xref: /openbmc/linux/kernel/rcu/tree.h (revision a34a3ed7)
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/rtmutex.h>
28 #include <linux/threads.h>
29 #include <linux/cpumask.h>
30 #include <linux/seqlock.h>
31 #include <linux/swait.h>
32 #include <linux/stop_machine.h>
33 #include <linux/rcu_node_tree.h>
34 
35 #include "rcu_segcblist.h"
36 
37 /*
38  * Dynticks per-CPU state.
39  */
40 struct rcu_dynticks {
41 	long dynticks_nesting;      /* Track process nesting level. */
42 	long dynticks_nmi_nesting;  /* Track irq/NMI nesting level. */
43 	atomic_t dynticks;	    /* Even value for idle, else odd. */
44 	bool rcu_need_heavy_qs;     /* GP old, need heavy quiescent state. */
45 	unsigned long rcu_qs_ctr;   /* Light universal quiescent state ctr. */
46 	bool rcu_urgent_qs;	    /* GP old need light quiescent state. */
47 #ifdef CONFIG_RCU_FAST_NO_HZ
48 	bool all_lazy;		    /* Are all CPU's CBs lazy? */
49 	unsigned long nonlazy_posted;
50 				    /* # times non-lazy CBs posted to CPU. */
51 	unsigned long nonlazy_posted_snap;
52 				    /* idle-period nonlazy_posted snapshot. */
53 	unsigned long last_accelerate;
54 				    /* Last jiffy CBs were accelerated. */
55 	unsigned long last_advance_all;
56 				    /* Last jiffy CBs were all advanced. */
57 	int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
58 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
59 };
60 
61 /* RCU's kthread states for tracing. */
62 #define RCU_KTHREAD_STOPPED  0
63 #define RCU_KTHREAD_RUNNING  1
64 #define RCU_KTHREAD_WAITING  2
65 #define RCU_KTHREAD_OFFCPU   3
66 #define RCU_KTHREAD_YIELDING 4
67 #define RCU_KTHREAD_MAX      4
68 
69 /*
70  * Definition for node within the RCU grace-period-detection hierarchy.
71  */
72 struct rcu_node {
73 	raw_spinlock_t __private lock;	/* Root rcu_node's lock protects */
74 					/*  some rcu_state fields as well as */
75 					/*  following. */
76 	unsigned long gpnum;	/* Current grace period for this node. */
77 				/*  This will either be equal to or one */
78 				/*  behind the root rcu_node's gpnum. */
79 	unsigned long completed; /* Last GP completed for this node. */
80 				/*  This will either be equal to or one */
81 				/*  behind the root rcu_node's gpnum. */
82 	unsigned long qsmask;	/* CPUs or groups that need to switch in */
83 				/*  order for current grace period to proceed.*/
84 				/*  In leaf rcu_node, each bit corresponds to */
85 				/*  an rcu_data structure, otherwise, each */
86 				/*  bit corresponds to a child rcu_node */
87 				/*  structure. */
88 	unsigned long qsmaskinit;
89 				/* Per-GP initial value for qsmask. */
90 				/*  Initialized from ->qsmaskinitnext at the */
91 				/*  beginning of each grace period. */
92 	unsigned long qsmaskinitnext;
93 				/* Online CPUs for next grace period. */
94 	unsigned long expmask;	/* CPUs or groups that need to check in */
95 				/*  to allow the current expedited GP */
96 				/*  to complete. */
97 	unsigned long expmaskinit;
98 				/* Per-GP initial values for expmask. */
99 				/*  Initialized from ->expmaskinitnext at the */
100 				/*  beginning of each expedited GP. */
101 	unsigned long expmaskinitnext;
102 				/* Online CPUs for next expedited GP. */
103 				/*  Any CPU that has ever been online will */
104 				/*  have its bit set. */
105 	unsigned long ffmask;	/* Fully functional CPUs. */
