kernel/rcu/tree.h

   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 /* Communicate arguments to a workqueue handler. */
  62 struct rcu_exp_work {
  63         smp_call_func_t rew_func;
  64         struct rcu_state *rew_rsp;
  65         unsigned long rew_s;
  66         struct work_struct rew_work;
  67 };
  68
  69 /* RCU's kthread states for tracing. */
  70 #define RCU_KTHREAD_STOPPED  0
  71 #define RCU_KTHREAD_RUNNING  1
  72 #define RCU_KTHREAD_WAITING  2
  73 #define RCU_KTHREAD_OFFCPU   3
  74 #define RCU_KTHREAD_YIELDING 4
  75 #define RCU_KTHREAD_MAX      4
  76
  77 /*
  78  * Definition for node within the RCU grace-period-detection hierarchy.
  79  */
  80 struct rcu_node {
  81         raw_spinlock_t __private lock;  /* Root rcu_node's lock protects */
  82                                         /*  some rcu_state fields as well as */
  83                                         /*  following. */
  84         unsigned long gp_seq;   /* Track rsp->rcu_gp_seq. */
  85         unsigned long gp_seq_needed; /* Track rsp->rcu_gp_seq_needed. */
  86         unsigned long completedqs; /* All QSes done for this node. */
  87         unsigned long qsmask;   /* CPUs or groups that need to switch in */
  88                                 /*  order for current grace period to proceed.*/
  89                                 /*  In leaf rcu_node, each bit corresponds to */
  90                                 /*  an rcu_data structure, otherwise, each */
  91                                 /*  bit corresponds to a child rcu_node */
  92                                 /*  structure. */
  93         unsigned long rcu_gp_init_mask; /* Mask of offline CPUs at GP init. */
  94         unsigned long qsmaskinit;
  95                                 /* Per-GP initial value for qsmask. */
  96                                 /*  Initialized from ->qsmaskinitnext at the */
  97                                 /*  beginning of each grace period. */
  98         unsigned long qsmaskinitnext;
  99                                 /* Online CPUs for next grace period. */
 100         unsigned long expmask;  /* CPUs or groups that need to check in */
 101                                 /*  to allow the current expedited GP */
 102                                 /*  to complete. */
 103         unsigned long expmaskinit;
 104                                 /* Per-GP initial values for expmask. */
 105                                 /*  Initialized from ->expmaskinitnext at the */
 106                                 /*  beginning of each expedited GP. */
 107         unsigned long expmaskinitnext;
 108                                 /* Online CPUs for next expedited GP. */
 109                                 /*  Any CPU that has ever been online will */
 110                                 /*  have its bit set. */
 111         unsigned long ffmask;   /* Fully functional CPUs. */
 112         unsigned long grpmask;  /* Mask to apply to parent qsmask. */
 113                                 /*  Only one bit will be set in this mask. */
 114         int     grplo;          /* lowest-numbered CPU or group here. */
 115         int     grphi;          /* highest-numbered CPU or group here. */
 116         u8      grpnum;         /* CPU/group number for next level up. */
 117         u8      level;          /* root is at level 0. */
 118         bool    wait_blkd_tasks;/* Necessary to wait for blocked tasks to */
 119                                 /*  exit RCU read-side critical sections */
 120                                 /*  before propagating offline up the */
 121                                 /*  rcu_node tree? */
 122         struct rcu_node *parent;
 123         struct list_head blkd_tasks;
 124                                 /* Tasks blocked in RCU read-side critical */
 125                                 /*  section.  Tasks are placed at the head */
 126                                 /*  of this list and age towards the tail. */
 127         struct list_head *gp_tasks;
 128                                 /* Pointer to the first task blocking the */
 129                                 /*  current grace period, or NULL if there */
 130                                 /*  is no such task. */
 131         struct list_head *exp_tasks;
 132                                 /* Pointer to the first task blocking the */
 133                                 /*  current expedited grace period, or NULL */
 134                                 /*  if there is no such task.  If there */
 135                                 /*  is no current expedited grace period, */
 136                                 /*  then there can cannot be any such task. */
 137         struct list_head *boost_tasks;
 138                                 /* Pointer to first task that needs to be */
