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rcutree.h
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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 <[email protected]>
22  * Paul E. McKenney <[email protected]>
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 #ifdef CONFIG_RCU_USER_QS
106  bool ignore_user_qs; /* Treat userspace as extended QS or not */
107  bool in_user; /* Is the CPU in userland from RCU POV? */
108 #endif
109 };
110 
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
118 
119 /*
120  * Definition for node within the RCU grace-period-detection hierarchy.
121  */
122 struct rcu_node {
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 */
136  /* structure. */
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  atomic_t wakemask; /* CPUs whose kthread needs to be awakened. */
142  /* Since this has meaning only for leaf */
143  /* rcu_node structures, 32 bits suffices. */
144  unsigned long qsmaskinit;
145  /* Per-GP initial value for qsmask & expmask. */
146  unsigned long grpmask; /* Mask to apply to parent qsmask. */
147  /* Only one bit will be set in this mask. */
148  int grplo; /* lowest-numbered CPU or group here. */
149  int grphi; /* highest-numbered CPU or group here. */
150  u8 grpnum; /* CPU/group number for next level up. */
151  u8 level; /* root is at level 0. */
152  struct rcu_node *parent;
153  struct list_head blkd_tasks;
154  /* Tasks blocked in RCU read-side critical */
155  /* section. Tasks are placed at the head */
156  /* of this list and age towards the tail. */
157  struct list_head *gp_tasks;
158  /* Pointer to the first task blocking the */
159  /* current grace period, or NULL if there */
160  /* is no such task. */
161  struct list_head *exp_tasks;
162  /* Pointer to the first task blocking the */
163  /* current expedited grace period, or NULL */
164  /* if there is no such task. If there */
165  /* is no current expedited grace period, */
166  /* then there can cannot be any such task. */
167 #ifdef CONFIG_RCU_BOOST
168  struct list_head *boost_tasks;
169  /* Pointer to first task that needs to be */
170  /* priority boosted, or NULL if no priority */
171  /* boosting is needed for this rcu_node */
172  /* structure. If there are no tasks */
173  /* queued on this rcu_node structure that */
174  /* are blocking the current grace period, */
175  /* there can be no such task. */
176  unsigned long boost_time;
177  /* When to start boosting (jiffies). */
178  struct task_struct *boost_kthread_task;
179  /* kthread that takes care of priority */
180  /* boosting for this rcu_node structure. */
181  unsigned int boost_kthread_status;
182  /* State of boost_kthread_task for tracing. */
183  unsigned long n_tasks_boosted;
184  /* Total number of tasks boosted. */
185  unsigned long n_exp_boosts;
186  /* Number of tasks boosted for expedited GP. */
187  unsigned long n_normal_boosts;
188  /* Number of tasks boosted for normal GP. */
189  unsigned long n_balk_blkd_tasks;
190  /* Refused to boost: no blocked tasks. */
191  unsigned long n_balk_exp_gp_tasks;
192  /* Refused to boost: nothing blocking GP. */
193  unsigned long n_balk_boost_tasks;
194  /* Refused to boost: already boosting. */
195  unsigned long n_balk_notblocked;
196  /* Refused to boost: RCU RS CS still running. */
197  unsigned long n_balk_notyet;
198  /* Refused to boost: not yet time. */
199  unsigned long n_balk_nos;
200  /* Refused to boost: not sure why, though. */
201  /* This can happen due to race conditions. */
202 #endif /* #ifdef CONFIG_RCU_BOOST */
203  raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;
204 } ____cacheline_internodealigned_in_smp;
205 
206 /*
207  * Do a full breadth-first scan of the rcu_node structures for the
208  * specified rcu_state structure.
209  */
210 #define rcu_for_each_node_breadth_first(rsp, rnp) \
211  for ((rnp) = &(rsp)->node[0]; \
212  (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
213 
214 /*
215  * Do a breadth-first scan of the non-leaf rcu_node structures for the
216  * specified rcu_state structure. Note that if there is a singleton
217  * rcu_node tree with but one rcu_node structure, this loop is a no-op.