106 	unsigned long grpmask;	/* Mask to apply to parent qsmask. */
107 				/*  Only one bit will be set in this mask. */
108 	int	grplo;		/* lowest-numbered CPU or group here. */
109 	int	grphi;		/* highest-numbered CPU or group here. */
110 	u8	grpnum;		/* CPU/group number for next level up. */
111 	u8	level;		/* root is at level 0. */
112 	bool	wait_blkd_tasks;/* Necessary to wait for blocked tasks to */
113 				/*  exit RCU read-side critical sections */
114 				/*  before propagating offline up the */
115 				/*  rcu_node tree? */
116 	struct rcu_node *parent;
117 	struct list_head blkd_tasks;
118 				/* Tasks blocked in RCU read-side critical */
119 				/*  section.  Tasks are placed at the head */
120 				/*  of this list and age towards the tail. */
121 	struct list_head *gp_tasks;
122 				/* Pointer to the first task blocking the */
123 				/*  current grace period, or NULL if there */
124 				/*  is no such task. */
125 	struct list_head *exp_tasks;
126 				/* Pointer to the first task blocking the */
127 				/*  current expedited grace period, or NULL */
128 				/*  if there is no such task.  If there */
129 				/*  is no current expedited grace period, */
130 				/*  then there can cannot be any such task. */
131 	struct list_head *boost_tasks;
132 				/* Pointer to first task that needs to be */
133 				/*  priority boosted, or NULL if no priority */
134 				/*  boosting is needed for this rcu_node */
135 				/*  structure.  If there are no tasks */
136 				/*  queued on this rcu_node structure that */
137 				/*  are blocking the current grace period, */
138 				/*  there can be no such task. */
139 	struct rt_mutex boost_mtx;
140 				/* Used only for the priority-boosting */
141 				/*  side effect, not as a lock. */
142 	unsigned long boost_time;
143 				/* When to start boosting (jiffies). */
144 	struct task_struct *boost_kthread_task;
145 				/* kthread that takes care of priority */
146 				/*  boosting for this rcu_node structure. */
147 	unsigned int boost_kthread_status;
148 				/* State of boost_kthread_task for tracing. */
149 	unsigned long n_tasks_boosted;
150 				/* Total number of tasks boosted. */
151 	unsigned long n_exp_boosts;
152 				/* Number of tasks boosted for expedited GP. */
153 	unsigned long n_normal_boosts;
154 				/* Number of tasks boosted for normal GP. */
155 #ifdef CONFIG_RCU_NOCB_CPU
156 	struct swait_queue_head nocb_gp_wq[2];
157 				/* Place for rcu_nocb_kthread() to wait GP. */
158 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
159 	int need_future_gp[2];
160 				/* Counts of upcoming no-CB GP requests. */
161 	raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;
162 
163 	spinlock_t exp_lock ____cacheline_internodealigned_in_smp;
164 	unsigned long exp_seq_rq;
165 	wait_queue_head_t exp_wq[4];
166 } ____cacheline_internodealigned_in_smp;
167 
168 /*
169  * Bitmasks in an rcu_node cover the interval [grplo, grphi] of CPU IDs, and
170  * are indexed relative to this interval rather than the global CPU ID space.
171  * This generates the bit for a CPU in node-local masks.
172  */
173 #define leaf_node_cpu_bit(rnp, cpu) (1UL << ((cpu) - (rnp)->grplo))
174 
175 /*
176  * Union to allow "aggregate OR" operation on the need for a quiescent
177  * state by the normal and expedited grace periods.
