1 /* 2 * Read-Copy Update definitions shared among RCU implementations. 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, you can access it online at 16 * http://www.gnu.org/licenses/gpl-2.0.html. 17 * 18 * Copyright IBM Corporation, 2011 19 * 20 * Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> 21 */ 22 23 #ifndef __LINUX_RCU_H 24 #define __LINUX_RCU_H 25 26 #include <trace/events/rcu.h> 27 #ifdef CONFIG_RCU_TRACE 28 #define RCU_TRACE(stmt) stmt 29 #else /* #ifdef CONFIG_RCU_TRACE */ 30 #define RCU_TRACE(stmt) 31 #endif /* #else #ifdef CONFIG_RCU_TRACE */ 32 33 /* Offset to allow for unmatched rcu_irq_{enter,exit}(). */ 34 #define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1) 35 36 37 /* 38 * Grace-period counter management. 39 */ 40 41 #define RCU_SEQ_CTR_SHIFT 2 42 #define RCU_SEQ_STATE_MASK ((1 << RCU_SEQ_CTR_SHIFT) - 1) 43 44 /* 45 * Return the counter portion of a sequence number previously returned 46 * by rcu_seq_snap() or rcu_seq_current(). 47 */ 48 static inline unsigned long rcu_seq_ctr(unsigned long s) 49 { 50 return s >> RCU_SEQ_CTR_SHIFT; 51 } 52 53 /* 54 * Return the state portion of a sequence number previously returned 55 * by rcu_seq_snap() or rcu_seq_current(). 56 */ 57 static inline int rcu_seq_state(unsigned long s) 58 { 59 return s & RCU_SEQ_STATE_MASK; 60 } 61 62 /* 63 * Set the state portion of the pointed-to sequence number. 64 * The caller is responsible for preventing conflicting updates. 65 */ 66 static inline void rcu_seq_set_state(unsigned long *sp, int newstate) 67 { 68 WARN_ON_ONCE(newstate & ~RCU_SEQ_STATE_MASK); 69 WRITE_ONCE(*sp, (*sp & ~RCU_SEQ_STATE_MASK) + newstate); 70 } 71 72 /* Adjust sequence number for start of update-side operation. */ 73 static inline void rcu_seq_start(unsigned long *sp) 74 { 75 WRITE_ONCE(*sp, *sp + 1); 76 smp_mb(); /* Ensure update-side operation after counter increment. */ 77 WARN_ON_ONCE(rcu_seq_state(*sp) != 1); 78 } 79 80 /* Compute the end-of-grace-period value for the specified sequence number. */ 81 static inline unsigned long rcu_seq_endval(unsigned long *sp) 82 { 83 return (*sp | RCU_SEQ_STATE_MASK) + 1; 84 } 85 86 /* Adjust sequence number for end of update-side operation. */ 87 static inline void rcu_seq_end(unsigned long *sp) 88 { 89 smp_mb(); /* Ensure update-side operation before counter increment. */ 90 WARN_ON_ONCE(!rcu_seq_state(*sp)); 91 WRITE_ONCE(*sp, rcu_seq_endval(sp)); 92 } 93 94 /* Take a snapshot of the update side's sequence number. */ 95 static inline unsigned long rcu_seq_snap(unsigned long *sp) 96 { 97 unsigned long s; 98 99 s = (READ_ONCE(*sp) + 2 * RCU_SEQ_STATE_MASK + 1) & ~RCU_SEQ_STATE_MASK; 100 smp_mb(); /* Above access must not bleed into critical section. */ 101 return s; 102 } 103 104 /* Return the current value the update side's sequence number, no ordering. */ 105 static inline unsigned long rcu_seq_current(unsigned long *sp) 106 { 107 return READ_ONCE(*sp); 108 } 109 110 /* 111 * Given a snapshot from rcu_seq_snap(), determine whether or not a 112 * full update-side operation has occurred. 113 */ 114 static inline bool rcu_seq_done(unsigned long *sp, unsigned long s) 115 { 116 return ULONG_CMP_GE(READ_ONCE(*sp), s); 117 } 118 119 /* 120 * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally 121 * by call_rcu() and rcu callback execution, and are therefore not part of the 122 * RCU API. Leaving in rcupdate.h because they are used by all RCU flavors. 