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 struct completion boost_completion; 176 /* Used to ensure that the rt_mutex used */ 177 /* to carry out the boosting is fully */ 178 /* released with no future boostee accesses */ 179 /* before that rt_mutex is re-initialized. */ 180 struct rt_mutex boost_mtx; 181 /* Used only for the priority-boosting */ 182 /* side effect, not as a lock. */ 183 unsigned long boost_time; 184 /* When to start boosting (jiffies). */ 185 struct task_struct *boost_kthread_task; 186 /* kthread that takes care of priority */ 187 /* boosting for this rcu_node structure. */ 188 unsigned int boost_kthread_status; 189 /* State of boost_kthread_task for tracing. */ 190 unsigned long n_tasks_boosted; 191 /* Total number of tasks boosted. */ 192 unsigned long n_exp_boosts; 193 /* Number of tasks boosted for expedited GP. */ 194 unsigned long n_normal_boosts; 195 /* Number of tasks boosted for normal GP. */ 196 unsigned long n_balk_blkd_tasks; 197 /* Refused to boost: no blocked tasks. */ 198 unsigned long n_balk_exp_gp_tasks; 199 /* Refused to boost: nothing blocking GP. */ 200 unsigned long n_balk_boost_tasks; 201 /* Refused to boost: already boosting. */ 202 unsigned long n_balk_notblocked; 203 /* Refused to boost: RCU RS CS still running. */ 204 unsigned long n_balk_notyet; 205 /* Refused to boost: not yet time. */ 206 unsigned long n_balk_nos; 207 /* Refused to boost: not sure why, though. */ 208 /* This can happen due to race conditions. */ 209 #endif /* #ifdef CONFIG_RCU_BOOST */ 210 #ifdef CONFIG_RCU_NOCB_CPU 211 wait_queue_head_t nocb_gp_wq[2]; 212 /* Place for rcu_nocb_kthread() to wait GP. */ 213 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 214 int need_future_gp[2]; 215 /* Counts of upcoming no-CB GP requests. */ 216 raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp; 217 } ____cacheline_internodealigned_in_smp; 218 219 /* 220 * Do a full breadth-first scan of the rcu_node structures for the 221 * specified rcu_state structure. 222 */ 223 #define rcu_for_each_node_breadth_first(rsp, rnp) \ 224 for ((rnp) = &(rsp)->node[0]; \ 225 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 226 227 /* 228 * Do a breadth-first scan of the non-leaf rcu_node structures for the 229 * specified rcu_state structure. Note that if there is a singleton 230 * rcu_node tree with but one rcu_node structure, this loop is a no-op. 231 */ 232 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ 233 for ((rnp) = &(rsp)->node[0]; \ 234 (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++) 235 236 /* 237 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state 238 * structure. Note that if there is a singleton rcu_node tree with but 239 * one rcu_node structure, this loop -will- visit the rcu_node structure. 240 * It is still a leaf node, even if it is also the root node. 241 */ 242 #define rcu_for_each_leaf_node(rsp, rnp) \ 243 for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \ 244 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 245 246 /* Index values for nxttail array in struct rcu_data. */ 247 #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */ 248 #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */ 249 #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */ 250 #define RCU_NEXT_TAIL 3 251 #define RCU_NEXT_SIZE 4 252 253 /* Per-CPU data for read-copy update. */ 254 struct rcu_data { 255 /* 1) quiescent-state and grace-period handling : */ 256 unsigned long completed; /* Track rsp->completed gp number */ 257 /* in order to detect GP end. */ 258 unsigned long gpnum; /* Highest gp number that this CPU */ 259 /* is aware of having started. */ 260 bool passed_quiesce; /* User-mode/idle loop etc. */ 261 bool qs_pending; /* Core waits for quiesc state. */ 262 bool beenonline; /* CPU online at least once. */ 263 struct rcu_node *mynode; /* This CPU's leaf of hierarchy */ 264 unsigned long grpmask; /* Mask to apply to leaf qsmask. */ 265 #ifdef CONFIG_RCU_CPU_STALL_INFO 266 unsigned long ticks_this_gp; /* The number of scheduling-clock */ 267 /* ticks this CPU has handled */ 268 /* during and after the last grace */ 269 /* period it is aware of. */ 270 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ 271 272 /* 2) batch handling */ 273 /* 274 * If nxtlist is not NULL, it is partitioned as follows. 