->nr_pwqs_to_flush, 0); 414930cdf249STejun Heo INIT_LIST_HEAD(&wq->pwqs); 415073f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_queue); 415173f53c4aSTejun Heo INIT_LIST_HEAD(&wq->flusher_overflow); 4152493a1724STejun Heo INIT_LIST_HEAD(&wq->maydays); 41533af24433SOleg Nesterov 4154eb13ba87SJohannes Berg lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); 4155cce1a165SOleg Nesterov INIT_LIST_HEAD(&wq->list); 41563af24433SOleg Nesterov 415730cdf249STejun Heo if (alloc_and_link_pwqs(wq) < 0) 4158d2c1d404STejun Heo goto err_free_wq; 41591537663fSTejun Heo 4160493008a8STejun Heo /* 4161493008a8STejun Heo * Workqueues which may be used during memory reclaim should 4162493008a8STejun Heo * have a rescuer to guarantee forward progress. 4163493008a8STejun Heo */ 4164493008a8STejun Heo if (flags & WQ_MEM_RECLAIM) { 4165e22bee78STejun Heo struct worker *rescuer; 4166e22bee78STejun Heo 4167d2c1d404STejun Heo rescuer = alloc_worker(); 4168e22bee78STejun Heo if (!rescuer) 4169d2c1d404STejun Heo goto err_destroy; 4170e22bee78STejun Heo 4171111c225aSTejun Heo rescuer->rescue_wq = wq; 4172111c225aSTejun Heo rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", 4173b196be89STejun Heo wq->name); 4174d2c1d404STejun Heo if (IS_ERR(rescuer->task)) { 4175d2c1d404STejun Heo kfree(rescuer); 4176d2c1d404STejun Heo goto err_destroy; 4177d2c1d404STejun Heo } 4178e22bee78STejun Heo 4179d2c1d404STejun Heo wq->rescuer = rescuer; 418014a40ffcSTejun Heo rescuer->task->flags |= PF_NO_SETAFFINITY; 4181e22bee78STejun Heo wake_up_process(rescuer->task); 41823af24433SOleg Nesterov } 41831537663fSTejun Heo 4184226223abSTejun Heo if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) 4185226223abSTejun Heo goto err_destroy; 4186226223abSTejun Heo 41873af24433SOleg Nesterov /* 418868e13a67SLai Jiangshan * wq_pool_mutex protects global freeze state and workqueues list. 418968e13a67SLai Jiangshan * Grab it, adjust max_active and add the new @wq to workqueues 419068e13a67SLai Jiangshan * list. 41913af24433SOleg Nesterov */ 419268e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 4193a0a1a5fdSTejun Heo 4194a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 419549e3cf44STejun Heo for_each_pwq(pwq, wq) 4196699ce097STejun Heo pwq_adjust_max_active(pwq); 4197a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 4198a0a1a5fdSTejun Heo 41993af24433SOleg Nesterov list_add(&wq->list, &workqueues); 4200a0a1a5fdSTejun Heo 420168e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 42023af24433SOleg Nesterov 42033af24433SOleg Nesterov return wq; 4204d2c1d404STejun Heo 4205d2c1d404STejun Heo err_free_wq: 42066029a918STejun Heo free_workqueue_attrs(wq->unbound_attrs); 42074690c4abSTejun Heo kfree(wq); 4208d2c1d404STejun Heo return NULL; 4209d2c1d404STejun Heo err_destroy: 4210d2c1d404STejun Heo destroy_workqueue(wq); 42114690c4abSTejun Heo return NULL; 42121da177e4SLinus Torvalds } 4213d320c038STejun Heo EXPORT_SYMBOL_GPL(__alloc_workqueue_key); 42141da177e4SLinus Torvalds 42153af24433SOleg Nesterov /** 42163af24433SOleg Nesterov * destroy_workqueue - safely terminate a workqueue 42173af24433SOleg Nesterov * @wq: target workqueue 42183af24433SOleg Nesterov * 42193af24433SOleg Nesterov * Safely destroy a workqueue. All work currently pending will be done first. 42203af24433SOleg Nesterov */ 42213af24433SOleg Nesterov void destroy_workqueue(struct workqueue_struct *wq) 42223af24433SOleg Nesterov { 422349e3cf44STejun Heo struct pool_workqueue *pwq; 42244c16bd32STejun Heo int node; 42253af24433SOleg Nesterov 42269c5a2ba7STejun Heo /* drain it before proceeding with destruction */ 42279c5a2ba7STejun Heo drain_workqueue(wq); 4228c8efcc25STejun Heo 42296183c009STejun Heo /* sanity checks */ 4230b09f4fd3SLai Jiangshan mutex_lock(&wq->mutex); 423149e3cf44STejun Heo for_each_pwq(pwq, wq) { 42326183c009STejun Heo int i; 42336183c009STejun Heo 423476af4d93STejun Heo for (i = 0; i < WORK_NR_COLORS; i++) { 423576af4d93STejun Heo if (WARN_ON(pwq->nr_in_flight[i])) { 4236b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 42376183c009STejun Heo return; 423876af4d93STejun Heo } 423976af4d93STejun Heo } 424076af4d93STejun Heo 42415c529597SLai Jiangshan if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) || 42428864b4e5STejun Heo WARN_ON(pwq->nr_active) || 424376af4d93STejun Heo WARN_ON(!list_empty(&pwq->delayed_works))) { 4244b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 42456183c009STejun Heo return; 42466183c009STejun Heo } 424776af4d93STejun Heo } 4248b09f4fd3SLai Jiangshan mutex_unlock(&wq->mutex); 42496183c009STejun Heo 4250a0a1a5fdSTejun Heo /* 4251a0a1a5fdSTejun Heo * wq list is used to freeze wq, remove from list after 4252a0a1a5fdSTejun Heo * flushing is complete in case freeze races us. 4253a0a1a5fdSTejun Heo */ 425468e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 4255d2c1d404STejun Heo list_del_init(&wq->list); 425668e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 42573af24433SOleg Nesterov 4258226223abSTejun Heo workqueue_sysfs_unregister(wq); 4259226223abSTejun Heo 4260493008a8STejun Heo if (wq->rescuer) { 4261e22bee78STejun Heo kthread_stop(wq->rescuer->task); 42628d9df9f0SXiaotian Feng kfree(wq->rescuer); 4263493008a8STejun Heo wq->rescuer = NULL; 4264e22bee78STejun Heo } 4265e22bee78STejun Heo 42668864b4e5STejun Heo if (!