178  */
179 union rcu_noqs {
180 	struct {
181 		u8 norm;
182 		u8 exp;
183 	} b; /* Bits. */
184 	u16 s; /* Set of bits, aggregate OR here. */
185 };
186 
187 /* Index values for nxttail array in struct rcu_data. */
188 #define RCU_DONE_TAIL		0	/* Also RCU_WAIT head. */
189 #define RCU_WAIT_TAIL		1	/* Also RCU_NEXT_READY head. */
190 #define RCU_NEXT_READY_TAIL	2	/* Also RCU_NEXT head. */
191 #define RCU_NEXT_TAIL		3
192 #define RCU_NEXT_SIZE		4
193 
194 /* Per-CPU data for read-copy update. */
195 struct rcu_data {
196 	/* 1) quiescent-state and grace-period handling : */
197 	unsigned long	completed;	/* Track rsp->completed gp number */
198 					/*  in order to detect GP end. */
199 	unsigned long	gpnum;		/* Highest gp number that this CPU */
200 					/*  is aware of having started. */
201 	unsigned long	rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */
202 					/*  for rcu_all_qs() invocations. */
203 	union rcu_noqs	cpu_no_qs;	/* No QSes yet for this CPU. */
204 	bool		core_needs_qs;	/* Core waits for quiesc state. */
205 	bool		beenonline;	/* CPU online at least once. */
206 	bool		gpwrap;		/* Possible gpnum/completed wrap. */
207 	struct rcu_node *mynode;	/* This CPU's leaf of hierarchy */
208 	unsigned long grpmask;		/* Mask to apply to leaf qsmask. */
209 	unsigned long	ticks_this_gp;	/* The number of scheduling-clock */
210 					/*  ticks this CPU has handled */
211 					/*  during and after the last grace */
212 					/* period it is aware of. */
213 
214 	/* 2) batch handling */
215 	struct rcu_segcblist cblist;	/* Segmented callback list, with */
216 					/* different callbacks waiting for */
217 					/* different grace periods. */
218 	long		qlen_last_fqs_check;
219 					/* qlen at last check for QS forcing */
220 	unsigned long	n_cbs_invoked;	/* count of RCU cbs invoked. */
221 	unsigned long	n_nocbs_invoked; /* count of no-CBs RCU cbs invoked. */
222 	unsigned long	n_force_qs_snap;
223 					/* did other CPU force QS recently? */
224 	long		blimit;		/* Upper limit on a processed batch */
225 
226 	/* 3) dynticks interface. */
227 	struct rcu_dynticks *dynticks;	/* Shared per-CPU dynticks state. */
228 	int dynticks_snap;		/* Per-GP tracking for dynticks. */
229 
230 	/* 4) reasons this CPU needed to be kicked by force_quiescent_state */
231 	unsigned long dynticks_fqs;	/* Kicked due to dynticks idle. */
232 	unsigned long offline_fqs;	/* Kicked due to being offline. */
233 	unsigned long cond_resched_completed;
234 					/* Grace period that needs help */
235 					/*  from cond_resched(). */
236 
237 	/* 5) __rcu_pending() statistics. */
238 	unsigned long n_rcu_pending;	/* rcu_pending() calls since boot. */
239 	unsigned long n_rp_core_needs_qs;
240 	unsigned long n_rp_report_qs;
241 	unsigned long n_rp_cb_ready;
242 	unsigned long n_rp_cpu_needs_gp;
243 	unsigned long n_rp_gp_completed;
244 	unsigned long n_rp_gp_started;
245 	unsigned long n_rp_nocb_defer_wakeup;
246 	unsigned long n_rp_need_nothing;
247 
248 	/* 6) _rcu_barrier(), OOM callbacks, and expediting. */
249 	struct rcu_head barrier_head;
250 #ifdef CONFIG_RCU_FAST_NO_HZ
251 	struct rcu_head oom_head;
252 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
253 	atomic_long_t exp_workdone0;	/* # done by workqueue. */
254 	atomic_long_t exp_workdone1;	/* # done by others #1. */
255 	atomic_long_t exp_workdone2;	/* # done by others #2. */