275 * Any of the partitions might be empty, in which case the 276 * pointer to that partition will be equal to the pointer for 277 * the following partition. When the list is empty, all of 278 * the nxttail elements point to the ->nxtlist pointer itself, 279 * which in that case is NULL. 280 * 281 * [nxtlist, *nxttail[RCU_DONE_TAIL]): 282 * Entries that batch # <= ->completed 283 * The grace period for these entries has completed, and 284 * the other grace-period-completed entries may be moved 285 * here temporarily in rcu_process_callbacks(). 286 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): 287 * Entries that batch # <= ->completed - 1: waiting for current GP 288 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): 289 * Entries known to have arrived before current GP ended 290 * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]): 291 * Entries that might have arrived after current GP ended 292 * Note that the value of *nxttail[RCU_NEXT_TAIL] will 293 * always be NULL, as this is the end of the list. 294 */ 295 struct rcu_head *nxtlist; 296 struct rcu_head **nxttail[RCU_NEXT_SIZE]; 297 unsigned long nxtcompleted[RCU_NEXT_SIZE]; 298 /* grace periods for sublists. */ 299 long qlen_lazy; /* # of lazy queued callbacks */ 300 long qlen; /* # of queued callbacks, incl lazy */ 301 long qlen_last_fqs_check; 302 /* qlen at last check for QS forcing */ 303 unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ 304 unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */ 305 unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ 306 unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ 307 unsigned long n_force_qs_snap; 308 /* did other CPU force QS recently? */ 309 long blimit; /* Upper limit on a processed batch */ 310 311 /* 3) dynticks interface. */ 312 struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ 313 int dynticks_snap; /* Per-GP tracking for dynticks. */ 314 315 /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ 316 unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ 317 unsigned long offline_fqs; /* Kicked due to being offline. */ 318 unsigned long cond_resched_completed; 319 /* Grace period that needs help */ 320 /* from cond_resched(). */ 321 322 /* 5) __rcu_pending() statistics. */ 323 unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ 324 unsigned long n_rp_qs_pending; 325 unsigned long n_rp_report_qs; 326 unsigned long n_rp_cb_ready; 327 unsigned long n_rp_cpu_needs_gp; 328 unsigned long n_rp_gp_completed; 329 unsigned long n_rp_gp_started; 330 unsigned long n_rp_nocb_defer_wakeup; 331 unsigned long n_rp_need_nothing; 332 333 /* 6) _rcu_barrier() and OOM callbacks. */ 334 struct rcu_head barrier_head; 335 #ifdef CONFIG_RCU_FAST_NO_HZ 336 struct rcu_head oom_head; 337 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */ 338 339 /* 7) Callback offloading. */ 340 #ifdef CONFIG_RCU_NOCB_CPU 341 struct rcu_head *nocb_head; /* CBs waiting for kthread. */ 342 struct rcu_head **nocb_tail; 343 atomic_long_t nocb_q_count; /* # CBs waiting for kthread */ 344 atomic_long_t nocb_q_count_lazy; /* (approximate). */ 345 struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */ 346 struct rcu_head **nocb_follower_tail; 347 atomic_long_t nocb_follower_count; /* # CBs ready to invoke. */ 348 atomic_long_t nocb_follower_count_lazy; /* (approximate). */ 349 int nocb_p_count; /* # CBs being invoked by kthread */ 350 int nocb_p_count_lazy; /* (approximate). */ 351 wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */ 352 struct task_struct *nocb_kthread; 353 bool nocb_defer_wakeup; /* Defer wakeup of nocb_kthread. */ 354 355 /* The following fields are used by the leader, hence own