1 /*- 2 * Copyright (c) 2000 Jake Burkholder <jake@freebsd.org>. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include "opt_ktrace.h" 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/lock.h> 35 #include <sys/mutex.h> 36 #include <sys/proc.h> 37 #include <sys/kernel.h> 38 #include <sys/ktr.h> 39 #include <sys/condvar.h> 40 #include <sys/sched.h> 41 #include <sys/signalvar.h> 42 #include <sys/sleepqueue.h> 43 #include <sys/resourcevar.h> 44 #ifdef KTRACE 45 #include <sys/uio.h> 46 #include <sys/ktrace.h> 47 #endif 48 49 /* 50 * Common sanity checks for cv_wait* functions. 51 */ 52 #define CV_ASSERT(cvp, lock, td) do { \ 53 KASSERT((td) != NULL, ("%s: td NULL", __func__)); \ 54 KASSERT(TD_IS_RUNNING(td), ("%s: not TDS_RUNNING", __func__)); \ 55 KASSERT((cvp) != NULL, ("%s: cvp NULL", __func__)); \ 56 KASSERT((lock) != NULL, ("%s: lock NULL", __func__)); \ 57 } while (0) 58 59 /* 60 * Initialize a condition variable. Must be called before use. 61 */ 62 void 63 cv_init(struct cv *cvp, const char *desc) 64 { 65 66 cvp->cv_description = desc; 67 cvp->cv_waiters = 0; 68 } 69 70 /* 71 * Destroy a condition variable. The condition variable must be re-initialized 72 * in order to be re-used. 73 */ 74 void 75 cv_destroy(struct cv *cvp) 76 { 77 #ifdef INVARIANTS 78 struct sleepqueue *sq; 79 80 sleepq_lock(cvp); 81 sq = sleepq_lookup(cvp); 82 sleepq_release(cvp); 83 KASSERT(sq == NULL, ("%s: associated sleep queue non-empty", __func__)); 84 #endif 85 } 86 87 /* 88 * Wait on a condition variable. The current thread is placed on the condition 89 * variable's wait queue and suspended. A cv_signal or cv_broadcast on the same 90 * condition variable will resume the thread. The mutex is released before 91 * sleeping and will be held on return. It is recommended that the mutex be 92 * held when cv_signal or cv_broadcast are called. 93 */ 94 void 95 _cv_wait(struct cv *cvp, struct lock_object *lock) 96 { 97 WITNESS_SAVE_DECL(lock_witness); 98 struct lock_class *class; 99 struct thread *td; 100 uintptr_t lock_state; 101 102 td = curthread; 103 lock_state = 0; 104 #ifdef KTRACE 105 if (KTRPOINT(td, KTR_CSW)) 106 ktrcsw(1, 0, cv_wmesg(cvp)); 107 #endif 108 CV_ASSERT(cvp, lock, td); 109 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 110 "Waiting on \"%s\"", cvp->cv_description); 111 class = LOCK_CLASS(lock); 112 113 if (cold || panicstr) { 114 /* 115 * During autoconfiguration, just give interrupts 116 * a chance, then just return. Don't run any other 117 * thread or panic below, in case this is the idle 118 * process and already asleep. 119 */ 120 return; 121 } 122 123 sleepq_lock(cvp); 124 125 cvp->cv_waiters++; 126 if (lock == &Giant.lock_object) 127 mtx_assert(&Giant, MA_OWNED); 128 DROP_GIANT(); 129 130 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 131 if (lock != &Giant.lock_object) { 132 if (class->lc_flags & LC_SLEEPABLE) 133 sleepq_release(cvp); 134 WITNESS_SAVE(lock, lock_witness); 135 lock_state = class->lc_unlock(lock); 136 if (class->lc_flags & LC_SLEEPABLE) 137 sleepq_lock(cvp); 138 } 139 sleepq_wait(cvp, 0); 140 141 #ifdef KTRACE 142 if (KTRPOINT(td, KTR_CSW)) 143 ktrcsw(0, 0, cv_wmesg(cvp)); 144 #endif 145 PICKUP_GIANT(); 146 if (lock != &Giant.lock_object) { 147 class->lc_lock(lock, lock_state); 148 WITNESS_RESTORE(lock, lock_witness); 149 } 150 } 151 152 /* 153 * Wait on a condition variable. This function differs from cv_wait by 154 * not aquiring the mutex after condition variable was signaled. 