2 * Read-Copy Update mechanism for mutual exclusion (tree-based version)
3 * Internal non-public definitions.
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.
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.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19 * Copyright IBM Corporation, 2008
21 * Author: Ingo Molnar <mingo@elte.hu>
22 * Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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>
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.
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)
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)
74 # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
75 #endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
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)
80 extern int rcu_num_lvls;
81 extern int rcu_num_nodes;
84 * Dynticks per-CPU state.
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 int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
108 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
111 /* RCU's kthread states for tracing. */
112 #define RCU_KTHREAD_STOPPED 0
113 #define RCU_KTHREAD_RUNNING 1
114 #define RCU_KTHREAD_WAITING 2
115 #define RCU_KTHREAD_OFFCPU 3
116 #define RCU_KTHREAD_YIELDING 4
117 #define RCU_KTHREAD_MAX 4
120 * Definition for node within the RCU grace-period-detection hierarchy.
123 raw_spinlock_t lock; /* Root rcu_node's lock protects some */
124 /* rcu_state fields as well as following. */
125 unsigned long gpnum; /* Current grace period for this node. */
126 /* This will either be equal to or one */
127 /* behind the root rcu_node's gpnum. */
128 unsigned long completed; /* Last GP completed for this node. */
129 /* This will either be equal to or one */
130 /* behind the root rcu_node's gpnum. */
131 unsigned long qsmask; /* CPUs or groups that need to switch in */
132 /* order for current grace period to proceed.*/
133 /* In leaf rcu_node, each bit corresponds to */
134 /* an rcu_data structure, otherwise, each */
135 /* bit corresponds to a child rcu_node */
137 unsigned long expmask; /* Groups that have ->blkd_tasks */
138 /* elements that need to drain to allow the */
139 /* current expedited grace period to */
140 /* complete (only for TREE_PREEMPT_RCU). */
141 unsigned long qsmaskinit;
142 /* Per-GP initial value for qsmask & expmask. */
143 unsigned long grpmask; /* Mask to apply to parent qsmask. */
144 /* Only one bit will be set in this mask. */
145 int grplo; /* lowest-numbered CPU or group here. */
146 int grphi; /* highest-numbered CPU or group here. */
147 u8 grpnum; /* CPU/group number for next level up. */
148 u8 level; /* root is at level 0. */
149 struct rcu_node *parent;
150 struct list_head blkd_tasks;
151 /* Tasks blocked in RCU read-side critical */
152 /* section. Tasks are placed at the head */
153 /* of this list and age towards the tail. */
154 struct list_head *gp_tasks;
155 /* Pointer to the first task blocking the */
156 /* current grace period, or NULL if there */
157 /* is no such task. */
158 struct list_head *exp_tasks;
159 /* Pointer to the first task blocking the */
160 /* current expedited grace period, or NULL */
161 /* if there is no such task. If there */
162 /* is no current expedited grace period, */
163 /* then there can cannot be any such task. */
164 #ifdef CONFIG_RCU_BOOST
165 struct list_head *boost_tasks;
166 /* Pointer to first task that needs to be */
167 /* priority boosted, or NULL if no priority */
168 /* boosting is needed for this rcu_node */
169 /* structure. If there are no tasks */
170 /* queued on this rcu_node structure that */
171 /* are blocking the current grace period, */
172 /* there can be no such task. */
173 unsigned long boost_time;
174 /* When to start boosting (jiffies). */
175 struct task_struct *boost_kthread_task;
176 /* kthread that takes care of priority */
177 /* boosting for this rcu_node structure. */
178 unsigned int boost_kthread_status;
179 /* State of boost_kthread_task for tracing. */
180 unsigned long n_tasks_boosted;
181 /* Total number of tasks boosted. */
182 unsigned long n_exp_boosts;
183 /* Number of tasks boosted for expedited GP. */
184 unsigned long n_normal_boosts;
185 /* Number of tasks boosted for normal GP. */
186 unsigned long n_balk_blkd_tasks;
187 /* Refused to boost: no blocked tasks. */
188 unsigned long n_balk_exp_gp_tasks;
189 /* Refused to boost: nothing blocking GP. */
190 unsigned long n_balk_boost_tasks;
191 /* Refused to boost: already boosting. */
192 unsigned long n_balk_notblocked;
193 /* Refused to boost: RCU RS CS still running. */
194 unsigned long n_balk_notyet;
195 /* Refused to boost: not yet time. */
196 unsigned long n_balk_nos;
197 /* Refused to boost: not sure why, though. */
198 /* This can happen due to race conditions. */
199 #endif /* #ifdef CONFIG_RCU_BOOST */
200 #ifdef CONFIG_RCU_NOCB_CPU
201 wait_queue_head_t nocb_gp_wq[2];
202 /* Place for rcu_nocb_kthread() to wait GP. */
203 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
204 int need_future_gp[2];
205 /* Counts of upcoming no-CB GP requests. */
206 raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;
207 } ____cacheline_internodealigned_in_smp;
210 * Do a full breadth-first scan of the rcu_node structures for the
211 * specified rcu_state structure.
