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/threads.h> 28 #include <linux/cpumask.h> 29 #include <linux/seqlock.h> 30 #include <linux/irq_work.h> 31 32 /* 33 * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and 34 * CONFIG_RCU_FANOUT_LEAF. 35 * In theory, it should be possible to add more levels straightforwardly. 36 * In practice, this did work well going from three levels to four. 37 * Of course, your mileage may vary. 38 */ 39 #define MAX_RCU_LVLS 4 40 #define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF) 41 #define RCU_FANOUT_2 (RCU_FANOUT_1 * CONFIG_RCU_FANOUT) 42 #define RCU_FANOUT_3 (RCU_FANOUT_2 * CONFIG_RCU_FANOUT) 43 #define RCU_FANOUT_4 (RCU_FANOUT_3 * CONFIG_RCU_FANOUT) 44 45 #if NR_CPUS <= RCU_FANOUT_1 46 # define RCU_NUM_LVLS 1 47 # define NUM_RCU_LVL_0 1 48 # define NUM_RCU_LVL_1 (NR_CPUS) 49 # define NUM_RCU_LVL_2 0 50 # define NUM_RCU_LVL_3 0 51 # define NUM_RCU_LVL_4 0 52 #elif NR_CPUS <= RCU_FANOUT_2 53 # define RCU_NUM_LVLS 2 54 # define NUM_RCU_LVL_0 1 55 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) 56 # define NUM_RCU_LVL_2 (NR_CPUS) 57 # define NUM_RCU_LVL_3 0 58 # define NUM_RCU_LVL_4 0 59 #elif NR_CPUS <= RCU_FANOUT_3 60 # define RCU_NUM_LVLS 3 61 # define NUM_RCU_LVL_0 1 62 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2) 63 # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) 64 # define NUM_RCU_LVL_3 (NR_CPUS) 65 # define NUM_RCU_LVL_4 0 66 #elif NR_CPUS <= RCU_FANOUT_4 67 # define RCU_NUM_LVLS 4 68 # define NUM_RCU_LVL_0 1 69 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3) 70 # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2) 71 # define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) 72 # define NUM_RCU_LVL_4 (NR_CPUS) 73 #else 74 # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS" 75 #endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */ 76 77 #define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4) 78 #define NUM_RCU_NODES (RCU_SUM - NR_CPUS) 79 80 extern int rcu_num_lvls; 81 extern int rcu_num_nodes; 82 83 /* 84 * Dynticks per-CPU state. 85 */ 86 struct rcu_dynticks { 87 long long dynticks_nesting; /* Track irq/process nesting level. */ 88 /* Process level is worth LLONG_MAX/2. */ 89 int dynticks_nmi_nesting; /* Track NMI nesting level. */ 90 atomic_t dynticks; /* Even value for idle, else odd. */ 91 #ifdef CONFIG_NO_HZ_FULL_SYSIDLE 92 long long dynticks_idle_nesting; 93 /* irq/process nesting level from idle. */ 94 atomic_t dynticks_idle; /* Even value for idle, else odd. */ 95 /* "Idle" excludes userspace execution. */ 96 unsigned long dynticks_idle_jiffies; 97 /* End of last non-NMI non-idle period. */ 98 #endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */ 99 #ifdef CONFIG_RCU_FAST_NO_HZ 100 bool all_lazy; /* Are all CPU's CBs lazy? */ 101 unsigned long nonlazy_posted; 102 /* # times non-lazy CBs posted to CPU. */ 103 unsigned long nonlazy_posted_snap; 104 /* idle-period nonlazy_posted snapshot. */ 105 unsigned long last_accelerate; 106 /* Last jiffy CBs were accelerated. */ 107 unsigned long last_advance_all; 108 /* Last jiffy CBs were all advanced. */ 109 int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */ 110 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ 111 }; 112 113 /* RCU's kthread states for tracing. */ 114 #define RCU_KTHREAD_STOPPED 0 115 #define RCU_KTHREAD_RUNNING 1 116 #define RCU_KTHREAD_WAITING 2 117 #define RCU_KTHREAD_OFFCPU 3 118 #define RCU_KTHREAD_YIELDING 4 119 #define RCU_KTHREAD_MAX 4 120 121 /* 122 * Definition for node within the RCU grace-period-detection hierarchy. 123 */ 124 struct rcu_node { 125 raw_spinlock_t lock; /* Root rcu_node's lock protects some */ 126 /* rcu_state fields as well as following. */ 127 unsigned long gpnum; /* Current grace period for this node. */ 128 /* This will either be equal to or one */ 129 /* behind the root rcu_node's gpnum. */ 130 unsigned long completed; /* Last GP completed for this node. */ 131 /* This will either be equal to or one */ 132 /* behind the root rcu_node's gpnum. */ 133 unsigned long qsmask; /* CPUs or groups that need to switch in */ 134 /* order for current grace period to proceed.