155 */ 156 void 157 _cv_wait_unlock(struct cv *cvp, struct lock_object *lock) 158 { 159 struct lock_class *class; 160 struct thread *td; 161 162 td = curthread; 163 #ifdef KTRACE 164 if (KTRPOINT(td, KTR_CSW)) 165 ktrcsw(1, 0, cv_wmesg(cvp)); 166 #endif 167 CV_ASSERT(cvp, lock, td); 168 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 169 "Waiting on \"%s\"", cvp->cv_description); 170 KASSERT(lock != &Giant.lock_object, 171 ("cv_wait_unlock cannot be used with Giant")); 172 class = LOCK_CLASS(lock); 173 174 if (cold || panicstr) { 175 /* 176 * During autoconfiguration, just give interrupts 177 * a chance, then just return. Don't run any other 178 * thread or panic below, in case this is the idle 179 * process and already asleep. 180 */ 181 class->lc_unlock(lock); 182 return; 183 } 184 185 sleepq_lock(cvp); 186 187 cvp->cv_waiters++; 188 DROP_GIANT(); 189 190 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 191 if (class->lc_flags & LC_SLEEPABLE) 192 sleepq_release(cvp); 193 class->lc_unlock(lock); 194 if (class->lc_flags & LC_SLEEPABLE) 195 sleepq_lock(cvp); 196 sleepq_wait(cvp, 0); 197 198 #ifdef KTRACE 199 if (KTRPOINT(td, KTR_CSW)) 200 ktrcsw(0, 0, cv_wmesg(cvp)); 201 #endif 202 PICKUP_GIANT(); 203 } 204 205 /* 206 * Wait on a condition variable, allowing interruption by signals. Return 0 if 207 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if 208 * a signal was caught. If ERESTART is returned the system call should be 209 * restarted if possible. 210 */ 211 int 212 _cv_wait_sig(struct cv *cvp, struct lock_object *lock) 213 { 214 WITNESS_SAVE_DECL(lock_witness); 215 struct lock_class *class; 216 struct thread *td; 217 uintptr_t lock_state; 218 int rval; 219 220 td = curthread; 221 lock_state = 0; 222 #ifdef KTRACE 223 if (KTRPOINT(td, KTR_CSW)) 224 ktrcsw(1, 0, cv_wmesg(cvp)); 225 #endif 226 CV_ASSERT(cvp, lock, td); 227 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 228 "Waiting on \"%s\"", cvp->cv_description); 229 class = LOCK_CLASS(lock); 230 231 if (cold || panicstr) { 232 /* 233 * After a panic, or during autoconfiguration, just give 234 * interrupts a chance, then just return; don't run any other 235 * procs or panic below, in case this is the idle process and 236 * already asleep. 237 */ 238 return (0); 239 } 240 241 sleepq_lock(cvp); 242 243 cvp->cv_waiters++; 244 if (lock == &Giant.lock_object) 245 mtx_assert(&Giant, MA_OWNED); 246 DROP_GIANT(); 247 248 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 249 SLEEPQ_INTERRUPTIBLE, 0); 250 if (lock != &Giant.lock_object) { 251 if (class->lc_flags & LC_SLEEPABLE) 252 sleepq_release(cvp); 253 WITNESS_SAVE(lock, lock_witness); 254 lock_state = class->lc_unlock(lock); 255 if (class->lc_flags & LC_SLEEPABLE) 256 sleepq_lock(cvp); 257 } 258 rval = sleepq_wait_sig(cvp, 0); 259 260 #ifdef KTRACE 261 if (KTRPOINT(td, KTR_CSW)) 262 ktrcsw(0, 0, cv_wmesg(cvp)); 263 #endif 264 PICKUP_GIANT(); 265 if (lock != &Giant.lock_object) { 266 class->lc_lock(lock, lock_state); 267 WITNESS_RESTORE(lock, lock_witness); 268 } 269 270 return (rval); 271 } 272 273 /* 274 * Wait on a condition variable for (at most) the value specified in sbt 275 * argument. Returns 0 if the process was resumed by cv_signal or cv_broadcast, 276 * EWOULDBLOCK if the timeout expires. 