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 #ifdef CONFIG_RCU_CPU_STALL_INFO 243 unsigned long ticks_this_gp; /* The number of scheduling-clock */ 244 /* ticks this CPU has handled */ 245 /* during and after the last grace */ 246 /* period it is aware of. */ 247 #endif /* #ifdef CONFIG_RCU_CPU_STALL_INFO */ 248 249 /* 2) batch handling */ 250 /* 251 * If nxtlist is not NULL, it is partitioned as follows. 252 * Any of the partitions might be empty, in which case the 253 * pointer to that partition will be equal to the pointer for 254 * the following partition. When the list is empty, all of 255 * the nxttail elements point to the ->nxtlist pointer itself, 256 * which in that case is NULL. 257 * 258 * [nxtlist, *nxttail[RCU_DONE_TAIL]): 259 * Entries that batch # <= ->completed 260 * The grace period for these entries has completed, and 261 * the other grace-period-completed entries may be moved 262 * here temporarily in rcu_process_callbacks(). 263 * [*nxttail[RCU_DONE_TAIL], *nxttail[RCU_WAIT_TAIL]): 264 * Entries that batch # <= ->completed - 1: waiting for current GP 265 * [*nxttail[RCU_WAIT_TAIL], *nxttail[RCU_NEXT_READY_TAIL]): 266 * Entries known to have arrived before current GP ended 267 * [*nxttail[RCU_NEXT_READY_TAIL], *nxttail[RCU_NEXT_TAIL]): 268 * Entries that might have arrived after current GP ended 269 * Note that the value of *nxttail[RCU_NEXT_TAIL] will 270 * always be NULL, as this is the end of the list. 271 */ 272 struct rcu_head *nxtlist; 273 struct rcu_head **nxttail[RCU_NEXT_SIZE]; 274 long qlen_lazy; /* # of lazy queued callbacks */ 275 long qlen; /* # of queued callbacks, incl lazy */ 276 long qlen_last_fqs_check; 277 /* qlen at last check for QS forcing */ 278 unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */ 279 unsigned long n_cbs_orphaned; /* RCU cbs orphaned by dying CPU */ 280 unsigned long n_cbs_adopted; /* RCU cbs adopted from dying CPU */ 281 unsigned long n_force_qs_snap; 282 /* did other CPU force QS recently? */ 283 long blimit; /* Upper limit on a processed batch */ 284 285 /* 3) dynticks interface. */ 286 struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ 287 int dynticks_snap; /* Per-GP tracking for dynticks. */ 288 289 /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ 290 unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ 291 unsigned long offline_fqs; /* Kicked due to being offline. */ 292 293 /* 5) __rcu_pending() statistics. */ 294 unsigned long n_rcu_pending; /* rcu_pending() calls since boot. */ 295 unsigned long n_rp_qs_pending; 296 unsigned long n_rp_report_qs; 297 unsigned long n_rp_cb_ready; 298 unsigned long n_rp_cpu_needs_gp; 299 unsigned long n_rp_gp_completed; 300 unsigned long n_rp_gp_started; 301 unsigned long n_rp_need_fqs; 302 unsigned long n_rp_need_nothing; 303 304 int cpu; 305 struct rcu_state *rsp; 306 }; 307 308 /* Values for fqs_state field in struct rcu_state. */ 309 #define RCU_GP_IDLE 0 /* No grace period in progress. */ 310 #define RCU_GP_INIT 1 /* Grace period being initialized. */ 311 #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */ 312 #define RCU_FORCE_QS 3 /* Need to force quiescent state. */ 313 #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK 314 315 #define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */ 316 317 #ifdef CONFIG_PROVE_RCU 318 #define RCU_STALL_DELAY_DELTA (5 * HZ) 319 #else 320 #define RCU_STALL_DELAY_DELTA 0 321 #endif 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 #endif /* #ifdef CONFIG_HOTPLUG_CPU */ 442 static void rcu_preempt_cleanup_dead_cpu(int 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_cpu_has_callbacks(int cpu); 452 static void __cpuinit rcu_preempt_init_percpu_data(int cpu); 453 static void rcu_preempt_cleanup_dying_cpu(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 static void print_cpu_stall_info_begin(void); 475 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu); 476 static void print_cpu_stall_info_end(void); 477 static void zero_cpu_stall_ticks(struct rcu_data *rdp); 478 static void increment_cpu_stall_ticks(void); 479 480 #endif /* #ifndef RCU_TREE_NONCORE */ 481