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 int 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 /* Values for nocb_defer_wakeup field in struct rcu_data. */
387 #define RCU_NOGP_WAKE_NOT 0
388 #define RCU_NOGP_WAKE 1
389 #define RCU_NOGP_WAKE_FORCE 2
390
391 #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500))
392 /* For jiffies_till_first_fqs and */
393 /* and jiffies_till_next_fqs. */
394
395 #define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */
396 /* delay between bouts of */
397 /* quiescent-state forcing. */
398
399 #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */
400 /* at least one scheduling clock */
401 /* irq before ratting on them. */
402
403 #define rcu_wait(cond) \
404 do { \
405 for (;;) { \
406 set_current_state(TASK_INTERRUPTIBLE); \
407 if (cond) \
408 break; \
409 schedule(); \
410 } \
411 __set_current_state(TASK_RUNNING); \
412 } while (0)
413
414 /*
415 * RCU global state, including node hierarchy. This hierarchy is
416 * represented in "heap" form in a dense array. The root (first level)
417 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
418 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
419 * and the third level in ->node[m+1] and following (->node[m+1] referenced
420 * by ->level[2]). The number of levels is determined by the number of
421 * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy"
422 * consisting of a single rcu_node.
423 */
424 struct rcu_state {
425 struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
426 struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */
427 u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
428 u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
429 u8 flavor_mask; /* bit in flavor mask. */
430 struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
431 void (*call)(struct rcu_head *head, /* call_rcu() flavor. */
432 void (*func)(struct rcu_head *head));
433
434 /* The following fields are guarded by the root rcu_node's lock. */
435
436 u8 fqs_state ____cacheline_internodealigned_in_smp;
437 /* Force QS state. */
438 u8 boost; /* Subject to priority boost. */
439 unsigned long gpnum; /* Current gp number. */
440 unsigned long completed; /* # of last completed gp. */
441 struct task_struct *gp_kthread; /* Task for grace periods. */
442 wait_queue_head_t gp_wq; /* Where GP task waits. */
443 short gp_flags; /* Commands for GP task. */
444 short gp_state; /* GP kthread sleep state. */
445
446 /* End of fields guarded by root rcu_node's lock. */
447
448 raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp;
449 /* Protect following fields. */
450 struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */
451 /* need a grace period. */
452 struct rcu_head **orphan_nxttail; /* Tail of above. */
453 struct rcu_head *orphan_donelist; /* Orphaned callbacks that */
454 /* are ready to invoke. */
455 struct rcu_head **orphan_donetail; /* Tail of above. */
456 long qlen_lazy; /* Number of lazy callbacks. */
457 long qlen; /* Total number of callbacks. */
458 /* End of fields guarded by orphan_lock. */
459
460 struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */
461
462 struct mutex barrier_mutex; /* Guards barrier fields. */
463 atomic_t barrier_cpu_count; /* # CPUs waiting on. */
464 struct completion barrier_completion; /* Wake at barrier end. */
465 unsigned long n_barrier_done; /* ++ at start and end of */
466 /* _rcu_barrier(). */
467 /* End of fields guarded by barrier_mutex. */
468
469 atomic_long_t expedited_start; /* Starting ticket. */
470 atomic_long_t expedited_done; /* Done ticket. */
471 atomic_long_t expedited_wrap; /* # near-wrap incidents. */
472 atomic_long_t expedited_tryfail; /* # acquisition failures. */
473 atomic_long_t expedited_workdone1; /* # done by others #1. */
474 atomic_long_t expedited_workdone2; /* # done by others #2. */
475 atomic_long_t expedited_normal; /* # fallbacks to normal. */
476 atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */
477 atomic_long_t expedited_done_tries; /* # tries to update _done. */
478 atomic_long_t expedited_done_lost; /* # times beaten to _done. */
479 atomic_long_t expedited_done_exit; /* # times exited _done loop. */
480
481 unsigned long jiffies_force_qs; /* Time at which to invoke */
482 /* force_quiescent_state(). */
483 unsigned long n_force_qs; /* Number of calls to */
484 /* force_quiescent_state(). */
485 unsigned long n_force_qs_lh; /* ~Number of calls leaving */
486 /* due to lock unavailable. */
487 unsigned long n_force_qs_ngp; /* Number of calls leaving */
488 /* due to no GP active. */
489 unsigned long gp_start; /* Time at which GP started, */
490 /* but in jiffies. */
491 unsigned long jiffies_stall; /* Time at which to check */
492 /* for CPU stalls. */
493 unsigned long jiffies_resched; /* Time at which to resched */
494 /* a reluctant CPU. */
495 unsigned long gp_max; /* Maximum GP duration in */
496 /* jiffies. */
497 const char *name; /* Name of structure. */
498 char abbr; /* Abbreviated name. */
499 struct list_head flavors; /* List of RCU flavors. */
500 };
501
502 /* Values for rcu_state structure's gp_flags field. */
503 #define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */
504 #define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
505
506 /* Values for rcu_state structure's gp_flags field. */
507 #define RCU_GP_WAIT_INIT 0 /* Initial state. */
508 #define RCU_GP_WAIT_GPS 1 /* Wait for grace-period start. */
509 #define RCU_GP_WAIT_FQS 2 /* Wait for force-quiescent-state time. */
