kernel/rcu/rcu.h

   1 /* SPDX-License-Identifier: GPL-2.0+ */
   2 /*
   3  * Read-Copy Update definitions shared among RCU implementations.
   4  *
   5  * Copyright IBM Corporation, 2011
   6  *
   7  * Author: Paul E. McKenney <paulmck@linux.ibm.com>
   8  */
   9
  10 #ifndef __LINUX_RCU_H
  11 #define __LINUX_RCU_H
  12
  13 #include <linux/slab.h>
  14 #include <trace/events/rcu.h>
  15
  16 /*
  17  * Grace-period counter management.
  18  *
  19  * The two least significant bits contain the control flags.
  20  * The most significant bits contain the grace-period sequence counter.
  21  *
  22  * When both control flags are zero, no grace period is in progress.
  23  * When either bit is non-zero, a grace period has started and is in
  24  * progress. When the grace period completes, the control flags are reset
  25  * to 0 and the grace-period sequence counter is incremented.
  26  *
  27  * However some specific RCU usages make use of custom values.
  28  *
  29  * SRCU special control values:
  30  *
  31  *      SRCU_SNP_INIT_SEQ       :       Invalid/init value set when SRCU node
  32  *                                      is initialized.
  33  *
  34  *      SRCU_STATE_IDLE         :       No SRCU gp is in progress
  35  *
  36  *      SRCU_STATE_SCAN1        :       State set by rcu_seq_start(). Indicates
  37  *                                      we are scanning the readers on the slot
  38  *                                      defined as inactive (there might well
  39  *                                      be pending readers that will use that
  40  *                                      index, but their number is bounded).
  41  *
  42  *      SRCU_STATE_SCAN2        :       State set manually via rcu_seq_set_state()
  43  *                                      Indicates we are flipping the readers
  44  *                                      index and then scanning the readers on the
  45  *                                      slot newly designated as inactive (again,
  46  *                                      the number of pending readers that will use
  47  *                                      this inactive index is bounded).
  48  *
  49  * RCU polled GP special control value:
  50  *
  51  *      RCU_GET_STATE_COMPLETED :       State value indicating an already-completed
  52  *                                      polled GP has completed.  This value covers
  53  *                                      both the state and the counter of the
  54  *                                      grace-period sequence number.
  55  */
  56
  57 /* Low-order bit definition for polled grace-period APIs. */
  58 #define RCU_GET_STATE_COMPLETED 0x1
  59
  60 extern int sysctl_sched_rt_runtime;
  61
  62 /*
  63  * Return the counter portion of a sequence number previously returned
  64  * by rcu_seq_snap() or rcu_seq_current().
  65  */
  66 static inline unsigned long rcu_seq_ctr(unsigned long s)
  67 {
  68         return s >> RCU_SEQ_CTR_SHIFT;
  69 }
  70
  71 /*
  72  * Return the state portion of a sequence number previously returned
  73  * by rcu_seq_snap() or rcu_seq_current().
  74  */
  75 static inline int rcu_seq_state(unsigned long s)
  76 {
  77         return s & RCU_SEQ_STATE_MASK;
  78 }
  79
  80 /*
  81  * Set the state portion of the pointed-to sequence number.
  82  * The caller is responsible for preventing conflicting updates.
  83  */
  84 static inline void rcu_seq_set_state(unsigned long *sp, int newstate)
  85 {
  86         WARN_ON_ONCE(newstate & ~RCU_SEQ_STATE_MASK);
  87         WRITE_ONCE(*sp, (*sp & ~RCU_SEQ_STATE_MASK) + newstate);
  88 }
  89
  90 /* Adjust sequence number for start of update-side operation. */
  91 static inline void rcu_seq_start(unsigned long *sp)
  92 {
  93         WRITE_ONCE(*sp, *sp + 1);
  94         smp_mb(); /* Ensure update-side operation after counter increment. */
  95         WARN_ON_ONCE(rcu_seq_state(*sp) != 1);
  96 }
  97
  98 /* Compute the end-of-grace-period value for the specified sequence number. */
  99 static inline unsigned long rcu_seq_endval(unsigned long *sp)
 100 {
 101         return (*sp | RCU_SEQ_STATE_MASK) + 1;
 102 }
 103
 104 /* Adjust sequence number for end of update-side operation. */
 105 static inline void rcu_seq_end(unsigned long *sp)
 106 {
 107         smp_mb(); /* Ensure update-side operation before counter increment. */
 108         WARN_ON_ONCE(!rcu_seq_state(*sp));
 109         WRITE_ONCE(*sp, rcu_seq_endval(sp));
 110 }
 111
 112 /*
 113  * rcu_seq_snap - Take a snapshot of the update side's sequence number.