 139                                 /*  priority boosted, or NULL if no priority */
 140                                 /*  boosting is needed for this rcu_node */
 141                                 /*  structure.  If there are no tasks */
 142                                 /*  queued on this rcu_node structure that */
 143                                 /*  are blocking the current grace period, */
 144                                 /*  there can be no such task. */
 145         struct rt_mutex boost_mtx;
 146                                 /* Used only for the priority-boosting */
 147                                 /*  side effect, not as a lock. */
 148         unsigned long boost_time;
 149                                 /* When to start boosting (jiffies). */
 150         struct task_struct *boost_kthread_task;
 151                                 /* kthread that takes care of priority */
 152                                 /*  boosting for this rcu_node structure. */
 153         unsigned int boost_kthread_status;
 154                                 /* State of boost_kthread_task for tracing. */
 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         raw_spinlock_t fqslock ____cacheline_internodealigned_in_smp;
 160
 161         spinlock_t exp_lock ____cacheline_internodealigned_in_smp;
 162         unsigned long exp_seq_rq;
 163         wait_queue_head_t exp_wq[4];
 164         struct rcu_exp_work rew;
 165         bool exp_need_flush;    /* Need to flush workitem? */
 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 /* Per-CPU data for read-copy update. */
 188 struct rcu_data {
 189         /* 1) quiescent-state and grace-period handling : */
 190         unsigned long   gp_seq;         /* Track rsp->rcu_gp_seq counter. */
 191         unsigned long   gp_seq_needed;  /* Track rsp->rcu_gp_seq_needed ctr. */
 192         unsigned long   rcu_qs_ctr_snap;/* Snapshot of rcu_qs_ctr to check */
 193                                         /*  for rcu_all_qs() invocations. */
 194         union rcu_noqs  cpu_no_qs;      /* No QSes yet for this CPU. */
 195         bool            core_needs_qs;  /* Core waits for quiesc state. */
 196         bool            beenonline;     /* CPU online at least once. */
 197         bool            gpwrap;         /* Possible ->gp_seq wrap. */
 198         struct rcu_node *mynode;        /* This CPU's leaf of hierarchy */
 199         unsigned long grpmask;          /* Mask to apply to leaf qsmask. */
 200         unsigned long   ticks_this_gp;  /* The number of scheduling-clock */
 201                                         /*  ticks this CPU has handled */
 202                                         /*  during and after the last grace */
 203                                         /* period it is aware of. */
 204
 205         /* 2) batch handling */
 206         struct rcu_segcblist cblist;    /* Segmented callback list, with */
 207                                         /* different callbacks waiting for */
 208                                         /* different grace periods. */
 209         long            qlen_last_fqs_check;
 210                                         /* qlen at last check for QS forcing */
 211         unsigned long   n_force_qs_snap;
 212                                         /* did other CPU force QS recently? */
 213         long            blimit;         /* Upper limit on a processed batch */
 214
 215         /* 3) dynticks interface. */
 216         struct rcu_dynticks *dynticks;  /* Shared per-CPU dynticks state. */
 217         int dynticks_snap;              /* Per-GP tracking for dynticks. */
 218
 219         /* 4) reasons this CPU needed to be kicked by force_quiescent_state */
 220         unsigned long dynticks_fqs;     /* Kicked due to dynticks idle. */
 221         unsigned long cond_resched_completed;
 222                                         /* Grace period that needs help */
 223                                         /*  from cond_resched(). */
 224
 225         /* 5) _rcu_barrier(), OOM callbacks, and expediting. */
 226         struct rcu_head barrier_head;
 227 #ifdef CONFIG_RCU_FAST_NO_HZ
 228         struct rcu_head oom_head;
 229 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
 230         int exp_dynticks_snap;          /* Double-check need for IPI. */
 231
 232         /* 6) Callback offloading. */
 233 #ifdef CONFIG_RCU_NOCB_CPU
 234         struct rcu_head *nocb_head;     /* CBs waiting for kthread. */
 235         struct rcu_head **nocb_tail;
 236         atomic_long_t nocb_q_count;     /* # CBs waiting for nocb */
 237         atomic_long_t nocb_q_count_lazy; /*  invocation (all stages). */
 238         struct rcu_head *nocb_follower_head; /* CBs ready to invoke. */
 239         struct rcu_head **nocb_follower_tail;
