summaryrefslogtreecommitdiffstats
path: root/kernel/rcutree.h
blob: a7c945d149cfa8ed3532af3b284ebc9de8906d8c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
/*
 * Read-Copy Update mechanism for mutual exclusion (tree-based version)
 * Internal non-public definitions.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright IBM Corporation, 2008
 *
 * Author: Ingo Molnar <mingo@elte.hu>
 *	   Paul E. McKenney <paulmck@linux.vnet.ibm.com>
 */

#include <linux/cache.h>
#include <linux/spinlock.h>
#include <linux/threads.h>
#include <linux/cpumask.h>
#include <linux/seqlock.h>

/*
 * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
 * CONFIG_RCU_FANOUT_LEAF.
 * In theory, it should be possible to add more levels straightforwardly.
 * In practice, this did work well going from three levels to four.
 * Of course, your mileage may vary.
 */
#define MAX_RCU_LVLS 4
#define RCU_FANOUT_1	      (CONFIG_RCU_FANOUT_LEAF)
#define RCU_FANOUT_2	      (RCU_FANOUT_1 * CONFIG_RCU_FANOUT)
#define RCU_FANOUT_3	      (RCU_FANOUT_2 * CONFIG_RCU_FANOUT)
#define RCU_FANOUT_4	      (RCU_FANOUT_3 * CONFIG_RCU_FANOUT)

#if NR_CPUS <= RCU_FANOUT_1
#  define RCU_NUM_LVLS	      1
#  define NUM_RCU_LVL_0	      1
#  define NUM_RCU_LVL_1	      (NR_CPUS)
#  define NUM_RCU_LVL_2	      0
#  define NUM_RCU_LVL_3	      0
#  define NUM_RCU_LVL_4	      0
#elif NR_CPUS <= RCU_FANOUT_2
#  define RCU_NUM_LVLS	      2
#  define NUM_RCU_LVL_0	      1
#  define NUM_RCU_LVL_1	      DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
#  define NUM_RCU_LVL_2	      (NR_CPUS)
#  define NUM_RCU_LVL_3	      0
#  define NUM_RCU_LVL_4	      0
#elif NR_CPUS <= RCU_FANOUT_3
#  define RCU_NUM_LVLS	      3
#  define NUM_RCU_LVL_0	      1
#  define NUM_RCU_LVL_1	      DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
#  define NUM_RCU_LVL_2	      DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
#  define NUM_RCU_LVL_3	      (NR_CPUS)
#  define NUM_RCU_LVL_4	      0
#elif NR_CPUS <= RCU_FANOUT_4
#  define RCU_NUM_LVLS	      4
#  define NUM_RCU_LVL_0	      1
#  define NUM_RCU_LVL_1	      DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
#  define NUM_RCU_LVL_2	      DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
#  define NUM_RCU_LVL_3	      DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
#  define NUM_RCU_LVL_4	      (NR_CPUS)
#else
# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
#endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */

#define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4)
#define NUM_RCU_NODES (RCU_SUM - NR_CPUS)

extern int rcu_num_lvls;
extern int rcu_num_nodes;

/*
 * Dynticks per-CPU state.
 */
struct rcu_dynticks {
	long long dynticks_nesting; /* Track irq/process nesting level. */
				    /* Process level is worth LLONG_MAX/2. */
	int dynticks_nmi_nesting;   /* Track NMI nesting level. */
	atomic_t dynticks;	    /* Even value for idle, else odd. */
#ifdef CONFIG_RCU_FAST_NO_HZ
	int dyntick_drain;	    /* Prepare-for-idle state variable. */
	unsigned long dyntick_holdoff;
				    /* No retries for the jiffy of failure. */
	struct timer_list idle_gp_timer;
				    /* Wake up CPU sleeping with callbacks. */
	unsigned long idle_gp_timer_expires;
				    /* When to wake up CPU (for repost). */
	bool idle_first_pass;	    /* First pass of attempt to go idle? */
	unsigned long nonlazy_posted;
				    /* # times non-lazy CBs posted to CPU. */
	unsigned long nonlazy_posted_snap;
				    /* idle-period nonlazy_posted snapshot. */
	int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
#ifdef CONFIG_RCU_USER_QS
	bool ignore_user_qs;	    /* Treat userspace as extended QS or not */
	bool in_user;		    /* Is the CPU in userland from RCU POV? */
#endif
};