 114  *
 115  * This function returns the earliest value of the grace-period sequence number
 116  * that will indicate that a full grace period has elapsed since the current
 117  * time.  Once the grace-period sequence number has reached this value, it will
 118  * be safe to invoke all callbacks that have been registered prior to the
 119  * current time. This value is the current grace-period number plus two to the
 120  * power of the number of low-order bits reserved for state, then rounded up to
 121  * the next value in which the state bits are all zero.
 122  */
 123 static inline unsigned long rcu_seq_snap(unsigned long *sp)
 124 {
 125         unsigned long s;
 126
 127         s = (READ_ONCE(*sp) + 2 * RCU_SEQ_STATE_MASK + 1) & ~RCU_SEQ_STATE_MASK;
 128         smp_mb(); /* Above access must not bleed into critical section. */
 129         return s;
 130 }
 131
 132 /* Return the current value the update side's sequence number, no ordering. */
 133 static inline unsigned long rcu_seq_current(unsigned long *sp)
 134 {
 135         return READ_ONCE(*sp);
 136 }
 137
 138 /*
 139  * Given a snapshot from rcu_seq_snap(), determine whether or not the
 140  * corresponding update-side operation has started.
 141  */
 142 static inline bool rcu_seq_started(unsigned long *sp, unsigned long s)
 143 {
 144         return ULONG_CMP_LT((s - 1) & ~RCU_SEQ_STATE_MASK, READ_ONCE(*sp));
 145 }
 146
 147 /*
 148  * Given a snapshot from rcu_seq_snap(), determine whether or not a
 149  * full update-side operation has occurred.
 150  */
 151 static inline bool rcu_seq_done(unsigned long *sp, unsigned long s)
 152 {
 153         return ULONG_CMP_GE(READ_ONCE(*sp), s);
 154 }
 155
 156 /*
 157  * Given a snapshot from rcu_seq_snap(), determine whether or not a
 158  * full update-side operation has occurred, but do not allow the
 159  * (ULONG_MAX / 2) safety-factor/guard-band.
 160  */
 161 static inline bool rcu_seq_done_exact(unsigned long *sp, unsigned long s)
 162 {
 163         unsigned long cur_s = READ_ONCE(*sp);
 164
 165         return ULONG_CMP_GE(cur_s, s) || ULONG_CMP_LT(cur_s, s - (2 * RCU_SEQ_STATE_MASK + 1));
 166 }
 167
 168 /*
 169  * Has a grace period completed since the time the old gp_seq was collected?
 170  */
 171 static inline bool rcu_seq_completed_gp(unsigned long old, unsigned long new)
 172 {
 173         return ULONG_CMP_LT(old, new & ~RCU_SEQ_STATE_MASK);
 174 }
 175
 176 /*
 177  * Has a grace period started since the time the old gp_seq was collected?
 178  */
 179 static inline bool rcu_seq_new_gp(unsigned long old, unsigned long new)
 180 {
 181         return ULONG_CMP_LT((old + RCU_SEQ_STATE_MASK) & ~RCU_SEQ_STATE_MASK,
 182                             new);
 183 }
 184
 185 /*
 186  * Roughly how many full grace periods have elapsed between the collection
 187  * of the two specified grace periods?
 188  */
 189 static inline unsigned long rcu_seq_diff(unsigned long new, unsigned long old)
 190 {
 191         unsigned long rnd_diff;
 192
 193         if (old == new)
 194                 return 0;
 195         /*
 196          * Compute the number of grace periods (still shifted up), plus
 197          * one if either of new and old is not an exact grace period.
 198          */
 199         rnd_diff = (new & ~RCU_SEQ_STATE_MASK) -
 200                    ((old + RCU_SEQ_STATE_MASK) & ~RCU_SEQ_STATE_MASK) +
 201                    ((new & RCU_SEQ_STATE_MASK) || (old & RCU_SEQ_STATE_MASK));
 202         if (ULONG_CMP_GE(RCU_SEQ_STATE_MASK, rnd_diff))
 203                 return 1; /* Definitely no grace period has elapsed. */
 204         return ((rnd_diff - RCU_SEQ_STATE_MASK - 1) >> RCU_SEQ_CTR_SHIFT) + 2;
 205 }
 206
 207 /*
 208  * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally
 209  * by call_rcu() and rcu callback execution, and are therefore not part
 210  * of the RCU API. These are in rcupdate.h because they are used by all
 211  * RCU implementations.