218  */
219 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
220  for ((rnp) = &(rsp)->node[0]; \
221  (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++)
222 
223 /*
224  * Scan the leaves of the rcu_node hierarchy for the specified rcu_state
225  * structure. Note that if there is a singleton rcu_node tree with but
226  * one rcu_node structure, this loop -will- visit the rcu_node structure.
227  * It is still a leaf node, even if it is also the root node.
228  */
229 #define rcu_for_each_leaf_node(rsp, rnp) \
230  for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \
231  (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++)
232 
233 /* Index values for nxttail array in struct rcu_data. */
234 #define RCU_DONE_TAIL 0 /* Also RCU_WAIT head. */
235 #define RCU_WAIT_TAIL 1 /* Also RCU_NEXT_READY head. */
236 #define RCU_NEXT_READY_TAIL 2 /* Also RCU_NEXT head. */
237 #define RCU_NEXT_TAIL 3
238 #define RCU_NEXT_SIZE 4
239 
240 /* Per-CPU data for read-copy update. */
241 struct rcu_data {
242  /* 1) quiescent-state and grace-period handling : */
243  unsigned long completed; /* Track rsp->completed gp number */
244  /* in order to detect GP end. */
245  unsigned long gpnum; /* Highest gp number that this CPU */
246  /* is aware of having started. */
247  bool passed_quiesce; /* User-mode/idle loop etc. */
248  bool qs_pending; /* Core waits for quiesc state. */
249  bool beenonline; /* CPU online at least once. */
250  bool preemptible; /* Preemptible RCU? */
251  struct rcu_node *mynode; /* This CPU's leaf of hierarchy */
252  unsigned long grpmask; /* Mask to apply to leaf qsmask. */
253 #ifdef CONFIG_RCU_CPU_STALL_INFO
254  unsigned long ticks_this_gp; /* The number of scheduling-clock */
255  /* ticks this CPU has handled */
256  /* during and after the last grace */
257  /* period it is aware of. */
258 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */
259 
260  /* 2) batch handling */
261  /*
262  * If nxtlist is not NULL, it is partitioned as follows.
263  * Any of the partitions might be empty, in which case the
264  * pointer to that partition will be equal to the pointer for
265  * the following partition. When the list is empty, all of
266  * the nxttail elements point to the ->nxtlist pointer itself,
267  * which in that case is NULL.
268  *
269  * [nxtlist, *nxttail[RCU_DONE_TAIL]):
270  * Entries that batch # <= ->completed
271  * The grace period for these entries has completed, and
272  * the other grace-period-completed entries may be moved
273  * here temporarily in rcu_process_callbacks().
274  * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]):
275  * Entries that batch # <= ->completed - 1: waiting for current GP
276  * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]):
277  * Entries known to have arrived before current GP ended
278  * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]):
279  * Entries that might have arrived after current GP ended
280  * Note that the value of *nxttail[RCU_NEXT_TAIL] will
281  * always be NULL, as this is the end of the list.