/* RCU's kthread states for tracing. */
#define RCU_KTHREAD_STOPPED  0
#define RCU_KTHREAD_RUNNING  1
#define RCU_KTHREAD_WAITING  2
#define RCU_KTHREAD_OFFCPU   3
#define RCU_KTHREAD_YIELDING 4
#define RCU_KTHREAD_MAX      4

/*
 * Definition for node within the RCU grace-period-detection hierarchy.
 */
struct rcu_node {
	raw_spinlock_t lock;	/* Root rcu_node's lock protects some */
				/*  rcu_state fields as well as following. */
	unsigned long gpnum;	/* Current grace period for this node. */
				/*  This will either be equal to or one */
				/*  behind the root rcu_node's gpnum. */
	unsigned long completed; /* Last GP completed for this node. */
				/*  This will either be equal to or one */
				/*  behind the root rcu_node's gpnum. */
	unsigned long qsmask;	/* CPUs or groups that need to switch in */
				/*  order for current grace period to proceed.*/
				/*  In leaf rcu_node, each bit corresponds to */
				/*  an rcu_data structure, otherwise, each */
				/*  bit corresponds to a child rcu_node */
				/*  structure. */
	unsigned long expmask;	/* Groups that have ->blkd_tasks */
				/*  elements that need to drain to allow the */
				/*  current expedited grace period to */
				/*  complete (only for TREE_PREEMPT_RCU). */
	atomic_t wakemask;	/* CPUs whose kthread needs to be awakened. */
				/*  Since this has meaning only for leaf */
				/*  rcu_node structures, 32 bits suffices. */
	unsigned long qsmaskinit;
				/* Per-GP initial value for qsmask & expmask. */
	unsigned long grpmask;	/* Mask to apply to parent qsmask. */
				/*  Only one bit will be set in this mask. */
	int	grplo;		/* lowest-numbered CPU or group here. */
	int	grphi;		/* highest-numbered CPU or group here. */
	u8	grpnum;		/* CPU/group number for next level up. */
	u8	level;		/* root is at level 0. */
	struct rcu_node *parent;
	struct list_head blkd_tasks;
				/* Tasks blocked in RCU read-side critical */
				/*  section.  Tasks are placed at the head */
				/*  of this list and age towards the tail. */
	struct list_head *gp_tasks;
				/* Pointer to the first task blocking the */
				/*  current grace period, or NULL if there */
				/*  is no such task. */
	struct list_head *exp_tasks;
				/* Pointer to the first task blocking the */
				/*  current expedited grace period, or NULL */
				/*  if there is no such task.  If there */
				/*  is no current expedited grace period, */
				/*  then there can cannot be any such task. */
#ifdef CONFIG_RCU_BOOST
	struct list_head *boost_tasks;
				/* Pointer to first task that needs to be */
				/*  priority boosted, or NULL if no priority */
				/*  boosting is needed for this rcu_node */
				/*  structure.  If there are no tasks */
				/*  queued on this rcu_node structure that */
				/*  are blocking the current grace period, */
				/*  there can be no such task. */
	unsigned long boost_time;
				/* When to start boosting (jiffies). */
	struct task_struct *boost_kthread_task;
				/* kthread that takes care of priority */
				/*  boosting for this rcu_node structure. */
	unsigned int boost_kthread_status;
				/* State of boost_kthread_task for tracing. */
	unsigned long n_tasks_boosted;
				/* Total number of tasks boosted. */
	unsigned long n_exp_boosts;
				/* Number of tasks boosted for expedited GP. */
	unsigned long n_normal_boosts;
				/* Number of tasks boosted for normal GP. */
	unsigned long n_balk_blkd_tasks;
				/* Refused to boost: no blocked tasks. */
	unsigned long n_balk_exp_gp_tasks;
				/* Refused to boost: nothing blocking GP. */
	unsigned long n_balk_boost_tasks;
				/* Refused to boost: already boosting. */
	unsigned long n_balk_notblocked;
				/* Refused to boost: RCU RS CS still running. */
	unsigned long n_balk_notyet;
				/* Refused to boost: not yet time. */
	unsigned long n_balk_nos;
				/* Refused to boost: not sure why, though. */
				/*  This can happen due to race conditions. */
#endif /* #ifdef CONFIG_RCU_BOOST */
	raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;
} ____cacheline_internodealigned_in_smp;