 212  */
 213
 214 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
 215 # define STATE_RCU_HEAD_READY   0
 216 # define STATE_RCU_HEAD_QUEUED  1
 217
 218 extern const struct debug_obj_descr rcuhead_debug_descr;
 219
 220 static inline int debug_rcu_head_queue(struct rcu_head *head)
 221 {
 222         int r1;
 223
 224         r1 = debug_object_activate(head, &rcuhead_debug_descr);
 225         debug_object_active_state(head, &rcuhead_debug_descr,
 226                                   STATE_RCU_HEAD_READY,
 227                                   STATE_RCU_HEAD_QUEUED);
 228         return r1;
 229 }
 230
 231 static inline void debug_rcu_head_unqueue(struct rcu_head *head)
 232 {
 233         debug_object_active_state(head, &rcuhead_debug_descr,
 234                                   STATE_RCU_HEAD_QUEUED,
 235                                   STATE_RCU_HEAD_READY);
 236         debug_object_deactivate(head, &rcuhead_debug_descr);
 237 }
 238 #else   /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 239 static inline int debug_rcu_head_queue(struct rcu_head *head)
 240 {
 241         return 0;
 242 }
 243
 244 static inline void debug_rcu_head_unqueue(struct rcu_head *head)
 245 {
 246 }
 247 #endif  /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 248
 249 static inline void debug_rcu_head_callback(struct rcu_head *rhp)
 250 {
 251         if (unlikely(!rhp->func))
 252                 kmem_dump_obj(rhp);
 253 }
 254
 255 static inline bool rcu_barrier_cb_is_done(struct rcu_head *rhp)
 256 {
 257         return rhp->next == rhp;
 258 }
 259
 260 extern int rcu_cpu_stall_suppress_at_boot;
 261
 262 static inline bool rcu_stall_is_suppressed_at_boot(void)
 263 {
 264         return rcu_cpu_stall_suppress_at_boot && !rcu_inkernel_boot_has_ended();
 265 }
 266
 267 extern int rcu_cpu_stall_notifiers;
 268
 269 #ifdef CONFIG_RCU_STALL_COMMON
 270
 271 extern int rcu_cpu_stall_ftrace_dump;
 272 extern int rcu_cpu_stall_suppress;
 273 extern int rcu_cpu_stall_timeout;
 274 extern int rcu_exp_cpu_stall_timeout;
 275 extern int rcu_cpu_stall_cputime;
 276 extern bool rcu_exp_stall_task_details __read_mostly;
 277 int rcu_jiffies_till_stall_check(void);
 278 int rcu_exp_jiffies_till_stall_check(void);
 279
 280 static inline bool rcu_stall_is_suppressed(void)
 281 {
 282         return rcu_stall_is_suppressed_at_boot() || rcu_cpu_stall_suppress;
 283 }
 284
 285 #define rcu_ftrace_dump_stall_suppress() \
 286 do { \
 287         if (!rcu_cpu_stall_suppress) \
 288                 rcu_cpu_stall_suppress = 3; \
 289 } while (0)
 290
 291 #define rcu_ftrace_dump_stall_unsuppress() \
 292 do { \
 293         if (rcu_cpu_stall_suppress == 3) \
 294                 rcu_cpu_stall_suppress = 0; \
 295 } while (0)
 296
 297 #else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */
 298
 299 static inline bool rcu_stall_is_suppressed(void)
 300 {
 301         return rcu_stall_is_suppressed_at_boot();
 302 }
 303 #define rcu_ftrace_dump_stall_suppress()
 304 #define rcu_ftrace_dump_stall_unsuppress()
 305 #endif /* #ifdef CONFIG_RCU_STALL_COMMON */
 306
 307 /*
 308  * Strings used in tracepoints need to be exported via the
 309  * tracing system such that tools like perf and trace-cmd can
 310  * translate the string address pointers to actual text.
 311  */
 312 #define TPS(x)  tracepoint_string(x)
 313
 314 /*
 315  * Dump the ftrace buffer, but only one time per callsite per boot.