213 #define rcu_for_each_node_breadth_first(rsp, rnp) \
214 for ((rnp) = &(rsp)->node[0]; \
215 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
218 * Do a breadth-first scan of the non-leaf rcu_node structures for the
219 * specified rcu_state structure. Note that if there is a singleton
220 * rcu_node tree with but one rcu_node structure, this loop is a no-op.
222 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
223 for ((rnp) = &(rsp)->node[0]; \
224 (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
227 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state
228 * structure. Note that if there is a singleton rcu_node tree with but
229 * one rcu_node structure, this loop -will- visit the rcu_node structure.
230 * It is still a leaf node, even if it is also the root node.
232 #define rcu_for_each_leaf_node(rsp, rnp) \
233 for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
234 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
236 /* Index values for nxttail array in struct rcu_data. */
237 #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */
238 #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */
239 #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */
240 #define RCU_NEXT_TAIL 3
241 #define RCU_NEXT_SIZE 4
243 /* Per-CPU data for read-copy update. */
245 /* 1) quiescent-state and grace-period handling : */
246 unsigned long completed; /* Track rsp->completed gp number */
247 /* in order to detect GP end. */
248 unsigned long gpnum; /* Highest gp number that this CPU */
249 /* is aware of having started. */
250 bool passed_quiesce; /* User-mode/idle loop etc. */
251 bool qs_pending; /* Core waits for quiesc state. */
252 bool beenonline; /* CPU online at least once. */
253 bool preemptible; /* Preemptible RCU? */
254 struct rcu_node *mynode; /* This CPU's leaf of hierarchy */
255 unsigned long grpmask; /* Mask to apply to leaf qsmask. */
256 #ifdef CONFIG_RCU_CPU_STALL_INFO
257 unsigned long ticks_this_gp; /* The number of scheduling-clock */
258 /* ticks this CPU has handled */
259 /* during and after the last grace */
260 /* period it is aware of. */
261 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */
263 /* 2) batch handling */
265 * If nxtlist is not NULL, it is partitioned as follows.
266 * Any of the partitions might be empty, in which case the
267 * pointer to that partition will be equal to the pointer for
268 * the following partition. When the list is empty, all of
269 * the nxttail elements point to the ->nxtlist pointer itself,
270 * which in that case is NULL.
272 * [nxtlist, *nxttail[RCU_DONE_TAIL]):
273 * Entries that batch # <= ->completed
274 * The grace period for these entries has completed, and
275 * the other grace-period-completed entries may be moved
276 * here temporarily in rcu_process_callbacks().
277 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]):
278 * Entries that batch # <= ->completed - 1: waiting for current GP
279 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]):
280 * Entries known to have arrived before current GP ended
281 * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]):
282 * Entries that might have arrived after current GP ended
283 * Note that the value of *nxttail[RCU_NEXT_TAIL] will
284 * always be NULL, as this is the end of the list.
286 struct rcu_head *nxtlist;
287 struct rcu_head **nxttail[RCU_NEXT_SIZE];
288 unsigned long nxtcompleted[RCU_NEXT_SIZE];
289 /* grace periods for sublists. */
290 long qlen_lazy; /* # of lazy queued callbacks */
291 long qlen; /* # of queued callbacks, incl lazy */
292 long qlen_last_fqs_check;
293 /* qlen at last check for QS forcing */
294 unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */
295 unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */
296 unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */
297 unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */
298 unsigned long n_force_qs_snap;
299 /* did other CPU force QS recently? */
300 long blimit; /* Upper limit on a processed batch */
302 /* 3) dynticks interface. */
303 struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */
304 int dynticks_snap; /* Per-GP tracking for dynticks. */
306 /* 4) reasons this CPU needed to be kicked by force_quiescent_state */
307 unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
308 unsigned long offline_fqs; /* Kicked due to being offline. */
310 /* 5) __rcu_pending() statistics. */
311 unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */
312 unsigned long n_rp_qs_pending;
313 unsigned long n_rp_report_qs;
314 unsigned long n_rp_cb_ready;
315 unsigned long n_rp_cpu_needs_gp;
316 unsigned long n_rp_gp_completed;
317 unsigned long n_rp_gp_started;
318 unsigned long n_rp_need_nothing;
320 /* 6) _rcu_barrier() and OOM callbacks. */
321 struct rcu_head barrier_head;
322 #ifdef CONFIG_RCU_FAST_NO_HZ
323 struct rcu_head oom_head;
324 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
326 /* 7) Callback offloading. */
327 #ifdef CONFIG_RCU_NOCB_CPU
328 struct rcu_head *nocb_head; /* CBs waiting for kthread. */
329 struct rcu_head **nocb_tail;
