1 /* 2 * Read-Copy Update mechanism for mutual exclusion (tree-based version) 3 * Internal non-public definitions. 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation; either version 2 of the License, or 8 * (at your option) any later version. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, you can access it online at 17 * http://www.gnu.org/licenses/gpl-2.0.html. 18 * 19 * Copyright IBM Corporation, 2008 20 * 21 * Author: Ingo Molnar <mingo@elte.hu> 22 * Paul E. McKenney <paulmck@linux.vnet.ibm.com> 23 */ 24 25 #include <linux/cache.h> 26 #include <linux/spinlock.h> 27 #include <linux/rtmutex.h> 28 #include <linux/threads.h> 29 #include <linux/cpumask.h> 30 #include <linux/seqlock.h> 31 #include <linux/swait.h> 32 #include <linux/stop_machine.h> 33 #include <linux/rcu_node_tree.h> 34 35 #include "rcu_segcblist.h" 36 37 /* 38 * Dynticks per-CPU state. 39 */ 40 struct rcu_dynticks { 41 long long dynticks_nesting; /* Track irq/process nesting level. */ 42 /* Process level is worth LLONG_MAX/2. */ 43 int dynticks_nmi_nesting; /* Track NMI nesting level. */ 44 atomic_t dynticks; /* Even value for idle, else odd. */ 45 bool rcu_need_heavy_qs; /* GP old, need heavy quiescent state. */ 46 unsigned long rcu_qs_ctr; /* Light universal quiescent state ctr. */ 47 bool rcu_urgent_qs; /* GP old need light quiescent state. */ 48 #ifdef CONFIG_NO_HZ_FULL_SYSIDLE 49 long long dynticks_idle_nesting; 50 /* irq/process nesting level from idle. */ 51 atomic_t dynticks_idle; /* Even value for idle, else odd. */ 52 /* "Idle" excludes userspace execution. */ 53 unsigned long dynticks_idle_jiffies; 54 /* End of last non-NMI non-idle period. */ 55 #endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */ 56 #ifdef CONFIG_RCU_FAST_NO_HZ 57 bool all_lazy; /* Are all CPU's CBs lazy? */ 58 unsigned long nonlazy_posted; 59 /* # times non-lazy CBs posted to CPU. */ 60 unsigned long nonlazy_posted_snap; 61 /* idle-period nonlazy_posted snapshot. */ 62 unsigned long last_accelerate; 63 /* Last jiffy CBs were accelerated. */ 64 unsigned long last_advance_all; 65 /* Last jiffy CBs were all advanced. */ 66 int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */ 67 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ 68 }; 69 70 /* RCU's kthread states for tracing. */ 71 #define RCU_KTHREAD_STOPPED 0 72 #define RCU_KTHREAD_RUNNING 1 73 #define RCU_KTHREAD_WAITING 2 74 #define RCU_KTHREAD_OFFCPU 3 75 #define RCU_KTHREAD_YIELDING 4 76 #define RCU_KTHREAD_MAX 4 77 78 /* 79 * Definition for node within the RCU grace-period-detection hierarchy. 80 */ 81 struct rcu_node { 82 raw_spinlock_t __private lock; /* Root rcu_node's lock protects */ 83 /* some rcu_state fields as well as */ 84 /* following. */ 85 unsigned long gpnum; /* Current grace period for this node. */ 86 /* This will either be equal to or one */ 87 /* behind the root rcu_node's gpnum. */ 88 unsigned long completed; /* Last GP completed for this node. */ 89 /* This will either be equal to or one */ 90 /* behind the root rcu_node's gpnum. */ 91 unsigned long qsmask; /* CPUs or groups that need to switch in */ 92 /* order for current grace period to proceed.