kernel/rcutree.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, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  *
  19  * Copyright IBM Corporation, 2008
  20  *
  21  * Author: Ingo Molnar <mingo@elte.hu>
  22  *         Paul E. McKenney <paulmck@linux.vnet.ibm.com>
  23  */
  24
  25 #include <linux/cache.h>
  26 #include <linux/spinlock.h>
  27 #include <linux/threads.h>
  28 #include <linux/cpumask.h>
  29 #include <linux/seqlock.h>
  30
  31 /*
  32  * Define shape of hierarchy based on NR_CPUS and CONFIG_RCU_FANOUT.
  33  * In theory, it should be possible to add more levels straightforwardly.
  34  * In practice, this did work well going from three levels to four.
  35  * Of course, your mileage may vary.
  36  */
  37 #define MAX_RCU_LVLS 4
  38 #if CONFIG_RCU_FANOUT > 16
  39 #define RCU_FANOUT_LEAF       16
  40 #else /* #if CONFIG_RCU_FANOUT > 16 */
  41 #define RCU_FANOUT_LEAF       (CONFIG_RCU_FANOUT)
  42 #endif /* #else #if CONFIG_RCU_FANOUT > 16 */
  43 #define RCU_FANOUT_1          (RCU_FANOUT_LEAF)
  44 #define RCU_FANOUT_2          (RCU_FANOUT_1 * CONFIG_RCU_FANOUT)
  45 #define RCU_FANOUT_3          (RCU_FANOUT_2 * CONFIG_RCU_FANOUT)
  46 #define RCU_FANOUT_4          (RCU_FANOUT_3 * CONFIG_RCU_FANOUT)
  47
  48 #if NR_CPUS <= RCU_FANOUT_1
  49 #  define NUM_RCU_LVLS        1
  50 #  define NUM_RCU_LVL_0       1
  51 #  define NUM_RCU_LVL_1       (NR_CPUS)
  52 #  define NUM_RCU_LVL_2       0
  53 #  define NUM_RCU_LVL_3       0
  54 #  define NUM_RCU_LVL_4       0
  55 #elif NR_CPUS <= RCU_FANOUT_2
  56 #  define NUM_RCU_LVLS        2
  57 #  define NUM_RCU_LVL_0       1
  58 #  define NUM_RCU_LVL_1       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
  59 #  define NUM_RCU_LVL_2       (NR_CPUS)
  60 #  define NUM_RCU_LVL_3       0
  61 #  define NUM_RCU_LVL_4       0
  62 #elif NR_CPUS <= RCU_FANOUT_3
  63 #  define NUM_RCU_LVLS        3
  64 #  define NUM_RCU_LVL_0       1
  65 #  define NUM_RCU_LVL_1       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
  66 #  define NUM_RCU_LVL_2       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
  67 #  define NUM_RCU_LVL_3       (NR_CPUS)
  68 #  define NUM_RCU_LVL_4       0
  69 #elif NR_CPUS <= RCU_FANOUT_4
  70 #  define NUM_RCU_LVLS        4
  71 #  define NUM_RCU_LVL_0       1
  72 #  define NUM_RCU_LVL_1       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
  73 #  define NUM_RCU_LVL_2       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
  74 #  define NUM_RCU_LVL_3       DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
  75 #  define NUM_RCU_LVL_4       (NR_CPUS)
  76 #else
  77 # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
  78 #endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
  79
  80 #define RCU_SUM (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3 + NUM_RCU_LVL_4)
  81 #define NUM_RCU_NODES (RCU_SUM - NR_CPUS)
  82
  83 /*
  84  * Dynticks per-CPU state.
  85  */
  86 struct rcu_dynticks {
  87         long long dynticks_nesting; /* Track irq/process nesting level. */
  88                                     /* Process level is worth LLONG_MAX/2. */
  89         int dynticks_nmi_nesting;   /* Track NMI nesting level. */
  90         atomic_t dynticks;          /* Even value for idle, else odd. */
  91 };
  92
  93 /* RCU's kthread states for tracing. */
  94 #define RCU_KTHREAD_STOPPED  0
  95 #define RCU_KTHREAD_RUNNING  1
  96 #define RCU_KTHREAD_WAITING  2
  97 #define RCU_KTHREAD_OFFCPU   3
  98 #define RCU_KTHREAD_YIELDING 4
  99 #define RCU_KTHREAD_MAX      4
 100
 101 /*
 102  * Definition for node within the RCU grace-period-detection hierarchy.