123 */ 124 125 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD 126 # define STATE_RCU_HEAD_READY 0 127 # define STATE_RCU_HEAD_QUEUED 1 128 129 extern struct debug_obj_descr rcuhead_debug_descr; 130 131 static inline int debug_rcu_head_queue(struct rcu_head *head) 132 { 133 int r1; 134 135 r1 = debug_object_activate(head, &rcuhead_debug_descr); 136 debug_object_active_state(head, &rcuhead_debug_descr, 137 STATE_RCU_HEAD_READY, 138 STATE_RCU_HEAD_QUEUED); 139 return r1; 140 } 141 142 static inline void debug_rcu_head_unqueue(struct rcu_head *head) 143 { 144 debug_object_active_state(head, &rcuhead_debug_descr, 145 STATE_RCU_HEAD_QUEUED, 146 STATE_RCU_HEAD_READY); 147 debug_object_deactivate(head, &rcuhead_debug_descr); 148 } 149 #else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ 150 static inline int debug_rcu_head_queue(struct rcu_head *head) 151 { 152 return 0; 153 } 154 155 static inline void debug_rcu_head_unqueue(struct rcu_head *head) 156 { 157 } 158 #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ 159 160 void kfree(const void *); 161 162 /* 163 * Reclaim the specified callback, either by invoking it (non-lazy case) 164 * or freeing it directly (lazy case). Return true if lazy, false otherwise. 165 */ 166 static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head) 167 { 168 unsigned long offset = (unsigned long)head->func; 169 170 rcu_lock_acquire(&rcu_callback_map); 171 if (__is_kfree_rcu_offset(offset)) { 172 RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset);) 173 kfree((void *)head - offset); 174 rcu_lock_release(&rcu_callback_map); 175 return true; 176 } else { 177 RCU_TRACE(trace_rcu_invoke_callback(rn, head);) 178 head->func(head); 179 rcu_lock_release(&rcu_callback_map); 180 return false; 181 } 182 } 183 184 #ifdef CONFIG_RCU_STALL_COMMON 185 186 extern int rcu_cpu_stall_suppress; 187 int rcu_jiffies_till_stall_check(void); 188 189 #define rcu_ftrace_dump_stall_suppress() \ 190 do { \ 191 if (!rcu_cpu_stall_suppress) \ 192 rcu_cpu_stall_suppress = 3; \ 193 } while (0) 194 195 #define rcu_ftrace_dump_stall_unsuppress() \ 196 do { \ 197 if (rcu_cpu_stall_suppress == 3) \ 198 rcu_cpu_stall_suppress = 0; \ 199 } while (0) 200 201 #else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */ 202 #define rcu_ftrace_dump_stall_suppress() 203 #define rcu_ftrace_dump_stall_unsuppress() 204 #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ 205 206 /* 207 * Strings used in tracepoints need to be exported via the 208 * tracing system such that tools like perf and trace-cmd can 209 * translate the string address pointers to actual text. 210 */ 211 #define TPS(x) tracepoint_string(x) 212 213 /* 214 * Dump the ftrace buffer, but only one time per callsite per boot. 215 */ 216 #define rcu_ftrace_dump(oops_dump_mode) \ 217 do { \ 218 static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \ 219 \ 220 if (!atomic_read(&___rfd_beenhere) && \ 221 !atomic_xchg(&___rfd_beenhere, 1)) { \ 222 tracing_off(); \ 223 rcu_ftrace_dump_stall_suppress(); \ 224 ftrace_dump(oops_dump_mode); \ 225 rcu_ftrace_dump_stall_unsuppress(); \ 226 } \ 227 } while (0) 228 229 void rcu_early_boot_tests(void); 230 void rcu_test_sync_prims(void); 231 232 /* 233 * This function really isn't for public consumption, but RCU is special in 234 * that context switches can allow the state machine to make progress. 