 240         struct swait_queue_head nocb_wq; /* For nocb kthreads to sleep on. */
 241         struct task_struct *nocb_kthread;
 242         raw_spinlock_t nocb_lock;       /* Guard following pair of fields. */
 243         int nocb_defer_wakeup;          /* Defer wakeup of nocb_kthread. */
 244         struct timer_list nocb_timer;   /* Enforce finite deferral. */
 245
 246         /* The following fields are used by the leader, hence own cacheline. */
 247         struct rcu_head *nocb_gp_head ____cacheline_internodealigned_in_smp;
 248                                         /* CBs waiting for GP. */
 249         struct rcu_head **nocb_gp_tail;
 250         bool nocb_leader_sleep;         /* Is the nocb leader thread asleep? */
 251         struct rcu_data *nocb_next_follower;
 252                                         /* Next follower in wakeup chain. */
 253
 254         /* The following fields are used by the follower, hence new cachline. */
 255         struct rcu_data *nocb_leader ____cacheline_internodealigned_in_smp;
 256                                         /* Leader CPU takes GP-end wakeups. */
 257 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
 258
 259         /* 7) Diagnostic data, including RCU CPU stall warnings. */
 260         unsigned int softirq_snap;      /* Snapshot of softirq activity. */
 261         /* ->rcu_iw* fields protected by leaf rcu_node ->lock. */
 262         struct irq_work rcu_iw;         /* Check for non-irq activity. */
 263         bool rcu_iw_pending;            /* Is ->rcu_iw pending? */
 264         unsigned long rcu_iw_gp_seq;    /* ->gp_seq associated with ->rcu_iw. */
 265         unsigned long rcu_ofl_gp_seq;   /* ->gp_seq at last offline. */
 266         short rcu_ofl_gp_flags;         /* ->gp_flags at last offline. */
 267         unsigned long rcu_onl_gp_seq;   /* ->gp_seq at last online. */
 268         short rcu_onl_gp_flags;         /* ->gp_flags at last online. */
 269
 270         int cpu;
 271         struct rcu_state *rsp;
 272 };
 273
 274 /* Values for nocb_defer_wakeup field in struct rcu_data. */
 275 #define RCU_NOCB_WAKE_NOT       0
 276 #define RCU_NOCB_WAKE           1
 277 #define RCU_NOCB_WAKE_FORCE     2
 278
 279 #define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500))
 280                                         /* For jiffies_till_first_fqs and */
 281                                         /*  and jiffies_till_next_fqs. */
 282
 283 #define RCU_JIFFIES_FQS_DIV     256     /* Very large systems need more */
 284                                         /*  delay between bouts of */
 285                                         /*  quiescent-state forcing. */
 286
 287 #define RCU_STALL_RAT_DELAY     2       /* Allow other CPUs time to take */
 288                                         /*  at least one scheduling clock */
 289                                         /*  irq before ratting on them. */
 290
 291 #define rcu_wait(cond)                                                  \
 292 do {                                                                    \
 293         for (;;) {                                                      \
 294                 set_current_state(TASK_INTERRUPTIBLE);                  \
 295                 if (cond)                                               \
 296                         break;                                          \
 297                 schedule();                                             \
 298         }                                                               \
 299         __set_current_state(TASK_RUNNING);                              \
 300 } while (0)
 301
 302 /*
 303  * RCU global state, including node hierarchy.  This hierarchy is
 304  * represented in "heap" form in a dense array.  The root (first level)
 305  * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
 306  * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
 307  * and the third level in ->node[m+1] and following (->node[m+1] referenced
 308  * by ->level[2]).  The number of levels is determined by the number of
 309  * CPUs and by CONFIG_RCU_FANOUT.  Small systems will have a "hierarchy"
 310  * consisting of a single rcu_node.
 311  */
 312 struct rcu_state {
 313         struct rcu_node node[NUM_RCU_NODES];    /* Hierarchy. */
 314         struct rcu_node *level[RCU_NUM_LVLS + 1];
 315                                                 /* Hierarchy levels (+1 to */
 316                                                 /*  shut bogus gcc warning) */
 317         struct rcu_data __percpu *rda;          /* pointer of percu rcu_data. */
 318         call_rcu_func_t call;                   /* call_rcu() flavor. */
 319         int ncpus;                              /* # CPUs seen so far. */
 320
 321         /* The following fields are guarded by the root rcu_node's lock. */
