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rcu: Distinguish "rcuo" kthreads by RCU flavor
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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, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 *
19 * Copyright IBM Corporation, 2008
20 *
21 * Author: Ingo Molnar <mingo@elte.hu>
22 * Paul E. McKenney <paulmck@linux.vnet.ibm.com>
23 */
24
25 #include <linux/cache.h>
26 #include <linux/spinlock.h>
27 #include <linux/threads.h>
28 #include <linux/cpumask.h>
29 #include <linux/seqlock.h>
30
31 /*
32 * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
33 * CONFIG_RCU_FANOUT_LEAF.
34 * In theory, it should be possible to add more levels straightforwardly.
35 * In practice, this did work well going from three levels to four.
36 * Of course, your mileage may vary.
37 */
38 #define MAX_RCU_LVLS 4
39 #define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF)
40 #define RCU_FANOUT_2 (RCU_FANOUT_1 * CONFIG_RCU_FANOUT)
41 #define RCU_FANOUT_3 (RCU_FANOUT_2 * CONFIG_RCU_FANOUT)
42 #define RCU_FANOUT_4 (RCU_FANOUT_3 * CONFIG_RCU_FANOUT)
43
44 #if NR_CPUS <= RCU_FANOUT_1
45 # define RCU_NUM_LVLS 1
46 # define NUM_RCU_LVL_0 1
47 # define NUM_RCU_LVL_1 (NR_CPUS)
48 # define NUM_RCU_LVL_2 0
49 # define NUM_RCU_LVL_3 0
50 # define NUM_RCU_LVL_4 0
51 #elif NR_CPUS <= RCU_FANOUT_2
52 # define RCU_NUM_LVLS 2
53 # define NUM_RCU_LVL_0 1
54 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
55 # define NUM_RCU_LVL_2 (NR_CPUS)
56 # define NUM_RCU_LVL_3 0
57 # define NUM_RCU_LVL_4 0
58 #elif NR_CPUS <= RCU_FANOUT_3
59 # define RCU_NUM_LVLS 3
60 # define NUM_RCU_LVL_0 1
61 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
62 # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
63 # define NUM_RCU_LVL_3 (NR_CPUS)
64 # define NUM_RCU_LVL_4 0
65 #elif NR_CPUS <= RCU_FANOUT_4
66 # define RCU_NUM_LVLS 4
67 # define NUM_RCU_LVL_0 1
68 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
69 # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
70 # define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
71 # define NUM_RCU_LVL_4 (NR_CPUS)
72 #else
73 # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
74 #endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
75
76 #define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4)
77 #define NUM_RCU_NODES (RCU_SUM - NR_CPUS)
78
79 extern int rcu_num_lvls;
80 extern int rcu_num_nodes;
81
82 /*
83 * Dynticks per-CPU state.
84 */
85 struct rcu_dynticks {
86 long long dynticks_nesting; /* Track irq/process nesting level. */
87 /* Process level is worth LLONG_MAX/2. */
88 int dynticks_nmi_nesting; /* Track NMI nesting level. */
89 atomic_t dynticks; /* Even value for idle, else odd. */
90 #ifdef CONFIG_RCU_FAST_NO_HZ
91 int dyntick_drain; /* Prepare-for-idle state variable. */
92 unsigned long dyntick_holdoff;
93 /* No retries for the jiffy of failure. */
94 struct timer_list idle_gp_timer;
95 /* Wake up CPU sleeping with callbacks. */
96 unsigned long idle_gp_timer_expires;
97 /* When to wake up CPU (for repost). */
98 bool idle_first_pass; /* First pass of attempt to go idle? */
99 unsigned long nonlazy_posted;
100 /* # times non-lazy CBs posted to CPU. */
101 unsigned long nonlazy_posted_snap;
102 /* idle-period nonlazy_posted snapshot. */
103 int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
104 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
105 };
106
107 /* RCU's kthread states for tracing. */
108 #define RCU_KTHREAD_STOPPED 0
109 #define RCU_KTHREAD_RUNNING 1
110 #define RCU_KTHREAD_WAITING 2
111 #define RCU_KTHREAD_OFFCPU 3
112 #define RCU_KTHREAD_YIELDING 4
113 #define RCU_KTHREAD_MAX 4
114
115 /*
116 * Definition for node within the RCU grace-period-detection hierarchy.