256 	atomic_long_t exp_workdone3;	/* # done by others #3. */
257 	int exp_dynticks_snap;		/* Double-check need for IPI. */
258 
259 	/* 7) Callback offloading. */
260 #ifdef CONFIG_RCU_NOCB_CPU
261 	struct rcu_head *nocb_head;	/* CBs waiting for kthread. */
262 	struct rcu_head **nocb_tail;
263 	atomic_long_t nocb_q_count;	/* # CBs waiting for nocb */
264 	atomic_long_t nocb_q_count_lazy; /*  invocation (all stages). */
265 	struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */
266 	struct rcu_head **nocb_follower_tail;
267 	struct swait_queue_head nocb_wq; /* For nocb kthreads to sleep on. */
268 	struct task_struct *nocb_kthread;
269 	raw_spinlock_t nocb_lock;	/* Guard following pair of fields. */
270 	int nocb_defer_wakeup;		/* Defer wakeup of nocb_kthread. */
271 	struct timer_list nocb_timer;	/* Enforce finite deferral. */
272 
273 	/* The following fields are used by the leader, hence own cacheline. */
274 	struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp;
275 					/* CBs waiting for GP. */
276 	struct rcu_head **nocb_gp_tail;
277 	bool nocb_leader_sleep;		/* Is the nocb leader thread asleep? */
278 	struct rcu_data *nocb_next_follower;
279 					/* Next follower in wakeup chain. */
280 
281 	/* The following fields are used by the follower, hence new cachline. */
282 	struct rcu_data *nocb_leader ____cacheline_internodealigned_in_smp;
283 					/* Leader CPU takes GP-end wakeups. */
284 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
285 
286 	/* 8) RCU CPU stall data. */
287 	unsigned int softirq_snap;	/* Snapshot of softirq activity. */
288 	/* ->rcu_iw* fields protected by leaf rcu_node ->lock. */
289 	struct irq_work rcu_iw;		/* Check for non-irq activity. */
290 	bool rcu_iw_pending;		/* Is ->rcu_iw pending? */
291 	unsigned long rcu_iw_gpnum;	/* ->gpnum associated with ->rcu_iw. */
292 
293 	int cpu;
294 	struct rcu_state *rsp;
295 };
296 
297 /* Values for nocb_defer_wakeup field in struct rcu_data. */
298 #define RCU_NOCB_WAKE_NOT	0
299 #define RCU_NOCB_WAKE		1
300 #define RCU_NOCB_WAKE_FORCE	2
301 
302 #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500))
303 					/* For jiffies_till_first_fqs and */
304 					/*  and jiffies_till_next_fqs. */
305 
306 #define RCU_JIFFIES_FQS_DIV	256	/* Very large systems need more */
307 					/*  delay between bouts of */
308 					/*  quiescent-state forcing. */
309 
310 #define RCU_STALL_RAT_DELAY	2	/* Allow other CPUs time to take */
311 					/*  at least one scheduling clock */
312 					/*  irq before ratting on them. */
313 
314 #define rcu_wait(cond)							\
315 do {									\
316 	for (;;) {							\
317 		set_current_state(TASK_INTERRUPTIBLE);			\
318 		if (cond)						\
319 			break;						\
320 		schedule();						\
321 	}								\
322 	__set_current_state(TASK_RUNNING);				\
323 } while (0)
324 
325 /*
326  * RCU global state, including node hierarchy.  This hierarchy is
327  * represented in "heap" form in a dense array.  The root (first level)
328  * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
329  * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
330  * and the third level in ->node[m+1] and following (->node[m+1] referenced
331  * by ->level[2]).  The number of levels is determined by the number of
332  * CPUs and by CONFIG_RCU_FANOUT.  Small systems will have a "hierarchy"
333  * consisting of a single rcu_node.