*/ 135 /* In leaf rcu_node, each bit corresponds to */ 136 /* an rcu_data structure, otherwise, each */ 137 /* bit corresponds to a child rcu_node */ 138 /* structure. */ 139 unsigned long expmask; /* Groups that have ->blkd_tasks */ 140 /* elements that need to drain to allow the */ 141 /* current expedited grace period to */ 142 /* complete (only for TREE_PREEMPT_RCU). */ 143 unsigned long qsmaskinit; 144 /* Per-GP initial value for qsmask & expmask. */ 145 unsigned long grpmask; /* Mask to apply to parent qsmask. */ 146 /* Only one bit will be set in this mask. */ 147 int grplo; /* lowest-numbered CPU or group here. */ 148 int grphi; /* highest-numbered CPU or group here. */ 149 u8 grpnum; /* CPU/group number for next level up. */ 150 u8 level; /* root is at level 0. */ 151 struct rcu_node *parent; 152 struct list_head blkd_tasks; 153 /* Tasks blocked in RCU read-side critical */ 154 /* section. Tasks are placed at the head */ 155 /* of this list and age towards the tail. */ 156 struct list_head *gp_tasks; 157 /* Pointer to the first task blocking the */ 158 /* current grace period, or NULL if there */ 159 /* is no such task. */ 160 struct list_head *exp_tasks; 161 /* Pointer to the first task blocking the */ 162 /* current expedited grace period, or NULL */ 163 /* if there is no such task. If there */ 164 /* is no current expedited grace period, */ 165 /* then there can cannot be any such task. */ 166 #ifdef CONFIG_RCU_BOOST 167 struct list_head *boost_tasks; 168 /* Pointer to first task that needs to be */ 169 /* priority boosted, or NULL if no priority */ 170 /* boosting is needed for this rcu_node */ 171 /* structure. If there are no tasks */ 172 /* queued on this rcu_node structure that */ 173 /* are blocking the current grace period, */ 174 /* there can be no such task. */ 175 unsigned long boost_time; 176 /* When to start boosting (jiffies). */ 177 struct task_struct *boost_kthread_task; 178 /* kthread that takes care of priority */ 179 /* boosting for this rcu_node structure. */ 180 unsigned int boost_kthread_status; 181 /* State of boost_kthread_task for tracing. */ 182 unsigned long n_tasks_boosted; 183 /* Total number of tasks boosted. */ 184 unsigned long n_exp_boosts; 185 /* Number of tasks boosted for expedited GP. */ 186 unsigned long n_normal_boosts; 187 /* Number of tasks boosted for normal GP. */ 188 unsigned long n_balk_blkd_tasks; 189 /* Refused to boost: no blocked tasks. */ 190 unsigned long n_balk_exp_gp_tasks; 191 /* Refused to boost: nothing blocking GP. */ 192 unsigned long n_balk_boost_tasks; 193 /* Refused to boost: already boosting. */ 194 unsigned long n_balk_notblocked; 195 /* Refused to boost: RCU RS CS still running. */ 196 unsigned long n_balk_notyet; 197 /* Refused to boost: not yet time. */ 198 unsigned long n_balk_nos; 199 /* Refused to boost: not sure why, though. */ 200 /* This can happen due to race conditions. */ 201 #endif /* #ifdef CONFIG_RCU_BOOST */ 202 #ifdef CONFIG_RCU_NOCB_CPU 203 wait_queue_head_t nocb_gp_wq[2]; 204 /* Place for rcu_nocb_kthread() to wait GP. */ 205 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 206 int need_future_gp[2]; 207 /* Counts of upcoming no-CB GP requests. */ 208 raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp; 209 } ____cacheline_internodealigned_in_smp; 210 211 /* 212 * Do a full breadth-first scan of the rcu_node structures for the 213 * specified rcu_state structure. 214 */ 215 #define rcu_for_each_node_breadth_first(rsp, rnp) \ 216 for ((rnp) = &(rsp)->node[0]; \ 217 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 218 219 /* 220 * Do a breadth-first scan of the non-leaf rcu_node structures for the 221 * specified rcu_state structure. Note that if there is a singleton 222 * rcu_node tree with but one rcu_node structure, this loop is a no-op. 223 */ 224 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ 225 for ((rnp) = &(rsp)->node[0]; \ 226 (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++) 227 228 /* 229 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state 230 * structure. Note that if there is a singleton rcu_node tree with but 231 * one rcu_node structure, this loop -will- visit the rcu_node structure. 