117 */
118 struct rcu_node {
119 raw_spinlock_t lock; /* Root rcu_node's lock protects some */
120 /* rcu_state fields as well as following. */
121 unsigned long gpnum; /* Current grace period for this node. */
122 /* This will either be equal to or one */
123 /* behind the root rcu_node's gpnum. */
124 unsigned long completed; /* Last GP completed for this node. */
125 /* This will either be equal to or one */
126 /* behind the root rcu_node's gpnum. */
127 unsigned long qsmask; /* CPUs or groups that need to switch in */
128 /* order for current grace period to proceed.*/
129 /* In leaf rcu_node, each bit corresponds to */
130 /* an rcu_data structure, otherwise, each */
131 /* bit corresponds to a child rcu_node */
132 /* structure. */
133 unsigned long expmask; /* Groups that have ->blkd_tasks */
134 /* elements that need to drain to allow the */
135 /* current expedited grace period to */
136 /* complete (only for TREE_PREEMPT_RCU). */
137 atomic_t wakemask; /* CPUs whose kthread needs to be awakened. */
138 /* Since this has meaning only for leaf */
139 /* rcu_node structures, 32 bits suffices. */
140 unsigned long qsmaskinit;
141 /* Per-GP initial value for qsmask & expmask. */
142 unsigned long grpmask; /* Mask to apply to parent qsmask. */
143 /* Only one bit will be set in this mask. */
144 int grplo; /* lowest-numbered CPU or group here. */
145 int grphi; /* highest-numbered CPU or group here. */
146 u8 grpnum; /* CPU/group number for next level up. */
147 u8 level; /* root is at level 0. */
148 struct rcu_node *parent;
149 struct list_head blkd_tasks;
150 /* Tasks blocked in RCU read-side critical */
151 /* section. Tasks are placed at the head */
152 /* of this list and age towards the tail. */
153 struct list_head *gp_tasks;
154 /* Pointer to the first task blocking the */
155 /* current grace period, or NULL if there */
156 /* is no such task. */
157 struct list_head *exp_tasks;
158 /* Pointer to the first task blocking the */
159 /* current expedited grace period, or NULL */
160 /* if there is no such task. If there */
161 /* is no current expedited grace period, */
162 /* then there can cannot be any such task. */
163 #ifdef CONFIG_RCU_BOOST
164 struct list_head *boost_tasks;
165 /* Pointer to first task that needs to be */
166 /* priority boosted, or NULL if no priority */
167 /* boosting is needed for this rcu_node */
168 /* structure. If there are no tasks */
169 /* queued on this rcu_node structure that */
170 /* are blocking the current grace period, */
171 /* there can be no such task. */
172 unsigned long boost_time;
173 /* When to start boosting (jiffies). */
174 struct task_struct *boost_kthread_task;
175 /* kthread that takes care of priority */
176 /* boosting for this rcu_node structure. */
177 unsigned int boost_kthread_status;
178 /* State of boost_kthread_task for tracing. */
179 unsigned long n_tasks_boosted;
180 /* Total number of tasks boosted. */
181 unsigned long n_exp_boosts;
182 /* Number of tasks boosted for expedited GP. */
183 unsigned long n_normal_boosts;
184 /* Number of tasks boosted for normal GP. */
185 unsigned long n_balk_blkd_tasks;
186 /* Refused to boost: no blocked tasks. */
187 unsigned long n_balk_exp_gp_tasks;
188 /* Refused to boost: nothing blocking GP. */
189 unsigned long n_balk_boost_tasks;
190 /* Refused to boost: already boosting. */
191 unsigned long n_balk_notblocked;
192 /* Refused to boost: RCU RS CS still running. */
193 unsigned long n_balk_notyet;
194 /* Refused to boost: not yet time. */
195 unsigned long n_balk_nos;
196 /* Refused to boost: not sure why, though. */
197 /* This can happen due to race conditions. */
198 #endif /* #ifdef CONFIG_RCU_BOOST */
199 #ifdef CONFIG_RCU_NOCB_CPU
200 wait_queue_head_t nocb_gp_wq[2];
201 /* Place for rcu_nocb_kthread() to wait GP. */
202 int n_nocb_gp_requests[2];
203 /* Counts of upcoming no-CB GP requests. */
204 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
205 raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;
206 } ____cacheline_internodealigned_in_smp;
207
208 /*
209 * Do a full breadth-first scan of the rcu_node structures for the
210 * specified rcu_state structure.
211 */
212 #define rcu_for_each_node_breadth_first(rsp, rnp) \
213 for ((rnp) = &(rsp)->node[0]; \
214 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
215
216 /*
217 * Do a breadth-first scan of the non-leaf rcu_node structures for the
218 * specified rcu_state structure. Note that if there is a singleton
219 * rcu_node tree with but one rcu_node structure, this loop is a no-op.