 322
 323         u8      boost ____cacheline_internodealigned_in_smp;
 324                                                 /* Subject to priority boost. */
 325         unsigned long gp_seq;                   /* Grace-period sequence #. */
 326         struct task_struct *gp_kthread;         /* Task for grace periods. */
 327         struct swait_queue_head gp_wq;          /* Where GP task waits. */
 328         short gp_flags;                         /* Commands for GP task. */
 329         short gp_state;                         /* GP kthread sleep state. */
 330
 331         /* End of fields guarded by root rcu_node's lock. */
 332
 333         struct mutex barrier_mutex;             /* Guards barrier fields. */
 334         atomic_t barrier_cpu_count;             /* # CPUs waiting on. */
 335         struct completion barrier_completion;   /* Wake at barrier end. */
 336         unsigned long barrier_sequence;         /* ++ at start and end of */
 337                                                 /*  _rcu_barrier(). */
 338         /* End of fields guarded by barrier_mutex. */
 339
 340         struct mutex exp_mutex;                 /* Serialize expedited GP. */
 341         struct mutex exp_wake_mutex;            /* Serialize wakeup. */
 342         unsigned long expedited_sequence;       /* Take a ticket. */
 343         atomic_t expedited_need_qs;             /* # CPUs left to check in. */
 344         struct swait_queue_head expedited_wq;   /* Wait for check-ins. */
 345         int ncpus_snap;                         /* # CPUs seen last time. */
 346
 347         unsigned long jiffies_force_qs;         /* Time at which to invoke */
 348                                                 /*  force_quiescent_state(). */
 349         unsigned long jiffies_kick_kthreads;    /* Time at which to kick */
 350                                                 /*  kthreads, if configured. */
 351         unsigned long n_force_qs;               /* Number of calls to */
 352                                                 /*  force_quiescent_state(). */
 353         unsigned long gp_start;                 /* Time at which GP started, */
 354                                                 /*  but in jiffies. */
 355         unsigned long gp_activity;              /* Time of last GP kthread */
 356                                                 /*  activity in jiffies. */
 357         unsigned long gp_req_activity;          /* Time of last GP request */
 358                                                 /*  in jiffies. */
 359         unsigned long jiffies_stall;            /* Time at which to check */
 360                                                 /*  for CPU stalls. */
 361         unsigned long jiffies_resched;          /* Time at which to resched */
 362                                                 /*  a reluctant CPU. */
 363         unsigned long n_force_qs_gpstart;       /* Snapshot of n_force_qs at */
 364                                                 /*  GP start. */
 365         unsigned long gp_max;                   /* Maximum GP duration in */
 366                                                 /*  jiffies. */
 367         const char *name;                       /* Name of structure. */
 368         char abbr;                              /* Abbreviated name. */
 369         struct list_head flavors;               /* List of RCU flavors. */
 370
 371         spinlock_t ofl_lock ____cacheline_internodealigned_in_smp;
 372                                                 /* Synchronize offline with */
 373                                                 /*  GP pre-initialization. */
 374 };
 375
 376 /* Values for rcu_state structure's gp_flags field. */
 377 #define RCU_GP_FLAG_INIT 0x1    /* Need grace-period initialization. */
 378 #define RCU_GP_FLAG_FQS  0x2    /* Need grace-period quiescent-state forcing. */
 379
 380 /* Values for rcu_state structure's gp_state field. */
 381 #define RCU_GP_IDLE      0      /* Initial state and no GP in progress. */
 382 #define RCU_GP_WAIT_GPS  1      /* Wait for grace-period start. */
 383 #define RCU_GP_DONE_GPS  2      /* Wait done for grace-period start. */
 384 #define RCU_GP_ONOFF     3      /* Grace-period initialization hotplug. */
 385 #define RCU_GP_INIT      4      /* Grace-period initialization. */
 386 #define RCU_GP_WAIT_FQS  5      /* Wait for force-quiescent-state time. */
 387 #define RCU_GP_DOING_FQS 6      /* Wait done for force-quiescent-state time. */
 388 #define RCU_GP_CLEANUP   7      /* Grace-period cleanup started. */
 389 #define RCU_GP_CLEANED   8      /* Grace-period cleanup complete. */
 390
 391 #ifndef RCU_TREE_NONCORE
 392 static const char * const gp_state_names[] = {
 393         "RCU_GP_IDLE",
 394         "RCU_GP_WAIT_GPS",
 395         "RCU_GP_DONE_GPS",
 396         "RCU_GP_ONOFF",