 103  */
 104 struct rcu_node {
 105         raw_spinlock_t lock;    /* Root rcu_node's lock protects some */
 106                                 /*  rcu_state fields as well as following. */
 107         unsigned long gpnum;    /* Current grace period for this node. */
 108                                 /*  This will either be equal to or one */
 109                                 /*  behind the root rcu_node's gpnum. */
 110         unsigned long completed; /* Last GP completed for this node. */
 111                                 /*  This will either be equal to or one */
 112                                 /*  behind the root rcu_node's gpnum. */
 113         unsigned long qsmask;   /* CPUs or groups that need to switch in */
 114                                 /*  order for current grace period to proceed.*/
 115                                 /*  In leaf rcu_node, each bit corresponds to */
 116                                 /*  an rcu_data structure, otherwise, each */
 117                                 /*  bit corresponds to a child rcu_node */
 118                                 /*  structure. */
 119         unsigned long expmask;  /* Groups that have ->blkd_tasks */
 120                                 /*  elements that need to drain to allow the */
 121                                 /*  current expedited grace period to */
 122                                 /*  complete (only for TREE_PREEMPT_RCU). */
 123         atomic_t wakemask;      /* CPUs whose kthread needs to be awakened. */
 124                                 /*  Since this has meaning only for leaf */
 125                                 /*  rcu_node structures, 32 bits suffices. */
 126         unsigned long qsmaskinit;
 127                                 /* Per-GP initial value for qsmask & expmask. */
 128         unsigned long grpmask;  /* Mask to apply to parent qsmask. */
 129                                 /*  Only one bit will be set in this mask. */
 130         int     grplo;          /* lowest-numbered CPU or group here. */
 131         int     grphi;          /* highest-numbered CPU or group here. */
 132         u8      grpnum;         /* CPU/group number for next level up. */
 133         u8      level;          /* root is at level 0. */
 134         struct rcu_node *parent;
 135         struct list_head blkd_tasks;
 136                                 /* Tasks blocked in RCU read-side critical */
 137                                 /*  section.  Tasks are placed at the head */
 138                                 /*  of this list and age towards the tail. */
 139         struct list_head *gp_tasks;
 140                                 /* Pointer to the first task blocking the */
 141                                 /*  current grace period, or NULL if there */
 142                                 /*  is no such task. */
 143         struct list_head *exp_tasks;
 144                                 /* Pointer to the first task blocking the */
 145                                 /*  current expedited grace period, or NULL */
 146                                 /*  if there is no such task.  If there */
 147                                 /*  is no current expedited grace period, */
 148                                 /*  then there can cannot be any such task. */
 149 #ifdef CONFIG_RCU_BOOST
 150         struct list_head *boost_tasks;
 151                                 /* Pointer to first task that needs to be */
 152                                 /*  priority boosted, or NULL if no priority */
 153                                 /*  boosting is needed for this rcu_node */
 154                                 /*  structure.  If there are no tasks */
 155                                 /*  queued on this rcu_node structure that */
 156                                 /*  are blocking the current grace period, */
 157                                 /*  there can be no such task. */
 158         unsigned long boost_time;
 159                                 /* When to start boosting (jiffies). */
 160         struct task_struct *boost_kthread_task;
 161                                 /* kthread that takes care of priority */
 162                                 /*  boosting for this rcu_node structure. */
 163         unsigned int boost_kthread_status;
 164                                 /* State of boost_kthread_task for tracing. */
 165         unsigned long n_tasks_boosted;