232 * It is still a leaf node, even if it is also the root node. 233 */ 234 #define rcu_for_each_leaf_node(rsp, rnp) \ 235 for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \ 236 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 237 238 /* Index values for nxttail array in struct rcu_data. */ 239 #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ 240 #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ 241 #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */ 242 #define RCU_NEXT_TAIL 3 243 #define RCU_NEXT_SIZE 4 244 245 /* Per-CPU data for read-copy update. */ 246 struct rcu_data { 247 /* 1) quiescent-state and grace-period handling : */ 248 unsigned long completed; /* Track rsp->completed gp number */ 249 /* in order to detect GP end. */ 250 unsigned long gpnum; /* Highest gp number that this CPU */ 251 /* is aware of having started. */ 252 bool passed_quiesce; /* User-mode/idle loop etc. */ 253 bool qs_pending; /* Core waits for quiesc state. */ 254 bool beenonline; /* CPU online at least once. */ 255 bool preemptible; /* Preemptible RCU? */ 256 struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ 257 unsigned long grpmask; /* Mask to apply to leaf qsmask. */ 258 #ifdef CONFIG_RCU_CPU_STALL_INFO 259 unsigned long ticks_this_gp; /* The number of scheduling-clock */ 260 /* ticks this CPU has handled */ 261 /* during and after the last grace */ 262 /* period it is aware of. */ 263 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ 264 265 /* 2) batch handling */ 266 /* 267 * If nxtlist is not NULL, it is partitioned as follows. 268 * Any of the partitions might be empty, in which case the 269 * pointer to that partition will be equal to the pointer for 270 * the following partition. When the list is empty, all of 271 * the nxttail elements point to the ->nxtlist pointer itself, 272 * which in that case is NULL. 273 * 274 * [nxtlist, *nxttail[RCU_DONE_TAIL]): 275 * Entries that batch # <= ->completed 276 * The grace period for these entries has completed, and 277 * the other grace-period-completed entries may be moved 278 * here temporarily in rcu_process_callbacks(). 279 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): 280 * Entries that batch # <= ->completed - 1: waiting for current GP 281 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): 282 * Entries known to have arrived before current GP ended 283 * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]): 284 * Entries that might have arrived after current GP ended 285 * Note that the value of *nxttail[RCU_NEXT_TAIL] will 286 * always be NULL, as this is the end of the list. 287 */ 288 struct rcu_head *nxtlist; 289 struct rcu_head **nxttail[RCU_NEXT_SIZE]; 290 unsigned long nxtcompleted[RCU_NEXT_SIZE]; 291 /* grace periods for sublists. */ 292 long qlen_lazy; /* # of lazy queued callbacks */ 293 long qlen; /* # of queued callbacks, incl lazy */ 294 long qlen_last_fqs_check; 295 /* qlen at last check for QS forcing */ 296 unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ 297 unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */ 298 unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ 299 unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ 300 unsigned long n_force_qs_snap; 301 /* did other CPU force QS recently? */ 302 long blimit; /* Upper limit on a processed batch */ 303 304 /* 3) dynticks interface. */ 305 struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ 306 int dynticks_snap; /* Per-GP tracking for dynticks. */ 307 308 /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ 309 unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ 310 unsigned long offline_fqs; /* Kicked due to being offline. */ 311 312 /* 5) __rcu_pending() statistics. */ 313 unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ 314 unsigned long n_rp_qs_pending; 315 unsigned long n_rp_report_qs; 316 unsigned long n_rp_cb_ready; 317 unsigned long n_rp_cpu_needs_gp; 318 unsigned long n_rp_gp_completed; 319 unsigned long n_rp_gp_started; 320 unsigned long n_rp_nocb_defer_wakeup; 321 unsigned long n_rp_need_nothing; 322 323 /* 6) _rcu_barrier() and OOM callbacks. */ 324 struct rcu_head barrier_head; 325 #ifdef CONFIG_RCU_FAST_NO_HZ 326 struct rcu_head oom_head; 327 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ 328 329 /* 7) Callback offloading. */ 330 #ifdef CONFIG_RCU_NOCB_CPU 331 struct rcu_head *nocb_head; /* CBs waiting for kthread. */ 332 struct rcu_head **nocb_tail; 333 atomic_long_t nocb_q_count; /* # CBs waiting for kthread */ 334 atomic_long_t nocb_q_count_lazy; /* (approximate). */ 335 int nocb_p_count; /* # CBs being invoked by kthread */ 336 int nocb_p_count_lazy; /* (approximate). */ 337 wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */ 338 struct task_struct *nocb_kthread; 339 bool nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */ 340 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 341 342 /* 8) RCU CPU stall data. */ 343 #ifdef CONFIG_RCU_CPU_STALL_INFO 344 unsigned int softirq_snap; /* Snapshot of softirq activity. */ 345 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ 346 347 int cpu; 348 struct rcu_state *rsp; 349 }; 350 351 /* Values for fqs_state field in struct rcu_state. */ 352 #define RCU_GP_IDLE 0 /* No grace period in progress. */ 353 #define RCU_GP_INIT 1 /* Grace period being initialized. */ 354 #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */ 355 #define RCU_FORCE_QS 3 /* Need to force quiescent state. */ 356 #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK 357 358 #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500)) 359 /* For jiffies_till_first_fqs and */ 360 /* and jiffies_till_next_fqs. */ 361 362 #define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */ 363 /* delay between bouts of */ 364 /* quiescent-state forcing. */ 365 366 #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */ 367 /* at least one scheduling clock */ 368 /* irq before ratting on them. */ 369 370 #define rcu_wait(cond) \ 371 do { \ 372 for (;;) { \ 373 set_current_state(TASK_INTERRUPTIBLE); \ 374 if (cond) \ 375 break; \ 376 schedule(); \ 377 } \ 378 __set_current_state(TASK_RUNNING); \ 379 } while (0) 380 381 /* 382 * RCU global state, including node hierarchy. This hierarchy is 383 * represented in "heap" form in a dense array. The root (first level) 384 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second 385 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]), 386 * and the third level in ->node[m+1] and following (->node[m+1] referenced 387 * by ->level[2]). The number of levels is determined by the number of 388 * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy" 389 * consisting of a single rcu_node. 390 */ 391 struct rcu_state { 392 struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */ 393 struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */ 394 u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */ 395 u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */ 396 struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */ 397 void (*call)(struct rcu_head *head, /* call_rcu() flavor. */ 398 void (*func)(struct rcu_head *head)); 399 400 /* The following fields are guarded by the root rcu_node's lock. */ 401 402 u8 fqs_state ____cacheline_internodealigned_in_smp; 403 /* Force QS state. */ 404 u8 boost; /* Subject to priority boost. */ 405 unsigned long gpnum; /* Current gp number. */ 406 unsigned long completed; /* # of last completed gp. */ 407 struct task_struct *gp_kthread; /* Task for grace periods. */ 408 wait_queue_head_t gp_wq; /* Where GP task waits. */ 409 int gp_flags; /* Commands for GP task. */ 410 411 /* End of fields guarded by root rcu_node's lock. */ 412 413 raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp; 414 /* Protect