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 39 #define MAX_RCU_LVLS 4 40 41 #ifdef CONFIG_RCU_FANOUT 42 #define RCU_FANOUT CONFIG_RCU_FANOUT 43 #else /* #ifdef CONFIG_RCU_FANOUT */ 44 # ifdef CONFIG_64BIT 45 # define RCU_FANOUT 64 46 # else 47 # define RCU_FANOUT 32 48 # endif 49 #endif /* #else #ifdef CONFIG_RCU_FANOUT */ 50 51 #ifdef CONFIG_RCU_FANOUT_LEAF 52 #define RCU_FANOUT_LEAF CONFIG_RCU_FANOUT_LEAF 53 #else /* #ifdef CONFIG_RCU_FANOUT_LEAF */ 54 # ifdef CONFIG_64BIT 55 # define RCU_FANOUT_LEAF 64 56 # else 57 # define RCU_FANOUT_LEAF 32 58 # endif 59 #endif /* #else #ifdef CONFIG_RCU_FANOUT_LEAF */ 60 61 #define RCU_FANOUT_1 (RCU_FANOUT_LEAF) 62 #define RCU_FANOUT_2 (RCU_FANOUT_1 * RCU_FANOUT) 63 #define RCU_FANOUT_3 (RCU_FANOUT_2 * RCU_FANOUT) 64 #define RCU_FANOUT_4 (RCU_FANOUT_3 * RCU_FANOUT) 65 66 #if NR_CPUS <= RCU_FANOUT_1 67 # define RCU_NUM_LVLS 1 68 # define NUM_RCU_LVL_0 1 69 # define NUM_RCU_LVL_1 (NR_CPUS) 70 # define NUM_RCU_LVL_2 0 71 # define NUM_RCU_LVL_3 0 72 # define NUM_RCU_LVL_4 0 73 #elif NR_CPUS <= RCU_FANOUT_2 74 # define RCU_NUM_LVLS 2 75 # define NUM_RCU_LVL_0 1 76 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) 77 # define NUM_RCU_LVL_2 (NR_CPUS) 78 # define NUM_RCU_LVL_3 0 79 # define NUM_RCU_LVL_4 0 80 #elif NR_CPUS <= RCU_FANOUT_3 81 # define RCU_NUM_LVLS 3 82 # define NUM_RCU_LVL_0 1 83 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2) 84 # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) 85 # define NUM_RCU_LVL_3 (NR_CPUS) 86 # define NUM_RCU_LVL_4 0 87 #elif NR_CPUS <= RCU_FANOUT_4 88 # define RCU_NUM_LVLS 4 89 # define NUM_RCU_LVL_0 1 90 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3) 91 # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2) 92 # define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1) 93 # define NUM_RCU_LVL_4 (NR_CPUS) 94 #else 95 # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS" 96 #endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */ 97 98 #define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4) 99 #define NUM_RCU_NODES (RCU_SUM - NR_CPUS) 100 101 extern int rcu_num_lvls; 102 extern int rcu_num_nodes; 103 104 /* 105 * Dynticks per-CPU state. 106 */ 107 struct rcu_dynticks { 108 long long dynticks_nesting; /* Track irq/process nesting level. */ 109 /* Process level is worth LLONG_MAX/2. */ 110 int dynticks_nmi_nesting; /* Track NMI nesting level. */ 111 atomic_t dynticks; /* Even value for idle, else odd. */ 112 #ifdef CONFIG_NO_HZ_FULL_SYSIDLE 113 long long dynticks_idle_nesting; 114 /* irq/process nesting level from idle. */ 115 atomic_t dynticks_idle; /* Even value for idle, else odd. */ 116 /* "Idle" excludes userspace execution. */ 117 unsigned long dynticks_idle_jiffies; 118 /* End of last non-NMI non-idle period. */ 119 #endif /* #ifdef CONFIG_NO_HZ_FULL_SYSIDLE */ 120 #ifdef CONFIG_RCU_FAST_NO_HZ 121 bool all_lazy; /* Are all CPU's CBs lazy? */ 122 unsigned long nonlazy_posted; 123 /* # times non-lazy CBs posted to CPU. */ 124 unsigned long nonlazy_posted_snap; 125 /* idle-period nonlazy_posted snapshot. */ 126 unsigned long last_accelerate; 127 /* Last jiffy CBs were accelerated. */ 128 unsigned long last_advance_all; 129 /* Last jiffy CBs were all advanced. */ 130 int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */ 131 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ 132 }; 133 134 /* RCU's kthread states for tracing. */ 135 #define RCU_KTHREAD_STOPPED 0 136 #define RCU_KTHREAD_RUNNING 1 137 #define RCU_KTHREAD_WAITING 2 138 #define RCU_KTHREAD_OFFCPU 3 139 #define RCU_KTHREAD_YIELDING 4 140 #define RCU_KTHREAD_MAX 4 141 142 /* 143 * Definition for node within the RCU grace-period-detection hierarchy. 144 */ 145 struct rcu_node { 146 raw_spinlock_t lock; /* Root rcu_node's lock protects some */ 147 /* rcu_state fields as well as following. */ 148 unsigned long gpnum; /* Current grace period for this node. */ 149 /* This will either be equal to or one */ 150 /* behind the root rcu_node's gpnum. */ 151 unsigned long completed; /* Last GP completed for this node. */ 152 /* This will either be equal to or one */ 153 /* behind the root rcu_node's gpnum. */ 154 unsigned long qsmask; /* CPUs or groups that need to switch in */ 155 /* order for current grace period to proceed.