(wq->flags & WQ_UNBOUND)) { 426729c91e99STejun Heo /* 42688864b4e5STejun Heo * The base ref is never dropped on per-cpu pwqs. Directly 42698864b4e5STejun Heo * free the pwqs and wq. 427029c91e99STejun Heo */ 42718864b4e5STejun Heo free_percpu(wq->cpu_pwqs); 42728864b4e5STejun Heo kfree(wq); 42738864b4e5STejun Heo } else { 42748864b4e5STejun Heo /* 42758864b4e5STejun Heo * We're the sole accessor of @wq at this point. Directly 42764c16bd32STejun Heo * access numa_pwq_tbl[] and dfl_pwq to put the base refs. 42774c16bd32STejun Heo * @wq will be freed when the last pwq is released. 42788864b4e5STejun Heo */ 42794c16bd32STejun Heo for_each_node(node) { 42804c16bd32STejun Heo pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); 42814c16bd32STejun Heo RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL); 42824c16bd32STejun Heo put_pwq_unlocked(pwq); 42834c16bd32STejun Heo } 42844c16bd32STejun Heo 42854c16bd32STejun Heo /* 42864c16bd32STejun Heo * Put dfl_pwq. @wq may be freed any time after dfl_pwq is 42874c16bd32STejun Heo * put. Don't access it afterwards. 42884c16bd32STejun Heo */ 42894c16bd32STejun Heo pwq = wq->dfl_pwq; 42904c16bd32STejun Heo wq->dfl_pwq = NULL; 4291dce90d47STejun Heo put_pwq_unlocked(pwq); 429229c91e99STejun Heo } 42933af24433SOleg Nesterov } 42943af24433SOleg Nesterov EXPORT_SYMBOL_GPL(destroy_workqueue); 42953af24433SOleg Nesterov 4296dcd989cbSTejun Heo /** 4297dcd989cbSTejun Heo * workqueue_set_max_active - adjust max_active of a workqueue 4298dcd989cbSTejun Heo * @wq: target workqueue 4299dcd989cbSTejun Heo * @max_active: new max_active value. 4300dcd989cbSTejun Heo * 4301dcd989cbSTejun Heo * Set max_active of @wq to @max_active. 4302dcd989cbSTejun Heo * 4303dcd989cbSTejun Heo * CONTEXT: 4304dcd989cbSTejun Heo * Don't call from IRQ context. 4305dcd989cbSTejun Heo */ 4306dcd989cbSTejun Heo void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) 4307dcd989cbSTejun Heo { 430849e3cf44STejun Heo struct pool_workqueue *pwq; 4309dcd989cbSTejun Heo 43108719dceaSTejun Heo /* disallow meddling with max_active for ordered workqueues */ 43118719dceaSTejun Heo if (WARN_ON(wq->flags & __WQ_ORDERED)) 43128719dceaSTejun Heo return; 43138719dceaSTejun Heo 4314f3421797STejun Heo max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); 4315dcd989cbSTejun Heo 4316a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 4317dcd989cbSTejun Heo 4318dcd989cbSTejun Heo wq->saved_max_active = max_active; 4319dcd989cbSTejun Heo 4320699ce097STejun Heo for_each_pwq(pwq, wq) 4321699ce097STejun Heo pwq_adjust_max_active(pwq); 4322dcd989cbSTejun Heo 4323a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 4324dcd989cbSTejun Heo } 4325dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_set_max_active); 4326dcd989cbSTejun Heo 4327dcd989cbSTejun Heo /** 4328e6267616STejun Heo * current_is_workqueue_rescuer - is %current workqueue rescuer? 4329e6267616STejun Heo * 4330e6267616STejun Heo * Determine whether %current is a workqueue rescuer. Can be used from 4331e6267616STejun Heo * work functions to determine whether it's being run off the rescuer task. 4332e6267616STejun Heo */ 4333e6267616STejun Heo bool current_is_workqueue_rescuer(void) 4334e6267616STejun Heo { 4335e6267616STejun Heo struct worker *worker = current_wq_worker(); 4336e6267616STejun Heo 43376a092dfdSLai Jiangshan return worker && worker->rescue_wq; 4338e6267616STejun Heo } 4339e6267616STejun Heo 4340e6267616STejun Heo /** 4341dcd989cbSTejun Heo * workqueue_congested - test whether a workqueue is congested 4342dcd989cbSTejun Heo * @cpu: CPU in question 4343dcd989cbSTejun Heo * @wq: target workqueue 4344dcd989cbSTejun Heo * 4345dcd989cbSTejun Heo * Test whether @wq's cpu workqueue for @cpu is congested. There is 4346dcd989cbSTejun Heo * no synchronization around this function and the test result is 4347dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 4348dcd989cbSTejun Heo * 4349d3251859STejun Heo * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. 4350d3251859STejun Heo * Note that both per-cpu and unbound workqueues may be associated with 4351d3251859STejun Heo * multiple pool_workqueues which have separate congested states. A 4352d3251859STejun Heo * workqueue being congested on one CPU doesn't mean the workqueue is also 4353d3251859STejun Heo * contested on other CPUs / NUMA nodes. 4354d3251859STejun Heo * 4355dcd989cbSTejun Heo * RETURNS: 4356dcd989cbSTejun Heo * %true if congested, %false otherwise. 4357dcd989cbSTejun Heo */ 4358d84ff051STejun Heo bool workqueue_congested(int cpu, struct workqueue_struct *wq) 4359dcd989cbSTejun Heo { 43607fb98ea7STejun Heo struct pool_workqueue *pwq; 436176af4d93STejun Heo bool ret; 436276af4d93STejun Heo 436388109453SLai Jiangshan rcu_read_lock_sched(); 43647fb98ea7STejun Heo 4365d3251859STejun Heo if (cpu == WORK_CPU_UNBOUND) 4366d3251859STejun Heo cpu = smp_processor_id(); 4367d3251859STejun Heo 43687fb98ea7STejun Heo if (!(wq->flags & WQ_UNBOUND)) 43697fb98ea7STejun Heo pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); 43707fb98ea7STejun Heo else 4371df2d5ae4STejun Heo pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); 4372dcd989cbSTejun Heo 437376af4d93STejun Heo ret = !list_empty(&pwq->delayed_works); 437488109453SLai Jiangshan rcu_read_unlock_sched(); 437576af4d93STejun Heo 437676af4d93STejun Heo return ret; 4377dcd989cbSTejun Heo } 4378dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(workqueue_congested); 4379dcd989cbSTejun Heo 4380dcd989cbSTejun Heo /** 4381dcd989cbSTejun Heo * work_busy - test whether a work is currently pending or running 4382dcd989cbSTejun Heo * @work: the work to be tested 4383dcd989cbSTejun Heo * 4384dcd989cbSTejun Heo * Test whether @work is currently pending or running. There is no 4385dcd989cbSTejun Heo * synchronization around this function and the test result is 4386dcd989cbSTejun Heo * unreliable and only useful as advisory hints or for debugging. 