220 */
221 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
222 for ((rnp) = &(rsp)->node[0]; \
223 (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
224
225 /*
226 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state
227 * structure. Note that if there is a singleton rcu_node tree with but
228 * one rcu_node structure, this loop -will- visit the rcu_node structure.
229 * It is still a leaf node, even if it is also the root node.
230 */
231 #define rcu_for_each_leaf_node(rsp, rnp) \
232 for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
233 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
234
235 /* Index values for nxttail array in struct rcu_data. */
236 #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */
237 #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */
238 #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */
239 #define RCU_NEXT_TAIL 3
240 #define RCU_NEXT_SIZE 4
241
242 /* Per-CPU data for read-copy update. */
243 struct rcu_data {
244 /* 1) quiescent-state and grace-period handling : */
245 unsigned long completed; /* Track rsp->completed gp number */
246 /* in order to detect GP end. */
247 unsigned long gpnum; /* Highest gp number that this CPU */
248 /* is aware of having started. */
249 bool passed_quiesce; /* User-mode/idle loop etc. */
250 bool qs_pending; /* Core waits for quiesc state. */
251 bool beenonline; /* CPU online at least once. */
252 bool preemptible; /* Preemptible RCU? */
253 struct rcu_node *mynode; /* This CPU's leaf of hierarchy */
254 unsigned long grpmask; /* Mask to apply to leaf qsmask. */
255 #ifdef CONFIG_RCU_CPU_STALL_INFO
256 unsigned long ticks_this_gp; /* The number of scheduling-clock */
257 /* ticks this CPU has handled */
258 /* during and after the last grace */
259 /* period it is aware of. */
260 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */
261
262 /* 2) batch handling */
263 /*
264 * If nxtlist is not NULL, it is partitioned as follows.
265 * Any of the partitions might be empty, in which case the
266 * pointer to that partition will be equal to the pointer for
267 * the following partition. When the list is empty, all of
268 * the nxttail elements point to the ->nxtlist pointer itself,
269 * which in that case is NULL.
270 *
271 * [nxtlist, *nxttail[RCU_DONE_TAIL]):
272 * Entries that batch # <= ->completed
273 * The grace period for these entries has completed, and
274 * the other grace-period-completed entries may be moved
275 * here temporarily in rcu_process_callbacks().
276 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]):
277 * Entries that batch # <= ->completed - 1: waiting for current GP
278 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]):
279 * Entries known to have arrived before current GP ended
280 * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]):
281 * Entries that might have arrived after current GP ended
282 * Note that the value of *nxttail[RCU_NEXT_TAIL] will
283 * always be NULL, as this is the end of the list.
284 */
285 struct rcu_head *nxtlist;
286 struct rcu_head **nxttail[RCU_NEXT_SIZE];
287 unsigned long nxtcompleted[RCU_NEXT_SIZE];
288 /* grace periods for sublists. */
289 long qlen_lazy; /* # of lazy queued callbacks */
290 long qlen; /* # of queued callbacks, incl lazy */
291 long qlen_last_fqs_check;
292 /* qlen at last check for QS forcing */
293 unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */
294 unsigned long n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */
295 unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */
296 unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */
297 unsigned long n_force_qs_snap;
298 /* did other CPU force QS recently? */
299 long blimit; /* Upper limit on a processed batch */
300
301 /* 3) dynticks interface. */
302 struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */
303 int dynticks_snap; /* Per-GP tracking for dynticks. */
304
305 /* 4) reasons this CPU needed to be kicked by force_quiescent_state */
306 unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
307 unsigned long offline_fqs; /* Kicked due to being offline. */
308
309 /* 5) __rcu_pending() statistics. */
310 unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */
311 unsigned long n_rp_qs_pending;
312 unsigned long n_rp_report_qs;
313 unsigned long n_rp_cb_ready;
314 unsigned long n_rp_cpu_needs_gp;
315 unsigned long n_rp_gp_completed;
316 unsigned long n_rp_gp_started;
317 unsigned long n_rp_need_nothing;
318
319 /* 6) _rcu_barrier() and OOM callbacks. */
320 struct rcu_head barrier_head;
321 #ifdef CONFIG_RCU_FAST_NO_HZ
322 struct rcu_head oom_head;
323 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
324
325 /* 7) Callback offloading. */
326 #ifdef CONFIG_RCU_NOCB_CPU
327 struct rcu_head *nocb_head; /* CBs waiting for kthread. */
328 struct rcu_head **nocb_tail;
329 atomic_long_t nocb_q_count; /* # CBs waiting for kthread */
330 atomic_long_t nocb_q_count_lazy; /* (approximate). */