 166                                 /* Total number of tasks boosted. */
 167         unsigned long n_exp_boosts;
 168                                 /* Number of tasks boosted for expedited GP. */
 169         unsigned long n_normal_boosts;
 170                                 /* Number of tasks boosted for normal GP. */
 171         unsigned long n_balk_blkd_tasks;
 172                                 /* Refused to boost: no blocked tasks. */
 173         unsigned long n_balk_exp_gp_tasks;
 174                                 /* Refused to boost: nothing blocking GP. */
 175         unsigned long n_balk_boost_tasks;
 176                                 /* Refused to boost: already boosting. */
 177         unsigned long n_balk_notblocked;
 178                                 /* Refused to boost: RCU RS CS still running. */
 179         unsigned long n_balk_notyet;
 180                                 /* Refused to boost: not yet time. */
 181         unsigned long n_balk_nos;
 182                                 /* Refused to boost: not sure why, though. */
 183                                 /*  This can happen due to race conditions. */
 184 #endif /* #ifdef CONFIG_RCU_BOOST */
 185         struct task_struct *node_kthread_task;
 186                                 /* kthread that takes care of this rcu_node */
 187                                 /*  structure, for example, awakening the */
 188                                 /*  per-CPU kthreads as needed. */
 189         unsigned int node_kthread_status;
 190                                 /* State of node_kthread_task for tracing. */
 191 } ____cacheline_internodealigned_in_smp;
 192
 193 /*
 194  * Do a full breadth-first scan of the rcu_node structures for the
 195  * specified rcu_state structure.
 196  */
 197 #define rcu_for_each_node_breadth_first(rsp, rnp) \
 198         for ((rnp) = &(rsp)->node[0]; \
 199              (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++)
 200
 201 /*
 202  * Do a breadth-first scan of the non-leaf rcu_node structures for the
 203  * specified rcu_state structure.  Note that if there is a singleton
 204  * rcu_node tree with but one rcu_node structure, this loop is a no-op.
 205  */
 206 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \
 207         for ((rnp) = &(rsp)->node[0]; \
 208              (rnp) < (rsp)->level[NUM_RCU_LVLS - 1]; (rnp)++)
 209
 210 /*
 211  * Scan the leaves of the rcu_node hierarchy for the specified rcu_state
 212  * structure.  Note that if there is a singleton rcu_node tree with but
 213  * one rcu_node structure, this loop -will- visit the rcu_node structure.
 214  * It is still a leaf node, even if it is also the root node.
 215  */
 216 #define rcu_for_each_leaf_node(rsp, rnp) \
 217         for ((rnp) = (rsp)->level[NUM_RCU_LVLS - 1]; \
 218              (rnp) < &(rsp)->node[NUM_RCU_NODES]; (rnp)++)
 219
 220 /* Index values for nxttail array in struct rcu_data. */
 221 #define RCU_DONE_TAIL           0       /* Also RCU_WAIT head. */
 222 #define RCU_WAIT_TAIL           1       /* Also RCU_NEXT_READY head. */
 223 #define RCU_NEXT_READY_TAIL     2       /* Also RCU_NEXT head. */
 224 #define RCU_NEXT_TAIL           3
 225 #define RCU_NEXT_SIZE           4
 226
 227 /* Per-CPU data for read-copy update. */
 228 struct rcu_data {
 229         /* 1) quiescent-state and grace-period handling : */
 230         unsigned long   completed;      /* Track rsp->completed gp number */
 231                                         /*  in order to detect GP end. */
 232         unsigned long   gpnum;          /* Highest gp number that this CPU */
 233                                         /*  is aware of having started. */
 234         unsigned long   passed_quiesce_gpnum;
 235                                         /* gpnum at time of quiescent state. */
 236         bool            passed_quiesce; /* User-mode/idle loop etc. */
 237         bool            qs_pending;     /* Core waits for quiesc state. */
 238         bool            beenonline;     /* CPU online at least once. */
 239         bool            preemptible;    /* Preemptible RCU? */
 240         struct rcu_node *mynode;        /* This CPU's leaf of hierarchy */
 241         unsigned long grpmask;          /* Mask to apply to leaf qsmask. */
 242
 243         /* 2) batch handling */
 244         /*
 245          * If nxtlist is not NULL, it is partitioned as follows.