4387dcd989cbSTejun Heo * 4388dcd989cbSTejun Heo * RETURNS: 4389dcd989cbSTejun Heo * OR'd bitmask of WORK_BUSY_* bits. 4390dcd989cbSTejun Heo */ 4391dcd989cbSTejun Heo unsigned int work_busy(struct work_struct *work) 4392dcd989cbSTejun Heo { 4393fa1b54e6STejun Heo struct worker_pool *pool; 4394dcd989cbSTejun Heo unsigned long flags; 4395dcd989cbSTejun Heo unsigned int ret = 0; 4396dcd989cbSTejun Heo 4397dcd989cbSTejun Heo if (work_pending(work)) 4398dcd989cbSTejun Heo ret |= WORK_BUSY_PENDING; 4399038366c5SLai Jiangshan 4400fa1b54e6STejun Heo local_irq_save(flags); 4401fa1b54e6STejun Heo pool = get_work_pool(work); 4402038366c5SLai Jiangshan if (pool) { 4403fa1b54e6STejun Heo spin_lock(&pool->lock); 4404c9e7cf27STejun Heo if (find_worker_executing_work(pool, work)) 4405dcd989cbSTejun Heo ret |= WORK_BUSY_RUNNING; 4406fa1b54e6STejun Heo spin_unlock(&pool->lock); 4407038366c5SLai Jiangshan } 4408fa1b54e6STejun Heo local_irq_restore(flags); 4409dcd989cbSTejun Heo 4410dcd989cbSTejun Heo return ret; 4411dcd989cbSTejun Heo } 4412dcd989cbSTejun Heo EXPORT_SYMBOL_GPL(work_busy); 4413dcd989cbSTejun Heo 44143d1cb205STejun Heo /** 44153d1cb205STejun Heo * set_worker_desc - set description for the current work item 44163d1cb205STejun Heo * @fmt: printf-style format string 44173d1cb205STejun Heo * @...: arguments for the format string 44183d1cb205STejun Heo * 44193d1cb205STejun Heo * This function can be called by a running work function to describe what 44203d1cb205STejun Heo * the work item is about. If the worker task gets dumped, this 44213d1cb205STejun Heo * information will be printed out together to help debugging. The 44223d1cb205STejun Heo * description can be at most WORKER_DESC_LEN including the trailing '\0'. 44233d1cb205STejun Heo */ 44243d1cb205STejun Heo void set_worker_desc(const char *fmt, ...) 44253d1cb205STejun Heo { 44263d1cb205STejun Heo struct worker *worker = current_wq_worker(); 44273d1cb205STejun Heo va_list args; 44283d1cb205STejun Heo 44293d1cb205STejun Heo if (worker) { 44303d1cb205STejun Heo va_start(args, fmt); 44313d1cb205STejun Heo vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); 44323d1cb205STejun Heo va_end(args); 44333d1cb205STejun Heo worker->desc_valid = true; 44343d1cb205STejun Heo } 44353d1cb205STejun Heo } 44363d1cb205STejun Heo 44373d1cb205STejun Heo /** 44383d1cb205STejun Heo * print_worker_info - print out worker information and description 44393d1cb205STejun Heo * @log_lvl: the log level to use when printing 44403d1cb205STejun Heo * @task: target task 44413d1cb205STejun Heo * 44423d1cb205STejun Heo * If @task is a worker and currently executing a work item, print out the 44433d1cb205STejun Heo * name of the workqueue being serviced and worker description set with 44443d1cb205STejun Heo * set_worker_desc() by the currently executing work item. 44453d1cb205STejun Heo * 44463d1cb205STejun Heo * This function can be safely called on any task as long as the 44473d1cb205STejun Heo * task_struct itself is accessible. While safe, this function isn't 44483d1cb205STejun Heo * synchronized and may print out mixups or garbages of limited length. 44493d1cb205STejun Heo */ 44503d1cb205STejun Heo void print_worker_info(const char *log_lvl, struct task_struct *task) 44513d1cb205STejun Heo { 44523d1cb205STejun Heo work_func_t *fn = NULL; 44533d1cb205STejun Heo char name[WQ_NAME_LEN] = { }; 44543d1cb205STejun Heo char desc[WORKER_DESC_LEN] = { }; 44553d1cb205STejun Heo struct pool_workqueue *pwq = NULL; 44563d1cb205STejun Heo struct workqueue_struct *wq = NULL; 44573d1cb205STejun Heo bool desc_valid = false; 44583d1cb205STejun Heo struct worker *worker; 44593d1cb205STejun Heo 44603d1cb205STejun Heo if (!(task->flags & PF_WQ_WORKER)) 44613d1cb205STejun Heo return; 44623d1cb205STejun Heo 44633d1cb205STejun Heo /* 44643d1cb205STejun Heo * This function is called without any synchronization and @task 44653d1cb205STejun Heo * could be in any state. Be careful with dereferences. 44663d1cb205STejun Heo */ 44673d1cb205STejun Heo worker = probe_kthread_data(task); 44683d1cb205STejun Heo 44693d1cb205STejun Heo /* 44703d1cb205STejun Heo * Carefully copy the associated workqueue's workfn and name. Keep 44713d1cb205STejun Heo * the original last '\0' in case the original contains garbage. 44723d1cb205STejun Heo */ 44733d1cb205STejun Heo probe_kernel_read(&fn, &worker->current_func, sizeof(fn)); 44743d1cb205STejun Heo probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq)); 44753d1cb205STejun Heo probe_kernel_read(&wq, &pwq->wq, sizeof(wq)); 44763d1cb205STejun Heo probe_kernel_read(name, wq->name, sizeof(name) - 1); 44773d1cb205STejun Heo 44783d1cb205STejun Heo /* copy worker description */ 44793d1cb205STejun Heo probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid)); 44803d1cb205STejun Heo if (desc_valid) 44813d1cb205STejun Heo probe_kernel_read(desc, worker->desc, sizeof(desc) - 1); 44823d1cb205STejun Heo 44833d1cb205STejun Heo if (fn || name[0] || desc[0]) { 44843d1cb205STejun Heo printk("%sWorkqueue: %s %pf", log_lvl, name, fn); 44853d1cb205STejun Heo if (desc[0]) 44863d1cb205STejun Heo pr_cont(" (%s)", desc); 44873d1cb205STejun Heo pr_cont("\n"); 44883d1cb205STejun Heo } 44893d1cb205STejun Heo } 44903d1cb205STejun Heo 4491db7bccf4STejun Heo /* 4492db7bccf4STejun Heo * CPU hotplug. 