/*
 * Do a full breadth-first scan of the rcu_node structures for the
 * specified rcu_state structure.
 */
#define rcu_for_each_node_breadth_first(rsp, rnp) \
	for ((rnp) = &(rsp)->node[0]; \
	     (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)

/*
 * Do a breadth-first scan of the non-leaf rcu_node structures for the
 * specified rcu_state structure.  Note that if there is a singleton
 * rcu_node tree with but one rcu_node structure, this loop is a no-op.
 */
#define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
	for ((rnp) = &(rsp)->node[0]; \
	     (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)

/*
 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state
 * structure.  Note that if there is a singleton rcu_node tree with but
 * one rcu_node structure, this loop -will- visit the rcu_node structure.
 * It is still a leaf node, even if it is also the root node.
 */
#define rcu_for_each_leaf_node(rsp, rnp) \
	for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
	     (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)

/* Index values for nxttail array in struct rcu_data. */
#define RCU_DONE_TAIL		0	/* Also RCU_WAIT head. */
#define RCU_WAIT_TAIL		1	/* Also RCU_NEXT_READY head. */
#define RCU_NEXT_READY_TAIL	2	/* Also RCU_NEXT head. */
#define RCU_NEXT_TAIL		3
#define RCU_NEXT_SIZE		4

/* Per-CPU data for read-copy update. */
struct rcu_data {
	/* 1) quiescent-state and grace-period handling : */
	unsigned long	completed;	/* Track rsp->completed gp number */
					/*  in order to detect GP end. */
	unsigned long	gpnum;		/* Highest gp number that this CPU */
					/*  is aware of having started. */
	bool		passed_quiesce;	/* User-mode/idle loop etc. */
	bool		qs_pending;	/* Core waits for quiesc state. */
	bool		beenonline;	/* CPU online at least once. */
	bool		preemptible;	/* Preemptible RCU? */
	struct rcu_node *mynode;	/* This CPU's leaf of hierarchy */
	unsigned long grpmask;		/* Mask to apply to leaf qsmask. */
#ifdef CONFIG_RCU_CPU_STALL_INFO
	unsigned long	ticks_this_gp;	/* The number of scheduling-clock */
					/*  ticks this CPU has handled */
					/*  during and after the last grace */
					/* period it is aware of. */
#endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */

	/* 2) batch handling */
	/*
	 * If nxtlist is not NULL, it is partitioned as follows.
	 * Any of the partitions might be empty, in which case the
	 * pointer to that partition will be equal to the pointer for
	 * the following partition.  When the list is empty, all of
	 * the nxttail elements point to the ->nxtlist pointer itself,
	 * which in that case is NULL.
	 *
	 * [nxtlist, *nxttail[RCU_DONE_TAIL]):
	 *	Entries that batch # <= ->completed
	 *	The grace period for these entries has completed, and
	 *	the other grace-period-completed entries may be moved
	 *	here temporarily in rcu_process_callbacks().
	 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]):
	 *	Entries that batch # <= ->completed - 1: waiting for current GP
	 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]):
	 *	Entries known to have arrived before current GP ended
	 * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]):
	 *	Entries that might have arrived after current GP ended
	 *	Note that the value of *nxttail[RCU_NEXT_TAIL] will
	 *	always be NULL, as this is the end of the list.
	 */
	struct rcu_head *nxtlist;
	struct rcu_head **nxttail[RCU_NEXT_SIZE];
	long		qlen_lazy;	/* # of lazy queued callbacks */
	long		qlen;		/* # of queued callbacks, incl lazy */
	long		qlen_last_fqs_check;
					/* qlen at last check for QS forcing */
	unsigned long	n_cbs_invoked;	/* count of RCU cbs invoked. */
	unsigned long   n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */
	unsigned long   n_cbs_adopted;  /* RCU cbs adopted from dying CPU */
	unsigned long	n_force_qs_snap;
					/* did other CPU force QS recently? */
	long		blimit;		/* Upper limit on a processed batch */

	/* 3) dynticks interface. */
	struct rcu_dynticks *dynticks;	/* Shared per-CPU dynticks state. */
	int dynticks_snap;		/* Per-GP tracking for dynticks. */