510
511 extern struct list_head rcu_struct_flavors;
512
513 /* Sequence through rcu_state structures for each RCU flavor. */
514 #define for_each_rcu_flavor(rsp) \
515 list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
516
517 /* Return values for rcu_preempt_offline_tasks(). */
518
519 #define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */
520 /* GP were moved to root. */
521 #define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */
522 /* GP were moved to root. */
523
524 /*
525 * RCU implementation internal declarations:
526 */
527 extern struct rcu_state rcu_sched_state;
528 DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
529
530 extern struct rcu_state rcu_bh_state;
531 DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
532
533 #ifdef CONFIG_TREE_PREEMPT_RCU
534 extern struct rcu_state rcu_preempt_state;
535 DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
536 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
537
538 #ifdef CONFIG_RCU_BOOST
539 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
540 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
541 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
542 DECLARE_PER_CPU(char, rcu_cpu_has_work);
543 #endif /* #ifdef CONFIG_RCU_BOOST */
544
545 #ifndef RCU_TREE_NONCORE
546
547 /* Forward declarations for rcutree_plugin.h */
548 static void rcu_bootup_announce(void);
549 long rcu_batches_completed(void);
550 static void rcu_preempt_note_context_switch(int cpu);
551 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
552 #ifdef CONFIG_HOTPLUG_CPU
553 static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
554 unsigned long flags);
555 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
556 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
557 static int rcu_print_task_stall(struct rcu_node *rnp);
558 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
559 #ifdef CONFIG_HOTPLUG_CPU
560 static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
561 struct rcu_node *rnp,
562 struct rcu_data *rdp);
563 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
564 static void rcu_preempt_check_callbacks(int cpu);
565 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
566 #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)
567 static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
568 bool wake);
569 #endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_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(int cpu);
583 static void rcu_prepare_for_idle(int cpu);
584 static void rcu_idle_count_callbacks_posted(void);
585 static void print_cpu_stall_info_begin(void);
586 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
587 static void print_cpu_stall_info_end(void);
588 static void zero_cpu_stall_ticks(struct rcu_data *rdp);
589 static void increment_cpu_stall_ticks(void);
590 static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu);
591 static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq);
592 static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp);
593 static void rcu_init_one_nocb(struct rcu_node *rnp);
594 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
595 bool lazy, unsigned long flags);
596 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
597 struct rcu_data *rdp,
598 unsigned long flags);
599 static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp);
600 static void do_nocb_deferred_wakeup(struct rcu_data *rdp);
601 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
602 static void rcu_spawn_all_nocb_kthreads(int cpu);
603 static void __init rcu_spawn_nocb_kthreads(void);
604 #ifdef CONFIG_RCU_NOCB_CPU
605 static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp);
606 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
607 static void __maybe_unused rcu_kick_nohz_cpu(int cpu);
608 static bool init_nocb_callback_list(struct rcu_data *rdp);
609 static void rcu_sysidle_enter(struct rcu_dynticks *rdtp, int irq);
610 static void rcu_sysidle_exit(struct rcu_dynticks *rdtp, int irq);
611 static void rcu_sysidle_check_cpu(struct rcu_data *rdp, bool *isidle,
612 unsigned long *maxj);
613 static bool is_sysidle_rcu_state(struct rcu_state *rsp);
614 static void rcu_sysidle_report_gp(struct rcu_state *rsp, int isidle,
615 unsigned long maxj);
616 static void rcu_bind_gp_kthread(void);
617 static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp);
618 static bool rcu_nohz_full_cpu(struct rcu_state *rsp);
619 static void rcu_dynticks_task_enter(void);
620 static void rcu_dynticks_task_exit(void);
621
622 #endif /* #ifndef RCU_TREE_NONCORE */
623
624 #ifdef CONFIG_RCU_TRACE
625 #ifdef CONFIG_RCU_NOCB_CPU
626 /* Sum up queue lengths for tracing. */
rcu_nocb_q_lengths(struct rcu_data * rdp,long * ql,long * qll)627 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
628 {
629 *ql = atomic_long_read(&rdp->nocb_q_count) +
630 rdp->nocb_p_count +
631 atomic_long_read(&rdp->nocb_follower_count) +
632 rdp->nocb_p_count + rdp->nocb_gp_count;
633 *qll = atomic_long_read(&rdp->nocb_q_count_lazy) +
634 rdp->nocb_p_count_lazy +
635 atomic_long_read(&rdp->nocb_follower_count_lazy) +
636 rdp->nocb_p_count_lazy + rdp->nocb_gp_count_lazy;
637 }
638 #else /* #ifdef CONFIG_RCU_NOCB_CPU */
rcu_nocb_q_lengths(struct rcu_data * rdp,long * ql,long * qll)639 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
640 {
641 *ql = 0;
642 *qll = 0;
643 }
644 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
645 #endif /* #ifdef CONFIG_RCU_TRACE */
646