334  */
335 struct rcu_state {
336 	struct rcu_node node[NUM_RCU_NODES];	/* Hierarchy. */
337 	struct rcu_node *level[RCU_NUM_LVLS + 1];
338 						/* Hierarchy levels (+1 to */
339 						/*  shut bogus gcc warning) */
340 	struct rcu_data __percpu *rda;		/* pointer of percu rcu_data. */
341 	call_rcu_func_t call;			/* call_rcu() flavor. */
342 	int ncpus;				/* # CPUs seen so far. */
343 
344 	/* The following fields are guarded by the root rcu_node's lock. */
345 
346 	u8	boost ____cacheline_internodealigned_in_smp;
347 						/* Subject to priority boost. */
348 	unsigned long gpnum;			/* Current gp number. */
349 	unsigned long completed;		/* # of last completed gp. */
350 	struct task_struct *gp_kthread;		/* Task for grace periods. */
351 	struct swait_queue_head gp_wq;		/* Where GP task waits. */
352 	short gp_flags;				/* Commands for GP task. */
353 	short gp_state;				/* GP kthread sleep state. */
354 
355 	/* End of fields guarded by root rcu_node's lock. */
356 
357 	struct mutex barrier_mutex;		/* Guards barrier fields. */
358 	atomic_t barrier_cpu_count;		/* # CPUs waiting on. */
359 	struct completion barrier_completion;	/* Wake at barrier end. */
360 	unsigned long barrier_sequence;		/* ++ at start and end of */
361 						/*  _rcu_barrier(). */
362 	/* End of fields guarded by barrier_mutex. */
363 
364 	struct mutex exp_mutex;			/* Serialize expedited GP. */
365 	struct mutex exp_wake_mutex;		/* Serialize wakeup. */
366 	unsigned long expedited_sequence;	/* Take a ticket. */
367 	atomic_t expedited_need_qs;		/* # CPUs left to check in. */
368 	struct swait_queue_head expedited_wq;	/* Wait for check-ins. */
369 	int ncpus_snap;				/* # CPUs seen last time. */
370 
371 	unsigned long jiffies_force_qs;		/* Time at which to invoke */
372 						/*  force_quiescent_state(). */
373 	unsigned long jiffies_kick_kthreads;	/* Time at which to kick */
374 						/*  kthreads, if configured. */
375 	unsigned long n_force_qs;		/* Number of calls to */
376 						/*  force_quiescent_state(). */
377 	unsigned long n_force_qs_lh;		/* ~Number of calls leaving */
378 						/*  due to lock unavailable. */
379 	unsigned long n_force_qs_ngp;		/* Number of calls leaving */
380 						/*  due to no GP active. */
381 	unsigned long gp_start;			/* Time at which GP started, */
382 						/*  but in jiffies. */
383 	unsigned long gp_activity;		/* Time of last GP kthread */
384 						/*  activity in jiffies. */
385 	unsigned long jiffies_stall;		/* Time at which to check */
386 						/*  for CPU stalls. */
387 	unsigned long jiffies_resched;		/* Time at which to resched */
388 						/*  a reluctant CPU. */
389 	unsigned long n_force_qs_gpstart;	/* Snapshot of n_force_qs at */
390 						/*  GP start. */
391 	unsigned long gp_max;			/* Maximum GP duration in */
392 						/*  jiffies. */
393 	const char *name;			/* Name of structure. */
394 	char abbr;				/* Abbreviated name. */
395 	struct list_head flavors;		/* List of RCU flavors. */
396 };
397 
398 /* Values for rcu_state structure's gp_flags field. */
399 #define RCU_GP_FLAG_INIT 0x1	/* Need grace-period initialization. */
400 #define RCU_GP_FLAG_FQS  0x2	/* Need grace-period quiescent-state forcing. */
401 
402 /* Values for rcu_state structure's gp_state field. */
403 #define RCU_GP_IDLE	 0	/* Initial state and no GP in progress. */
404 #define RCU_GP_WAIT_GPS  1	/* Wait for grace-period start. */
405 #define RCU_GP_DONE_GPS  2	/* Wait done for grace-period start. */
406 #define RCU_GP_WAIT_FQS  3	/* Wait for force-quiescent-state time. */
407 #define RCU_GP_DOING_FQS 4	/* Wait done for force-quiescent-state time. */
408 #define RCU_GP_CLEANUP   5	/* Grace-period cleanup started. */
409 #define RCU_GP_CLEANED   6	/* Grace-period cleanup complete. */
410 
411 #ifndef RCU_TREE_NONCORE
412 static const char * const gp_state_names[] = {
413 	"RCU_GP_IDLE",
414 	"RCU_GP_WAIT_GPS",
415 	"RCU_GP_DONE_GPS",
416 	"RCU_GP_WAIT_FQS",
417 	"RCU_GP_DOING_FQS",
418 	"RCU_GP_CLEANUP",
419 	"RCU_GP_CLEANED",
420 };
421 #endif /* #ifndef RCU_TREE_NONCORE */
422 
423 extern struct list_head rcu_struct_flavors;
424 
425 /* Sequence through rcu_state structures for each RCU flavor. */
426 #define for_each_rcu_flavor(rsp) \
