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 31/* 32 * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and 33 * CONFIG_RCU_FANOUT_LEAF. 34 * In theory, it should be possible to add more levels straightforwardly. 35 * In practice, this did work well going from three levels to four. 36 * Of course, your mileage may vary. 37 */ 38#define MAX_RCU_LVLS 4 39#define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF) 40#define RCU_FANOUT_2 (RCU_FANOUT_1 * CONFIG_RCU_FANOUT) 41#define RCU_FANOUT_3 (RCU_FANOUT_2 * CONFIG_RCU_FANOUT) 42#define RCU_FANOUT_4 (RCU_FANOUT_3 * CONFIG_RCU_FANOUT) 43 44#if NR_CPUS <= RCU_FANOUT_1 45# define RCU_NUM_LVLS 1 46# define NUM_RCU_LVL_0 1 47# define NUM_RCU_LVL_1 (NR_CPUS) 48# define NUM_RCU_LVL_2 0 49# define NUM_RCU_LVL_3 0 50# define NUM_RCU_LVL_4 0 51#elif NR_CPUS <= RCU_FANOUT_2 52# define RCU_NUM_LVLS 2 53# define NUM_RCU_LVL_0 1 54# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) 55# define NUM_RCU_LVL_2 (NR_CPUS) 56# define NUM_RCU_LVL_3 0 57# define NUM_RCU_LVL_4 0 58#elif NR_CPUS <= RCU_FANOUT_3 59# define RCU_NUM_LVLS 3 60# define NUM_RCU_LVL_0 1 61# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2) 62# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) 63# define NUM_RCU_LVL_3 (NR_CPUS) 64# define NUM_RCU_LVL_4 0 65#elif NR_CPUS <= RCU_FANOUT_4 66# define RCU_NUM_LVLS 4 67# define NUM_RCU_LVL_0 1 68# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3) 69# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2) 70# define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) 71# define NUM_RCU_LVL_4 (NR_CPUS) 72#else 73# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS" 74#endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */ 75 76#define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4) 77#define NUM_RCU_NODES (RCU_SUM - NR_CPUS) 78 79extern int rcu_num_lvls; 80extern int rcu_num_nodes; 81 82/* 83 * Dynticks per-CPU state. 84 */ 85struct rcu_dynticks { 86 long long dynticks_nesting; /* Track irq/process nesting level. */ 87 /* Process level is worth LLONG_MAX/2. */ 88 int dynticks_nmi_nesting; /* Track NMI nesting level. */ 89 atomic_t dynticks; /* Even value for idle, else odd. */ 90#ifdef CONFIG_NO_HZ_FULL_SYSIDLE 91 long long dynticks_idle_nesting; 92 /* irq/process nesting level from idle. */ 93 atomic_t dynticks_idle; /* Even value for idle, else odd. */ 94 /* "Idle" excludes userspace execution. */ 95 unsigned long dynticks_idle_jiffies; 96 /* End of last non-NMI non-idle period. */ 97#endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */ 98#ifdef CONFIG_RCU_FAST_NO_HZ 99 bool all_lazy; /* Are all CPU's CBs lazy? */ 100 unsigned long nonlazy_posted; 101 /* # times non-lazy CBs posted to CPU. */ 102 unsigned long nonlazy_posted_snap; 103 /* idle-period nonlazy_posted snapshot. */ 104 unsigned long last_accelerate; 105 /* Last jiffy CBs were accelerated. */ 106 unsigned long last_advance_all; 107 /* Last jiffy CBs were all advanced. */ 108 int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */ 109#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ 110}; 111 112/* RCU's kthread states for tracing. */ 113#define RCU_KTHREAD_STOPPED 0 114#define RCU_KTHREAD_RUNNING 1 115#define RCU_KTHREAD_WAITING 2 116#define RCU_KTHREAD_OFFCPU 3 117#define RCU_KTHREAD_YIELDING 4 118#define RCU_KTHREAD_MAX 4 119 120/* 121 * Definition for node within the RCU grace-period-detection hierarchy. 122 */ 123struct rcu_node { 124 raw_spinlock_t lock; /* Root rcu_node's lock protects some */ 125 /* rcu_state fields as well as following. */ 126 unsigned long gpnum; /* Current grace period for this node. */ 127 /* This will either be equal to or one */ 128 /* behind the root rcu_node's gpnum. */ 129 unsigned long completed; /* Last GP completed for this node. */ 130 /* This will either be equal to or one */ 131 /* behind the root rcu_node's gpnum. */ 132 unsigned long qsmask; /* CPUs or groups that need to switch in */ 133 /* order for current grace period to proceed.