282  */
283  struct rcu_head *nxtlist;
284  struct rcu_head **nxttail[RCU_NEXT_SIZE];
285  long qlen_lazy; /* # of lazy queued callbacks */
286  long qlen; /* # of queued callbacks, incl lazy */
287  long qlen_last_fqs_check;
288  /* qlen at last check for QS forcing */
289  unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */
290  unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */
291  unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */
292  unsigned long n_force_qs_snap;
293  /* did other CPU force QS recently? */
294  long blimit; /* Upper limit on a processed batch */
295 
296  /* 3) dynticks interface. */
297  struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */
298  int dynticks_snap; /* Per-GP tracking for dynticks. */
299 
300  /* 4) reasons this CPU needed to be kicked by force_quiescent_state */
301  unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
302  unsigned long offline_fqs; /* Kicked due to being offline. */
303 
304  /* 5) __rcu_pending() statistics. */
305  unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */
306  unsigned long n_rp_qs_pending;
307  unsigned long n_rp_report_qs;
308  unsigned long n_rp_cb_ready;
309  unsigned long n_rp_cpu_needs_gp;
310  unsigned long n_rp_gp_completed;
311  unsigned long n_rp_gp_started;
312  unsigned long n_rp_need_nothing;
313 
314  /* 6) _rcu_barrier() and OOM callbacks. */
315  struct rcu_head barrier_head;
316 #ifdef CONFIG_RCU_FAST_NO_HZ
317  struct rcu_head oom_head;
318 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
319 
320  int cpu;
321  struct rcu_state *rsp;
322 };
323 
324 /* Values for fqs_state field in struct rcu_state. */
325 #define RCU_GP_IDLE 0 /* No grace period in progress. */
326 #define RCU_GP_INIT 1 /* Grace period being initialized. */
327 #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */
328 #define RCU_FORCE_QS 3 /* Need to force quiescent state. */
329 #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK
330 
331 #define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */
332 
333 #ifdef CONFIG_PROVE_RCU
334 #define RCU_STALL_DELAY_DELTA (5 * HZ)
335 #else
336 #define RCU_STALL_DELAY_DELTA 0
337 #endif
338 #define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time */
339  /* to take at least one */
340  /* scheduling clock irq */
341  /* before ratting on them. */
342 
343 #define rcu_wait(cond) \
344 do { \
345  for (;;) { \
346  set_current_state(TASK_INTERRUPTIBLE); \
347  if (cond) \
348  break; \
349  schedule(); \
350  } \
351  __set_current_state(TASK_RUNNING); \
352 } while (0)
353 
354 /*
355  * RCU global state, including node hierarchy. This hierarchy is
356  * represented in "heap" form in a dense array. The root (first level)
357  * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
358  * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
359  * and the third level in ->node[m+1] and following (->node[m+1] referenced
360  * by ->level[2]). The number of levels is determined by the number of
361  * CPUs and by CONFIG_RCU_FANOUT. Small systems will have a "hierarchy"
362  * consisting of a single rcu_node.
363  */
364 struct rcu_state {
365  struct rcu_node node[NUM_RCU_NODES]; /* Hierarchy. */
366  struct rcu_node *level[RCU_NUM_LVLS]; /* Hierarchy levels. */
367  u32 levelcnt[MAX_RCU_LVLS + 1]; /* # nodes in each level. */
368  u8 levelspread[RCU_NUM_LVLS]; /* kids/node in each level. */
369  struct rcu_data __percpu *rda; /* pointer of percu rcu_data. */
370  void (*call)(struct rcu_head *head, /* call_rcu() flavor. */
371  void (*func)(struct rcu_head *head));
372 
373  /* The following fields are guarded by the root rcu_node's lock. */
374 
375  u8 fqs_state ____cacheline_internodealigned_in_smp;
376  /* Force QS state. */
377  u8 boost; /* Subject to priority boost. */
378  unsigned long gpnum; /* Current gp number. */
379  unsigned long completed; /* # of last completed gp. */
380  struct task_struct *gp_kthread; /* Task for grace periods. */
381  wait_queue_head_t gp_wq; /* Where GP task waits. */
382  int gp_flags; /* Commands for GP task. */
383 
384  /* End of fields guarded by root rcu_node's lock. */
385 
386  raw_spinlock_t onofflock ____cacheline_internodealigned_in_smp;
387  /* exclude on/offline and */
388  /* starting new GP. */
389  struct rcu_head *orphan_nxtlist; /* Orphaned callbacks that */
390  /* need a grace period. */
391  struct rcu_head **orphan_nxttail; /* Tail of above. */
392  struct rcu_head *orphan_donelist; /* Orphaned callbacks that */
393  /* are ready to invoke. */
394  struct rcu_head **orphan_donetail; /* Tail of above. */
395  long qlen_lazy; /* Number of lazy callbacks. */
396  long qlen; /* Total number of callbacks. */
397  /* End of fields guarded by onofflock. */
398 