4493db7bccf4STejun Heo * 4494e22bee78STejun Heo * There are two challenges in supporting CPU hotplug. Firstly, there 4495112202d9STejun Heo * are a lot of assumptions on strong associations among work, pwq and 4496706026c2STejun Heo * pool which make migrating pending and scheduled works very 4497e22bee78STejun Heo * difficult to implement without impacting hot paths. Secondly, 449894cf58bbSTejun Heo * worker pools serve mix of short, long and very long running works making 4499e22bee78STejun Heo * blocked draining impractical. 4500e22bee78STejun Heo * 450124647570STejun Heo * This is solved by allowing the pools to be disassociated from the CPU 4502628c78e7STejun Heo * running as an unbound one and allowing it to be reattached later if the 4503628c78e7STejun Heo * cpu comes back online. 4504db7bccf4STejun Heo */ 4505db7bccf4STejun Heo 4506706026c2STejun Heo static void wq_unbind_fn(struct work_struct *work) 4507db7bccf4STejun Heo { 450838db41d9STejun Heo int cpu = smp_processor_id(); 45094ce62e9eSTejun Heo struct worker_pool *pool; 4510db7bccf4STejun Heo struct worker *worker; 4511a9ab775bSTejun Heo int wi; 4512db7bccf4STejun Heo 4513f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 45146183c009STejun Heo WARN_ON_ONCE(cpu != smp_processor_id()); 4515db7bccf4STejun Heo 4516bc3a1afcSTejun Heo mutex_lock(&pool->manager_mutex); 451794cf58bbSTejun Heo spin_lock_irq(&pool->lock); 4518e22bee78STejun Heo 4519f2d5a0eeSTejun Heo /* 4520bc3a1afcSTejun Heo * We've blocked all manager operations. Make all workers 452194cf58bbSTejun Heo * unbound and set DISASSOCIATED. Before this, all workers 452294cf58bbSTejun Heo * except for the ones which are still executing works from 452394cf58bbSTejun Heo * before the last CPU down must be on the cpu. After 452494cf58bbSTejun Heo * this, they may become diasporas. 4525f2d5a0eeSTejun Heo */ 4526a9ab775bSTejun Heo for_each_pool_worker(worker, wi, pool) 4527403c821dSTejun Heo worker->flags |= WORKER_UNBOUND; 4528db7bccf4STejun Heo 452924647570STejun Heo pool->flags |= POOL_DISASSOCIATED; 4530f2d5a0eeSTejun Heo 453194cf58bbSTejun Heo spin_unlock_irq(&pool->lock); 4532bc3a1afcSTejun Heo mutex_unlock(&pool->manager_mutex); 4533e22bee78STejun Heo 4534e22bee78STejun Heo /* 4535eb283428SLai Jiangshan * Call schedule() so that we cross rq->lock and thus can 4536eb283428SLai Jiangshan * guarantee sched callbacks see the %WORKER_UNBOUND flag. 4537eb283428SLai Jiangshan * This is necessary as scheduler callbacks may be invoked 4538eb283428SLai Jiangshan * from other cpus. 4539628c78e7STejun Heo */ 4540628c78e7STejun Heo schedule(); 4541628c78e7STejun Heo 4542628c78e7STejun Heo /* 4543eb283428SLai Jiangshan * Sched callbacks are disabled now. Zap nr_running. 4544eb283428SLai Jiangshan * After this, nr_running stays zero and need_more_worker() 4545eb283428SLai Jiangshan * and keep_working() are always true as long as the 4546eb283428SLai Jiangshan * worklist is not empty. This pool now behaves as an 4547eb283428SLai Jiangshan * unbound (in terms of concurrency management) pool which 4548eb283428SLai Jiangshan * are served by workers tied to the pool. 4549e22bee78STejun Heo */ 4550e19e397aSTejun Heo atomic_set(&pool->nr_running, 0); 4551eb283428SLai Jiangshan 4552eb283428SLai Jiangshan /* 4553eb283428SLai Jiangshan * With concurrency management just turned off, a busy 4554eb283428SLai Jiangshan * worker blocking could lead to lengthy stalls. Kick off 4555eb283428SLai Jiangshan * unbound chain execution of currently pending work items. 4556eb283428SLai Jiangshan */ 4557eb283428SLai Jiangshan spin_lock_irq(&pool->lock); 4558eb283428SLai Jiangshan wake_up_worker(pool); 4559eb283428SLai Jiangshan spin_unlock_irq(&pool->lock); 4560eb283428SLai Jiangshan } 4561db7bccf4STejun Heo } 4562db7bccf4STejun Heo 4563bd7c089eSTejun Heo /** 4564bd7c089eSTejun Heo * rebind_workers - rebind all workers of a pool to the associated CPU 4565bd7c089eSTejun Heo * @pool: pool of interest 4566bd7c089eSTejun Heo * 4567a9ab775bSTejun Heo * @pool->cpu is coming online. Rebind all workers to the CPU. 4568bd7c089eSTejun Heo */ 4569bd7c089eSTejun Heo static void rebind_workers(struct worker_pool *pool) 4570bd7c089eSTejun Heo { 4571a9ab775bSTejun Heo struct worker *worker; 4572a9ab775bSTejun Heo int wi; 4573bd7c089eSTejun Heo 4574bd7c089eSTejun Heo lockdep_assert_held(&pool->manager_mutex); 4575bd7c089eSTejun Heo 4576bd7c089eSTejun Heo /* 4577a9ab775bSTejun Heo * Restore CPU affinity of all workers. As all idle workers should 4578a9ab775bSTejun Heo * be on the run-queue of the associated CPU before any local 4579a9ab775bSTejun Heo * wake-ups for concurrency management happen, restore CPU affinty 4580a9ab775bSTejun Heo * of all workers first and then clear UNBOUND. As we're called 4581a9ab775bSTejun Heo * from CPU_ONLINE, the following shouldn't fail. 4582bd7c089eSTejun Heo */ 4583a9ab775bSTejun Heo for_each_pool_worker(worker, wi, pool) 4584a9ab775bSTejun Heo WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, 4585a9ab775bSTejun Heo pool->attrs->cpumask) < 0); 4586a9ab775bSTejun Heo 4587a9ab775bSTejun Heo spin_lock_irq(&pool->lock); 4588a9ab775bSTejun Heo 4589a9ab775bSTejun Heo for_each_pool_worker(worker, wi, pool) { 4590a9ab775bSTejun Heo unsigned int worker_flags = worker->flags; 4591a9ab775bSTejun Heo 4592a9ab775bSTejun Heo /* 4593a9ab775bSTejun Heo * A bound idle worker should actually be on the runqueue 4594a9ab775bSTejun Heo * of the associated CPU for local wake-ups targeting it to 4595a9ab775bSTejun Heo * work. Kick all idle workers so that they migrate to the 4596a9ab775bSTejun Heo * associated CPU. Doing this in the same loop as 4597a9ab775bSTejun Heo * replacing UNBOUND with REBOUND is safe as no worker will 4598a9ab775bSTejun Heo * be bound before @pool->lock is released. 