*/ 134 /* In leaf rcu_node, each bit corresponds to */ 135 /* an rcu_data structure, otherwise, each */ 136 /* bit corresponds to a child rcu_node */ 137 /* structure. */ 138 unsigned long expmask; /* Groups that have ->blkd_tasks */ 139 /* elements that need to drain to allow the */ 140 /* current expedited grace period to */ 141 /* complete (only for PREEMPT_RCU). */ 142 unsigned long qsmaskinit; 143 /* Per-GP initial value for qsmask & expmask. */ 144 /* Initialized from ->qsmaskinitnext at the */ 145 /* beginning of each grace period. */ 146 unsigned long qsmaskinitnext; 147 /* Online CPUs for next grace period. */ 148 unsigned long grpmask; /* Mask to apply to parent qsmask. */ 149 /* Only one bit will be set in this mask. */ 150 int grplo; /* lowest-numbered CPU or group here. */ 151 int grphi; /* highest-numbered CPU or group here. */ 152 u8 grpnum; /* CPU/group number for next level up. */ 153 u8 level; /* root is at level 0. */ 154 bool wait_blkd_tasks;/* Necessary to wait for blocked tasks to */ 155 /* exit RCU read-side critical sections */ 156 /* before propagating offline up the */ 157 /* rcu_node tree? */ 158 struct rcu_node *parent; 159 struct list_head blkd_tasks; 160 /* Tasks blocked in RCU read-side critical */ 161 /* section. Tasks are placed at the head */ 162 /* of this list and age towards the tail. */ 163 struct list_head *gp_tasks; 164 /* Pointer to the first task blocking the */ 165 /* current grace period, or NULL if there */ 166 /* is no such task. */ 167 struct list_head *exp_tasks; 168 /* Pointer to the first task blocking the */ 169 /* current expedited grace period, or NULL */ 170 /* if there is no such task. If there */ 171 /* is no current expedited grace period, */ 172 /* then there can cannot be any such task. */ 173#ifdef CONFIG_RCU_BOOST 174 struct list_head *boost_tasks; 175 /* Pointer to first task that needs to be */ 176 /* priority boosted, or NULL if no priority */ 177 /* boosting is needed for this rcu_node */ 178 /* structure. If there are no tasks */ 179 /* queued on this rcu_node structure that */ 180 /* are blocking the current grace period, */ 181 /* there can be no such task. */ 182 struct rt_mutex boost_mtx; 183 /* Used only for the priority-boosting */ 184 /* side effect, not as a lock. */ 185 unsigned long boost_time; 186 /* When to start boosting (jiffies). */ 187 struct task_struct *boost_kthread_task; 188 /* kthread that takes care of priority */ 189 /* boosting for this rcu_node structure. */ 190 unsigned int boost_kthread_status; 191 /* State of boost_kthread_task for tracing. */ 192 unsigned long n_tasks_boosted; 193 /* Total number of tasks boosted. */ 194 unsigned long n_exp_boosts; 195 /* Number of tasks boosted for expedited GP. */ 196 unsigned long n_normal_boosts; 197 /* Number of tasks boosted for normal GP. */ 198 unsigned long n_balk_blkd_tasks; 199 /* Refused to boost: no blocked tasks. */ 200 unsigned long n_balk_exp_gp_tasks; 201 /* Refused to boost: nothing blocking GP. */ 202 unsigned long n_balk_boost_tasks; 203 /* Refused to boost: already boosting. */ 204 unsigned long n_balk_notblocked; 205 /* Refused to boost: RCU RS CS still running. */ 206 unsigned long n_balk_notyet; 207 /* Refused to boost: not yet time. */ 208 unsigned long n_balk_nos; 209 /* Refused to boost: not sure why, though. */ 210 /* This can happen due to race conditions. */ 211#endif /* #ifdef CONFIG_RCU_BOOST */ 212#ifdef CONFIG_RCU_NOCB_CPU 213 wait_queue_head_t nocb_gp_wq[2]; 214 /* Place for rcu_nocb_kthread() to wait GP. */ 215#endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 216 int need_future_gp[2]; 217 /* Counts of upcoming no-CB GP requests. */ 218 raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp; 219} ____cacheline_internodealigned_in_smp; 220 221/* 222 * Do a full breadth-first scan of the rcu_node structures for the 223 * specified rcu_state structure. 224 */ 225#define rcu_for_each_node_breadth_first(rsp, rnp) \ 226 for ((rnp) = &(rsp)->node[0]; \ 227 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 228 229/* 230 * Do a breadth-first scan of the non-leaf rcu_node structures for the 231 * specified rcu_state structure. Note that if there is a singleton 232 * rcu_node tree with but one rcu_node structure, this loop is a no-op. 233 */ 234#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ 235 for ((rnp) = &(rsp)->node[0]; \ 236 (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++) 237 238/* 239 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state 240 * structure. Note that if there is a singleton rcu_node tree with but 241 * one rcu_node structure, this loop -will- visit the rcu_node structure. 