 316  */
 317 #define rcu_ftrace_dump(oops_dump_mode) \
 318 do { \
 319         static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \
 320         \
 321         if (!atomic_read(&___rfd_beenhere) && \
 322             !atomic_xchg(&___rfd_beenhere, 1)) { \
 323                 tracing_off(); \
 324                 rcu_ftrace_dump_stall_suppress(); \
 325                 ftrace_dump(oops_dump_mode); \
 326                 rcu_ftrace_dump_stall_unsuppress(); \
 327         } \
 328 } while (0)
 329
 330 void rcu_early_boot_tests(void);
 331 void rcu_test_sync_prims(void);
 332
 333 /*
 334  * This function really isn't for public consumption, but RCU is special in
 335  * that context switches can allow the state machine to make progress.
 336  */
 337 extern void resched_cpu(int cpu);
 338
 339 #if !defined(CONFIG_TINY_RCU)
 340
 341 #include <linux/rcu_node_tree.h>
 342
 343 extern int rcu_num_lvls;
 344 extern int num_rcu_lvl[];
 345 extern int rcu_num_nodes;
 346 static bool rcu_fanout_exact;
 347 static int rcu_fanout_leaf;
 348
 349 /*
 350  * Compute the per-level fanout, either using the exact fanout specified
 351  * or balancing the tree, depending on the rcu_fanout_exact boot parameter.
 352  */
 353 static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
 354 {
 355         int i;
 356
 357         for (i = 0; i < RCU_NUM_LVLS; i++)
 358                 levelspread[i] = INT_MIN;
 359         if (rcu_fanout_exact) {
 360                 levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
 361                 for (i = rcu_num_lvls - 2; i >= 0; i--)
 362                         levelspread[i] = RCU_FANOUT;
 363         } else {
 364                 int ccur;
 365                 int cprv;
 366
 367                 cprv = nr_cpu_ids;
 368                 for (i = rcu_num_lvls - 1; i >= 0; i--) {
 369                         ccur = levelcnt[i];
 370                         levelspread[i] = (cprv + ccur - 1) / ccur;
 371                         cprv = ccur;
 372                 }
 373         }
 374 }
 375
 376 extern void rcu_init_geometry(void);
 377
 378 /* Returns a pointer to the first leaf rcu_node structure. */
 379 #define rcu_first_leaf_node() (rcu_state.level[rcu_num_lvls - 1])
 380
 381 /* Is this rcu_node a leaf? */
 382 #define rcu_is_leaf_node(rnp) ((rnp)->level == rcu_num_lvls - 1)
 383
 384 /* Is this rcu_node the last leaf? */
 385 #define rcu_is_last_leaf_node(rnp) ((rnp) == &rcu_state.node[rcu_num_nodes - 1])
 386
 387 /*
 388  * Do a full breadth-first scan of the {s,}rcu_node structures for the
 389  * specified state structure (for SRCU) or the only rcu_state structure
 390  * (for RCU).
 391  */
 392 #define _rcu_for_each_node_breadth_first(sp, rnp) \
 393         for ((rnp) = &(sp)->node[0]; \
 394              (rnp) < &(sp)->node[rcu_num_nodes]; (rnp)++)
 395 #define rcu_for_each_node_breadth_first(rnp) \
 396         _rcu_for_each_node_breadth_first(&rcu_state, rnp)
 397 #define srcu_for_each_node_breadth_first(ssp, rnp) \
 398         _rcu_for_each_node_breadth_first(ssp->srcu_sup, rnp)
 399
 400 /*
 401  * Scan the leaves of the rcu_node hierarchy for the rcu_state structure.
 402  * Note that if there is a singleton rcu_node tree with but one rcu_node
 403  * structure, this loop -will- visit the rcu_node structure.  It is still
 404  * a leaf node, even if it is also the root node.
 405  */
 406 #define rcu_for_each_leaf_node(rnp) \
 407         for ((rnp) = rcu_first_leaf_node(); \
 408              (rnp) < &rcu_state.node[rcu_num_nodes]; (rnp)++)
 409
 410 /*
 411  * Iterate over all possible CPUs in a leaf RCU node.
 412  */
 413 #define for_each_leaf_node_possible_cpu(rnp, cpu) \
 414         for (WARN_ON_ONCE(!rcu_is_leaf_node(rnp)), \
 415              (cpu) = cpumask_next((rnp)->grplo - 1, cpu_possible_mask); \
 416              (cpu) <= rnp->grphi; \
 417              (cpu) = cpumask_next((cpu), cpu_possible_mask))
 418
 419 /*
 420  * Iterate over all CPUs in a leaf RCU node's specified mask.