330 atomic_long_t nocb_q_count; /* # CBs waiting for kthread */
331 atomic_long_t nocb_q_count_lazy; /* (approximate). */
332 int nocb_p_count; /* # CBs being invoked by kthread */
333 int nocb_p_count_lazy; /* (approximate). */
334 wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */
335 struct task_struct *nocb_kthread;
336 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
338 /* 8) RCU CPU stall data. */
339 #ifdef CONFIG_RCU_CPU_STALL_INFO
340 unsigned int softirq_snap; /* Snapshot of softirq activity. */
341 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */
344 struct rcu_state *rsp;
347 /* Values for fqs_state field in struct rcu_state. */
348 #define RCU_GP_IDLE 0 /* No grace period in progress. */
349 #define RCU_GP_INIT 1 /* Grace period being initialized. */
350 #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */
351 #define RCU_FORCE_QS 3 /* Need to force quiescent state. */
352 #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK
354 #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500))
355 /* For jiffies_till_first_fqs and */
356 /* and jiffies_till_next_fqs. */
358 #define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */
359 /* delay between bouts of */
360 /* quiescent-state forcing. */
362 #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */
363 /* at least one scheduling clock */
364 /* irq before ratting on them. */
366 #define rcu_wait(cond) \
369 set_current_state(TASK_INTERRUPTIBLE); \
374 __set_current_state(TASK_RUNNING); \
378 * RCU global state, including node hierarchy. This hierarchy is
379 * represented in "heap" form in a dense array. The root (first level)
380 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
381 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
382 * and the third level in ->node[m+1] and following (->node[m+1] referenced
383 * by ->level[2]). The number of levels is determined by the number of
384 * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy"
385 * consisting of a single rcu_node.
388 struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
389 struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */
390 u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
391 u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
392 struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
393 void (*call)(struct rcu_head *head, /* call_rcu() flavor. */
394 void (*func)(struct rcu_head *head));
396 /* The following fields are guarded by the root rcu_node's lock. */
398 u8 fqs_state ____cacheline_internodealigned_in_smp;
399 /* Force QS state. */
400 u8 boost; /* Subject to priority boost. */
401 unsigned long gpnum; /* Current gp number. */
402 unsigned long completed; /* # of last completed gp. */
403 struct task_struct *gp_kthread; /* Task for grace periods. */
404 wait_queue_head_t gp_wq; /* Where GP task waits. */
405 int gp_flags; /* Commands for GP task. */
407 /* End of fields guarded by root rcu_node's lock. */
409 raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp;
410 /* Protect following fields. */
411 struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */
412 /* need a grace period. */
413 struct rcu_head **orphan_nxttail; /* Tail of above. */
414 struct rcu_head *orphan_donelist; /* Orphaned callbacks that */
415 /* are ready to invoke. */
416 struct rcu_head **orphan_donetail; /* Tail of above. */
417 long qlen_lazy; /* Number of lazy callbacks. */
418 long qlen; /* Total number of callbacks. */
419 /* End of fields guarded by orphan_lock. */
421 struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */
423 struct mutex barrier_mutex; /* Guards barrier fields. */
424 atomic_t barrier_cpu_count; /* # CPUs waiting on. */
425 struct completion barrier_completion; /* Wake at barrier end. */
426 unsigned long n_barrier_done; /* ++ at start and end of */
427 /* _rcu_barrier(). */
428 /* End of fields guarded by barrier_mutex. */
430 atomic_long_t expedited_start; /* Starting ticket. */
431 atomic_long_t expedited_done; /* Done ticket. */
432 atomic_long_t expedited_wrap; /* # near-wrap incidents. */
433 atomic_long_t expedited_tryfail; /* # acquisition failures. */
434 atomic_long_t expedited_workdone1; /* # done by others #1. */
435 atomic_long_t expedited_workdone2; /* # done by others #2. */
436 atomic_long_t expedited_normal; /* # fallbacks to normal. */
437 atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */
438 atomic_long_t expedited_done_tries; /* # tries to update _done. */
439 atomic_long_t expedited_done_lost; /* # times beaten to _done. */
440 atomic_long_t expedited_done_exit; /* # times exited _done loop. */
442 unsigned long jiffies_force_qs; /* Time at which to invoke */
443 /* force_quiescent_state(). */
444 unsigned long n_force_qs; /* Number of calls to */
445 /* force_quiescent_state(). */
446 unsigned long n_force_qs_lh; /* ~Number of calls leaving */
447 /* due to lock unavailable. */
448 unsigned long n_force_qs_ngp; /* Number of calls leaving */
449 /* due to no GP active. */
450 unsigned long gp_start; /* Time at which GP started, */