*/ 156 /* In leaf rcu_node, each bit corresponds to */ 157 /* an rcu_data structure, otherwise, each */ 158 /* bit corresponds to a child rcu_node */ 159 /* structure. */ 160 unsigned long expmask; /* Groups that have ->blkd_tasks */ 161 /* elements that need to drain to allow the */ 162 /* current expedited grace period to */ 163 /* complete (only for PREEMPT_RCU). */ 164 unsigned long qsmaskinit; 165 /* Per-GP initial value for qsmask & expmask. */ 166 /* Initialized from ->qsmaskinitnext at the */ 167 /* beginning of each grace period. */ 168 unsigned long qsmaskinitnext; 169 /* Online CPUs for next grace period. */ 170 unsigned long grpmask; /* Mask to apply to parent qsmask. */ 171 /* Only one bit will be set in this mask. */ 172 int grplo; /* lowest-numbered CPU or group here. */ 173 int grphi; /* highest-numbered CPU or group here. */ 174 u8 grpnum; /* CPU/group number for next level up. */ 175 u8 level; /* root is at level 0. */ 176 bool wait_blkd_tasks;/* Necessary to wait for blocked tasks to */ 177 /* exit RCU read-side critical sections */ 178 /* before propagating offline up the */ 179 /* rcu_node tree? */ 180 struct rcu_node *parent; 181 struct list_head blkd_tasks; 182 /* Tasks blocked in RCU read-side critical */ 183 /* section. Tasks are placed at the head */ 184 /* of this list and age towards the tail. */ 185 struct list_head *gp_tasks; 186 /* Pointer to the first task blocking the */ 187 /* current grace period, or NULL if there */ 188 /* is no such task. */ 189 struct list_head *exp_tasks; 190 /* Pointer to the first task blocking the */ 191 /* current expedited grace period, or NULL */ 192 /* if there is no such task. If there */ 193 /* is no current expedited grace period, */ 194 /* then there can cannot be any such task. */ 195 struct list_head *boost_tasks; 196 /* Pointer to first task that needs to be */ 197 /* priority boosted, or NULL if no priority */ 198 /* boosting is needed for this rcu_node */ 199 /* structure. If there are no tasks */ 200 /* queued on this rcu_node structure that */ 201 /* are blocking the current grace period, */ 202 /* there can be no such task. */ 203 struct rt_mutex boost_mtx; 204 /* Used only for the priority-boosting */ 205 /* side effect, not as a lock. */ 206 unsigned long boost_time; 207 /* When to start boosting (jiffies). */ 208 struct task_struct *boost_kthread_task; 209 /* kthread that takes care of priority */ 210 /* boosting for this rcu_node structure. */ 211 unsigned int boost_kthread_status; 212 /* State of boost_kthread_task for tracing. */ 213 unsigned long n_tasks_boosted; 214 /* Total number of tasks boosted. */ 215 unsigned long n_exp_boosts; 216 /* Number of tasks boosted for expedited GP. */ 217 unsigned long n_normal_boosts; 218 /* Number of tasks boosted for normal GP. */ 219 unsigned long n_balk_blkd_tasks; 220 /* Refused to boost: no blocked tasks. */ 221 unsigned long n_balk_exp_gp_tasks; 222 /* Refused to boost: nothing blocking GP. */ 223 unsigned long n_balk_boost_tasks; 224 /* Refused to boost: already boosting. */ 225 unsigned long n_balk_notblocked; 226 /* Refused to boost: RCU RS CS still running. */ 227 unsigned long n_balk_notyet; 228 /* Refused to boost: not yet time. */ 229 unsigned long n_balk_nos; 230 /* Refused to boost: not sure why, though. */ 231 /* This can happen due to race conditions. */ 232 #ifdef CONFIG_RCU_NOCB_CPU 233 wait_queue_head_t nocb_gp_wq[2]; 234 /* Place for rcu_nocb_kthread() to wait GP. */ 235 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 236 int need_future_gp[2]; 237 /* Counts of upcoming no-CB GP requests. */ 238 raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp; 239 } ____cacheline_internodealigned_in_smp; 240 241 /* 242 * Do a full breadth-first scan of the rcu_node structures for the 243 * specified rcu_state structure. 