following fields. */ 415 struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */ 416 /* need a grace period. */ 417 struct rcu_head **orphan_nxttail; /* Tail of above. */ 418 struct rcu_head *orphan_donelist; /* Orphaned callbacks that */ 419 /* are ready to invoke. */ 420 struct rcu_head **orphan_donetail; /* Tail of above. */ 421 long qlen_lazy; /* Number of lazy callbacks. */ 422 long qlen; /* Total number of callbacks. */ 423 /* End of fields guarded by orphan_lock. */ 424 425 struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */ 426 427 struct mutex barrier_mutex; /* Guards barrier fields. */ 428 atomic_t barrier_cpu_count; /* # CPUs waiting on. */ 429 struct completion barrier_completion; /* Wake at barrier end. */ 430 unsigned long n_barrier_done; /* ++ at start and end of */ 431 /* _rcu_barrier(). */ 432 /* End of fields guarded by barrier_mutex. */ 433 434 atomic_long_t expedited_start; /* Starting ticket. */ 435 atomic_long_t expedited_done; /* Done ticket. */ 436 atomic_long_t expedited_wrap; /* # near-wrap incidents. */ 437 atomic_long_t expedited_tryfail; /* # acquisition failures. */ 438 atomic_long_t expedited_workdone1; /* # done by others #1. */ 439 atomic_long_t expedited_workdone2; /* # done by others #2. */ 440 atomic_long_t expedited_normal; /* # fallbacks to normal. */ 441 atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */ 442 atomic_long_t expedited_done_tries; /* # tries to update _done. */ 443 atomic_long_t expedited_done_lost; /* # times beaten to _done. */ 444 atomic_long_t expedited_done_exit; /* # times exited _done loop. */ 445 446 unsigned long jiffies_force_qs; /* Time at which to invoke */ 447 /* force_quiescent_state(). */ 448 unsigned long n_force_qs; /* Number of calls to */ 449 /* force_quiescent_state(). */ 450 unsigned long n_force_qs_lh; /* ~Number of calls leaving */ 451 /* due to lock unavailable. */ 452 unsigned long n_force_qs_ngp; /* Number of calls leaving */ 453 /* due to no GP active. */ 454 unsigned long gp_start; /* Time at which GP started, */ 455 /* but in jiffies. */ 456 unsigned long jiffies_stall; /* Time at which to check */ 457 /* for CPU stalls. */ 458 unsigned long jiffies_resched; /* Time at which to resched */ 459 /* a reluctant CPU. */ 460 unsigned long gp_max; /* Maximum GP duration in */ 461 /* jiffies. */ 462 const char *name; /* Name of structure. */ 463 char abbr; /* Abbreviated name. */ 464 struct list_head flavors; /* List of RCU flavors. */ 465 struct irq_work wakeup_work; /* Postponed wakeups */ 466 }; 467 468 /* Values for rcu_state structure's gp_flags field. */ 469 #define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */ 470 #define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */ 471 472 extern struct list_head rcu_struct_flavors; 473 474 /* Sequence through rcu_state structures for each RCU flavor. */ 475 #define for_each_rcu_flavor(rsp) \ 476 list_for_each_entry((rsp), &rcu_struct_flavors, flavors) 477 478 /* Return values for rcu_preempt_offline_tasks(). */ 479 480 #define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */ 481 /* GP were moved to root. */ 482 #define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */ 483 /* GP were moved to root. */ 484 485 /* 486 * RCU implementation internal declarations: 487 */ 488 extern struct rcu_state rcu_sched_state; 489 DECLARE_PER_CPU(struct rcu_data, rcu_sched_data); 490 491 extern struct rcu_state rcu_bh_state; 492 DECLARE_PER_CPU(struct rcu_data, rcu_bh_data); 493 494 #ifdef CONFIG_TREE_PREEMPT_RCU 495 extern struct rcu_state rcu_preempt_state; 496 DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data); 497 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ 498 499 #ifdef CONFIG_RCU_BOOST 500 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); 501 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu); 502 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); 503 DECLARE_PER_CPU(char, rcu_cpu_has_work); 504 #endif /* #ifdef CONFIG_RCU_BOOST */ 505 506 #ifndef RCU_TREE_NONCORE 507 508 /* Forward