 421  */
 422 #define rcu_find_next_bit(rnp, cpu, mask) \
 423         ((rnp)->grplo + find_next_bit(&(mask), BITS_PER_LONG, (cpu)))
 424 #define for_each_leaf_node_cpu_mask(rnp, cpu, mask) \
 425         for (WARN_ON_ONCE(!rcu_is_leaf_node(rnp)), \
 426              (cpu) = rcu_find_next_bit((rnp), 0, (mask)); \
 427              (cpu) <= rnp->grphi; \
 428              (cpu) = rcu_find_next_bit((rnp), (cpu) + 1 - (rnp->grplo), (mask)))
 429
 430 #endif /* !defined(CONFIG_TINY_RCU) */
 431
 432 #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_TASKS_RCU_GENERIC)
 433
 434 /*
 435  * Wrappers for the rcu_node::lock acquire and release.
 436  *
 437  * Because the rcu_nodes form a tree, the tree traversal locking will observe
 438  * different lock values, this in turn means that an UNLOCK of one level
 439  * followed by a LOCK of another level does not imply a full memory barrier;
 440  * and most importantly transitivity is lost.
 441  *
 442  * In order to restore full ordering between tree levels, augment the regular
 443  * lock acquire functions with smp_mb__after_unlock_lock().
 444  *
 445  * As ->lock of struct rcu_node is a __private field, therefore one should use
 446  * these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock.
 447  */
 448 #define raw_spin_lock_rcu_node(p)                                       \
 449 do {                                                                    \
 450         raw_spin_lock(&ACCESS_PRIVATE(p, lock));                        \
 451         smp_mb__after_unlock_lock();                                    \
 452 } while (0)
 453
 454 #define raw_spin_unlock_rcu_node(p)                                     \
 455 do {                                                                    \
 456         lockdep_assert_irqs_disabled();                                 \
 457         raw_spin_unlock(&ACCESS_PRIVATE(p, lock));                      \
 458 } while (0)
 459
 460 #define raw_spin_lock_irq_rcu_node(p)                                   \
 461 do {                                                                    \
 462         raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock));                    \
 463         smp_mb__after_unlock_lock();                                    \
 464 } while (0)
 465
 466 #define raw_spin_unlock_irq_rcu_node(p)                                 \
 467 do {                                                                    \
 468         lockdep_assert_irqs_disabled();                                 \
 469         raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock));                  \
 470 } while (0)
 471
 472 #define raw_spin_lock_irqsave_rcu_node(p, flags)                        \
 473 do {                                                                    \
 474         raw_spin_lock_irqsave(&ACCESS_PRIVATE(p, lock), flags); \
 475         smp_mb__after_unlock_lock();                                    \
 476 } while (0)
 477
 478 #define raw_spin_unlock_irqrestore_rcu_node(p, flags)                   \
 479 do {                                                                    \
 480         lockdep_assert_irqs_disabled();                                 \
 481         raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(p, lock), flags);    \
 482 } while (0)
 483
 484 #define raw_spin_trylock_rcu_node(p)                                    \
 485 ({                                                                      \
 486         bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock));    \
 487                                                                         \
 488         if (___locked)                                                  \
 489                 smp_mb__after_unlock_lock();                            \
 490         ___locked;                                                      \