427 	list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
428 
429 /*
430  * RCU implementation internal declarations:
431  */
432 extern struct rcu_state rcu_sched_state;
433 
434 extern struct rcu_state rcu_bh_state;
435 
436 #ifdef CONFIG_PREEMPT_RCU
437 extern struct rcu_state rcu_preempt_state;
438 #endif /* #ifdef CONFIG_PREEMPT_RCU */
439 
440 int rcu_dynticks_snap(struct rcu_dynticks *rdtp);
441 bool rcu_eqs_special_set(int cpu);
442 
443 #ifdef CONFIG_RCU_BOOST
444 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
445 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
446 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
447 DECLARE_PER_CPU(char, rcu_cpu_has_work);
448 #endif /* #ifdef CONFIG_RCU_BOOST */
449 
450 #ifndef RCU_TREE_NONCORE
451 
452 /* Forward declarations for rcutree_plugin.h */
453 static void rcu_bootup_announce(void);
454 static void rcu_preempt_note_context_switch(bool preempt);
455 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
456 #ifdef CONFIG_HOTPLUG_CPU
457 static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
458 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
459 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
460 static int rcu_print_task_stall(struct rcu_node *rnp);
461 static int rcu_print_task_exp_stall(struct rcu_node *rnp);
462 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
463 static void rcu_preempt_check_callbacks(void);
464 void call_rcu(struct rcu_head *head, rcu_callback_t func);
465 static void __init __rcu_init_preempt(void);
466 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
467 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
468 static void invoke_rcu_callbacks_kthread(void);
469 static bool rcu_is_callbacks_kthread(void);
470 #ifdef CONFIG_RCU_BOOST
471 static void rcu_preempt_do_callbacks(void);
472 static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
473 						 struct rcu_node *rnp);
474 #endif /* #ifdef CONFIG_RCU_BOOST */
475 static void __init rcu_spawn_boost_kthreads(void);
476 static void rcu_prepare_kthreads(int cpu);
477 static void rcu_cleanup_after_idle(void);
478 static void rcu_prepare_for_idle(void);
479 static void rcu_idle_count_callbacks_posted(void);
480 static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
481 static void print_cpu_stall_info_begin(void);
482 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
483 static void print_cpu_stall_info_end(void);
484 static void zero_cpu_stall_ticks(struct rcu_data *rdp);
485 static void increment_cpu_stall_ticks(void);
486 static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu);
487 static void rcu_nocb_gp_set(struct rcu_node *rnp, int nrq);
488 static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp);
489 static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq);
490 static void rcu_init_one_nocb(struct rcu_node *rnp);
491 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
492 			    bool lazy, unsigned long flags);
493 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_data *my_rdp,
494 				      struct rcu_data *rdp,
495 				      unsigned long flags);
496 static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp);
497 static void do_nocb_deferred_wakeup(struct rcu_data *rdp);
498 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
499 static void rcu_spawn_all_nocb_kthreads(int cpu);
500 static void __init rcu_spawn_nocb_kthreads(void);
501 #ifdef CONFIG_RCU_NOCB_CPU
502 static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp);
503 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
504 static void __maybe_unused rcu_kick_nohz_cpu(int cpu);
505 static bool init_nocb_callback_list(struct rcu_data *rdp);
506 static void rcu_bind_gp_kthread(void);
507 static bool rcu_nohz_full_cpu(struct rcu_state *rsp);
508 static void rcu_dynticks_task_enter(void);
509 static void rcu_dynticks_task_exit(void);
510 
511 #ifdef CONFIG_SRCU
512 void srcu_online_cpu(unsigned int cpu);
513 void srcu_offline_cpu(unsigned int cpu);
514 #else /* #ifdef CONFIG_SRCU */
515 void srcu_online_cpu(unsigned int cpu) { }
516 void srcu_offline_cpu(unsigned int cpu) { }
517 #endif /* #else #ifdef CONFIG_SRCU */
518 
519 #endif /* #ifndef RCU_TREE_NONCORE */
520