 246          * Any of the partitions might be empty, in which case the
 247          * pointer to that partition will be equal to the pointer for
 248          * the following partition.  When the list is empty, all of
 249          * the nxttail elements point to the ->nxtlist pointer itself,
 250          * which in that case is NULL.
 251          *
 252          * [nxtlist, *nxttail[RCU_DONE_TAIL]):
 253          *      Entries that batch # <= ->completed
 254          *      The grace period for these entries has completed, and
 255          *      the other grace-period-completed entries may be moved
 256          *      here temporarily in rcu_process_callbacks().
 257          * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]):
 258          *      Entries that batch # <= ->completed - 1: waiting for current GP
 259          * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]):
 260          *      Entries known to have arrived before current GP ended
 261          * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]):
 262          *      Entries that might have arrived after current GP ended
 263          *      Note that the value of *nxttail[RCU_NEXT_TAIL] will
 264          *      always be NULL, as this is the end of the list.
 265          */
 266         struct rcu_head *nxtlist;
 267         struct rcu_head **nxttail[RCU_NEXT_SIZE];
 268         long            qlen;           /* # of queued callbacks */
 269         long            qlen_last_fqs_check;
 270                                         /* qlen at last check for QS forcing */
 271         unsigned long   n_cbs_invoked;  /* count of RCU cbs invoked. */
 272         unsigned long   n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */
 273         unsigned long   n_cbs_adopted;  /* RCU cbs adopted from dying CPU */
 274         unsigned long   n_force_qs_snap;
 275                                         /* did other CPU force QS recently? */
 276         long            blimit;         /* Upper limit on a processed batch */
 277
 278         /* 3) dynticks interface. */
 279         struct rcu_dynticks *dynticks;  /* Shared per-CPU dynticks state. */
 280         int dynticks_snap;              /* Per-GP tracking for dynticks. */
 281
 282         /* 4) reasons this CPU needed to be kicked by force_quiescent_state */
 283         unsigned long dynticks_fqs;     /* Kicked due to dynticks idle. */
 284         unsigned long offline_fqs;      /* Kicked due to being offline. */
 285         unsigned long resched_ipi;      /* Sent a resched IPI. */
 286
 287         /* 5) __rcu_pending() statistics. */
 288         unsigned long n_rcu_pending;    /* rcu_pending() calls since boot. */
 289         unsigned long n_rp_qs_pending;
 290         unsigned long n_rp_report_qs;
 291         unsigned long n_rp_cb_ready;
 292         unsigned long n_rp_cpu_needs_gp;
 293         unsigned long n_rp_gp_completed;
 294         unsigned long n_rp_gp_started;
 295         unsigned long n_rp_need_fqs;
 296         unsigned long n_rp_need_nothing;
 297
 298         int cpu;
 299         struct rcu_state *rsp;
 300 };
 301
 302 /* Values for fqs_state field in struct rcu_state. */
 303 #define RCU_GP_IDLE             0       /* No grace period in progress. */
 304 #define RCU_GP_INIT             1       /* Grace period being initialized. */
 305 #define RCU_SAVE_DYNTICK        2       /* Need to scan dyntick state. */
 306 #define RCU_FORCE_QS            3       /* Need to force quiescent state. */
 307 #define RCU_SIGNAL_INIT         RCU_SAVE_DYNTICK
 308
 309 #define RCU_JIFFIES_TILL_FORCE_QS        3      /* for rsp->jiffies_force_qs */
 310
 311 #ifdef CONFIG_PROVE_RCU
 312 #define RCU_STALL_DELAY_DELTA          (5 * HZ)
 313 #else
 314 #define RCU_STALL_DELAY_DELTA          0
 315 #endif
 316
 317 #define RCU_SECONDS_TILL_STALL_CHECK   (CONFIG_RCU_CPU_STALL_TIMEOUT * HZ + \
 318                                         RCU_STALL_DELAY_DELTA)
 319                                                 /* for rsp->jiffies_stall */
 320 #define RCU_SECONDS_TILL_STALL_RECHECK (3 * RCU_SECONDS_TILL_STALL_CHECK + 30)
 321                                                 /* for rsp->jiffies_stall */
 322 #define RCU_STALL_RAT_DELAY             2       /* Allow other CPUs time */
 323                                                 /*  to take at least one */