244 */ 245 #define rcu_for_each_node_breadth_first(rsp, rnp) \ 246 for ((rnp) = &(rsp)->node[0]; \ 247 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 248 249 /* 250 * Do a breadth-first scan of the non-leaf rcu_node structures for the 251 * specified rcu_state structure. Note that if there is a singleton 252 * rcu_node tree with but one rcu_node structure, this loop is a no-op. 253 */ 254 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ 255 for ((rnp) = &(rsp)->node[0]; \ 256 (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++) 257 258 /* 259 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state 260 * structure. Note that if there is a singleton rcu_node tree with but 261 * one rcu_node structure, this loop -will- visit the rcu_node structure. 262 * It is still a leaf node, even if it is also the root node. 263 */ 264 #define rcu_for_each_leaf_node(rsp, rnp) \ 265 for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \ 266 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 267 268 /* Index values for nxttail array in struct rcu_data. */ 269 #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ 270 #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ 271 #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */ 272 #define RCU_NEXT_TAIL 3 273 #define RCU_NEXT_SIZE 4 274 275 /* Per-CPU data for read-copy update. */ 276 struct rcu_data { 277 /* 1) quiescent-state and grace-period handling : */ 278 unsigned long completed; /* Track rsp->completed gp number */ 279 /* in order to detect GP end. */ 280 unsigned long gpnum; /* Highest gp number that this CPU */ 281 /* is aware of having started. */ 282 unsigned long rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */ 283 /* for rcu_all_qs() invocations. */ 284 bool passed_quiesce; /* User-mode/idle loop etc. */ 285 bool qs_pending; /* Core waits for quiesc state. */ 286 bool beenonline; /* CPU online at least once. */ 287 bool gpwrap; /* Possible gpnum/completed wrap. */ 288 struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ 289 unsigned long grpmask; /* Mask to apply to leaf qsmask. */ 290 #ifdef CONFIG_RCU_CPU_STALL_INFO 291 unsigned long ticks_this_gp; /* The number of scheduling-clock */ 292 /* ticks this CPU has handled */ 293 /* during and after the last grace */ 294 /* period it is aware of. */ 295 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ 296 297 /* 2) batch handling */ 298 /* 299 * If nxtlist is not NULL, it is partitioned as follows. 300 * Any of the partitions might be empty, in which case the 301 * pointer to that partition will be equal to the pointer for 302 * the following partition. When the list is empty, all of 303 * the nxttail elements point to the ->nxtlist pointer itself, 304 * which in that case is NULL. 305 * 306 * [nxtlist, *nxttail[RCU_DONE_TAIL]): 307 * Entries that batch # <= ->completed 308 * The grace period for these entries has completed, and 309 * the other grace-period-completed entries may be moved 310 * here temporarily in rcu_process_callbacks(). 311 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): 312 * Entries that batch # <= ->completed - 1: waiting for current GP 313 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): 314 * Entries known to have arrived before current GP ended 315 * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]): 316 * Entries that might have arrived after current GP ended 317 * Note that the value of *nxttail[RCU_NEXT_TAIL] will 318 * always be NULL, as this is the end of the list. 319 */ 320 struct rcu_head *nxtlist; 321 struct rcu_head **nxttail[RCU_NEXT_SIZE]; 322 unsigned long nxtcompleted[RCU_NEXT_SIZE]; 323 /* grace periods for sublists. */ 324 long qlen_lazy; /* # of lazy queued callbacks */ 325 long qlen; /* # of queued callbacks, incl lazy */ 326 long qlen_last_fqs_check; 327 /* qlen at last check for QS forcing */ 328 unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ 329 unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */ 330 unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ 331 unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ 332 unsigned long n_force_qs_snap; 333 /* did other CPU force QS recently? */ 334 long blimit; /* Upper limit on a processed batch */ 335 336 /* 3) dynticks interface. */ 337 struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ 338 int dynticks_snap; /* Per-GP tracking for dynticks. */ 339 340 /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ 341 unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ 342 unsigned long offline_fqs; /* Kicked due to being offline. */ 343 unsigned long