4599a9ab775bSTejun Heo */ 4600a9ab775bSTejun Heo if (worker_flags & WORKER_IDLE) 4601bd7c089eSTejun Heo wake_up_process(worker->task); 4602bd7c089eSTejun Heo 4603bd7c089eSTejun Heo /* 4604a9ab775bSTejun Heo * We want to clear UNBOUND but can't directly call 4605a9ab775bSTejun Heo * worker_clr_flags() or adjust nr_running. Atomically 4606a9ab775bSTejun Heo * replace UNBOUND with another NOT_RUNNING flag REBOUND. 4607a9ab775bSTejun Heo * @worker will clear REBOUND using worker_clr_flags() when 4608a9ab775bSTejun Heo * it initiates the next execution cycle thus restoring 4609a9ab775bSTejun Heo * concurrency management. Note that when or whether 4610a9ab775bSTejun Heo * @worker clears REBOUND doesn't affect correctness. 4611a9ab775bSTejun Heo * 4612a9ab775bSTejun Heo * ACCESS_ONCE() is necessary because @worker->flags may be 4613a9ab775bSTejun Heo * tested without holding any lock in 4614a9ab775bSTejun Heo * wq_worker_waking_up(). Without it, NOT_RUNNING test may 4615a9ab775bSTejun Heo * fail incorrectly leading to premature concurrency 4616a9ab775bSTejun Heo * management operations. 4617bd7c089eSTejun Heo */ 4618a9ab775bSTejun Heo WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); 4619a9ab775bSTejun Heo worker_flags |= WORKER_REBOUND; 4620a9ab775bSTejun Heo worker_flags &= ~WORKER_UNBOUND; 4621a9ab775bSTejun Heo ACCESS_ONCE(worker->flags) = worker_flags; 4622bd7c089eSTejun Heo } 4623a9ab775bSTejun Heo 4624a9ab775bSTejun Heo spin_unlock_irq(&pool->lock); 4625bd7c089eSTejun Heo } 4626bd7c089eSTejun Heo 46277dbc725eSTejun Heo /** 46287dbc725eSTejun Heo * restore_unbound_workers_cpumask - restore cpumask of unbound workers 46297dbc725eSTejun Heo * @pool: unbound pool of interest 46307dbc725eSTejun Heo * @cpu: the CPU which is coming up 46317dbc725eSTejun Heo * 46327dbc725eSTejun Heo * An unbound pool may end up with a cpumask which doesn't have any online 46337dbc725eSTejun Heo * CPUs. When a worker of such pool get scheduled, the scheduler resets 46347dbc725eSTejun Heo * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any 46357dbc725eSTejun Heo * online CPU before, cpus_allowed of all its workers should be restored. 46367dbc725eSTejun Heo */ 46377dbc725eSTejun Heo static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) 46387dbc725eSTejun Heo { 46397dbc725eSTejun Heo static cpumask_t cpumask; 46407dbc725eSTejun Heo struct worker *worker; 46417dbc725eSTejun Heo int wi; 46427dbc725eSTejun Heo 46437dbc725eSTejun Heo lockdep_assert_held(&pool->manager_mutex); 46447dbc725eSTejun Heo 46457dbc725eSTejun Heo /* is @cpu allowed for @pool? */ 46467dbc725eSTejun Heo if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) 46477dbc725eSTejun Heo return; 46487dbc725eSTejun Heo 46497dbc725eSTejun Heo /* is @cpu the only online CPU? */ 46507dbc725eSTejun Heo cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); 46517dbc725eSTejun Heo if (cpumask_weight(&cpumask) != 1) 46527dbc725eSTejun Heo return; 46537dbc725eSTejun Heo 46547dbc725eSTejun Heo /* as we're called from CPU_ONLINE, the following shouldn't fail */ 46557dbc725eSTejun Heo for_each_pool_worker(worker, wi, pool) 46567dbc725eSTejun Heo WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, 46577dbc725eSTejun Heo pool->attrs->cpumask) < 0); 46587dbc725eSTejun Heo } 46597dbc725eSTejun Heo 46608db25e78STejun Heo /* 46618db25e78STejun Heo * Workqueues should be brought up before normal priority CPU notifiers. 46628db25e78STejun Heo * This will be registered high priority CPU notifier. 46638db25e78STejun Heo */ 46649fdf9b73SLai Jiangshan static int __cpuinit workqueue_cpu_up_callback(struct notifier_block *nfb, 46651da177e4SLinus Torvalds unsigned long action, 46661da177e4SLinus Torvalds void *hcpu) 46671da177e4SLinus Torvalds { 4668d84ff051STejun Heo int cpu = (unsigned long)hcpu; 46694ce62e9eSTejun Heo struct worker_pool *pool; 46704c16bd32STejun Heo struct workqueue_struct *wq; 46717dbc725eSTejun Heo int pi; 46721da177e4SLinus Torvalds 46738db25e78STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 46743af24433SOleg Nesterov case CPU_UP_PREPARE: 4675f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 46763ce63377STejun Heo if (pool->nr_workers) 46773ce63377STejun Heo continue; 4678ebf44d16STejun Heo if (create_and_start_worker(pool) < 0) 46793ce63377STejun Heo return NOTIFY_BAD; 46803af24433SOleg Nesterov } 46811da177e4SLinus Torvalds break; 46821da177e4SLinus Torvalds 468365758202STejun Heo case CPU_DOWN_FAILED: 468465758202STejun Heo case CPU_ONLINE: 468568e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 46867dbc725eSTejun Heo 46877dbc725eSTejun Heo for_each_pool(pool, pi) { 4688bc3a1afcSTejun Heo mutex_lock(&pool->manager_mutex); 468994cf58bbSTejun Heo 46907dbc725eSTejun Heo if (pool->cpu == cpu) { 4691a9ab775bSTejun Heo spin_lock_irq(&pool->lock); 469224647570STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 4693a9ab775bSTejun Heo spin_unlock_irq(&pool->lock); 4694a9ab775bSTejun Heo 469594cf58bbSTejun Heo rebind_workers(pool); 46967dbc725eSTejun Heo } else if (pool->cpu < 0) { 46977dbc725eSTejun Heo restore_unbound_workers_cpumask(pool, cpu); 46987dbc725eSTejun Heo } 469994cf58bbSTejun Heo 4700bc3a1afcSTejun Heo mutex_unlock(&pool->manager_mutex); 470194cf58bbSTejun Heo } 47027dbc725eSTejun Heo 47034c16bd32STejun Heo /* update NUMA affinity of unbound workqueues */ 47044c16bd32STejun Heo list_for_each_entry(wq, &workqueues, list) 47054c16bd32STejun Heo wq_update_unbound_numa(wq, cpu, true); 47064c16bd32STejun Heo 470768e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 47088db25e78STejun Heo break; 470965758202STejun Heo } 471065758202STejun Heo return NOTIFY_OK; 471165758202STejun Heo } 471265758202STejun Heo 471365758202STejun Heo /* 471465758202STejun Heo * Workqueues should be brought down after normal priority CPU notifiers. 