cacheline. */ 356 struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp; 357 /* CBs waiting for GP. */ 358 struct rcu_head **nocb_gp_tail; 359 long nocb_gp_count; 360 long nocb_gp_count_lazy; 361 bool nocb_leader_sleep; /* Is the nocb leader thread asleep? */ 362 struct rcu_data *nocb_next_follower; 363 /* Next follower in wakeup chain. */ 364 365 /* The following fields are used by the follower, hence new cachline. */ 366 struct rcu_data *nocb_leader ____cacheline_internodealigned_in_smp; 367 /* Leader CPU takes GP-end wakeups. */ 368 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */ 369 370 /* 8) RCU CPU stall data. */ 371 #ifdef CONFIG_RCU_CPU_STALL_INFO 372 unsigned int softirq_snap; /* Snapshot of softirq activity. */ 373 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ 374 375 int cpu; 376 struct rcu_state *rsp; 377 }; 378 379 /* Values for fqs_state field in struct rcu_state. */ 380 #define RCU_GP_IDLE 0 /* No grace period in progress. */ 381 #define RCU_GP_INIT 1 /* Grace period being initialized. */ 382 #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */ 383 #define RCU_FORCE_QS 3 /* Need to force quiescent state. */ 384 #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK 385 386 #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500)) 387 /* For jiffies_till_first_fqs and */ 388 /* and jiffies_till_next_fqs. */ 389 390 #define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */ 391 /* delay between bouts of */ 392 /* quiescent-state forcing. */ 393 394 #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */ 395 /* at least one scheduling clock */ 396 /* irq before ratting on them. */ 397 398 #define rcu_wait(cond) \ 399 do { \ 400 for (;;) { \ 401 set_current_state(TASK_INTERRUPTIBLE); \ 402 if (cond) \ 403 break; \ 404 schedule(); \ 405 } \ 406 __set_current_state(TASK_RUNNING); \ 407 } while (0) 408 409 /* 410 * RCU global state, including node hierarchy. This hierarchy is 411 * represented in "heap" form in a dense array. The root (first level) 412 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second 413 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]), 414 * and the third level in ->node[m+1] and following (->node[m+1] referenced 415 * by ->level[2]). The number of levels is determined by the number of 416 * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy" 417 * consisting of a single rcu_node. 418 */ 419 struct rcu_state { 420 struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */ 421 struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */ 422 u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */ 423 u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */ 424 u8 flavor_mask; /* bit in flavor mask. */ 425 struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */ 426 void (*call)(struct rcu_head *head, /* call_rcu() flavor. */ 427 void (*func)(struct rcu_head *head)); 428 429 /* The following fields are guarded by the root rcu_node's lock. */ 430 431 u8 fqs_state ____cacheline_internodealigned_in_smp; 432 /* Force QS state. */ 433 u8 boost; /* Subject to priority boost. */ 434 unsigned long gpnum; /* Current gp number. */ 435 unsigned long completed; /* # of last completed gp. */ 436 struct task_struct *gp_kthread; /* Task for grace periods. */ 437 wait_queue_head_t gp_wq; /* Where GP task waits. */ 438 short gp_flags; /* Commands for GP task. */ 439 short gp_state; /* GP kthread sleep state. */ 440 441 /* End of fields guarded by root rcu_node's lock. */ 442 443 raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp; 444 /* Protect following fields. */ 445 struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */ 446 /* need a grace period. */ 447 struct rcu_head **orphan_nxttail; /* Tail of above. */ 448 struct rcu_head *orphan_donelist; /* Orphaned callbacks that */ 449 /* are ready to invoke. */ 450 struct rcu_head **orphan_donetail; /* Tail of above. */ 451 long qlen_lazy; /* Number of lazy callbacks. */ 452 long qlen; /* Total number of callbacks. */ 