 491 })
 492
 493 #define raw_lockdep_assert_held_rcu_node(p)                             \
 494         lockdep_assert_held(&ACCESS_PRIVATE(p, lock))
 495
 496 #endif // #if !defined(CONFIG_TINY_RCU) || defined(CONFIG_TASKS_RCU_GENERIC)
 497
 498 #ifdef CONFIG_TINY_RCU
 499 /* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */
 500 static inline bool rcu_gp_is_normal(void) { return true; }
 501 static inline bool rcu_gp_is_expedited(void) { return false; }
 502 static inline bool rcu_async_should_hurry(void) { return false; }
 503 static inline void rcu_expedite_gp(void) { }
 504 static inline void rcu_unexpedite_gp(void) { }
 505 static inline void rcu_async_hurry(void) { }
 506 static inline void rcu_async_relax(void) { }
 507 static inline bool rcu_cpu_online(int cpu) { return true; }
 508 #else /* #ifdef CONFIG_TINY_RCU */
 509 bool rcu_gp_is_normal(void);     /* Internal RCU use. */
 510 bool rcu_gp_is_expedited(void);  /* Internal RCU use. */
 511 bool rcu_async_should_hurry(void);  /* Internal RCU use. */
 512 void rcu_expedite_gp(void);
 513 void rcu_unexpedite_gp(void);
 514 void rcu_async_hurry(void);
 515 void rcu_async_relax(void);
 516 void rcupdate_announce_bootup_oddness(void);
 517 bool rcu_cpu_online(int cpu);
 518 #ifdef CONFIG_TASKS_RCU_GENERIC
 519 void show_rcu_tasks_gp_kthreads(void);
 520 #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
 521 static inline void show_rcu_tasks_gp_kthreads(void) {}
 522 #endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */
 523 #endif /* #else #ifdef CONFIG_TINY_RCU */
 524
 525 #ifdef CONFIG_TASKS_RCU
 526 struct task_struct *get_rcu_tasks_gp_kthread(void);
 527 void rcu_tasks_get_gp_data(int *flags, unsigned long *gp_seq);
 528 #endif // # ifdef CONFIG_TASKS_RCU
 529
 530 #ifdef CONFIG_TASKS_RUDE_RCU
 531 struct task_struct *get_rcu_tasks_rude_gp_kthread(void);
 532 void rcu_tasks_rude_get_gp_data(int *flags, unsigned long *gp_seq);
 533 #endif // # ifdef CONFIG_TASKS_RUDE_RCU
 534
 535 #ifdef CONFIG_TASKS_TRACE_RCU
 536 void rcu_tasks_trace_get_gp_data(int *flags, unsigned long *gp_seq);
 537 #endif
 538
 539 #ifdef CONFIG_TASKS_RCU_GENERIC
 540 void tasks_cblist_init_generic(void);
 541 #else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
 542 static inline void tasks_cblist_init_generic(void) { }
 543 #endif /* #else #ifdef CONFIG_TASKS_RCU_GENERIC */
 544
 545 #define RCU_SCHEDULER_INACTIVE  0
 546 #define RCU_SCHEDULER_INIT      1
 547 #define RCU_SCHEDULER_RUNNING   2
 548
 549 enum rcutorture_type {
 550         RCU_FLAVOR,
 551         RCU_TASKS_FLAVOR,
 552         RCU_TASKS_RUDE_FLAVOR,
 553         RCU_TASKS_TRACING_FLAVOR,
 554         RCU_TRIVIAL_FLAVOR,
 555         SRCU_FLAVOR,
 556         INVALID_RCU_FLAVOR
 557 };
 558
 559 #if defined(CONFIG_RCU_LAZY)
 560 unsigned long rcu_get_jiffies_lazy_flush(void);
 561 void rcu_set_jiffies_lazy_flush(unsigned long j);
 562 #else
 563 static inline unsigned long rcu_get_jiffies_lazy_flush(void) { return 0; }
 564 static inline void rcu_set_jiffies_lazy_flush(unsigned long j) { }
 565 #endif
 566
 567 #if defined(CONFIG_TREE_RCU)
 568 void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq);
 569 void do_trace_rcu_torture_read(const char *rcutorturename,
 570                                struct rcu_head *rhp,
 571                                unsigned long secs,
 572                                unsigned long c_old,
 573                                unsigned long c);
 574 void rcu_gp_set_torture_wait(int duration);
 575 #else
 576 static inline void rcutorture_get_gp_data(int *flags, unsigned long *gp_seq)
 577 {
 578         *flags = 0;
 579         *gp_seq = 0;
 580 }
 581 #ifdef CONFIG_RCU_TRACE
 582 void do_trace_rcu_torture_read(const char *rcutorturename,
 583                                struct rcu_head *rhp,