 397         "RCU_GP_INIT",
 398         "RCU_GP_WAIT_FQS",
 399         "RCU_GP_DOING_FQS",
 400         "RCU_GP_CLEANUP",
 401         "RCU_GP_CLEANED",
 402 };
 403 #endif /* #ifndef RCU_TREE_NONCORE */
 404
 405 extern struct list_head rcu_struct_flavors;
 406
 407 /* Sequence through rcu_state structures for each RCU flavor. */
 408 #define for_each_rcu_flavor(rsp) \
 409         list_for_each_entry((rsp), &rcu_struct_flavors, flavors)
 410
 411 /*
 412  * RCU implementation internal declarations:
 413  */
 414 extern struct rcu_state rcu_sched_state;
 415
 416 extern struct rcu_state rcu_bh_state;
 417
 418 #ifdef CONFIG_PREEMPT_RCU
 419 extern struct rcu_state rcu_preempt_state;
 420 #endif /* #ifdef CONFIG_PREEMPT_RCU */
 421
 422 int rcu_dynticks_snap(struct rcu_dynticks *rdtp);
 423
 424 #ifdef CONFIG_RCU_BOOST
 425 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
 426 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
 427 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
 428 DECLARE_PER_CPU(char, rcu_cpu_has_work);
 429 #endif /* #ifdef CONFIG_RCU_BOOST */
 430
 431 #ifndef RCU_TREE_NONCORE
 432
 433 /* Forward declarations for rcutree_plugin.h */
 434 static void rcu_bootup_announce(void);
 435 static void rcu_preempt_note_context_switch(bool preempt);
 436 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
 437 #ifdef CONFIG_HOTPLUG_CPU
 438 static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
 439 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 440 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
 441 static int rcu_print_task_stall(struct rcu_node *rnp);
 442 static int rcu_print_task_exp_stall(struct rcu_node *rnp);
 443 static void rcu_preempt_check_blocked_tasks(struct rcu_state *rsp,
 444                                             struct rcu_node *rnp);
 445 static void rcu_preempt_check_callbacks(void);
 446 void call_rcu(struct rcu_head *head, rcu_callback_t func);
 447 static void __init __rcu_init_preempt(void);
 448 static void dump_blkd_tasks(struct rcu_state *rsp, struct rcu_node *rnp,
 449                             int ncheck);
 450 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
 451 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
 452 static void invoke_rcu_callbacks_kthread(void);
 453 static bool rcu_is_callbacks_kthread(void);
 454 #ifdef CONFIG_RCU_BOOST
 455 static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
 456                                                  struct rcu_node *rnp);
 457 #endif /* #ifdef CONFIG_RCU_BOOST */
 458 static void __init rcu_spawn_boost_kthreads(void);
 459 static void rcu_prepare_kthreads(int cpu);
 460 static void rcu_cleanup_after_idle(void);
 461 static void rcu_prepare_for_idle(void);
 462 static void rcu_idle_count_callbacks_posted(void);
 463 static bool rcu_preempt_has_tasks(struct rcu_node *rnp);
 464 static void print_cpu_stall_info_begin(void);
 465 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
 466 static void print_cpu_stall_info_end(void);
 467 static void zero_cpu_stall_ticks(struct rcu_data *rdp);
 468 static void increment_cpu_stall_ticks(void);
 469 static bool rcu_nocb_cpu_needs_barrier(struct rcu_state *rsp, int cpu);
 470 static struct swait_queue_head *rcu_nocb_gp_get(struct rcu_node *rnp);
 471 static void rcu_nocb_gp_cleanup(struct swait_queue_head *sq);
 472 static void rcu_init_one_nocb(struct rcu_node *rnp);
 473 static bool __call_rcu_nocb(struct rcu_data *rdp, struct rcu_head *rhp,
 474                             bool lazy, unsigned long flags);
 475 static bool rcu_nocb_adopt_orphan_cbs(struct rcu_data *my_rdp,
 476                                       struct rcu_data *rdp,
 477                                       unsigned long flags);
 478 static int rcu_nocb_need_deferred_wakeup(struct rcu_data *rdp);
 479 static void do_nocb_deferred_wakeup(struct rcu_data *rdp);
 480 static void rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp);
 481 static void rcu_spawn_all_nocb_kthreads(int cpu);
 482 static void __init rcu_spawn_nocb_kthreads(void);
 483 #ifdef CONFIG_RCU_NOCB_CPU
 484 static void __init rcu_organize_nocb_kthreads(struct rcu_state *rsp);
 485 #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
 486 static bool init_nocb_callback_list(struct rcu_data *rdp);
 487 static void rcu_bind_gp_kthread(void);
 488 static bool rcu_nohz_full_cpu(struct rcu_state *rsp);
 489 static void rcu_dynticks_task_enter(void);
 490 static void rcu_dynticks_task_exit(void);
 491
 492 #ifdef CONFIG_SRCU
 493 void srcu_online_cpu(unsigned int cpu);
 494 void srcu_offline_cpu(unsigned int cpu);
 495 #else /* #ifdef CONFIG_SRCU */
 496 void srcu_online_cpu(unsigned int cpu) { }
 497 void srcu_offline_cpu(unsigned int cpu) { }
 498 #endif /* #else #ifdef CONFIG_SRCU */
 499
 500 #endif /* #ifndef RCU_TREE_NONCORE */