*/ 93 /* In leaf rcu_node, each bit corresponds to */ 94 /* an rcu_data structure, otherwise, each */ 95 /* bit corresponds to a child rcu_node */ 96 /* structure. */ 97 unsigned long qsmaskinit; 98 /* Per-GP initial value for qsmask. */ 99 /* Initialized from ->qsmaskinitnext at the */ 100 /* beginning of each grace period. */ 101 unsigned long qsmaskinitnext; 102 /* Online CPUs for next grace period. */ 103 unsigned long expmask; /* CPUs or groups that need to check in */ 104 /* to allow the current expedited GP */ 105 /* to complete. */ 106 unsigned long expmaskinit; 107 /* Per-GP initial values for expmask. */ 108 /* Initialized from ->expmaskinitnext at the */ 109 /* beginning of each expedited GP. */ 110 unsigned long expmaskinitnext; 111 /* Online CPUs for next expedited GP. */ 112 /* Any CPU that has ever been online will */ 113 /* have its bit set. */ 114 unsigned long grpmask; /* Mask to apply to parent qsmask. */ 115 /* Only one bit will be set in this mask. */ 116 int grplo; /* lowest-numbered CPU or group here. */ 117 int grphi; /* highest-numbered CPU or group here. */ 118 u8 grpnum; /* CPU/group number for next level up. */ 119 u8 level; /* root is at level 0. */ 120 bool wait_blkd_tasks;/* Necessary to wait for blocked tasks to */ 121 /* exit RCU read-side critical sections */ 122 /* before propagating offline up the */ 123 /* rcu_node tree? */ 124 struct rcu_node *parent; 125 struct list_head blkd_tasks; 126 /* Tasks blocked in RCU read-side critical */ 127 /* section. Tasks are placed at the head */ 128 /* of this list and age towards the tail. */ 129 struct list_head *gp_tasks; 130 /* Pointer to the first task blocking the */ 131 /* current grace period, or NULL if there */ 132 /* is no such task. */ 133 struct list_head *exp_tasks; 134 /* Pointer to the first task blocking the */ 135 /* current expedited grace period, or NULL */ 136 /* if there is no such task. If there */ 137 /* is no current expedited grace period, */ 138 /* then there can cannot be any such task. */ 139 struct list_head *boost_tasks; 140 /* Pointer to first task that needs to be */ 141 /* priority boosted, or NULL if no priority */ 142 /* boosting is needed for this rcu_node */ 143 /* structure. If there are no tasks */ 144 /* queued on this rcu_node structure that */ 145 /* are blocking the current grace period, */ 146 /* there can be no such task. */ 147 struct rt_mutex boost_mtx; 148 /* Used only for the priority-boosting */ 149 /* side effect, not as a lock. */ 150 unsigned long boost_time; 151 /* When to start boosting (jiffies). */ 152 struct task_struct *boost_kthread_task; 153 /* kthread that takes care of priority */ 154 /* boosting for this rcu_node structure. */ 155 unsigned int boost_kthread_status; 156 /* State of boost_kthread_task for tracing. */ 157 unsigned long n_tasks_boosted; 158 /* Total number of tasks boosted. */ 159 unsigned long n_exp_boosts; 160 /* Number of tasks boosted for expedited GP. */ 161 unsigned long n_normal_boosts; 162 /* Number of tasks boosted for normal GP. */ 163 unsigned long n_balk_blkd_tasks; 164 /* Refused to boost: no blocked tasks. */ 165 unsigned long n_balk_exp_gp_tasks; 166 /* Refused to boost: nothing blocking GP. */ 167 unsigned long n_balk_boost_tasks; 168 /* Refused to boost: already boosting. */ 169 unsigned long n_balk_notblocked; 170 /* Refused to boost: RCU RS CS still running. */ 171 unsigned long n_balk_notyet; 172 /* Refused to boost: not yet time. */ 173 unsigned long n_balk_nos; 174 /* Refused to boost: not sure why, though. */ 175 /* This can happen due to race conditions. */ 176 #ifdef CONFIG_RCU_NOCB_CPU 177 struct swait_queue_head nocb_gp_wq[2]; 178 /* Place for rcu_nocb_kthread() to wait GP. */ 179 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 180 int need_future_gp[2]; 181 /* Counts of upcoming no-CB GP requests. */ 182 raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp; 183 184 spinlock_t exp_lock ____cacheline_internodealigned_in_smp; 185 unsigned long exp_seq_rq; 186 wait_queue_head_t exp_wq[4]; 187 } ____cacheline_internodealigned_in_smp; 188 189 /* 190 * Bitmasks in an rcu_node cover the interval [grplo, grphi] of CPU IDs, and 191 * are indexed relative to this interval rather than the global CPU ID space. 