 584                                unsigned long secs,
 585                                unsigned long c_old,
 586                                unsigned long c);
 587 #else
 588 #define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \
 589         do { } while (0)
 590 #endif
 591 static inline void rcu_gp_set_torture_wait(int duration) { }
 592 #endif
 593
 594 #ifdef CONFIG_TINY_SRCU
 595
 596 static inline void srcutorture_get_gp_data(struct srcu_struct *sp, int *flags,
 597                                            unsigned long *gp_seq)
 598 {
 599         *flags = 0;
 600         *gp_seq = sp->srcu_idx;
 601 }
 602
 603 #elif defined(CONFIG_TREE_SRCU)
 604
 605 void srcutorture_get_gp_data(struct srcu_struct *sp, int *flags,
 606                              unsigned long *gp_seq);
 607
 608 #endif
 609
 610 #ifdef CONFIG_TINY_RCU
 611 static inline bool rcu_watching_zero_in_eqs(int cpu, int *vp) { return false; }
 612 static inline unsigned long rcu_get_gp_seq(void) { return 0; }
 613 static inline unsigned long rcu_exp_batches_completed(void) { return 0; }
 614 static inline unsigned long
 615 srcu_batches_completed(struct srcu_struct *sp) { return 0; }
 616 static inline void rcu_force_quiescent_state(void) { }
 617 static inline bool rcu_check_boost_fail(unsigned long gp_state, int *cpup) { return true; }
 618 static inline void show_rcu_gp_kthreads(void) { }
 619 static inline int rcu_get_gp_kthreads_prio(void) { return 0; }
 620 static inline void rcu_fwd_progress_check(unsigned long j) { }
 621 static inline void rcu_gp_slow_register(atomic_t *rgssp) { }
 622 static inline void rcu_gp_slow_unregister(atomic_t *rgssp) { }
 623 #else /* #ifdef CONFIG_TINY_RCU */
 624 bool rcu_watching_zero_in_eqs(int cpu, int *vp);
 625 unsigned long rcu_get_gp_seq(void);
 626 unsigned long rcu_exp_batches_completed(void);
 627 unsigned long srcu_batches_completed(struct srcu_struct *sp);
 628 bool rcu_check_boost_fail(unsigned long gp_state, int *cpup);
 629 void show_rcu_gp_kthreads(void);
 630 int rcu_get_gp_kthreads_prio(void);
 631 void rcu_fwd_progress_check(unsigned long j);
 632 void rcu_force_quiescent_state(void);
 633 extern struct workqueue_struct *rcu_gp_wq;
 634 extern struct kthread_worker *rcu_exp_gp_kworker;
 635 void rcu_gp_slow_register(atomic_t *rgssp);
 636 void rcu_gp_slow_unregister(atomic_t *rgssp);
 637 #endif /* #else #ifdef CONFIG_TINY_RCU */
 638
 639 #ifdef CONFIG_RCU_NOCB_CPU
 640 void rcu_bind_current_to_nocb(void);
 641 #else
 642 static inline void rcu_bind_current_to_nocb(void) { }
 643 #endif
 644
 645 #if !defined(CONFIG_TINY_RCU) && defined(CONFIG_TASKS_RCU)
 646 void show_rcu_tasks_classic_gp_kthread(void);
 647 #else
 648 static inline void show_rcu_tasks_classic_gp_kthread(void) {}
 649 #endif
 650 #if !defined(CONFIG_TINY_RCU) && defined(CONFIG_TASKS_RUDE_RCU)
 651 void show_rcu_tasks_rude_gp_kthread(void);
 652 #else
 653 static inline void show_rcu_tasks_rude_gp_kthread(void) {}
 654 #endif
 655 #if !defined(CONFIG_TINY_RCU) && defined(CONFIG_TASKS_TRACE_RCU)
 656 void show_rcu_tasks_trace_gp_kthread(void);
 657 #else
 658 static inline void show_rcu_tasks_trace_gp_kthread(void) {}
 659 #endif
 660
 661 #ifdef CONFIG_TINY_RCU
 662 static inline bool rcu_cpu_beenfullyonline(int cpu) { return true; }
 663 #else
 664 bool rcu_cpu_beenfullyonline(int cpu);
 665 #endif
 666
 667 #if defined(CONFIG_RCU_STALL_COMMON) && defined(CONFIG_RCU_CPU_STALL_NOTIFIER)
 668 int rcu_stall_notifier_call_chain(unsigned long val, void *v);
 669 #else // #if defined(CONFIG_RCU_STALL_COMMON) && defined(CONFIG_RCU_CPU_STALL_NOTIFIER)
 670 static inline int rcu_stall_notifier_call_chain(unsigned long val, void *v) { return NOTIFY_DONE; }
 671 #endif // #else // #if defined(CONFIG_RCU_STALL_COMMON) && defined(CONFIG_RCU_CPU_STALL_NOTIFIER)
 672
 673 #endif /* __LINUX_RCU_H */