cond_resched_completed; 344 /* Grace period that needs help */ 345 /* from cond_resched(). */ 346 347 /* 5) __rcu_pending() statistics. */ 348 unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ 349 unsigned long n_rp_qs_pending; 350 unsigned long n_rp_report_qs; 351 unsigned long n_rp_cb_ready; 352 unsigned long n_rp_cpu_needs_gp; 353 unsigned long n_rp_gp_completed; 354 unsigned long n_rp_gp_started; 355 unsigned long n_rp_nocb_defer_wakeup; 356 unsigned long n_rp_need_nothing; 357 358 /* 6) _rcu_barrier() and OOM callbacks. */ 359 struct rcu_head barrier_head; 360 #ifdef CONFIG_RCU_FAST_NO_HZ 361 struct rcu_head oom_head; 362 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ 363 364 /* 7) Callback offloading. */ 365 #ifdef CONFIG_RCU_NOCB_CPU 366 struct rcu_head *nocb_head; /* CBs waiting for kthread. */ 367 struct rcu_head **nocb_tail; 368 atomic_long_t nocb_q_count; /* # CBs waiting for nocb */ 369 atomic_long_t nocb_q_count_lazy; /* invocation (all stages). */ 370 struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */ 371 struct rcu_head **nocb_follower_tail; 372 wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */ 373 struct task_struct *nocb_kthread; 374 int nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */ 375 376 /* The following fields are used by the leader, hence own cacheline. */ 377 struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp; 378 /* CBs waiting for GP. */ 379 struct rcu_head **nocb_gp_tail; 380 bool nocb_leader_sleep; /* Is the nocb leader thread asleep? */ 381 struct rcu_data *nocb_next_follower; 382 /* Next follower in wakeup chain. */ 383 384 /* The following fields are used by the follower, hence new cachline. */ 385 struct rcu_data *nocb_leader ____cacheline_internodealigned_in_smp; 386 /* Leader CPU takes GP-end wakeups. */ 387 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 388 389 /* 8) RCU CPU stall data. */ 390 #ifdef CONFIG_RCU_CPU_STALL_INFO 391 unsigned int softirq_snap; /* Snapshot of softirq activity. */ 392 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ 393 394 int cpu; 395 struct rcu_state *rsp; 396 }; 397 398 /* Values for fqs_state field in struct rcu_state. */ 399 #define RCU_GP_IDLE 0 /* No grace period in progress. */ 400 #define RCU_GP_INIT 1 /* Grace period being initialized. */ 401 #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */ 402 #define RCU_FORCE_QS 3 /* Need to force quiescent state. */ 403 #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK 404 405 /* Values for nocb_defer_wakeup field in struct rcu_data. */ 406 #define RCU_NOGP_WAKE_NOT 0 407 #define RCU_NOGP_WAKE 1 408 #define RCU_NOGP_WAKE_FORCE 2 409 410 #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500)) 411 /* For jiffies_till_first_fqs and */ 412 /* and jiffies_till_next_fqs. */ 413 414 #define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */ 415 /* delay between bouts of */ 416 /* quiescent-state forcing. */ 417 418 #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */ 419 /* at least one scheduling clock */ 420 /* irq before ratting on them. */ 421 422 #define rcu_wait(cond) \ 423 do { \ 424 for (;;) { \ 425 set_current_state(TASK_INTERRUPTIBLE); \ 426 if (cond) \ 427 break; \ 428 schedule(); \ 429 } \ 430 __set_current_state(TASK_RUNNING); \ 431 } while (0) 432 433 /* 434 * RCU global state, including node hierarchy. This hierarchy is 435 * represented in "heap" form in a dense array. The root (first level) 436 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second 437 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]), 438 * and the third level in ->node[m+1] and following (->node[m+1] referenced 439 * by ->level[2]). The number of levels is determined by the number of 440 * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy" 441 * consisting of a single rcu_node. 442 */ 443 struct rcu_state { 444 struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */ 445 struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */ 446 u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */ 447 u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */ 448 u8 flavor_mask; /* bit in flavor mask. */ 449 struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */ 450 void (*call)(struct