242 * It is still a leaf node, even if it is also the root node. 243 */ 244#define rcu_for_each_leaf_node(rsp, rnp) \ 245 for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \ 246 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 247 248/* Index values for nxttail array in struct rcu_data. */ 249#define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ 250#define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ 251#define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */ 252#define RCU_NEXT_TAIL 3 253#define RCU_NEXT_SIZE 4 254 255/* Per-CPU data for read-copy update. */ 256struct rcu_data { 257 /* 1) quiescent-state and grace-period handling : */ 258 unsigned long completed; /* Track rsp->completed gp number */ 259 /* in order to detect GP end. */ 260 unsigned long gpnum; /* Highest gp number that this CPU */ 261 /* is aware of having started. */ 262 unsigned long rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */ 263 /* for rcu_all_qs() invocations. */ 264 bool passed_quiesce; /* User-mode/idle loop etc. */ 265 bool qs_pending; /* Core waits for quiesc state. */ 266 bool beenonline; /* CPU online at least once. */ 267 bool gpwrap; /* Possible gpnum/completed wrap. */ 268 struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ 269 unsigned long grpmask; /* Mask to apply to leaf qsmask. */ 270#ifdef CONFIG_RCU_CPU_STALL_INFO 271 unsigned long ticks_this_gp; /* The number of scheduling-clock */ 272 /* ticks this CPU has handled */ 273 /* during and after the last grace */ 274 /* period it is aware of. */ 275#endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ 276 277 /* 2) batch handling */ 278 /* 279 * If nxtlist is not NULL, it is partitioned as follows. 280 * Any of the partitions might be empty, in which case the 281 * pointer to that partition will be equal to the pointer for 282 * the following partition. When the list is empty, all of 283 * the nxttail elements point to the ->nxtlist pointer itself, 284 * which in that case is NULL. 285 * 286 * [nxtlist, *nxttail[RCU_DONE_TAIL]): 287 * Entries that batch # <= ->completed 288 * The grace period for these entries has completed, and 289 * the other grace-period-completed entries may be moved 290 * here temporarily in rcu_process_callbacks(). 291 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): 292 * Entries that batch # <= ->completed - 1: waiting for current GP 293 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): 294 * Entries known to have arrived before current GP ended 295 * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]): 296 * Entries that might have arrived after current GP ended 297 * Note that the value of *nxttail[RCU_NEXT_TAIL] will 298 * always be NULL, as this is the end of the list. 299 */ 300 struct rcu_head *nxtlist; 301 struct rcu_head **nxttail[RCU_NEXT_SIZE]; 302 unsigned long nxtcompleted[RCU_NEXT_SIZE]; 303 /* grace periods for sublists. */ 304 long qlen_lazy; /* # of lazy queued callbacks */ 305 long qlen; /* # of queued callbacks, incl lazy */ 306 long qlen_last_fqs_check; 307 /* qlen at last check for QS forcing */ 308 unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ 309 unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */ 310 unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ 311 unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ 312 unsigned long n_force_qs_snap; 313 /* did other CPU force QS recently? */ 314 long blimit; /* Upper limit on a processed batch */ 315 316 /* 3) dynticks interface. */ 317 struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ 318 int dynticks_snap; /* Per-GP tracking for dynticks. */ 319 320 /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ 321 unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ 322 unsigned long offline_fqs; /* Kicked due to being offline. */ 323 unsigned long cond_resched_completed; 324 /* Grace period that needs help */ 325 /* from cond_resched(). */ 326 327 /* 5) __rcu_pending() statistics. */ 328 unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ 329 unsigned long n_rp_qs_pending; 330 unsigned long n_rp_report_qs; 331 unsigned long n_rp_cb_ready; 332 unsigned long n_rp_cpu_needs_gp; 333 unsigned long n_rp_gp_completed; 334 unsigned long n_rp_gp_started; 335 unsigned long n_rp_nocb_defer_wakeup; 336 unsigned long n_rp_need_nothing; 337 338 /* 6) _rcu_barrier() and OOM callbacks. */ 339 struct rcu_head barrier_head; 340#ifdef CONFIG_RCU_FAST_NO_HZ 341 struct rcu_head oom_head; 342#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ 343 344 /* 7) Callback offloading. */ 345#ifdef CONFIG_RCU_NOCB_CPU 346 struct rcu_head *nocb_head; /* CBs waiting for kthread. */ 347 struct rcu_head **nocb_tail; 348 atomic_long_t nocb_q_count; /* # CBs waiting for nocb */ 349 atomic_long_t nocb_q_count_lazy; /* invocation (all stages). */ 350 struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */ 351 struct rcu_head **nocb_follower_tail; 352 wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */ 353 struct task_struct *nocb_kthread; 354 int nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */ 355 356 /* The following fields are used by the leader, hence own cacheline. */ 357 struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp; 358 /* CBs waiting for GP. */ 359 struct rcu_head **nocb_gp_tail; 360 bool nocb_leader_sleep; /* Is the nocb leader thread asleep? */ 361 struct rcu_data *nocb_next_follower; 362 /* Next follower in wakeup chain. */ 363 364 /* The following fields are used by the follower, hence new cachline. */ 365 struct rcu_data *nocb_leader ____cacheline_internodealigned_in_smp; 366 /* Leader CPU takes GP-end wakeups. */ 367#endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 368 369 /* 8) RCU CPU stall data. */ 370#ifdef CONFIG_RCU_CPU_STALL_INFO 371 unsigned int softirq_snap; /* Snapshot of softirq activity. */ 372#endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ 373 374 int cpu; 375 struct rcu_state *rsp; 376}; 377 378/* Values for fqs_state field in struct rcu_state. */ 379#define RCU_GP_IDLE 0 /* No grace period in progress. */ 380#define RCU_GP_INIT 1 /* Grace period being initialized. */ 381#define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */ 382#define RCU_FORCE_QS 3 /* Need to force quiescent state. */ 383#define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK 384 385/* Values for nocb_defer_wakeup field in struct rcu_data. */ 386#define RCU_NOGP_WAKE_NOT 0 387#define RCU_NOGP_WAKE 1 388#define RCU_NOGP_WAKE_FORCE 2 389 390#define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500)) 391 /* For jiffies_till_first_fqs and */ 392 /* and jiffies_till_next_fqs. */ 393 394#define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */ 395 /* delay between bouts of */ 396 /* quiescent-state forcing. */ 397 398#define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */ 399 /* at least one scheduling clock */ 400 /* irq before ratting on them. */ 401 402#define rcu_wait(cond) \ 403do { \ 404 for (;;) { \ 405 set_current_state(TASK_INTERRUPTIBLE); \ 406 if (cond) \ 407 break; \ 408 schedule(); \ 409 } \ 410 __set_current_state(TASK_RUNNING); \ 411} while (0) 412 413/* 414 * RCU global state, including node hierarchy. This hierarchy is 415 * represented in "heap" form in a dense array. The root (first level) 416 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second 417 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]), 418 * and the third level in ->node[m+1] and following (->node[m+1] referenced 419 * by ->level[2]). The number of levels is determined by the number of 420 * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy" 421 * consisting of a single rcu_node. 422 */ 423struct rcu_state { 424 struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */ 425 struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */ 426 u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */ 427 u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */ 428 u8 flavor_mask; /* bit in flavor mask. */ 429 struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */ 430 void (*call)(struct rcu_head *head, /* call_rcu() flavor. */ 431 void (*func)(struct rcu_head *head)); 432 433 /* The following fields are guarded by the root rcu_node's lock. */ 434 