235 */ 236 extern void resched_cpu(int cpu); 237 238 #if defined(SRCU) || !defined(TINY_RCU) 239 240 #include <linux/rcu_node_tree.h> 241 242 extern int rcu_num_lvls; 243 extern int num_rcu_lvl[]; 244 extern int rcu_num_nodes; 245 static bool rcu_fanout_exact; 246 static int rcu_fanout_leaf; 247 248 /* 249 * Compute the per-level fanout, either using the exact fanout specified 250 * or balancing the tree, depending on the rcu_fanout_exact boot parameter. 251 */ 252 static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) 253 { 254 int i; 255 256 if (rcu_fanout_exact) { 257 levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf; 258 for (i = rcu_num_lvls - 2; i >= 0; i--) 259 levelspread[i] = RCU_FANOUT; 260 } else { 261 int ccur; 262 int cprv; 263 264 cprv = nr_cpu_ids; 265 for (i = rcu_num_lvls - 1; i >= 0; i--) { 266 ccur = levelcnt[i]; 267 levelspread[i] = (cprv + ccur - 1) / ccur; 268 cprv = ccur; 269 } 270 } 271 } 272 273 /* Returns first leaf rcu_node of the specified RCU flavor. */ 274 #define rcu_first_leaf_node(rsp) ((rsp)->level[rcu_num_lvls - 1]) 275 276 /* Is this rcu_node a leaf? */ 277 #define rcu_is_leaf_node(rnp) ((rnp)->level == rcu_num_lvls - 1) 278 279 /* 280 * Do a full breadth-first scan of the rcu_node structures for the 281 * specified rcu_state structure. 282 */ 283 #define rcu_for_each_node_breadth_first(rsp, rnp) \ 284 for ((rnp) = &(rsp)->node[0]; \ 285 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 286 287 /* 288 * Do a breadth-first scan of the non-leaf rcu_node structures for the 289 * specified rcu_state structure. Note that if there is a singleton 290 * rcu_node tree with but one rcu_node structure, this loop is a no-op. 291 */ 292 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ 293 for ((rnp) = &(rsp)->node[0]; !rcu_is_leaf_node(rsp, rnp); (rnp)++) 294 295 /* 296 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state 297 * structure. Note that if there is a singleton rcu_node tree with but 298 * one rcu_node structure, this loop -will- visit the rcu_node structure. 299 * It is still a leaf node, even if it is also the root node. 300 */ 301 #define rcu_for_each_leaf_node(rsp, rnp) \ 302 for ((rnp) = rcu_first_leaf_node(rsp); \ 303 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 304 305 /* 306 * Iterate over all possible CPUs in a leaf RCU node. 307 */ 308 #define for_each_leaf_node_possible_cpu(rnp, cpu) \ 309 for ((cpu) = cpumask_next((rnp)->grplo - 1, cpu_possible_mask); \ 310 (cpu) <= rnp->grphi; \ 311 (cpu) = cpumask_next((cpu), cpu_possible_mask)) 312 313 /* 314 * Iterate over all CPUs in a leaf RCU node's specified mask. 315 */ 316 #define rcu_find_next_bit(rnp, cpu, mask) \ 317 ((rnp)->grplo + find_next_bit(&(mask), BITS_PER_LONG, (cpu))) 318 #define for_each_leaf_node_cpu_mask(rnp, cpu, mask) \ 319 for ((cpu) = rcu_find_next_bit((rnp), 0, (mask)); \ 320 (cpu) <= rnp->grphi; \ 321 (cpu) = rcu_find_next_bit((rnp), (cpu) + 1 - (rnp->grplo), (mask))) 322 323 /* 324 * Wrappers for the rcu_node::lock acquire and release. 