399  struct mutex onoff_mutex; /* Coordinate hotplug & GPs. */
400 
401  struct mutex barrier_mutex; /* Guards barrier fields. */
402  atomic_t barrier_cpu_count; /* # CPUs waiting on. */
403  struct completion barrier_completion; /* Wake at barrier end. */
404  unsigned long n_barrier_done; /* ++ at start and end of */
405  /* _rcu_barrier(). */
406  /* End of fields guarded by barrier_mutex. */
407 
408  unsigned long jiffies_force_qs; /* Time at which to invoke */
409  /* force_quiescent_state(). */
410  unsigned long n_force_qs; /* Number of calls to */
411  /* force_quiescent_state(). */
412  unsigned long n_force_qs_lh; /* ~Number of calls leaving */
413  /* due to lock unavailable. */
414  unsigned long n_force_qs_ngp; /* Number of calls leaving */
415  /* due to no GP active. */
416  unsigned long gp_start; /* Time at which GP started, */
417  /* but in jiffies. */
418  unsigned long jiffies_stall; /* Time at which to check */
419  /* for CPU stalls. */
420  unsigned long gp_max; /* Maximum GP duration in */
421  /* jiffies. */
422  char *name; /* Name of structure. */
423  struct list_head flavors; /* List of RCU flavors. */
424 };
425 
426 /* Values for rcu_state structure's gp_flags field. */
427 #define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */
428 #define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
429 
430 extern struct list_head rcu_struct_flavors;
431 #define for_each_rcu_flavor(rsp) \
432  list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
433 
434 /* Return values for rcu_preempt_offline_tasks(). */
435 
436 #define RCU_OFL_TASKS_NORM_GP 0x1 /* Tasks blocking normal */
437  /* GP were moved to root. */
438 #define RCU_OFL_TASKS_EXP_GP 0x2 /* Tasks blocking expedited */
439  /* GP were moved to root. */
440 
441 /*
442  * RCU implementation internal declarations:
443  */
444 extern struct rcu_state rcu_sched_state;
445 DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
446 
447 extern struct rcu_state rcu_bh_state;
448 DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
449 
450 #ifdef CONFIG_TREE_PREEMPT_RCU
451 extern struct rcu_state rcu_preempt_state;
452 DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
453 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
454 
455 #ifdef CONFIG_RCU_BOOST
456 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
457 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
458 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
459 DECLARE_PER_CPU(char, rcu_cpu_has_work);
460 #endif /* #ifdef CONFIG_RCU_BOOST */
461 
462 #ifndef RCU_TREE_NONCORE
463 
464 /* Forward declarations for rcutree_plugin.h */
465 static void rcu_bootup_announce(void);
466 long rcu_batches_completed(void);
467 static void rcu_preempt_note_context_switch(int cpu);
468 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
469 #ifdef CONFIG_HOTPLUG_CPU
470 static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
471  unsigned long flags);
472 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
473 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
474 static int rcu_print_task_stall(struct rcu_node *rnp);
475 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
476 #ifdef CONFIG_HOTPLUG_CPU
477 static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
478  struct rcu_node *rnp,
479  struct rcu_data *rdp);
480 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
481 static void rcu_preempt_check_callbacks(int cpu);
482 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
483 #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)
484 static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
485  bool wake);
486 #endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */
487 static void __init __rcu_init_preempt(void);
488 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
489 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
490 static void invoke_rcu_callbacks_kthread(void);
491 static bool rcu_is_callbacks_kthread(void);
492 #ifdef CONFIG_RCU_BOOST
493 static void rcu_preempt_do_callbacks(void);
494 static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
495  struct rcu_node *rnp);
496 #endif /* #ifdef CONFIG_RCU_BOOST */
497 static void __cpuinit rcu_prepare_kthreads(int cpu);
498 static void rcu_prepare_for_idle_init(int cpu);
499 static void rcu_cleanup_after_idle(int cpu);
500 static void rcu_prepare_for_idle(int cpu);
501 static void rcu_idle_count_callbacks_posted(void);
502 static void print_cpu_stall_info_begin(void);
503 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
504 static void print_cpu_stall_info_end(void);
505 static void zero_cpu_stall_ticks(struct rcu_data *rdp);
506 static void increment_cpu_stall_ticks(void);
507 
508 #endif /* #ifndef RCU_TREE_NONCORE */
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