435 u8 fqs_state ____cacheline_internodealigned_in_smp; 436 /* Force QS state. */ 437 u8 boost; /* Subject to priority boost. */ 438 unsigned long gpnum; /* Current gp number. */ 439 unsigned long completed; /* # of last completed gp. */ 440 struct task_struct *gp_kthread; /* Task for grace periods. */ 441 wait_queue_head_t gp_wq; /* Where GP task waits. */ 442 short gp_flags; /* Commands for GP task. */ 443 short gp_state; /* GP kthread sleep state. */ 444 445 /* End of fields guarded by root rcu_node's lock. */ 446 447 raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp; 448 /* Protect following fields. */ 449 struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */ 450 /* need a grace period. */ 451 struct rcu_head **orphan_nxttail; /* Tail of above. */ 452 struct rcu_head *orphan_donelist; /* Orphaned callbacks that */ 453 /* are ready to invoke. */ 454 struct rcu_head **orphan_donetail; /* Tail of above. */ 455 long qlen_lazy; /* Number of lazy callbacks. */ 456 long qlen; /* Total number of callbacks. */ 457 /* End of fields guarded by orphan_lock. */ 458 459 struct mutex barrier_mutex; /* Guards barrier fields. */ 460 atomic_t barrier_cpu_count; /* # CPUs waiting on. */ 461 struct completion barrier_completion; /* Wake at barrier end. */ 462 unsigned long n_barrier_done; /* ++ at start and end of */ 463 /* _rcu_barrier(). */ 464 /* End of fields guarded by barrier_mutex. */ 465 466 atomic_long_t expedited_start; /* Starting ticket. */ 467 atomic_long_t expedited_done; /* Done ticket. */ 468 atomic_long_t expedited_wrap; /* # near-wrap incidents. */ 469 atomic_long_t expedited_tryfail; /* # acquisition failures. */ 470 atomic_long_t expedited_workdone1; /* # done by others #1. */ 471 atomic_long_t expedited_workdone2; /* # done by others #2. */ 472 atomic_long_t expedited_normal; /* # fallbacks to normal. */ 473 atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */ 474 atomic_long_t expedited_done_tries; /* # tries to update _done. */ 475 atomic_long_t expedited_done_lost; /* # times beaten to _done. */ 476 atomic_long_t expedited_done_exit; /* # times exited _done loop. */ 477 478 unsigned long jiffies_force_qs; /* Time at which to invoke */ 479 /* force_quiescent_state(). */ 480 unsigned long n_force_qs; /* Number of calls to */ 481 /* force_quiescent_state(). */ 482 unsigned long n_force_qs_lh; /* ~Number of calls leaving */ 483 /* due to lock unavailable. */ 484 unsigned long n_force_qs_ngp; /* Number of calls leaving */ 485 /* due to no GP active. */ 486 unsigned long gp_start; /* Time at which GP started, */ 487 /* but in jiffies. */ 488 unsigned long gp_activity; /* Time of last GP kthread */ 489 /* activity in jiffies. */ 490 unsigned long jiffies_stall; /* Time at which to check */ 491 /* for CPU stalls. */ 492 unsigned long jiffies_resched; /* Time at which to resched */ 493 /* a reluctant CPU. */ 494 unsigned long n_force_qs_gpstart; /* Snapshot of n_force_qs at */ 495 /* GP start. */ 496 unsigned long gp_max; /* Maximum GP duration in */ 497 /* jiffies. */ 498 const char *name; /* Name of structure. */ 499 char abbr; /* Abbreviated name. */ 500 struct list_head flavors; /* List of RCU flavors. */ 501}; 502 503/* Values for rcu_state structure's gp_flags field. */ 504#define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */ 505#define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */ 506 507/* Values for rcu_state structure's gp_flags field. */ 508#define RCU_GP_WAIT_INIT 0 /* Initial state. */ 509#define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */ 510#define RCU_GP_WAIT_FQS 2 /* Wait for force-quiescent-state time. */ 511 512extern struct list_head rcu_struct_flavors; 513 514/* Sequence through rcu_state structures for each RCU flavor. */ 515#define for_each_rcu_flavor(rsp) \ 516 list_for_each_entry((rsp), &rcu_struct_flavors, flavors) 517 518/* 519 * RCU implementation internal declarations: 520 */ 521extern struct rcu_state rcu_sched_state; 522DECLARE_PER_CPU(struct rcu_data, rcu_sched_data); 523 524extern struct rcu_state rcu_bh_state; 525DECLARE_PER_CPU(struct rcu_data, rcu_bh_data); 526 527#ifdef CONFIG_PREEMPT_RCU 528extern struct rcu_state rcu_preempt_state; 529DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data); 