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 /* Adjust sequence number for end of update-side operation. */ 81 static inline void rcu_seq_end(unsigned long *sp) 82 { 83 smp_mb(); /* Ensure update-side operation before counter increment. */ 84 WARN_ON_ONCE(!rcu_seq_state(*sp)); 85 WRITE_ONCE(*sp, (*sp | RCU_SEQ_STATE_MASK) + 1); 86 } 87 88 /* Take a snapshot of the update side's sequence number. */ 89 static inline unsigned long rcu_seq_snap(unsigned long *sp) 90 { 91 unsigned long s; 92 93 s = (READ_ONCE(*sp) + 2 * RCU_SEQ_STATE_MASK + 1) & ~RCU_SEQ_STATE_MASK; 94 smp_mb(); /* Above access must not bleed into critical section. */ 95 return s; 96 } 97 98 /* Return the current value the update side's sequence number, no ordering. */ 99 static inline unsigned long rcu_seq_current(unsigned long *sp) 100 { 101 return READ_ONCE(*sp); 102 } 103 104 /* 105 * Given a snapshot from rcu_seq_snap(), determine whether or not a 106 * full update-side operation has occurred. 107 */ 108 static inline bool rcu_seq_done(unsigned long *sp, unsigned long s) 109 { 110 return ULONG_CMP_GE(READ_ONCE(*sp), s); 111 } 112 113 /* 114 * debug_rcu_head_queue()/debug_rcu_head_unqueue() are used internally 115 * by call_rcu() and rcu callback execution, and are therefore not part of the 116 * RCU API. Leaving in rcupdate.h because they are used by all RCU flavors. 117 */ 118 119 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD 120 # define STATE_RCU_HEAD_READY 0 121 # define STATE_RCU_HEAD_QUEUED 1 122 123 extern struct debug_obj_descr rcuhead_debug_descr; 124 125 static inline int debug_rcu_head_queue(struct rcu_head *head) 126 { 127 int r1; 128 129 r1 = debug_object_activate(head, &rcuhead_debug_descr); 130 debug_object_active_state(head, &rcuhead_debug_descr, 131 STATE_RCU_HEAD_READY, 132 STATE_RCU_HEAD_QUEUED); 133 return r1; 134 } 135 136 static inline void debug_rcu_head_unqueue(struct rcu_head *head) 137 { 138 debug_object_active_state(head, &rcuhead_debug_descr, 139 STATE_RCU_HEAD_QUEUED, 140 STATE_RCU_HEAD_READY); 141 debug_object_deactivate(head, &rcuhead_debug_descr); 142 } 143 #else /* !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ 144 static inline int debug_rcu_head_queue(struct rcu_head *head) 145 { 146 return 0; 147 } 148 149 static inline void debug_rcu_head_unqueue(struct rcu_head *head) 150 { 151 } 152 #endif /* #else !CONFIG_DEBUG_OBJECTS_RCU_HEAD */ 153 154 void kfree(const void *); 155 156 /* 157 * Reclaim the specified callback, either by invoking it (non-lazy case) 158 * or freeing it directly (lazy case). Return true if lazy, false otherwise. 159 */ 160 static inline bool __rcu_reclaim(const char *rn, struct rcu_head *head) 161 { 162 unsigned long offset = (unsigned long)head->func; 163 164 rcu_lock_acquire(&rcu_callback_map); 165 if (__is_kfree_rcu_offset(offset)) { 166 RCU_TRACE(trace_rcu_invoke_kfree_callback(rn, head, offset);) 167 kfree((void *)head - offset); 168 rcu_lock_release(&rcu_callback_map); 169 return true; 170 } else { 171 RCU_TRACE(trace_rcu_invoke_callback(rn, head);) 172 head->func(head); 173 rcu_lock_release(&rcu_callback_map); 174 return false; 175 } 176 } 177 178 #ifdef CONFIG_RCU_STALL_COMMON 179 180 extern int rcu_cpu_stall_suppress; 181 int rcu_jiffies_till_stall_check(void); 182 183 #define rcu_ftrace_dump_stall_suppress() \ 184 do { \ 185 if (!rcu_cpu_stall_suppress) \ 186 rcu_cpu_stall_suppress = 3; \ 187 } while (0) 188 189 #define rcu_ftrace_dump_stall_unsuppress() \ 190 do { \ 191 if (rcu_cpu_stall_suppress == 3) \ 192 rcu_cpu_stall_suppress = 0; \ 193 } while (0) 194 195 #else /* #endif #ifdef CONFIG_RCU_STALL_COMMON */ 196 #define rcu_ftrace_dump_stall_suppress() 197 #define rcu_ftrace_dump_stall_unsuppress() 198 #endif /* #ifdef CONFIG_RCU_STALL_COMMON */ 199 200 /* 201 * Strings used in tracepoints need to be exported via the 202 * tracing system such that tools like perf and trace-cmd can 203 * translate the string address pointers to actual text. 204 */ 205 #define TPS(x) tracepoint_string(x) 206 207 /* 208 * Dump the ftrace buffer, but only one time per callsite per boot. 209 */ 210 #define rcu_ftrace_dump(oops_dump_mode) \ 211 do { \ 212 static atomic_t ___rfd_beenhere = ATOMIC_INIT(0); \ 213 \ 214 if (!atomic_read(&___rfd_beenhere) && \ 215 !atomic_xchg(&___rfd_beenhere, 1)) { \ 216 tracing_off(); \ 217 rcu_ftrace_dump_stall_suppress(); \ 218 ftrace_dump(oops_dump_mode); \ 219 rcu_ftrace_dump_stall_unsuppress(); \ 220 } \ 221 } while (0) 222 223 void rcu_early_boot_tests(void); 224 void rcu_test_sync_prims(void); 225 226 /* 227 * This function really isn't for public consumption, but RCU is special in 228 * that context switches can allow the state machine to make progress. 229 */ 230 extern void resched_cpu(int cpu); 231 232 #if defined(SRCU) || !defined(TINY_RCU) 233 234 #include <linux/rcu_node_tree.h> 235 236 extern int rcu_num_lvls; 237 extern int num_rcu_lvl[]; 238 extern int rcu_num_nodes; 239 static bool rcu_fanout_exact; 240 static int rcu_fanout_leaf; 241 242 /* 243 * Compute the per-level fanout, either using the exact fanout specified 244 * or balancing the tree, depending on the rcu_fanout_exact boot parameter. 245 */ 246 static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) 247 { 248 int i; 249 250 if (rcu_fanout_exact) { 251 levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf; 252 for (i = rcu_num_lvls - 2; i >= 0; i--) 253 levelspread[i] = RCU_FANOUT; 254 } else { 255 int ccur; 256 int cprv; 257 258 cprv = nr_cpu_ids; 259 for (i = rcu_num_lvls - 1; i >= 0; i--) { 260 ccur = levelcnt[i]; 261 levelspread[i] = (cprv + ccur - 1) / ccur; 262 cprv = ccur; 263 } 264 } 265 } 266 267 /* 268 * Do a full breadth-first scan of the rcu_node structures for the 269 * specified rcu_state structure. 270 */ 271 #define rcu_for_each_node_breadth_first(rsp, rnp) \ 272 for ((rnp) = &(rsp)->node[0]; \ 273 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 274 275 /* 276 * Do a breadth-first scan of the non-leaf rcu_node structures for the 277 * specified rcu_state structure. Note that if there is a singleton 278 * rcu_node tree with but one rcu_node structure, this loop is a no-op. 279 */ 280 #define rcu_for_each_nonleaf_node_breadth_first(rsp, rnp) \ 281 for ((rnp) = &(rsp)->node[0]; \ 282 (rnp) < (rsp)->level[rcu_num_lvls - 1]; (rnp)++) 283 284 /* 285 * Scan the leaves of the rcu_node hierarchy for the specified rcu_state 286 * structure. Note that if there is a singleton rcu_node tree with but 287 * one rcu_node structure, this loop -will- visit the rcu_node structure. 