rcu_head *head, /* call_rcu() flavor. */ 451 void (*func)(struct rcu_head *head)); 452 453 /* The following fields are guarded by the root rcu_node's lock. */ 454 455 u8 fqs_state ____cacheline_internodealigned_in_smp; 456 /* Force QS state. */ 457 u8 boost; /* Subject to priority boost. */ 458 unsigned long gpnum; /* Current gp number. */ 459 unsigned long completed; /* # of last completed gp. */ 460 struct task_struct *gp_kthread; /* Task for grace periods. */ 461 wait_queue_head_t gp_wq; /* Where GP task waits. */ 462 short gp_flags; /* Commands for GP task. */ 463 short gp_state; /* GP kthread sleep state. */ 464 465 /* End of fields guarded by root rcu_node's lock. */ 466 467 raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp; 468 /* Protect following fields. */ 469 struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */ 470 /* need a grace period. */ 471 struct rcu_head **orphan_nxttail; /* Tail of above. */ 472 struct rcu_head *orphan_donelist; /* Orphaned callbacks that */ 473 /* are ready to invoke. */ 474 struct rcu_head **orphan_donetail; /* Tail of above. */ 475 long qlen_lazy; /* Number of lazy callbacks. */ 476 long qlen; /* Total number of callbacks. */ 477 /* End of fields guarded by orphan_lock. */ 478 479 struct mutex barrier_mutex; /* Guards barrier fields. */ 480 atomic_t barrier_cpu_count; /* # CPUs waiting on. */ 481 struct completion barrier_completion; /* Wake at barrier end. */ 482 unsigned long n_barrier_done; /* ++ at start and end of */ 483 /* _rcu_barrier(). */ 484 /* End of fields guarded by barrier_mutex. */ 485 486 atomic_long_t expedited_start; /* Starting ticket. */ 487 atomic_long_t expedited_done; /* Done ticket. */ 488 atomic_long_t expedited_wrap; /* # near-wrap incidents. */ 489 atomic_long_t expedited_tryfail; /* # acquisition failures. */ 490 atomic_long_t expedited_workdone1; /* # done by others #1. */ 491 atomic_long_t expedited_workdone2; /* # done by others #2. */ 492 atomic_long_t expedited_normal; /* # fallbacks to normal. */ 493 atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */ 494 atomic_long_t expedited_done_tries; /* # tries to update _done. */ 495 atomic_long_t expedited_done_lost; /* # times beaten to _done. */ 496 atomic_long_t expedited_done_exit; /* # times exited _done loop. */ 497 498 unsigned long jiffies_force_qs; /* Time at which to invoke */ 499 /* force_quiescent_state(). */ 500 unsigned long n_force_qs; /* Number of calls to */ 501 /* force_quiescent_state(). */ 502 unsigned long n_force_qs_lh; /* ~Number of calls leaving */ 503 /* due to lock unavailable. */ 504 unsigned long n_force_qs_ngp; /* Number of calls leaving */ 505 /* due to no GP active. */ 506 unsigned long gp_start; /* Time at which GP started, */ 507 /* but in jiffies. */ 508 unsigned long gp_activity; /* Time of last GP kthread */ 509 /* activity in jiffies. */ 510 unsigned long jiffies_stall; /* Time at which to check */ 511 /* for CPU stalls. */ 512 unsigned long jiffies_resched; /* Time at which to resched */ 513 /* a reluctant CPU. */ 514 unsigned long n_force_qs_gpstart; /* Snapshot of n_force_qs at */ 515 /* GP start. */ 516 unsigned long gp_max; /* Maximum GP duration in */ 517 /* jiffies. */ 518 const char *name; /* Name of structure. */ 519 char abbr; /* Abbreviated name. */ 520 struct list_head flavors; /* List of RCU flavors. */ 521 }; 522 523 /* Values for rcu_state structure's gp_flags field. */ 524 #define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */ 525 #define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */ 526 527 /* Values for rcu_state structure's gp_flags field. */ 528 #define RCU_GP_WAIT_INIT 0 /* Initial state. */ 529 #define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */ 530 #define RCU_GP_WAIT_FQS 2 /* Wait for force-quiescent-state time. */ 531 532 extern struct list_head rcu_struct_flavors; 533 534 /* Sequence through rcu_state structures for each RCU flavor. */ 535 #define for_each_rcu_flavor(rsp) \ 536 list_for_each_entry((rsp), &rcu_struct_flavors, flavors) 537 538 /* 539 * RCU implementation internal declarations: 540 */ 541 extern struct rcu_state rcu_sched_state; 542 543 extern struct rcu_state rcu_bh_state; 544 545 #ifdef CONFIG_PREEMPT_RCU 546 extern struct