471565758202STejun Heo * This will be registered as low priority CPU notifier. 471665758202STejun Heo */ 47179fdf9b73SLai Jiangshan static int __cpuinit workqueue_cpu_down_callback(struct notifier_block *nfb, 471865758202STejun Heo unsigned long action, 471965758202STejun Heo void *hcpu) 472065758202STejun Heo { 4721d84ff051STejun Heo int cpu = (unsigned long)hcpu; 47228db25e78STejun Heo struct work_struct unbind_work; 47234c16bd32STejun Heo struct workqueue_struct *wq; 47248db25e78STejun Heo 472565758202STejun Heo switch (action & ~CPU_TASKS_FROZEN) { 472665758202STejun Heo case CPU_DOWN_PREPARE: 47274c16bd32STejun Heo /* unbinding per-cpu workers should happen on the local CPU */ 4728706026c2STejun Heo INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn); 47297635d2fdSJoonsoo Kim queue_work_on(cpu, system_highpri_wq, &unbind_work); 47304c16bd32STejun Heo 47314c16bd32STejun Heo /* update NUMA affinity of unbound workqueues */ 47324c16bd32STejun Heo mutex_lock(&wq_pool_mutex); 47334c16bd32STejun Heo list_for_each_entry(wq, &workqueues, list) 47344c16bd32STejun Heo wq_update_unbound_numa(wq, cpu, false); 47354c16bd32STejun Heo mutex_unlock(&wq_pool_mutex); 47364c16bd32STejun Heo 47374c16bd32STejun Heo /* wait for per-cpu unbinding to finish */ 47388db25e78STejun Heo flush_work(&unbind_work); 47398db25e78STejun Heo break; 474065758202STejun Heo } 474165758202STejun Heo return NOTIFY_OK; 474265758202STejun Heo } 474365758202STejun Heo 47442d3854a3SRusty Russell #ifdef CONFIG_SMP 47458ccad40dSRusty Russell 47462d3854a3SRusty Russell struct work_for_cpu { 4747ed48ece2STejun Heo struct work_struct work; 47482d3854a3SRusty Russell long (*fn)(void *); 47492d3854a3SRusty Russell void *arg; 47502d3854a3SRusty Russell long ret; 47512d3854a3SRusty Russell }; 47522d3854a3SRusty Russell 4753ed48ece2STejun Heo static void work_for_cpu_fn(struct work_struct *work) 47542d3854a3SRusty Russell { 4755ed48ece2STejun Heo struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); 4756ed48ece2STejun Heo 47572d3854a3SRusty Russell wfc->ret = wfc->fn(wfc->arg); 47582d3854a3SRusty Russell } 47592d3854a3SRusty Russell 47602d3854a3SRusty Russell /** 47612d3854a3SRusty Russell * work_on_cpu - run a function in user context on a particular cpu 47622d3854a3SRusty Russell * @cpu: the cpu to run on 47632d3854a3SRusty Russell * @fn: the function to run 47642d3854a3SRusty Russell * @arg: the function arg 47652d3854a3SRusty Russell * 476631ad9081SRusty Russell * This will return the value @fn returns. 476731ad9081SRusty Russell * It is up to the caller to ensure that the cpu doesn't go offline. 47686b44003eSAndrew Morton * The caller must not hold any locks which would prevent @fn from completing. 47692d3854a3SRusty Russell */ 4770d84ff051STejun Heo long work_on_cpu(int cpu, long (*fn)(void *), void *arg) 47712d3854a3SRusty Russell { 4772ed48ece2STejun Heo struct work_for_cpu wfc = { .fn = fn, .arg = arg }; 47732d3854a3SRusty Russell 4774ed48ece2STejun Heo INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); 4775ed48ece2STejun Heo schedule_work_on(cpu, &wfc.work); 4776c2fda509SLai Jiangshan 4777c2fda509SLai Jiangshan /* 4778c2fda509SLai Jiangshan * The work item is on-stack and can't lead to deadlock through 4779c2fda509SLai Jiangshan * flushing. Use __flush_work() to avoid spurious lockdep warnings 4780c2fda509SLai Jiangshan * when work_on_cpu()s are nested. 4781c2fda509SLai Jiangshan */ 4782c2fda509SLai Jiangshan __flush_work(&wfc.work); 4783c2fda509SLai Jiangshan 47842d3854a3SRusty Russell return wfc.ret; 47852d3854a3SRusty Russell } 47862d3854a3SRusty Russell EXPORT_SYMBOL_GPL(work_on_cpu); 47872d3854a3SRusty Russell #endif /* CONFIG_SMP */ 47882d3854a3SRusty Russell 4789a0a1a5fdSTejun Heo #ifdef CONFIG_FREEZER 4790e7577c50SRusty Russell 4791a0a1a5fdSTejun Heo /** 4792a0a1a5fdSTejun Heo * freeze_workqueues_begin - begin freezing workqueues 4793a0a1a5fdSTejun Heo * 479458a69cb4STejun Heo * Start freezing workqueues. After this function returns, all freezable 4795c5aa87bbSTejun Heo * workqueues will queue new works to their delayed_works list instead of 4796706026c2STejun Heo * pool->worklist. 