	/* 4) reasons this CPU needed to be kicked by force_quiescent_state */
	unsigned long dynticks_fqs;	/* Kicked due to dynticks idle. */
	unsigned long offline_fqs;	/* Kicked due to being offline. */

	/* 5) __rcu_pending() statistics. */
	unsigned long n_rcu_pending;	/* rcu_pending() calls since boot. */
	unsigned long n_rp_qs_pending;
	unsigned long n_rp_report_qs;
	unsigned long n_rp_cb_ready;
	unsigned long n_rp_cpu_needs_gp;
	unsigned long n_rp_gp_completed;
	unsigned long n_rp_gp_started;
	unsigned long n_rp_need_nothing;

	/* 6) _rcu_barrier() and OOM callbacks. */
	struct rcu_head barrier_head;
#ifdef CONFIG_RCU_FAST_NO_HZ
	struct rcu_head oom_head;
#endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */

	int cpu;
	struct rcu_state *rsp;
};

/* Values for fqs_state field in struct rcu_state. */
#define RCU_GP_IDLE		0	/* No grace period in progress. */
#define RCU_GP_INIT		1	/* Grace period being initialized. */
#define RCU_SAVE_DYNTICK	2	/* Need to scan dyntick state. */
#define RCU_FORCE_QS		3	/* Need to force quiescent state. */
#define RCU_SIGNAL_INIT		RCU_SAVE_DYNTICK

#define RCU_JIFFIES_TILL_FORCE_QS	 3	/* for rsp->jiffies_force_qs */

#ifdef CONFIG_PROVE_RCU
#define RCU_STALL_DELAY_DELTA	       (5 * HZ)
#else
#define RCU_STALL_DELAY_DELTA	       0
#endif
#define RCU_STALL_RAT_DELAY		2	/* Allow other CPUs time */
						/*  to take at least one */
						/*  scheduling clock irq */
						/*  before ratting on them. */

#define rcu_wait(cond)							\
do {									\
	for (;;) {							\
		set_current_state(TASK_INTERRUPTIBLE);			\
		if (cond)						\
			break;						\
		schedule();						\
	}								\
	__set_current_state(TASK_RUNNING);				\
} while (0)

/*
 * RCU global state, including node hierarchy.  This hierarchy is
 * represented in "heap" form in a dense array.  The root (first level)
 * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
 * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
 * and the third level in ->node[m+1] and following (->node[m+1] referenced
 * by ->level[2]).  The number of levels is determined by the number of
 * CPUs and by CONFIG_RCU_FANOUT.  Small systems will have a "hierarchy"
 * consisting of a single rcu_node.
 */
struct rcu_state {
	struct rcu_node node[NUM_RCU_NODES];	/* Hierarchy. */
	struct rcu_node *level[RCU_NUM_LVLS];	/* Hierarchy levels. */
	u32 levelcnt[MAX_RCU_LVLS + 1];		/* # nodes in each level. */
	u8 levelspread[RCU_NUM_LVLS];		/* kids/node in each level. */
	struct rcu_data __percpu *rda;		/* pointer of percu rcu_data. */
	void (*call)(struct rcu_head *head,	/* call_rcu() flavor. */
		     void (*func)(struct rcu_head *head));

	/* The following fields are guarded by the root rcu_node's lock. */

	u8	fqs_state ____cacheline_internodealigned_in_smp;
						/* Force QS state. */
	u8	boost;				/* Subject to priority boost. */
	unsigned long gpnum;			/* Current gp number. */
	unsigned long completed;		/* # of last completed gp. */
	struct task_struct *gp_kthread;		/* Task for grace periods. */
	wait_queue_head_t gp_wq;		/* Where GP task waits. */
	int gp_flags;				/* Commands for GP task. */