192 * This generates the bit for a CPU in node-local masks. 193 */ 194 #define leaf_node_cpu_bit(rnp, cpu) (1UL << ((cpu) - (rnp)->grplo)) 195 196 /* 197 * Union to allow "aggregate OR" operation on the need for a quiescent 198 * state by the normal and expedited grace periods. 199 */ 200 union rcu_noqs { 201 struct { 202 u8 norm; 203 u8 exp; 204 } b; /* Bits. */ 205 u16 s; /* Set of bits, aggregate OR here. */ 206 }; 207 208 /* Index values for nxttail array in struct rcu_data. */ 209 #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ 210 #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ 211 #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */ 212 #define RCU_NEXT_TAIL 3 213 #define RCU_NEXT_SIZE 4 214 215 /* Per-CPU data for read-copy update. */ 216 struct rcu_data { 217 /* 1) quiescent-state and grace-period handling : */ 218 unsigned long completed; /* Track rsp->completed gp number */ 219 /* in order to detect GP end. */ 220 unsigned long gpnum; /* Highest gp number that this CPU */ 221 /* is aware of having started. */ 222 unsigned long rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */ 223 /* for rcu_all_qs() invocations. */ 224 union rcu_noqs cpu_no_qs; /* No QSes yet for this CPU. */ 225 bool core_needs_qs; /* Core waits for quiesc state. */ 226 bool beenonline; /* CPU online at least once. */ 227 bool gpwrap; /* Possible gpnum/completed wrap. */ 228 struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ 229 unsigned long grpmask; /* Mask to apply to leaf qsmask. */ 230 unsigned long ticks_this_gp; /* The number of scheduling-clock */ 231 /* ticks this CPU has handled */ 232 /* during and after the last grace */ 233 /* period it is aware of. */ 234 235 /* 2) batch handling */ 236 struct rcu_segcblist cblist; /* Segmented callback list, with */ 237 /* different callbacks waiting for */ 238 /* different grace periods. */ 239 long qlen_last_fqs_check; 240 /* qlen at last check for QS forcing */ 241 unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ 242 unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */ 243 unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ 244 unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ 245 unsigned long n_force_qs_snap; 246 /* did other CPU force QS recently? */ 247 long blimit; /* Upper limit on a processed batch */ 248 249 /* 3) dynticks interface. */ 250 struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ 251 int dynticks_snap; /* Per-GP tracking for dynticks. */ 252 253 /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ 254 unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ 255 unsigned long offline_fqs; /* Kicked due to being offline. */ 256 unsigned long cond_resched_completed; 257 /* Grace period that needs help */ 258 /* from cond_resched(). */ 259 260 /* 5) __rcu_pending() statistics. */ 261 unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ 262 unsigned long n_rp_core_needs_qs; 263 unsigned long n_rp_report_qs; 264 unsigned long n_rp_cb_ready; 265 unsigned long n_rp_cpu_needs_gp; 266 unsigned long n_rp_gp_completed; 267 unsigned long n_rp_gp_started; 268 unsigned long n_rp_nocb_defer_wakeup; 269 unsigned long n_rp_need_nothing; 270 271 /* 6) _rcu_barrier(), OOM callbacks, and expediting. */ 272 struct rcu_head barrier_head; 273 #ifdef CONFIG_RCU_FAST_NO_HZ 274 struct rcu_head oom_head; 275 