331 int nocb_p_count; /* # CBs being invoked by kthread */
332 int nocb_p_count_lazy; /* (approximate). */
333 wait_queue_head_t nocb_wq; /* For nocb kthreads to sleep on. */
334 struct task_struct *nocb_kthread;
335 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
336
337 int cpu;
338 struct rcu_state *rsp;
339 };
340
341 /* Values for fqs_state field in struct rcu_state. */
342 #define RCU_GP_IDLE 0 /* No grace period in progress. */
343 #define RCU_GP_INIT 1 /* Grace period being initialized. */
344 #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */
345 #define RCU_FORCE_QS 3 /* Need to force quiescent state. */
346 #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK
347
348 #define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */
349
350 #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time */
351 /* to take at least one */
352 /* scheduling clock irq */
353 /* before ratting on them. */
354
355 #define rcu_wait(cond) \
356 do { \
357 for (;;) { \
358 set_current_state(TASK_INTERRUPTIBLE); \
359 if (cond) \
360 break; \
361 schedule(); \
362 } \
363 __set_current_state(TASK_RUNNING); \
364 } while (0)
365
366 /*
367 * RCU global state, including node hierarchy. This hierarchy is
368 * represented in "heap" form in a dense array. The root (first level)
369 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
370 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
371 * and the third level in ->node[m+1] and following (->node[m+1] referenced
372 * by ->level[2]). The number of levels is determined by the number of
373 * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy"
374 * consisting of a single rcu_node.
375 */
376 struct rcu_state {
377 struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
378 struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */
379 u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
380 u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
381 struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
382 void (*call)(struct rcu_head *head, /* call_rcu() flavor. */
383 void (*func)(struct rcu_head *head));
384
385 /* The following fields are guarded by the root rcu_node's lock. */
386
387 u8 fqs_state ____cacheline_internodealigned_in_smp;
388 /* Force QS state. */
389 u8 boost; /* Subject to priority boost. */
390 unsigned long gpnum; /* Current gp number. */
391 unsigned long completed; /* # of last completed gp. */
392 struct task_struct *gp_kthread; /* Task for grace periods. */
393 wait_queue_head_t gp_wq; /* Where GP task waits. */
394 int gp_flags; /* Commands for GP task. */
395
396 /* End of fields guarded by root rcu_node's lock. */
397
398 raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp;
399 /* Protect following fields. */
400 struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */
401 /* need a grace period. */
402 struct rcu_head **orphan_nxttail; /* Tail of above. */
403 struct rcu_head *orphan_donelist; /* Orphaned callbacks that */
404 /* are ready to invoke. */
405 struct rcu_head **orphan_donetail; /* Tail of above. */
406 long qlen_lazy; /* Number of lazy callbacks. */
407 long qlen; /* Total number of callbacks. */
408 /* End of fields guarded by orphan_lock. */
409
410 struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */
411
412 struct mutex barrier_mutex; /* Guards barrier fields. */
413 atomic_t barrier_cpu_count; /* # CPUs waiting on. */
414 struct completion barrier_completion; /* Wake at barrier end. */
415 unsigned long n_barrier_done; /* ++ at start and end of */
416 /* _rcu_barrier(). */
417 /* End of fields guarded by barrier_mutex. */
418
419 atomic_long_t expedited_start; /* Starting ticket. */
420 atomic_long_t expedited_done; /* Done ticket. */
421 atomic_long_t expedited_wrap; /* # near-wrap incidents. */
422 atomic_long_t expedited_tryfail; /* # acquisition failures. */
423 atomic_long_t expedited_workdone1; /* # done by others #1. */
424 atomic_long_t expedited_workdone2; /* # done by others #2. */
425 atomic_long_t expedited_normal; /* # fallbacks to normal. */
426 atomic_long_t expedited_stoppedcpus; /* # successful stop_cpus. */
427 atomic_long_t expedited_done_tries; /* # tries to update _done. */
428 atomic_long_t expedited_done_lost; /* # times beaten to _done. */
429 atomic_long_t expedited_done_exit; /* # times exited _done loop. */
430
431 unsigned long jiffies_force_qs; /* Time at which to invoke */
432 /* force_quiescent_state(). */
433 unsigned long n_force_qs; /* Number of calls to */
434 /* force_quiescent_state(). */
435 unsigned long n_force_qs_lh; /* ~Number of calls leaving */
436 /* due to lock unavailable. */
437 unsigned long n_force_qs_ngp; /* Number of calls leaving */
438 /* due to no GP active. */
439 unsigned long gp_start; /* Time at which GP started, */
440 /* but in jiffies. */
441 unsigned long jiffies_stall; /* Time at which to check */
442 /* for CPU stalls. */
443 unsigned long gp_max; /* Maximum GP duration in */
444 /* jiffies. */
445 char *name; /* Name of structure. */