	/* End of fields guarded by root rcu_node's lock. */

	raw_spinlock_t orphan_lock ____cacheline_internodealigned_in_smp;
						/* Protect following fields. */
	struct rcu_head *orphan_nxtlist;	/* Orphaned callbacks that */
						/*  need a grace period. */
	struct rcu_head **orphan_nxttail;	/* Tail of above. */
	struct rcu_head *orphan_donelist;	/* Orphaned callbacks that */
						/*  are ready to invoke. */
	struct rcu_head **orphan_donetail;	/* Tail of above. */
	long qlen_lazy;				/* Number of lazy callbacks. */
	long qlen;				/* Total number of callbacks. */
	/* End of fields guarded by orphan_lock. */

	struct mutex onoff_mutex;		/* Coordinate hotplug & GPs. */

	struct mutex barrier_mutex;		/* Guards barrier fields. */
	atomic_t barrier_cpu_count;		/* # CPUs waiting on. */
	struct completion barrier_completion;	/* Wake at barrier end. */
	unsigned long n_barrier_done;		/* ++ at start and end of */
						/*  _rcu_barrier(). */
	/* End of fields guarded by barrier_mutex. */

	unsigned long jiffies_force_qs;		/* Time at which to invoke */
						/*  force_quiescent_state(). */
	unsigned long n_force_qs;		/* Number of calls to */
						/*  force_quiescent_state(). */
	unsigned long n_force_qs_lh;		/* ~Number of calls leaving */
						/*  due to lock unavailable. */
	unsigned long n_force_qs_ngp;		/* Number of calls leaving */
						/*  due to no GP active. */
	unsigned long gp_start;			/* Time at which GP started, */
						/*  but in jiffies. */
	unsigned long jiffies_stall;		/* Time at which to check */
						/*  for CPU stalls. */
	unsigned long gp_max;			/* Maximum GP duration in */
						/*  jiffies. */
	char *name;				/* Name of structure. */
	struct list_head flavors;		/* List of RCU flavors. */
};

/* Values for rcu_state structure's gp_flags field. */
#define RCU_GP_FLAG_INIT 0x1	/* Need grace-period initialization. */
#define RCU_GP_FLAG_FQS  0x2	/* Need grace-period quiescent-state forcing. */

extern struct list_head rcu_struct_flavors;
#define for_each_rcu_flavor(rsp) \
	list_for_each_entry((rsp), &rcu_struct_flavors, flavors)

/* Return values for rcu_preempt_offline_tasks(). */

#define RCU_OFL_TASKS_NORM_GP	0x1		/* Tasks blocking normal */
						/*  GP were moved to root. */
#define RCU_OFL_TASKS_EXP_GP	0x2		/* Tasks blocking expedited */
						/*  GP were moved to root. */

/*
 * RCU implementation internal declarations:
 */
extern struct rcu_state rcu_sched_state;
DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);

extern struct rcu_state rcu_bh_state;
DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);

#ifdef CONFIG_TREE_PREEMPT_RCU
extern struct rcu_state rcu_preempt_state;
DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
#endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */

#ifdef CONFIG_RCU_BOOST
DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
DECLARE_PER_CPU(char, rcu_cpu_has_work);
#endif /* #ifdef CONFIG_RCU_BOOST */

#ifndef RCU_TREE_NONCORE

/* Forward declarations for rcutree_plugin.h */
static void rcu_bootup_announce(void);
long rcu_batches_completed(void);
static void rcu_preempt_note_context_switch(int cpu);
static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
#ifdef CONFIG_HOTPLUG_CPU
static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
				      unsigned long flags);
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
static void rcu_print_detail_task_stall(struct rcu_state *rsp);
static int rcu_print_task_stall(struct rcu_node *rnp);
static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
#ifdef CONFIG_HOTPLUG_CPU
static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
				     struct rcu_node *rnp,
				     struct rcu_data *rdp);
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
static void rcu_preempt_check_callbacks(int cpu);
void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)
static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
			       bool wake);
#endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */
static void __init __rcu_init_preempt(void);
static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
static void invoke_rcu_callbacks_kthread(void);
static bool rcu_is_callbacks_kthread(void);
#ifdef CONFIG_RCU_BOOST
static void rcu_preempt_do_callbacks(void);
static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
						 struct rcu_node *rnp);
#endif /* #ifdef CONFIG_RCU_BOOST */
static void __cpuinit rcu_prepare_kthreads(int cpu);
static void rcu_prepare_for_idle_init(int cpu);
static void rcu_cleanup_after_idle(int cpu);
static void rcu_prepare_for_idle(int cpu);
static void rcu_idle_count_callbacks_posted(void);
static void print_cpu_stall_info_begin(void);
static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
static void print_cpu_stall_info_end(void);
static void zero_cpu_stall_ticks(struct rcu_data *rdp);
static void increment_cpu_stall_ticks(void);

#endif /* #ifndef RCU_TREE_NONCORE */