288 * It is still a leaf node, even if it is also the root node. 289 */ 290 #define rcu_for_each_leaf_node(rsp, rnp) \ 291 for ((rnp) = (rsp)->level[rcu_num_lvls - 1]; \ 292 (rnp) < &(rsp)->node[rcu_num_nodes]; (rnp)++) 293 294 /* 295 * Iterate over all possible CPUs in a leaf RCU node. 296 */ 297 #define for_each_leaf_node_possible_cpu(rnp, cpu) \ 298 for ((cpu) = cpumask_next(rnp->grplo - 1, cpu_possible_mask); \ 299 cpu <= rnp->grphi; \ 300 cpu = cpumask_next((cpu), cpu_possible_mask)) 301 302 /* 303 * Wrappers for the rcu_node::lock acquire and release. 304 * 305 * Because the rcu_nodes form a tree, the tree traversal locking will observe 306 * different lock values, this in turn means that an UNLOCK of one level 307 * followed by a LOCK of another level does not imply a full memory barrier; 308 * and most importantly transitivity is lost. 309 * 310 * In order to restore full ordering between tree levels, augment the regular 311 * lock acquire functions with smp_mb__after_unlock_lock(). 312 * 313 * As ->lock of struct rcu_node is a __private field, therefore one should use 314 * these wrappers rather than directly call raw_spin_{lock,unlock}* on ->lock. 315 */ 316 #define raw_spin_lock_rcu_node(p) \ 317 do { \ 318 raw_spin_lock(&ACCESS_PRIVATE(p, lock)); \ 319 smp_mb__after_unlock_lock(); \ 320 } while (0) 321 322 #define raw_spin_unlock_rcu_node(p) raw_spin_unlock(&ACCESS_PRIVATE(p, lock)) 323 324 #define raw_spin_lock_irq_rcu_node(p) \ 325 do { \ 326 raw_spin_lock_irq(&ACCESS_PRIVATE(p, lock)); \ 327 smp_mb__after_unlock_lock(); \ 328 } while (0) 329 330 #define raw_spin_unlock_irq_rcu_node(p) \ 331 raw_spin_unlock_irq(&ACCESS_PRIVATE(p, lock)) 332 333 #define raw_spin_lock_irqsave_rcu_node(p, flags) \ 334 do { \ 335 raw_spin_lock_irqsave(&ACCESS_PRIVATE(p, lock), flags); \ 336 smp_mb__after_unlock_lock(); \ 337 } while (0) 338 339 #define raw_spin_unlock_irqrestore_rcu_node(p, flags) \ 340 raw_spin_unlock_irqrestore(&ACCESS_PRIVATE(p, lock), flags) \ 341 342 #define raw_spin_trylock_rcu_node(p) \ 343 ({ \ 344 bool ___locked = raw_spin_trylock(&ACCESS_PRIVATE(p, lock)); \ 345 \ 346 if (___locked) \ 347 smp_mb__after_unlock_lock(); \ 348 ___locked; \ 349 }) 350 351 #endif /* #if defined(SRCU) || !defined(TINY_RCU) */ 352 353 #ifdef CONFIG_TINY_RCU 354 /* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */ 355 static inline bool rcu_gp_is_normal(void) { return true; } 356 static inline bool rcu_gp_is_expedited(void) { return false; } 357 static inline void rcu_expedite_gp(void) { } 358 static inline void rcu_unexpedite_gp(void) { } 359 #else /* #ifdef CONFIG_TINY_RCU */ 360 bool rcu_gp_is_normal(void); /* Internal RCU use. */ 361 bool rcu_gp_is_expedited(void); /* Internal RCU use. */ 362 void rcu_expedite_gp(void); 363 void rcu_unexpedite_gp(void); 364 void rcupdate_announce_bootup_oddness(void); 365 #endif /* #else #ifdef CONFIG_TINY_RCU */ 366 367 #define RCU_SCHEDULER_INACTIVE 0 368 #define RCU_SCHEDULER_INIT 1 369 #define RCU_SCHEDULER_RUNNING 2 370 371 #ifdef CONFIG_TINY_RCU 372 static inline void rcu_request_urgent_qs_task(struct task_struct *t) { } 373 #else /* #ifdef CONFIG_TINY_RCU */ 374 void rcu_request_urgent_qs_task(struct task_struct *t); 375 #endif /* #else #ifdef CONFIG_TINY_RCU */ 376 377 enum rcutorture_type { 378 RCU_FLAVOR, 379 RCU_BH_FLAVOR, 380 RCU_SCHED_FLAVOR, 381 RCU_TASKS_FLAVOR, 382 SRCU_FLAVOR, 383 INVALID_RCU_FLAVOR 384 }; 385 386 #if defined(CONFIG_TREE_RCU) || defined(CONFIG_PREEMPT_RCU) 387 void rcutorture_get_gp_data(enum rcutorture_type test_type, int *flags, 388 unsigned long *gpnum, unsigned long *completed); 389 void rcutorture_record_test_transition(void); 390 void rcutorture_record_progress(unsigned