rcu_state rcu_preempt_state; 547 #endif /* #ifdef CONFIG_PREEMPT_RCU */ 548 549 #ifdef CONFIG_RCU_BOOST 550 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); 551 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu); 552 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); 553 DECLARE_PER_CPU(char, rcu_cpu_has_work); 554 #endif /* #ifdef CONFIG_RCU_BOOST */ 555 556 #ifndef RCU_TREE_NONCORE 557 558 /* Forward declarations for rcutree_plugin.h */ 559 static void rcu_bootup_announce(void); 560 static void rcu_preempt_note_context_switch(void); 561 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp); 562 #ifdef CONFIG_HOTPLUG_CPU 563 static bool rcu_preempt_has_tasks(struct rcu_node *rnp); 564 #endif /* #ifdef CONFIG_HOTPLUG_CPU */ 565 static void rcu_print_detail_task_stall(struct rcu_state *rsp); 566 static int rcu_print_task_stall(struct rcu_node *rnp); 567 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); 568 static void rcu_preempt_check_callbacks(void); 569 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); 570 static void __init __rcu_init_preempt(void); 571 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); 572 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); 573 static void invoke_rcu_callbacks_kthread(void); 574 static bool rcu_is_callbacks_kthread(void); 575 #ifdef CONFIG_RCU_BOOST 576 static void rcu_preempt_do_callbacks(void); 577 static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp, 578 struct rcu_node *rnp); 579 #endif /* #ifdef CONFIG_RCU_BOOST */ 580 static void __init rcu_spawn_boost_kthreads(void); 581 static void rcu_prepare_kthreads(int cpu); 582 static void rcu_cleanup_after_idle(void); 583 static void rcu_prepare_for_idle(void); 584 static void rcu_idle_count_callbacks_posted(void); 585 static bool rcu_preempt_has_tasks(struct rcu_node *rnp); 586 static void print_cpu_stall_info_begin(void); 587 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu); 588 static void print_cpu_stall_info_end(void); 589 static void zero_cpu_stall_ticks(struct rcu_data *rdp); 590 static void increment_cpu_stall_ticks(void); 591 static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu); 592 static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq); 593 static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp); 594 static void rcu_init_one_nocb(struct rcu_node *rnp); 595 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp, 596 bool lazy, unsigned long flags); 597 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp, 598 struct rcu_data *rdp, 599 unsigned long flags); 600 static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp); 601 static void do_nocb_deferred_wakeup(struct rcu_data *rdp); 602 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp); 603 static void rcu_spawn_all_nocb_kthreads(int cpu); 604 static void __init rcu_spawn_nocb_kthreads(void); 605 #ifdef CONFIG_RCU_NOCB_CPU 606 static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp); 607 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 608 static void __maybe_unused rcu_kick_nohz_cpu(int cpu); 609 static bool init_nocb_callback_list(struct rcu_data *rdp); 610 static void rcu_sysidle_enter(int irq); 611 static void rcu_sysidle_exit(int irq); 612 static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle, 613 unsigned long *maxj); 614 static bool is_sysidle_rcu_state(struct rcu_state *rsp); 615 static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle, 616 unsigned long maxj); 617 static void rcu_bind_gp_kthread(void); 618 static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp); 619 static bool rcu_nohz_full_cpu(struct rcu_state *rsp); 620 static void rcu_dynticks_task_enter(void); 621 static void rcu_dynticks_task_exit(void); 622 623 #endif /* #ifndef RCU_TREE_NONCORE */ 624 625 #ifdef CONFIG_RCU_TRACE 626 /* Read out queue lengths for tracing. */ 627 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll) 628 { 629 #ifdef CONFIG_RCU_NOCB_CPU 630 *ql = atomic_long_read(&rdp->nocb_q_count); 631 *qll = atomic_long_read(&rdp->nocb_q_count_lazy); 632 #else /* #ifdef CONFIG_RCU_NOCB_CPU */ 633 *ql = 0; 634 *qll = 0; 635 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ 636 } 637 #endif /* #ifdef CONFIG_RCU_TRACE */ 638