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ 276 atomic_long_t exp_workdone0; /* # done by workqueue. */ 277 atomic_long_t exp_workdone1; /* # done by others #1. */ 278 atomic_long_t exp_workdone2; /* # done by others #2. */ 279 atomic_long_t exp_workdone3; /* # done by others #3. */ 280 int exp_dynticks_snap; /* Double-check need for IPI. */ 281 282 /* 7) Callback offloading. */ 283 #ifdef CONFIG_RCU_NOCB_CPU 284 struct rcu_head *nocb_head; /* CBs waiting for kthread. */ 285 struct rcu_head **nocb_tail; 286 atomic_long_t nocb_q_count; /* # CBs waiting for nocb */ 287 atomic_long_t nocb_q_count_lazy; /* invocation (all stages). */ 288 struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */ 289 struct rcu_head **nocb_follower_tail; 290 struct swait_queue_head nocb_wq; /* For nocb kthreads to sleep on. */ 291 struct task_struct *nocb_kthread; 292 int nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */ 293 294 /* The following fields are used by the leader, hence own cacheline. */ 295 struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp; 296 /* CBs waiting for GP. */ 297 struct rcu_head **nocb_gp_tail; 298 bool nocb_leader_sleep; /* Is the nocb leader thread asleep? */ 299 struct rcu_data *nocb_next_follower; 300 /* Next follower in wakeup chain. */ 301 302 /* The following fields are used by the follower, hence new cachline. */ 303 struct rcu_data *nocb_leader ____cacheline_internodealigned_in_smp; 304 /* Leader CPU takes GP-end wakeups. */ 305 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 306 307 /* 8) RCU CPU stall data. */ 308 unsigned int softirq_snap; /* Snapshot of softirq activity. */ 309 310 int cpu; 311 struct rcu_state *rsp; 312 }; 313 314 /* Values for nocb_defer_wakeup field in struct rcu_data. */ 315 #define RCU_NOGP_WAKE_NOT 0 316 #define RCU_NOGP_WAKE 1 317 #define RCU_NOGP_WAKE_FORCE 2 318 319 #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500)) 320 /* For jiffies_till_first_fqs and */ 321 /* and jiffies_till_next_fqs. */ 322 323 #define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */ 324 /* delay between bouts of */ 325 /* quiescent-state forcing. */ 326 327 #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */ 328 /* at least one scheduling clock */ 329 /* irq before ratting on them. */ 330 331 #define rcu_wait(cond) \ 332 do { \ 333 for (;;) { \ 334 set_current_state(TASK_INTERRUPTIBLE); \ 335 if (cond) \ 336 break; \ 337 schedule(); \ 338 } \ 339 __set_current_state(TASK_RUNNING); \ 340 } while (0) 341 342 /* 343 * RCU global state, including node hierarchy. This hierarchy is 344 * represented in "heap" form in a dense array. The root (first level) 345 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second 346 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]), 347 * and the third level in ->node[m+1] and following (->node[m+1] referenced 348 * by ->level[2]). The number of levels is determined by the number of 349 * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy" 350 * consisting of a single rcu_node. 351 */ 352 struct rcu_state { 353 struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */ 354 struct rcu_node *level[RCU_NUM_LVLS + 1]; 355 /* Hierarchy levels (+1 to */ 356 /* shut bogus gcc warning) */ 357 struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */ 358 call_rcu_func_t call; /* call_rcu() flavor. */ 359 int ncpus; /* # CPUs seen so far. */ 360 361 /* The following fields are guarded by the root rcu_node's lock. */ 362 363 u8 boost ____cacheline_internodealigned_in_smp; 364 /* Subject to priority boost. */ 365 unsigned long gpnum; /* Current