4797a0a1a5fdSTejun Heo * 4798a0a1a5fdSTejun Heo * CONTEXT: 4799a357fc03SLai Jiangshan * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 4800a0a1a5fdSTejun Heo */ 4801a0a1a5fdSTejun Heo void freeze_workqueues_begin(void) 4802a0a1a5fdSTejun Heo { 480317116969STejun Heo struct worker_pool *pool; 480424b8a847STejun Heo struct workqueue_struct *wq; 480524b8a847STejun Heo struct pool_workqueue *pwq; 4806611c92a0STejun Heo int pi; 4807a0a1a5fdSTejun Heo 480868e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 4809a0a1a5fdSTejun Heo 48106183c009STejun Heo WARN_ON_ONCE(workqueue_freezing); 4811a0a1a5fdSTejun Heo workqueue_freezing = true; 4812a0a1a5fdSTejun Heo 481324b8a847STejun Heo /* set FREEZING */ 4814611c92a0STejun Heo for_each_pool(pool, pi) { 48155bcab335STejun Heo spin_lock_irq(&pool->lock); 481635b6bb63STejun Heo WARN_ON_ONCE(pool->flags & POOL_FREEZING); 481735b6bb63STejun Heo pool->flags |= POOL_FREEZING; 48185bcab335STejun Heo spin_unlock_irq(&pool->lock); 48191da177e4SLinus Torvalds } 48208b03ae3cSTejun Heo 482124b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 4822a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 4823699ce097STejun Heo for_each_pwq(pwq, wq) 4824699ce097STejun Heo pwq_adjust_max_active(pwq); 4825a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 4826a1056305STejun Heo } 48275bcab335STejun Heo 482868e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 4829a0a1a5fdSTejun Heo } 4830a0a1a5fdSTejun Heo 4831a0a1a5fdSTejun Heo /** 483258a69cb4STejun Heo * freeze_workqueues_busy - are freezable workqueues still busy? 4833a0a1a5fdSTejun Heo * 4834a0a1a5fdSTejun Heo * Check whether freezing is complete. This function must be called 4835a0a1a5fdSTejun Heo * between freeze_workqueues_begin() and thaw_workqueues(). 4836a0a1a5fdSTejun Heo * 4837a0a1a5fdSTejun Heo * CONTEXT: 483868e13a67SLai Jiangshan * Grabs and releases wq_pool_mutex. 4839a0a1a5fdSTejun Heo * 4840a0a1a5fdSTejun Heo * RETURNS: 484158a69cb4STejun Heo * %true if some freezable workqueues are still busy. %false if freezing 484258a69cb4STejun Heo * is complete. 4843a0a1a5fdSTejun Heo */ 4844a0a1a5fdSTejun Heo bool freeze_workqueues_busy(void) 4845a0a1a5fdSTejun Heo { 4846a0a1a5fdSTejun Heo bool busy = false; 484724b8a847STejun Heo struct workqueue_struct *wq; 484824b8a847STejun Heo struct pool_workqueue *pwq; 4849a0a1a5fdSTejun Heo 485068e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 4851a0a1a5fdSTejun Heo 48526183c009STejun Heo WARN_ON_ONCE(!workqueue_freezing); 4853a0a1a5fdSTejun Heo 485424b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 485524b8a847STejun Heo if (!(wq->flags & WQ_FREEZABLE)) 485624b8a847STejun Heo continue; 4857a0a1a5fdSTejun Heo /* 4858a0a1a5fdSTejun Heo * nr_active is monotonically decreasing. It's safe 4859a0a1a5fdSTejun Heo * to peek without lock. 4860a0a1a5fdSTejun Heo */ 486188109453SLai Jiangshan rcu_read_lock_sched(); 486224b8a847STejun Heo for_each_pwq(pwq, wq) { 48636183c009STejun Heo WARN_ON_ONCE(pwq->nr_active < 0); 4864112202d9STejun Heo if (pwq->nr_active) { 4865a0a1a5fdSTejun Heo busy = true; 486688109453SLai Jiangshan rcu_read_unlock_sched(); 4867a0a1a5fdSTejun Heo goto out_unlock; 4868a0a1a5fdSTejun Heo } 4869a0a1a5fdSTejun Heo } 487088109453SLai Jiangshan rcu_read_unlock_sched(); 4871a0a1a5fdSTejun Heo } 4872a0a1a5fdSTejun Heo out_unlock: 487368e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 4874a0a1a5fdSTejun Heo return busy; 4875a0a1a5fdSTejun Heo } 4876a0a1a5fdSTejun Heo 4877a0a1a5fdSTejun Heo /** 4878a0a1a5fdSTejun Heo * thaw_workqueues - thaw workqueues 4879a0a1a5fdSTejun Heo * 4880a0a1a5fdSTejun Heo * Thaw workqueues. Normal queueing is restored and all collected 4881706026c2STejun Heo * frozen works are transferred to their respective pool worklists. 4882a0a1a5fdSTejun Heo * 4883a0a1a5fdSTejun Heo * CONTEXT: 4884a357fc03SLai Jiangshan * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. 4885a0a1a5fdSTejun Heo */ 4886a0a1a5fdSTejun Heo void thaw_workqueues(void) 4887a0a1a5fdSTejun Heo { 488824b8a847STejun Heo struct workqueue_struct *wq; 488924b8a847STejun Heo struct pool_workqueue *pwq; 489024b8a847STejun Heo struct worker_pool *pool; 4891611c92a0STejun Heo int pi; 4892a0a1a5fdSTejun Heo 489368e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 4894a0a1a5fdSTejun Heo 4895a0a1a5fdSTejun Heo if (!workqueue_freezing) 4896a0a1a5fdSTejun Heo goto out_unlock; 4897a0a1a5fdSTejun Heo 489824b8a847STejun Heo /* clear FREEZING */ 4899611c92a0STejun Heo for_each_pool(pool, pi) { 49005bcab335STejun Heo spin_lock_irq(&pool->lock); 490135b6bb63STejun Heo WARN_ON_ONCE(!(pool->flags & POOL_FREEZING)); 490235b6bb63STejun Heo pool->flags &= ~POOL_FREEZING; 49035bcab335STejun Heo spin_unlock_irq(&pool->lock); 4904d565ed63STejun Heo } 490524b8a847STejun Heo 490624b8a847STejun Heo /* restore max_active and repopulate worklist */ 490724b8a847STejun Heo list_for_each_entry(wq, &workqueues, list) { 4908a357fc03SLai Jiangshan mutex_lock(&wq->mutex); 4909699ce097STejun Heo for_each_pwq(pwq, wq) 4910699ce097STejun Heo pwq_adjust_max_active(pwq); 4911a357fc03SLai Jiangshan mutex_unlock(&wq->mutex); 491224b8a847STejun Heo } 491324b8a847STejun Heo 4914a0a1a5fdSTejun Heo workqueue_freezing = false; 4915a0a1a5fdSTejun Heo out_unlock: 491668e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 4917a0a1a5fdSTejun Heo } 4918a0a1a5fdSTejun Heo #endif /* CONFIG_FREEZER */ 4919a0a1a5fdSTejun Heo 4920bce90380STejun Heo static void __init wq_numa_init(void) 4921bce90380STejun Heo { 4922bce90380STejun Heo cpumask_var_t *tbl; 4923bce90380STejun Heo int node, cpu; 4924bce90380STejun Heo 4925bce90380STejun Heo /* determine NUMA pwq table len - highest node id + 1 */ 4926bce90380STejun Heo for_each_node(node) 4927bce90380STejun Heo wq_numa_tbl_len = max(wq_numa_tbl_len, node + 1); 4928bce90380STejun Heo 4929bce90380STejun Heo if (num_possible_nodes() <= 1) 4930bce90380STejun Heo return; 4931bce90380STejun Heo 4932d55262c4STejun Heo if (wq_disable_numa) { 4933d55262c4STejun