declarations for rcutree_plugin.h */ 509 static void rcu_bootup_announce(void); 510 long rcu_batches_completed(void); 511 static void rcu_preempt_note_context_switch(int cpu); 512 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp); 513 #ifdef CONFIG_HOTPLUG_CPU 514 static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, 515 unsigned long flags); 516 #endif /* #ifdef CONFIG_HOTPLUG_CPU */ 517 static void rcu_print_detail_task_stall(struct rcu_state *rsp); 518 static int rcu_print_task_stall(struct rcu_node *rnp); 519 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); 520 #ifdef CONFIG_HOTPLUG_CPU 521 static int rcu_preempt_offline_tasks(struct rcu_state *rsp, 522 struct rcu_node *rnp, 523 struct rcu_data *rdp); 524 #endif /* #ifdef CONFIG_HOTPLUG_CPU */ 525 static void rcu_preempt_check_callbacks(int cpu); 526 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); 527 #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) 528 static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp, 529 bool wake); 530 #endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */ 531 static void __init __rcu_init_preempt(void); 532 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); 533 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); 534 static void invoke_rcu_callbacks_kthread(void); 535 static bool rcu_is_callbacks_kthread(void); 536 #ifdef CONFIG_RCU_BOOST 537 static void rcu_preempt_do_callbacks(void); 538 static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp, 539 struct rcu_node *rnp); 540 #endif /* #ifdef CONFIG_RCU_BOOST */ 541 static void rcu_prepare_kthreads(int cpu); 542 static void rcu_cleanup_after_idle(int cpu); 543 static void rcu_prepare_for_idle(int cpu); 544 static void rcu_idle_count_callbacks_posted(void); 545 static void print_cpu_stall_info_begin(void); 546 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu); 547 static void print_cpu_stall_info_end(void); 548 static void zero_cpu_stall_ticks(struct rcu_data *rdp); 549 static void increment_cpu_stall_ticks(void); 550 static int rcu_nocb_needs_gp(struct rcu_state *rsp); 551 static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq); 552 static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp); 553 static void rcu_init_one_nocb(struct rcu_node *rnp); 554 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp, 555 bool lazy, unsigned long flags); 556 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp, 557 struct rcu_data *rdp, 558 unsigned long flags); 559 static bool rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp); 560 static void do_nocb_deferred_wakeup(struct rcu_data *rdp); 561 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp); 562 static void rcu_spawn_nocb_kthreads(struct rcu_state *rsp); 563 static void rcu_kick_nohz_cpu(int cpu); 564 static bool init_nocb_callback_list(struct rcu_data *rdp); 565 static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq); 566 static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq); 567 static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle, 568 unsigned long *maxj); 569 static bool is_sysidle_rcu_state(struct rcu_state *rsp); 570 static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle, 571 unsigned long maxj); 572 static void rcu_bind_gp_kthread(void); 573 static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp); 574 static bool rcu_nohz_full_cpu(struct rcu_state *rsp); 575 576 #endif /* #ifndef RCU_TREE_NONCORE */ 577 578 #ifdef CONFIG_RCU_TRACE 579 #ifdef CONFIG_RCU_NOCB_CPU 580 /* Sum up queue lengths for tracing. */ 581 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll) 582 { 583 *ql = atomic_long_read(&rdp->nocb_q_count) + rdp->nocb_p_count; 584 *qll = atomic_long_read(&rdp->nocb_q_count_lazy) + rdp->nocb_p_count_lazy; 585 } 586 #else /* #ifdef CONFIG_RCU_NOCB_CPU */ 587 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll) 588 { 589 *ql = 0; 590 *qll = 0; 591 } 592 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ 593 #endif /* #ifdef CONFIG_RCU_TRACE */ 594