451 /* but in jiffies. */
452 unsigned long jiffies_stall; /* Time at which to check */
453 /* for CPU stalls. */
454 unsigned long gp_max; /* Maximum GP duration in */
456 const char *name; /* Name of structure. */
457 char abbr; /* Abbreviated name. */
458 struct list_head flavors; /* List of RCU flavors. */
459 struct irq_work wakeup_work; /* Postponed wakeups */
462 /* Values for rcu_state structure's gp_flags field. */
463 #define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */
464 #define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
466 extern struct list_head rcu_struct_flavors;
468 /* Sequence through rcu_state structures for each RCU flavor. */
469 #define for_each_rcu_flavor(rsp) \
470 list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
472 /* Return values for rcu_preempt_offline_tasks(). */
474 #define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */
475 /* GP were moved to root. */
476 #define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */
477 /* GP were moved to root. */
480 * RCU implementation internal declarations:
482 extern struct rcu_state rcu_sched_state;
483 DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
485 extern struct rcu_state rcu_bh_state;
486 DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
488 #ifdef CONFIG_TREE_PREEMPT_RCU
489 extern struct rcu_state rcu_preempt_state;
490 DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
491 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
493 #ifdef CONFIG_RCU_BOOST
494 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
495 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
496 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
497 DECLARE_PER_CPU(char, rcu_cpu_has_work);
498 #endif /* #ifdef CONFIG_RCU_BOOST */
500 #ifndef RCU_TREE_NONCORE
502 /* Forward declarations for rcutree_plugin.h */
503 static void rcu_bootup_announce(void);
504 long rcu_batches_completed(void);
505 static void rcu_preempt_note_context_switch(int cpu);
506 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
507 #ifdef CONFIG_HOTPLUG_CPU
508 static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
509 unsigned long flags);
510 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
511 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
512 static int rcu_print_task_stall(struct rcu_node *rnp);
513 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
514 #ifdef CONFIG_HOTPLUG_CPU
515 static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
516 struct rcu_node *rnp,
517 struct rcu_data *rdp);
518 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
519 static void rcu_preempt_check_callbacks(int cpu);
520 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
521 #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)
522 static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
524 #endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */
525 static void __init __rcu_init_preempt(void);
526 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
527 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
528 static void invoke_rcu_callbacks_kthread(void);
529 static bool rcu_is_callbacks_kthread(void);
530 #ifdef CONFIG_RCU_BOOST
531 static void rcu_preempt_do_callbacks(void);
532 static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
533 struct rcu_node *rnp);
534 #endif /* #ifdef CONFIG_RCU_BOOST */
535 static void rcu_prepare_kthreads(int cpu);
536 static void rcu_cleanup_after_idle(int cpu);
537 static void rcu_prepare_for_idle(int cpu);
538 static void rcu_idle_count_callbacks_posted(void);
539 static void print_cpu_stall_info_begin(void);
540 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
541 static void print_cpu_stall_info_end(void);
542 static void zero_cpu_stall_ticks(struct rcu_data *rdp);
543 static void increment_cpu_stall_ticks(void);
544 static int rcu_nocb_needs_gp(struct rcu_state *rsp);
545 static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq);
546 static void rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp);
547 static void rcu_init_one_nocb(struct rcu_node *rnp);
548 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
550 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
551 struct rcu_data *rdp);
552 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
553 static void rcu_spawn_nocb_kthreads(struct rcu_state *rsp);
554 static void rcu_kick_nohz_cpu(int cpu);
555 static bool init_nocb_callback_list(struct rcu_data *rdp);
556 static void rcu_sysidle_init_percpu_data(struct rcu_dynticks *rdtp);
558 #endif /* #ifndef RCU_TREE_NONCORE */
560 #ifdef CONFIG_RCU_TRACE
561 #ifdef CONFIG_RCU_NOCB_CPU
562 /* Sum up queue lengths for tracing. */
563 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
565 *ql = atomic_long_read(&rdp->nocb_q_count) + rdp->nocb_p_count;
566 *qll = atomic_long_read(&rdp->nocb_q_count_lazy) + rdp->nocb_p_count_lazy;
568 #else /* #ifdef CONFIG_RCU_NOCB_CPU */
569 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
574 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
575 #endif /* #ifdef CONFIG_RCU_TRACE */