530#endif /* #ifdef CONFIG_PREEMPT_RCU */ 531 532#ifdef CONFIG_RCU_BOOST 533DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); 534DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu); 535DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); 536DECLARE_PER_CPU(char, rcu_cpu_has_work); 537#endif /* #ifdef CONFIG_RCU_BOOST */ 538 539#ifndef RCU_TREE_NONCORE 540 541/* Forward declarations for rcutree_plugin.h */ 542static void rcu_bootup_announce(void); 543static void rcu_preempt_note_context_switch(void); 544static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp); 545#ifdef CONFIG_HOTPLUG_CPU 546static bool rcu_preempt_has_tasks(struct rcu_node *rnp); 547#endif /* #ifdef CONFIG_HOTPLUG_CPU */ 548static void rcu_print_detail_task_stall(struct rcu_state *rsp); 549static int rcu_print_task_stall(struct rcu_node *rnp); 550static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); 551static void rcu_preempt_check_callbacks(void); 552void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); 553static void __init __rcu_init_preempt(void); 554static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); 555static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); 556static void invoke_rcu_callbacks_kthread(void); 557static bool rcu_is_callbacks_kthread(void); 558#ifdef CONFIG_RCU_BOOST 559static void rcu_preempt_do_callbacks(void); 560static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp, 561 struct rcu_node *rnp); 562#endif /* #ifdef CONFIG_RCU_BOOST */ 563static void __init rcu_spawn_boost_kthreads(void); 564static void rcu_prepare_kthreads(int cpu); 565static void rcu_cleanup_after_idle(void); 566static void rcu_prepare_for_idle(void); 567static void rcu_idle_count_callbacks_posted(void); 568static bool rcu_preempt_has_tasks(struct rcu_node *rnp); 569static void print_cpu_stall_info_begin(void); 570static void print_cpu_stall_info(struct rcu_state *rsp, int cpu); 571static void print_cpu_stall_info_end(void); 572static void zero_cpu_stall_ticks(struct rcu_data *rdp); 573static void increment_cpu_stall_ticks(void); 574static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu); 575static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq); 576static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp); 577static void rcu_init_one_nocb(struct rcu_node *rnp); 578static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp, 579 bool lazy, unsigned long flags); 580static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp, 581 struct rcu_data *rdp, 582 unsigned long flags); 583static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp); 584static void do_nocb_deferred_wakeup(struct rcu_data *rdp); 585static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp); 586static void rcu_spawn_all_nocb_kthreads(int cpu); 587static void __init rcu_spawn_nocb_kthreads(void); 588#ifdef CONFIG_RCU_NOCB_CPU 589static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp); 590#endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 591static void __maybe_unused rcu_kick_nohz_cpu(int cpu); 592static bool init_nocb_callback_list(struct rcu_data *rdp); 593static void rcu_sysidle_enter(int irq); 594static void rcu_sysidle_exit(int irq); 595static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle, 596 unsigned long *maxj); 597static bool is_sysidle_rcu_state(struct rcu_state *rsp); 598static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle, 599 unsigned long maxj); 600static void rcu_bind_gp_kthread(void); 601static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp); 602static bool rcu_nohz_full_cpu(struct rcu_state *rsp); 603static void rcu_dynticks_task_enter(void); 604static void rcu_dynticks_task_exit(void); 605 606#endif /* #ifndef RCU_TREE_NONCORE */ 607 608#ifdef CONFIG_RCU_TRACE 609/* Read out queue lengths for tracing. */ 610static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll) 611{ 612#ifdef CONFIG_RCU_NOCB_CPU 613 *ql = atomic_long_read(&rdp->nocb_q_count); 614 *qll = atomic_long_read(&rdp->nocb_q_count_lazy); 615#else /* #ifdef CONFIG_RCU_NOCB_CPU */ 616 *ql = 0; 617 *qll = 0; 618#endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ 619} 620#endif /* #ifdef CONFIG_RCU_TRACE */ 621