 324                                                 /*  scheduling clock irq */
 325                                                 /*  before ratting on them. */
 326
 327 #define rcu_wait(cond)                                                  \
 328 do {                                                                    \
 329         for (;;) {                                                      \
 330                 set_current_state(TASK_INTERRUPTIBLE);                  \
 331                 if (cond)                                               \
 332                         break;                                          \
 333                 schedule();                                             \
 334         }                                                               \
 335         __set_current_state(TASK_RUNNING);                              \
 336 } while (0)
 337
 338 /*
 339  * RCU global state, including node hierarchy.  This hierarchy is
 340  * represented in "heap" form in a dense array.  The root (first level)
 341  * of the hierarchy is in ->node[0] (referenced by ->level[0]), the second
 342  * level in ->node[1] through ->node[m] (->node[1] referenced by ->level[1]),
 343  * and the third level in ->node[m+1] and following (->node[m+1] referenced
 344  * by ->level[2]).  The number of levels is determined by the number of
 345  * CPUs and by CONFIG_RCU_FANOUT.  Small systems will have a "hierarchy"
 346  * consisting of a single rcu_node.
 347  */
 348 struct rcu_state {
 349         struct rcu_node node[NUM_RCU_NODES];    /* Hierarchy. */
 350         struct rcu_node *level[NUM_RCU_LVLS];   /* Hierarchy levels. */
 351         u32 levelcnt[MAX_RCU_LVLS + 1];         /* # nodes in each level. */
 352         u8 levelspread[NUM_RCU_LVLS];           /* kids/node in each level. */
 353         struct rcu_data __percpu *rda;          /* pointer of percu rcu_data. */
 354
 355         /* The following fields are guarded by the root rcu_node's lock. */
 356
 357         u8      fqs_state ____cacheline_internodealigned_in_smp;
 358                                                 /* Force QS state. */
 359         u8      fqs_active;                     /* force_quiescent_state() */
 360                                                 /*  is running. */
 361         u8      fqs_need_gp;                    /* A CPU was prevented from */
 362                                                 /*  starting a new grace */
 363                                                 /*  period because */
 364                                                 /*  force_quiescent_state() */
 365                                                 /*  was running. */
 366         u8      boost;                          /* Subject to priority boost. */
 367         unsigned long gpnum;                    /* Current gp number. */
 368         unsigned long completed;                /* # of last completed gp. */
 369
 370         /* End of fields guarded by root rcu_node's lock. */
 371
 372         raw_spinlock_t onofflock;               /* exclude on/offline and */
 373                                                 /*  starting new GP. */
 374         raw_spinlock_t fqslock;                 /* Only one task forcing */
 375                                                 /*  quiescent states. */
 376         unsigned long jiffies_force_qs;         /* Time at which to invoke */
 377                                                 /*  force_quiescent_state(). */
 378         unsigned long n_force_qs;               /* Number of calls to */
 379                                                 /*  force_quiescent_state(). */
 380         unsigned long n_force_qs_lh;            /* ~Number of calls leaving */
 381                                                 /*  due to lock unavailable. */
 382         unsigned long n_force_qs_ngp;           /* Number of calls leaving */
 383                                                 /*  due to no GP active. */
 384         unsigned long gp_start;                 /* Time at which GP started, */
 385                                                 /*  but in jiffies. */
 386         unsigned long jiffies_stall;            /* Time at which to check */
 387                                                 /*  for CPU stalls. */