gp number. */ 366 unsigned long completed; /* # of last completed gp. */ 367 struct task_struct *gp_kthread; /* Task for grace periods. */ 368 struct swait_queue_head gp_wq; /* Where GP task waits. */ 369 short gp_flags; /* Commands for GP task. */ 370 short gp_state; /* GP kthread sleep state. */ 371 372 /* End of fields guarded by root rcu_node's lock. */ 373 374 raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp; 375 /* Protect following fields. */ 376 struct rcu_cblist orphan_pend; /* Orphaned callbacks that */ 377 /* need a grace period. */ 378 struct rcu_cblist orphan_done; /* Orphaned callbacks that */ 379 /* are ready to invoke. */ 380 /* (Contains counts.) */ 381 /* End of fields guarded by orphan_lock. */ 382 383 struct mutex barrier_mutex; /* Guards barrier fields. */ 384 atomic_t barrier_cpu_count; /* # CPUs waiting on. */ 385 struct completion barrier_completion; /* Wake at barrier end. */ 386 unsigned long barrier_sequence; /* ++ at start and end of */ 387 /* _rcu_barrier(). */ 388 /* End of fields guarded by barrier_mutex. */ 389 390 struct mutex exp_mutex; /* Serialize expedited GP. */ 391 struct mutex exp_wake_mutex; /* Serialize wakeup. */ 392 unsigned long expedited_sequence; /* Take a ticket. */ 393 atomic_t expedited_need_qs; /* # CPUs left to check in. */ 394 struct swait_queue_head expedited_wq; /* Wait for check-ins. */ 395 int ncpus_snap; /* # CPUs seen last time. */ 396 397 unsigned long jiffies_force_qs; /* Time at which to invoke */ 398 /* force_quiescent_state(). */ 399 unsigned long jiffies_kick_kthreads; /* Time at which to kick */ 400 /* kthreads, if configured. */ 401 unsigned long n_force_qs; /* Number of calls to */ 402 /* force_quiescent_state(). */ 403 unsigned long n_force_qs_lh; /* ~Number of calls leaving */ 404 /* due to lock unavailable. */ 405 unsigned long n_force_qs_ngp; /* Number of calls leaving */ 406 /* due to no GP active. */ 407 unsigned long gp_start; /* Time at which GP started, */ 408 /* but in jiffies. */ 409 unsigned long gp_activity; /* Time of last GP kthread */ 410 /* activity in jiffies. */ 411 unsigned long jiffies_stall; /* Time at which to check */ 412 /* for CPU stalls. */ 413 unsigned long jiffies_resched; /* Time at which to resched */ 414 /* a reluctant CPU. */ 415 unsigned long n_force_qs_gpstart; /* Snapshot of n_force_qs at */ 416 /* GP start. */ 417 unsigned long gp_max; /* Maximum GP duration in */ 418 /* jiffies. */ 419 const char *name; /* Name of structure. */ 420 char abbr; /* Abbreviated name. */ 421 struct list_head flavors; /* List of RCU flavors. */ 422 }; 423 424 /* Values for rcu_state structure's gp_flags field. */ 425 #define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */ 426 #define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */ 427 428 /* Values for rcu_state structure's gp_state field. */ 429 #define RCU_GP_IDLE 0 /* Initial state and no GP in progress. */ 430 #define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */ 431 #define RCU_GP_DONE_GPS 2 /* Wait done for grace-period start. */ 432 #define RCU_GP_WAIT_FQS 3 /* Wait for force-quiescent-state time. */ 433 #define RCU_GP_DOING_FQS 4 /* Wait done for force-quiescent-state time. */ 434 #define RCU_GP_CLEANUP 5 /* Grace-period cleanup started. */ 435 #define RCU_GP_CLEANED 6 /* Grace-period cleanup complete. */ 436 437 #ifndef RCU_TREE_NONCORE 438 static const char * const gp_state_names[] = { 439 "RCU_GP_IDLE", 440 "RCU_GP_WAIT_GPS", 441 "RCU_GP_DONE_GPS", 442 "RCU_GP_WAIT_FQS", 443 "RCU_GP_DOING_FQS", 444 "RCU_GP_CLEANUP", 445 "RCU_GP_CLEANED", 446 }; 447 #endif /* #ifndef RCU_TREE_NONCORE */ 448 449 extern struct list_head rcu_struct_flavors; 450 451 /* Sequence through rcu_state structures for each RCU flavor. */ 452 #define for_each_rcu_flavor(rsp) \ 453 list_for_each_entry((rsp), &rcu_struct_flavors, flavors) 454 455 /* 456 * RCU implementation internal declarations: 457 */ 458 extern struct rcu_state rcu_sched_state; 459 460 extern struct rcu_state rcu_bh_state; 461 462 #ifdef CONFIG_PREEMPT_RCU 463 extern struct rcu_state rcu_preempt_state; 464 #endif /* #ifdef CONFIG_PREEMPT_RCU */ 465 466 int rcu_dynticks_snap(struct rcu_dynticks *rdtp); 467 bool rcu_eqs_special_set(int cpu); 468 469 #ifdef CONFIG_RCU_BOOST 470 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); 471 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu); 472 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); 473 DECLARE_PER_CPU(char, rcu_cpu_has_work); 474 #endif /* #ifdef CONFIG_RCU_BOOST */ 475 476 #ifndef RCU_TREE_NONCORE 477 478 /* Forward declarations for rcutree_plugin.h */ 479 static void rcu_bootup_announce(void); 480 static void rcu_preempt_note_context_switch(void); 481 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp); 482 #ifdef CONFIG_HOTPLUG_CPU 483 static bool rcu_preempt_has_tasks(struct rcu_node *rnp); 484 #endif /* #ifdef CONFIG_HOTPLUG_CPU */ 485 static void rcu_print_detail_task_stall(struct rcu_state *rsp); 486 static int rcu_print_task_stall(struct rcu_node *rnp); 487 static int rcu_print_task_exp_stall(struct rcu_node *rnp); 488 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); 489 static void rcu_preempt_check_callbacks(void); 490 void call_rcu(struct rcu_head *head, rcu_callback_t func); 491 static void __init __rcu_init_preempt(void); 492 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); 493 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); 494 static void invoke_rcu_callbacks_kthread(void); 495 static bool rcu_is_callbacks_kthread(void); 496 #ifdef CONFIG_RCU_BOOST 497 static void rcu_preempt_do_callbacks(void); 498 static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp, 499 struct rcu_node *rnp); 500 #endif /* #ifdef CONFIG_RCU_BOOST */ 501 static void __init rcu_spawn_boost_kthreads(void); 502 static void rcu_prepare_kthreads(int cpu); 503 static void rcu_cleanup_after_idle(void); 504 static void rcu_prepare_for_idle(void); 505 static void rcu_idle_count_callbacks_posted(void); 506 static bool rcu_preempt_has_tasks(struct rcu_node *rnp); 507 static void print_cpu_stall_info_begin(void); 508 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu); 509 static void print_cpu_stall_info_end(void); 510 static void zero_cpu_stall_ticks(struct rcu_data *rdp); 511 static void increment_cpu_stall_ticks(void); 512 static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu); 513 static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq); 514 static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp); 515 static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq); 516 static void rcu_init_one_nocb(struct rcu_node *rnp); 517 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp, 518 bool lazy, unsigned long flags); 519 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp, 520 struct rcu_data *rdp, 521 unsigned long flags); 522 static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp); 523 static void do_nocb_deferred_wakeup(struct rcu_data *rdp); 524 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp); 525 static void rcu_spawn_all_nocb_kthreads(int cpu); 526 static void __init rcu_spawn_nocb_kthreads(void); 527 #ifdef