446 char abbr; /* Abbreviated name. */
447 struct list_head flavors; /* List of RCU flavors. */
448 };
449
450 /* Values for rcu_state structure's gp_flags field. */
451 #define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */
452 #define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
453
454 extern struct list_head rcu_struct_flavors;
455
456 /* Sequence through rcu_state structures for each RCU flavor. */
457 #define for_each_rcu_flavor(rsp) \
458 list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
459
460 /* Return values for rcu_preempt_offline_tasks(). */
461
462 #define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */
463 /* GP were moved to root. */
464 #define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */
465 /* GP were moved to root. */
466
467 /*
468 * RCU implementation internal declarations:
469 */
470 extern struct rcu_state rcu_sched_state;
471 DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
472
473 extern struct rcu_state rcu_bh_state;
474 DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
475
476 #ifdef CONFIG_TREE_PREEMPT_RCU
477 extern struct rcu_state rcu_preempt_state;
478 DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
479 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
480
481 #ifdef CONFIG_RCU_BOOST
482 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
483 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
484 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
485 DECLARE_PER_CPU(char, rcu_cpu_has_work);
486 #endif /* #ifdef CONFIG_RCU_BOOST */
487
488 #ifndef RCU_TREE_NONCORE
489
490 /* Forward declarations for rcutree_plugin.h */
491 static void rcu_bootup_announce(void);
492 long rcu_batches_completed(void);
493 static void rcu_preempt_note_context_switch(int cpu);
494 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
495 #ifdef CONFIG_HOTPLUG_CPU
496 static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
497 unsigned long flags);
498 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
499 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
500 static int rcu_print_task_stall(struct rcu_node *rnp);
501 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
502 #ifdef CONFIG_HOTPLUG_CPU
503 static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
504 struct rcu_node *rnp,
505 struct rcu_data *rdp);
506 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
507 static void rcu_preempt_check_callbacks(int cpu);
508 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
509 #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)
510 static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
511 bool wake);
512 #endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */
513 static void __init __rcu_init_preempt(void);
514 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
515 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
516 static void invoke_rcu_callbacks_kthread(void);
517 static bool rcu_is_callbacks_kthread(void);
518 #ifdef CONFIG_RCU_BOOST
519 static void rcu_preempt_do_callbacks(void);
520 static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
521 struct rcu_node *rnp);
522 #endif /* #ifdef CONFIG_RCU_BOOST */
523 static void __cpuinit rcu_prepare_kthreads(int cpu);
524 static void rcu_prepare_for_idle_init(int cpu);
525 static void rcu_cleanup_after_idle(int cpu);
526 static void rcu_prepare_for_idle(int cpu);
527 static void rcu_idle_count_callbacks_posted(void);
528 static void print_cpu_stall_info_begin(void);
529 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
530 static void print_cpu_stall_info_end(void);
531 static void zero_cpu_stall_ticks(struct rcu_data *rdp);
532 static void increment_cpu_stall_ticks(void);
533 static int rcu_nocb_needs_gp(struct rcu_state *rsp);
534 static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq);
535 static int rcu_nocb_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp);
536 static void rcu_init_one_nocb(struct rcu_node *rnp);
537 static bool is_nocb_cpu(int cpu);
538 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
539 bool lazy);
540 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
541 struct rcu_data *rdp);
542 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
543 static void rcu_spawn_nocb_kthreads(struct rcu_state *rsp);
544 static bool init_nocb_callback_list(struct rcu_data *rdp);
545
546 #endif /* #ifndef RCU_TREE_NONCORE */
547
548 #ifdef CONFIG_RCU_TRACE
549 #ifdef CONFIG_RCU_NOCB_CPU
550 /* Sum up queue lengths for tracing. */
551 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
552 {
553 *ql = atomic_long_read(&rdp->nocb_q_count) + rdp->nocb_p_count;
554 *qll = atomic_long_read(&rdp->nocb_q_count_lazy) + rdp->nocb_p_count_lazy;
555 }
556 #else /* #ifdef CONFIG_RCU_NOCB_CPU */
557 static inline void rcu_nocb_q_lengths(struct rcu_data *rdp, long *ql, long *qll)
558 {
559 *ql = 0;
560 *qll = 0;
561 }
562 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
563 #endif /* #ifdef CONFIG_RCU_TRACE */