453 /* End of fields guarded by orphan_lock. */ 454 455 struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */ 456 457 struct mutex barrier_mutex; /* Guards barrier fields. */ 458 atomic_t barrier_cpu_count; /* # CPUs waiting on. */ 459 struct completion barrier_completion; /* Wake at barrier end. */ 460 unsigned long n_barrier_done; /* ++ at start and end of */ 461 /* _rcu_barrier(). */ 462 /* End of fields guarded by barrier_mutex. */ 463 464 atomic_long_t expedited_start; /* Starting ticket. */ 465 atomic_long_t expedited_done; /* Done ticket. */ 466 atomic_long_t expedited_wrap; /* # near-wrap incidents. */ 467 atomic_long_t expedited_tryfail; /* # acquisition failures. */ 468 atomic_long_t expedited_workdone1; /* # done by others #1. */ 469 atomic_long_t expedited_workdone2; /* # done by others #2. */ 470 atomic_long_t expedited_normal; /* # fallbacks to normal. */ 471 atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */ 472 atomic_long_t expedited_done_tries; /* # tries to update _done. */ 473 atomic_long_t expedited_done_lost; /* # times beaten to _done. */ 474 atomic_long_t expedited_done_exit; /* # times exited _done loop. */ 475 476 unsigned long jiffies_force_qs; /* Time at which to invoke */ 477 /* force_quiescent_state(). */ 478 unsigned long n_force_qs; /* Number of calls to */ 479 /* force_quiescent_state(). */ 480 unsigned long n_force_qs_lh; /* ~Number of calls leaving */ 481 /* due to lock unavailable. */ 482 unsigned long n_force_qs_ngp; /* Number of calls leaving */ 483 /* due to no GP active. */ 484 unsigned long gp_start; /* Time at which GP started, */ 485 /* but in jiffies. */ 486 unsigned long jiffies_stall; /* Time at which to check */ 487 /* for CPU stalls. */ 488 unsigned long jiffies_resched; /* Time at which to resched */ 489 /* a reluctant CPU. */ 490 unsigned long gp_max; /* Maximum GP duration in */ 491 /* jiffies. */ 492 const char *name; /* Name of structure. */ 493 char abbr; /* Abbreviated name. */ 494 struct list_head flavors; /* List of RCU flavors. */ 495 }; 496 497 /* Values for rcu_state structure's gp_flags field. */ 498 #define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */ 499 #define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */ 500 501 /* Values for rcu_state structure's gp_flags field. */ 502 #define RCU_GP_WAIT_INIT 0 /* Initial state. */ 503 #define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */ 504 #define RCU_GP_WAIT_FQS 2 /* Wait for force-quiescent-state time. */ 505 506 extern struct list_head rcu_struct_flavors; 507 508 /* Sequence through rcu_state structures for each RCU flavor. */ 509 #define for_each_rcu_flavor(rsp) \ 510 list_for_each_entry((rsp), &rcu_struct_flavors, flavors) 511 512 /* Return values for rcu_preempt_offline_tasks(). */ 513 514 #define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */ 515 /* GP were moved to root. */ 516 #define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */ 517 /* GP were moved to root. */ 518 519 /* 520 * RCU implementation internal declarations: 521 */ 522 extern struct rcu_state rcu_sched_state; 523 DECLARE_PER_CPU(struct rcu_data, rcu_sched_data); 524 525 extern struct rcu_state rcu_bh_state; 526 DECLARE_PER_CPU(struct rcu_data, rcu_bh_data); 527 528 #ifdef CONFIG_TREE_PREEMPT_RCU 529 extern struct rcu_state rcu_preempt_state; 530 DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data); 531 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */ 532 533 #ifdef CONFIG_RCU_BOOST 534 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); 535 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu); 536 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); 537 DECLARE_PER_CPU(char, rcu_cpu_has_work); 538 #endif /* #ifdef CONFIG_RCU_BOOST */ 539 540 #ifndef RCU_TREE_NONCORE 541 542 /* Forward declarations for rcutree_plugin.h */ 543 static void rcu_bootup_announce(void); 544 long rcu_batches_completed(void); 545 static void rcu_preempt_note_context_switch(int cpu); 546 