CONFIG_RCU_NOCB_CPU 528 static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp); 529 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 530 static void __maybe_unused rcu_kick_nohz_cpu(int cpu); 531 static bool init_nocb_callback_list(struct rcu_data *rdp); 532 static void rcu_sysidle_enter(int irq); 533 static void rcu_sysidle_exit(int irq); 534 static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle, 535 unsigned long *maxj); 536 static bool is_sysidle_rcu_state(struct rcu_state *rsp); 537 static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle, 538 unsigned long maxj); 539 static void rcu_bind_gp_kthread(void); 540 static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp); 541 static bool rcu_nohz_full_cpu(struct rcu_state *rsp); 542 static void rcu_dynticks_task_enter(void); 543 static void rcu_dynticks_task_exit(void); 544 545 #ifdef CONFIG_SRCU 546 void srcu_online_cpu(unsigned int cpu); 547 void srcu_offline_cpu(unsigned int cpu); 548 #else /* #ifdef CONFIG_SRCU */ 549 void srcu_online_cpu(unsigned int cpu) { } 550 void srcu_offline_cpu(unsigned int cpu) { } 551 #endif /* #else #ifdef CONFIG_SRCU */ 552 553 #endif /* #ifndef RCU_TREE_NONCORE */ 554 555 #ifdef CONFIG_RCU_TRACE 556 /* Read out queue lengths for tracing. */ 557 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll) 558 { 559 #ifdef CONFIG_RCU_NOCB_CPU 560 *ql = atomic_long_read(&rdp->nocb_q_count); 561 *qll = atomic_long_read(&rdp->nocb_q_count_lazy); 562 #else /* #ifdef CONFIG_RCU_NOCB_CPU */ 563 *ql = 0; 564 *qll = 0; 565 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ 566 } 567 #endif /* #ifdef CONFIG_RCU_TRACE */ 568 569 /* 570 * Wrappers for the rcu_node::lock acquire and release. 571 * 572 * Because the rcu_nodes form a tree, the tree traversal locking will observe 573 * different lock values, this in turn means that an UNLOCK of one level 574 * followed by a LOCK of another level does not imply a full memory barrier; 575 * and most importantly transitivity is lost. 576 * 577 * In order to restore full ordering between tree levels, augment the regular 578 * lock acquire functions with smp_mb__after_unlock_lock(). 579 * 580 * As ->lock of struct rcu_node is a __private field, therefore one should use 581 * these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock. 582 */ 583 static inline void raw_spin_lock_rcu_node(struct rcu_node *rnp) 584 { 585 raw_spin_lock(&ACCESS_PRIVATE(rnp, lock)); 586 smp_mb__after_unlock_lock(); 587 } 588 589 static inline void raw_spin_unlock_rcu_node(struct rcu_node *rnp) 590 { 591 raw_spin_unlock(&ACCESS_PRIVATE(rnp, lock)); 592 } 593 594 static inline void raw_spin_lock_irq_rcu_node(struct rcu_node *rnp) 595 { 596 raw_spin_lock_irq(&ACCESS_PRIVATE(rnp, lock)); 597 smp_mb__after_unlock_lock(); 598 } 599 600 static inline void raw_spin_unlock_irq_rcu_node(struct rcu_node *rnp) 601 { 602 raw_spin_unlock_irq(&ACCESS_PRIVATE(rnp, lock)); 603 } 604 605 #define raw_spin_lock_irqsave_rcu_node(rnp, flags) \ 606 do { \ 607 typecheck(unsigned long, flags); \ 608 raw_spin_lock_irqsave(&ACCESS_PRIVATE(rnp, lock), flags); \ 609 smp_mb__after_unlock_lock(); \ 610 } while (0) 611 612 #define raw_spin_unlock_irqrestore_rcu_node(rnp, flags) \ 613 do { \ 614 typecheck(unsigned long, flags); \ 615 raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(rnp, lock), flags); \ 616 } while (0) 617 618 static inline bool raw_spin_trylock_rcu_node(struct rcu_node *rnp) 619 { 620 bool locked = raw_spin_trylock(&ACCESS_PRIVATE(rnp, lock)); 621 622 if (locked) 623 smp_mb__after_unlock_lock(); 624 return locked; 625 } 626