Heo pr_info("workqueue: NUMA affinity support disabled\n"); 4934d55262c4STejun Heo return; 4935d55262c4STejun Heo } 4936d55262c4STejun Heo 49374c16bd32STejun Heo wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL); 49384c16bd32STejun Heo BUG_ON(!wq_update_unbound_numa_attrs_buf); 49394c16bd32STejun Heo 4940bce90380STejun Heo /* 4941bce90380STejun Heo * We want masks of possible CPUs of each node which isn't readily 4942bce90380STejun Heo * available. Build one from cpu_to_node() which should have been 4943bce90380STejun Heo * fully initialized by now. 4944bce90380STejun Heo */ 4945bce90380STejun Heo tbl = kzalloc(wq_numa_tbl_len * sizeof(tbl[0]), GFP_KERNEL); 4946bce90380STejun Heo BUG_ON(!tbl); 4947bce90380STejun Heo 4948bce90380STejun Heo for_each_node(node) 49491be0c25dSTejun Heo BUG_ON(!alloc_cpumask_var_node(&tbl[node], GFP_KERNEL, 49501be0c25dSTejun Heo node_online(node) ? node : NUMA_NO_NODE)); 4951bce90380STejun Heo 4952bce90380STejun Heo for_each_possible_cpu(cpu) { 4953bce90380STejun Heo node = cpu_to_node(cpu); 4954bce90380STejun Heo if (WARN_ON(node == NUMA_NO_NODE)) { 4955bce90380STejun Heo pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu); 4956bce90380STejun Heo /* happens iff arch is bonkers, let's just proceed */ 4957bce90380STejun Heo return; 4958bce90380STejun Heo } 4959bce90380STejun Heo cpumask_set_cpu(cpu, tbl[node]); 4960bce90380STejun Heo } 4961bce90380STejun Heo 4962bce90380STejun Heo wq_numa_possible_cpumask = tbl; 4963bce90380STejun Heo wq_numa_enabled = true; 4964bce90380STejun Heo } 4965bce90380STejun Heo 49666ee0578bSSuresh Siddha static int __init init_workqueues(void) 49671da177e4SLinus Torvalds { 49687a4e344cSTejun Heo int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; 49697a4e344cSTejun Heo int i, cpu; 4970c34056a3STejun Heo 49717c3eed5cSTejun Heo /* make sure we have enough bits for OFFQ pool ID */ 49727c3eed5cSTejun Heo BUILD_BUG_ON((1LU << (BITS_PER_LONG - WORK_OFFQ_POOL_SHIFT)) < 49736be19588SLai Jiangshan WORK_CPU_END * NR_STD_WORKER_POOLS); 4974b5490077STejun Heo 4975e904e6c2STejun Heo WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); 4976e904e6c2STejun Heo 4977e904e6c2STejun Heo pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); 4978e904e6c2STejun Heo 497965758202STejun Heo cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); 4980a5b4e57dSLai Jiangshan hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); 49818b03ae3cSTejun Heo 4982bce90380STejun Heo wq_numa_init(); 4983bce90380STejun Heo 4984706026c2STejun Heo /* initialize CPU pools */ 498529c91e99STejun Heo for_each_possible_cpu(cpu) { 49864ce62e9eSTejun Heo struct worker_pool *pool; 49878b03ae3cSTejun Heo 49887a4e344cSTejun Heo i = 0; 4989f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 49907a4e344cSTejun Heo BUG_ON(init_worker_pool(pool)); 4991ec22ca5eSTejun Heo pool->cpu = cpu; 49927a4e344cSTejun Heo cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); 49937a4e344cSTejun Heo pool->attrs->nice = std_nice[i++]; 4994f3f90ad4STejun Heo pool->node = cpu_to_node(cpu); 49957a4e344cSTejun Heo 49969daf9e67STejun Heo /* alloc pool ID */ 499768e13a67SLai Jiangshan mutex_lock(&wq_pool_mutex); 49989daf9e67STejun Heo BUG_ON(worker_pool_assign_id(pool)); 499968e13a67SLai Jiangshan mutex_unlock(&wq_pool_mutex); 50004ce62e9eSTejun Heo } 50018b03ae3cSTejun Heo } 50028b03ae3cSTejun Heo 5003e22bee78STejun Heo /* create the initial worker */ 500429c91e99STejun Heo for_each_online_cpu(cpu) { 50054ce62e9eSTejun Heo struct worker_pool *pool; 5006e22bee78STejun Heo 5007f02ae73aSTejun Heo for_each_cpu_worker_pool(pool, cpu) { 500824647570STejun Heo pool->flags &= ~POOL_DISASSOCIATED; 5009ebf44d16STejun Heo BUG_ON(create_and_start_worker(pool) < 0); 5010e22bee78STejun Heo } 50114ce62e9eSTejun Heo } 5012e22bee78STejun Heo 501329c91e99STejun Heo /* create default unbound wq attrs */ 501429c91e99STejun Heo for (i = 0; i < NR_STD_WORKER_POOLS; i++) { 501529c91e99STejun Heo struct workqueue_attrs *attrs; 501629c91e99STejun Heo 501729c91e99STejun Heo BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL))); 501829c91e99STejun Heo attrs->nice = std_nice[i]; 501929c91e99STejun Heo unbound_std_wq_attrs[i] = attrs; 502029c91e99STejun Heo } 502129c91e99STejun Heo 5022d320c038STejun Heo system_wq = alloc_workqueue("events", 0, 0); 50231aabe902SJoonsoo Kim system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); 5024d320c038STejun Heo system_long_wq = alloc_workqueue("events_long", 0, 0); 5025f3421797STejun Heo system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, 5026f3421797STejun Heo WQ_UNBOUND_MAX_ACTIVE); 502724d51addSTejun Heo system_freezable_wq = alloc_workqueue("events_freezable", 502824d51addSTejun Heo WQ_FREEZABLE, 0); 50290668106cSViresh Kumar system_power_efficient_wq = alloc_workqueue("events_power_efficient", 50300668106cSViresh Kumar WQ_POWER_EFFICIENT, 0); 50310668106cSViresh Kumar system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", 50320668106cSViresh Kumar WQ_FREEZABLE | WQ_POWER_EFFICIENT, 50330668106cSViresh Kumar 0); 50341aabe902SJoonsoo Kim BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || 50350668106cSViresh Kumar !system_unbound_wq || !system_freezable_wq || 50360668106cSViresh Kumar !system_power_efficient_wq || 50370668106cSViresh Kumar !system_freezable_power_efficient_wq); 50386ee0578bSSuresh Siddha return 0; 50391da177e4SLinus Torvalds } 50406ee0578bSSuresh Siddha early_initcall(init_workqueues); 5041