long vernum); 391 void do_trace_rcu_torture_read(const char *rcutorturename, 392 struct rcu_head *rhp, 393 unsigned long secs, 394 unsigned long c_old, 395 unsigned long c); 396 #else 397 static inline void rcutorture_get_gp_data(enum rcutorture_type test_type, 398 int *flags, 399 unsigned long *gpnum, 400 unsigned long *completed) 401 { 402 *flags = 0; 403 *gpnum = 0; 404 *completed = 0; 405 } 406 static inline void rcutorture_record_test_transition(void) { } 407 static inline void rcutorture_record_progress(unsigned long vernum) { } 408 #ifdef CONFIG_RCU_TRACE 409 void do_trace_rcu_torture_read(const char *rcutorturename, 410 struct rcu_head *rhp, 411 unsigned long secs, 412 unsigned long c_old, 413 unsigned long c); 414 #else 415 #define do_trace_rcu_torture_read(rcutorturename, rhp, secs, c_old, c) \ 416 do { } while (0) 417 #endif 418 #endif 419 420 #ifdef CONFIG_TINY_SRCU 421 422 static inline void srcutorture_get_gp_data(enum rcutorture_type test_type, 423 struct srcu_struct *sp, int *flags, 424 unsigned long *gpnum, 425 unsigned long *completed) 426 { 427 if (test_type != SRCU_FLAVOR) 428 return; 429 *flags = 0; 430 *completed = sp->srcu_idx; 431 *gpnum = *completed; 432 } 433 434 #elif defined(CONFIG_TREE_SRCU) 435 436 void srcutorture_get_gp_data(enum rcutorture_type test_type, 437 struct srcu_struct *sp, int *flags, 438 unsigned long *gpnum, unsigned long *completed); 439 440 #endif 441 442 #ifdef CONFIG_TINY_RCU 443 static inline unsigned long rcu_batches_started(void) { return 0; } 444 static inline unsigned long rcu_batches_started_bh(void) { return 0; } 445 static inline unsigned long rcu_batches_started_sched(void) { return 0; } 446 static inline unsigned long rcu_batches_completed(void) { return 0; } 447 static inline unsigned long rcu_batches_completed_bh(void) { return 0; } 448 static inline unsigned long rcu_batches_completed_sched(void) { return 0; } 449 static inline unsigned long rcu_exp_batches_completed(void) { return 0; } 450 static inline unsigned long rcu_exp_batches_completed_sched(void) { return 0; } 451 static inline unsigned long 452 srcu_batches_completed(struct srcu_struct *sp) { return 0; } 453 static inline void rcu_force_quiescent_state(void) { } 454 static inline void rcu_bh_force_quiescent_state(void) { } 455 static inline void rcu_sched_force_quiescent_state(void) { } 456 static inline void show_rcu_gp_kthreads(void) { } 457 #else /* #ifdef CONFIG_TINY_RCU */ 458 extern unsigned long rcutorture_testseq; 459 extern unsigned long rcutorture_vernum; 460 unsigned long rcu_batches_started(void); 461 unsigned long rcu_batches_started_bh(void); 462 unsigned long rcu_batches_started_sched(void); 463 unsigned long rcu_batches_completed(void); 464 unsigned long rcu_batches_completed_bh(void); 465 unsigned long rcu_batches_completed_sched(void); 466 unsigned long rcu_exp_batches_completed(void); 467 unsigned long rcu_exp_batches_completed_sched(void); 468 unsigned long srcu_batches_completed(struct srcu_struct *sp); 469 void show_rcu_gp_kthreads(void); 470 void rcu_force_quiescent_state(void); 471 void rcu_bh_force_quiescent_state(void); 472 void rcu_sched_force_quiescent_state(void); 473 #endif /* #else #ifdef CONFIG_TINY_RCU */ 474 475 #ifdef CONFIG_RCU_NOCB_CPU 476 bool rcu_is_nocb_cpu(int cpu); 477 #else 478 static inline bool rcu_is_nocb_cpu(int cpu) { return false; } 479 #endif 480 481 #endif /* __LINUX_RCU_H */ 482