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp); 547 #ifdef CONFIG_HOTPLUG_CPU 548 static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, 549 unsigned long flags); 550 #endif /* #ifdef CONFIG_HOTPLUG_CPU */ 551 static void rcu_print_detail_task_stall(struct rcu_state *rsp); 552 static int rcu_print_task_stall(struct rcu_node *rnp); 553 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp); 554 #ifdef CONFIG_HOTPLUG_CPU 555 static int rcu_preempt_offline_tasks(struct rcu_state *rsp, 556 struct rcu_node *rnp, 557 struct rcu_data *rdp); 558 #endif /* #ifdef CONFIG_HOTPLUG_CPU */ 559 static void rcu_preempt_check_callbacks(int cpu); 560 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); 561 #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) 562 static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp, 563 bool wake); 564 #endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */ 565 static void __init __rcu_init_preempt(void); 566 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); 567 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); 568 static void invoke_rcu_callbacks_kthread(void); 569 static bool rcu_is_callbacks_kthread(void); 570 #ifdef CONFIG_RCU_BOOST 571 static void rcu_preempt_do_callbacks(void); 572 static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp, 573 struct rcu_node *rnp); 574 #endif /* #ifdef CONFIG_RCU_BOOST */ 575 static void rcu_prepare_kthreads(int cpu); 576 static void rcu_cleanup_after_idle(int cpu); 577 static void rcu_prepare_for_idle(int cpu); 578 static void rcu_idle_count_callbacks_posted(void); 579 static void print_cpu_stall_info_begin(void); 580 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu); 581 static void print_cpu_stall_info_end(void); 582 static void zero_cpu_stall_ticks(struct rcu_data *rdp); 583 static void increment_cpu_stall_ticks(void); 584 static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq); 585 static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp); 586 static void rcu_init_one_nocb(struct rcu_node *rnp); 587 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp, 588 bool lazy, unsigned long flags); 589 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp, 590 struct rcu_data *rdp, 591 unsigned long flags); 592 static bool rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp); 593 static void do_nocb_deferred_wakeup(struct rcu_data *rdp); 594 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp); 595 static void rcu_spawn_nocb_kthreads(struct rcu_state *rsp); 596 static void __maybe_unused rcu_kick_nohz_cpu(int cpu); 597 static bool init_nocb_callback_list(struct rcu_data *rdp); 598 static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq); 599 static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq); 600 static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle, 601 unsigned long *maxj); 602 static bool is_sysidle_rcu_state(struct rcu_state *rsp); 603 static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle, 604 unsigned long maxj); 605 static void rcu_bind_gp_kthread(void); 606 static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp); 607 static bool rcu_nohz_full_cpu(struct rcu_state *rsp); 608 609 #endif /* #ifndef RCU_TREE_NONCORE */ 610 611 #ifdef CONFIG_RCU_TRACE 612 #ifdef CONFIG_RCU_NOCB_CPU 613 /* Sum up queue lengths for tracing. */ 614 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll) 615 { 616 *ql = atomic_long_read(&rdp->nocb_q_count) + 617 rdp->nocb_p_count + 618 atomic_long_read(&rdp->nocb_follower_count) + 619 rdp->nocb_p_count + rdp->nocb_gp_count; 620 *qll = atomic_long_read(&rdp->nocb_q_count_lazy) + 621 rdp->nocb_p_count_lazy + 622 atomic_long_read(&rdp->nocb_follower_count_lazy) + 623 rdp->nocb_p_count_lazy + rdp->nocb_gp_count_lazy; 624 } 625 #else /* #ifdef CONFIG_RCU_NOCB_CPU */ 626 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll) 627 { 628 *ql = 0; 629 *qll = 0; 630 } 631 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */ 632 #endif /* #ifdef CONFIG_RCU_TRACE */ 633