325 * 326 * Because the rcu_nodes form a tree, the tree traversal locking will observe 327 * different lock values, this in turn means that an UNLOCK of one level 328 * followed by a LOCK of another level does not imply a full memory barrier; 329 * and most importantly transitivity is lost. 330 * 331 * In order to restore full ordering between tree levels, augment the regular 332 * lock acquire functions with smp_mb__after_unlock_lock(). 333 * 334 * As ->lock of struct rcu_node is a __private field, therefore one should use 335 * these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock. 336 */ 337 #define raw_spin_lock_rcu_node(p) \ 338 do { \ 339 raw_spin_lock(&ACCESS_PRIVATE(p, lock)); \ 340 smp_mb__after_unlock_lock(); \ 341 } while (0) 342 343 #define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, lock)) 344 345 #define raw_spin_lock_irq_rcu_node(p) \ 346 do { \ 347 raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock)); \ 348 smp_mb__after_unlock_lock(); \ 349 } while (0) 350 351 #define raw_spin_unlock_irq_rcu_node(p) \ 352 raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock)) 353 354 #define raw_spin_lock_irqsave_rcu_node(p, flags) \ 355 do { \ 356 raw_spin_lock_irqsave(&ACCESS_PRIVATE(p, lock), flags); \ 357 smp_mb__after_unlock_lock(); \ 358 } while (0) 359 360 #define raw_spin_unlock_irqrestore_rcu_node(p, flags) \ 361 raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(p, lock), flags) 362 363 #define raw_spin_trylock_rcu_node(p) \ 364 ({ \ 365 bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock)); \ 366 \ 367 if (___locked) \ 368 smp_mb__after_unlock_lock(); \ 369 ___locked; \ 370 }) 371 372 #define raw_lockdep_assert_held_rcu_node(p) \ 373 lockdep_assert_held(&ACCESS_PRIVATE(p, lock)) 374 375 #endif /* #if defined(SRCU) || !defined(TINY_RCU) */ 376 377 #ifdef CONFIG_TINY_RCU 378 /* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */ 379 static inline bool rcu_gp_is_normal(void) { return true; } 380 static inline bool rcu_gp_is_expedited(void) { return false; } 381 static inline void rcu_expedite_gp(void) { } 382 static inline void rcu_unexpedite_gp(void) { } 383 static inline void rcu_request_urgent_qs_task(struct task_struct *t) { } 384 #else /* #ifdef CONFIG_TINY_RCU */ 385 bool rcu_gp_is_normal(void); /* Internal RCU use. */ 386 bool rcu_gp_is_expedited(void); /* Internal RCU use. */ 387 void rcu_expedite_gp(void); 388 void rcu_unexpedite_gp(void); 389 void rcupdate_announce_bootup_oddness(void); 390 void rcu_request_urgent_qs_task(struct task_struct *t); 391 #endif /* #else #ifdef CONFIG_TINY_RCU */ 392 393 #define RCU_SCHEDULER_INACTIVE 0 394 #define RCU_SCHEDULER_INIT 1 395 #define RCU_SCHEDULER_RUNNING 2 396 397 enum rcutorture_type { 398 RCU_FLAVOR, 399 RCU_BH_FLAVOR, 400 RCU_SCHED_FLAVOR, 401 RCU_TASKS_FLAVOR, 402 SRCU_FLAVOR, 403 INVALID_RCU_FLAVOR 404 }; 405 406 #if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) 407 void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags, 408 unsigned long *gpnum, unsigned long *completed); 409 void rcutorture_record_test_transition(void); 410 void rcutorture_record_progress(unsigned long vernum); 411 void do_trace_rcu_torture_read(const char *rcutorturename, 412 struct rcu_head *rhp, 413 unsigned long secs, 414 unsigned long c_old, 415 unsigned long c); 416 #else 417 static