 388         unsigned long gp_max;                   /* Maximum GP duration in */
 389                                                 /*  jiffies. */
 390         char *name;                             /* Name of structure. */
 391 };
 392
 393 /* Return values for rcu_preempt_offline_tasks(). */
 394
 395 #define RCU_OFL_TASKS_NORM_GP   0x1             /* Tasks blocking normal */
 396                                                 /*  GP were moved to root. */
 397 #define RCU_OFL_TASKS_EXP_GP    0x2             /* Tasks blocking expedited */
 398                                                 /*  GP were moved to root. */
 399
 400 /*
 401  * RCU implementation internal declarations:
 402  */
 403 extern struct rcu_state rcu_sched_state;
 404 DECLARE_PER_CPU(struct rcu_data, rcu_sched_data);
 405
 406 extern struct rcu_state rcu_bh_state;
 407 DECLARE_PER_CPU(struct rcu_data, rcu_bh_data);
 408
 409 #ifdef CONFIG_TREE_PREEMPT_RCU
 410 extern struct rcu_state rcu_preempt_state;
 411 DECLARE_PER_CPU(struct rcu_data, rcu_preempt_data);
 412 #endif /* #ifdef CONFIG_TREE_PREEMPT_RCU */
 413
 414 #ifdef CONFIG_RCU_BOOST
 415 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
 416 DECLARE_PER_CPU(int, rcu_cpu_kthread_cpu);
 417 DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
 418 DECLARE_PER_CPU(char, rcu_cpu_has_work);
 419 #endif /* #ifdef CONFIG_RCU_BOOST */
 420
 421 #ifndef RCU_TREE_NONCORE
 422
 423 /* Forward declarations for rcutree_plugin.h */
 424 static void rcu_bootup_announce(void);
 425 long rcu_batches_completed(void);
 426 static void rcu_preempt_note_context_switch(int cpu);
 427 static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
 428 #ifdef CONFIG_HOTPLUG_CPU
 429 static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
 430                                       unsigned long flags);
 431 static void rcu_stop_cpu_kthread(int cpu);
 432 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 433 static void rcu_print_detail_task_stall(struct rcu_state *rsp);
 434 static int rcu_print_task_stall(struct rcu_node *rnp);
 435 static void rcu_preempt_stall_reset(void);
 436 static void rcu_preempt_check_blocked_tasks(struct rcu_node *rnp);
 437 #ifdef CONFIG_HOTPLUG_CPU
 438 static int rcu_preempt_offline_tasks(struct rcu_state *rsp,
 439                                      struct rcu_node *rnp,
 440                                      struct rcu_data *rdp);
 441 static void rcu_preempt_offline_cpu(int cpu);
 442 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 443 static void rcu_preempt_check_callbacks(int cpu);
 444 static void rcu_preempt_process_callbacks(void);
 445 void call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 446 #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU)
 447 static void rcu_report_exp_rnp(struct rcu_state *rsp, struct rcu_node *rnp,
 448                                bool wake);
 449 #endif /* #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_TREE_PREEMPT_RCU) */
 450 static int rcu_preempt_pending(int cpu);
 451 static int rcu_preempt_needs_cpu(int cpu);
 452 static void __cpuinit rcu_preempt_init_percpu_data(int cpu);
 453 static void rcu_preempt_send_cbs_to_online(void);
 454 static void __init __rcu_init_preempt(void);
 455 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
 456 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
 457 static void invoke_rcu_callbacks_kthread(void);
 458 static bool rcu_is_callbacks_kthread(void);
 459 #ifdef CONFIG_RCU_BOOST
 460 static void rcu_preempt_do_callbacks(void);
 461 static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
 462                                           cpumask_var_t cm);
 463 static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
 464                                                  struct rcu_node *rnp,
 465                                                  int rnp_index);
 466 static void invoke_rcu_node_kthread(struct rcu_node *rnp);
 467 static void rcu_yield(void (*f)(unsigned long), unsigned long arg);
 468 #endif /* #ifdef CONFIG_RCU_BOOST */
 469 static void rcu_cpu_kthread_setrt(int cpu, int to_rt);
 470 static void __cpuinit rcu_prepare_kthreads(int cpu);
 471 static void rcu_prepare_for_idle_init(int cpu);
 472 static void rcu_cleanup_after_idle(int cpu);
 473 static void rcu_prepare_for_idle(int cpu);
 474
 475 #endif /* #ifndef RCU_TREE_NONCORE */