inline void rcutorture_get_gp_data(enum rcutorture_type test_type, 418 int *flags, 419 unsigned long *gpnum, 420 unsigned long *completed) 421 { 422 *flags = 0; 423 *gpnum = 0; 424 *completed = 0; 425 } 426 static inline void rcutorture_record_test_transition(void) { } 427 static inline void rcutorture_record_progress(unsigned long vernum) { } 428 #ifdef CONFIG_RCU_TRACE 429 void do_trace_rcu_torture_read(const char *rcutorturename, 430 struct rcu_head *rhp, 431 unsigned long secs, 432 unsigned long c_old, 433 unsigned long c); 434 #else 435 #define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ 436 do { } while (0) 437 #endif 438 #endif 439 440 #ifdef CONFIG_TINY_SRCU 441 442 static inline void srcutorture_get_gp_data(enum rcutorture_type test_type, 443 struct srcu_struct *sp, int *flags, 444 unsigned long *gpnum, 445 unsigned long *completed) 446 { 447 if (test_type != SRCU_FLAVOR) 448 return; 449 *flags = 0; 450 *completed = sp->srcu_idx; 451 *gpnum = *completed; 452 } 453 454 #elif defined(CONFIG_TREE_SRCU) 455 456 void srcutorture_get_gp_data(enum rcutorture_type test_type, 457 struct srcu_struct *sp, int *flags, 458 unsigned long *gpnum, unsigned long *completed); 459 460 #endif 461 462 #ifdef CONFIG_TINY_RCU 463 static inline unsigned long rcu_batches_started(void) { return 0; } 464 static inline unsigned long rcu_batches_started_bh(void) { return 0; } 465 static inline unsigned long rcu_batches_started_sched(void) { return 0; } 466 static inline unsigned long rcu_batches_completed(void) { return 0; } 467 static inline unsigned long rcu_batches_completed_bh(void) { return 0; } 468 static inline unsigned long rcu_batches_completed_sched(void) { return 0; } 469 static inline unsigned long rcu_exp_batches_completed(void) { return 0; } 470 static inline unsigned long rcu_exp_batches_completed_sched(void) { return 0; } 471 static inline unsigned long 472 srcu_batches_completed(struct srcu_struct *sp) { return 0; } 473 static inline void rcu_force_quiescent_state(void) { } 474 static inline void rcu_bh_force_quiescent_state(void) { } 475 static inline void rcu_sched_force_quiescent_state(void) { } 476 static inline void show_rcu_gp_kthreads(void) { } 477 #else /* #ifdef CONFIG_TINY_RCU */ 478 extern unsigned long rcutorture_testseq; 479 extern unsigned long rcutorture_vernum; 480 unsigned long rcu_batches_started(void); 481 unsigned long rcu_batches_started_bh(void); 482 unsigned long rcu_batches_started_sched(void); 483 unsigned long rcu_batches_completed(void); 484 unsigned long rcu_batches_completed_bh(void); 485 unsigned long rcu_batches_completed_sched(void); 486 unsigned long rcu_exp_batches_completed(void); 487 unsigned long rcu_exp_batches_completed_sched(void); 488 unsigned long srcu_batches_completed(struct srcu_struct *sp); 489 void show_rcu_gp_kthreads(void); 490 void rcu_force_quiescent_state(void); 491 void rcu_bh_force_quiescent_state(void); 492 void rcu_sched_force_quiescent_state(void); 493 extern struct workqueue_struct *rcu_gp_wq; 494 extern struct workqueue_struct *rcu_par_gp_wq; 495 #endif /* #else #ifdef CONFIG_TINY_RCU */ 496 497 #ifdef CONFIG_RCU_NOCB_CPU 498 bool rcu_is_nocb_cpu(int cpu); 499 #else 500 static inline bool rcu_is_nocb_cpu(int cpu) { return false; } 501 #endif 502 503 #endif /* __LINUX_RCU_H */ 504