277 */ 278 int 279 _cv_timedwait_sbt(struct cv *cvp, struct lock_object *lock, sbintime_t sbt, 280 sbintime_t pr, int flags) 281 { 282 WITNESS_SAVE_DECL(lock_witness); 283 struct lock_class *class; 284 struct thread *td; 285 int lock_state, rval; 286 287 td = curthread; 288 lock_state = 0; 289 #ifdef KTRACE 290 if (KTRPOINT(td, KTR_CSW)) 291 ktrcsw(1, 0, cv_wmesg(cvp)); 292 #endif 293 CV_ASSERT(cvp, lock, td); 294 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 295 "Waiting on \"%s\"", cvp->cv_description); 296 class = LOCK_CLASS(lock); 297 298 if (cold || panicstr) { 299 /* 300 * After a panic, or during autoconfiguration, just give 301 * interrupts a chance, then just return; don't run any other 302 * thread or panic below, in case this is the idle process and 303 * already asleep. 304 */ 305 return 0; 306 } 307 308 sleepq_lock(cvp); 309 310 cvp->cv_waiters++; 311 if (lock == &Giant.lock_object) 312 mtx_assert(&Giant, MA_OWNED); 313 DROP_GIANT(); 314 315 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 316 sleepq_set_timeout_sbt(cvp, sbt, pr, flags); 317 if (lock != &Giant.lock_object) { 318 if (class->lc_flags & LC_SLEEPABLE) 319 sleepq_release(cvp); 320 WITNESS_SAVE(lock, lock_witness); 321 lock_state = class->lc_unlock(lock); 322 if (class->lc_flags & LC_SLEEPABLE) 323 sleepq_lock(cvp); 324 } 325 rval = sleepq_timedwait(cvp, 0); 326 327 #ifdef KTRACE 328 if (KTRPOINT(td, KTR_CSW)) 329 ktrcsw(0, 0, cv_wmesg(cvp)); 330 #endif 331 PICKUP_GIANT(); 332 if (lock != &Giant.lock_object) { 333 class->lc_lock(lock, lock_state); 334 WITNESS_RESTORE(lock, lock_witness); 335 } 336 337 return (rval); 338 } 339 340 /* 341 * Wait on a condition variable for (at most) the value specified in sbt 342 * argument, allowing interruption by signals. 343 * Returns 0 if the thread was resumed by cv_signal or cv_broadcast, 344 * EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if a signal 345 * was caught. 346 */ 347 int 348 _cv_timedwait_sig_sbt(struct cv *cvp, struct lock_object *lock, 349 sbintime_t sbt, sbintime_t pr, int flags) 350 { 351 WITNESS_SAVE_DECL(lock_witness); 352 struct lock_class *class; 353 struct thread *td; 354 int lock_state, rval; 355 356 td = curthread; 357 lock_state = 0; 358 #ifdef KTRACE 359 if (KTRPOINT(td, KTR_CSW)) 360 ktrcsw(1, 0, cv_wmesg(cvp)); 361 #endif 362 CV_ASSERT(cvp, lock, td); 363 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 364 "Waiting on \"%s\"", cvp->cv_description); 365 class = LOCK_CLASS(lock); 366 367 if (cold || panicstr) { 368 /* 369 * After a panic, or during autoconfiguration, just give 370 * interrupts a chance, then just return; don't run any other 371 * thread or panic below, in case this is the idle process and 372 * already asleep. 373 */ 374 return 0; 375 } 376 377 sleepq_lock(cvp); 378 379 cvp->cv_waiters++; 380 if (lock == &Giant.lock_object) 381 mtx_assert(&Giant, MA_OWNED); 382 DROP_GIANT(); 383 384 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 385 SLEEPQ_INTERRUPTIBLE, 0); 386 sleepq_set_timeout_sbt(cvp, sbt, pr, flags); 387 if (lock != &Giant.lock_object) { 388 if (class->lc_flags & LC_SLEEPABLE) 389 sleepq_release(cvp); 390 WITNESS_SAVE(lock, lock_witness); 391 lock_state = class->lc_unlock(lock); 392 if (class->lc_flags & LC_SLEEPABLE) 393 sleepq_lock(cvp); 394 } 395 rval = sleepq_timedwait_sig(cvp, 0); 396 397 #ifdef KTRACE 398 if (KTRPOINT(td, KTR_CSW)) 399 ktrcsw(0, 0, cv_wmesg(cvp)); 400 #endif 401 PICKUP_GIANT(); 402 if (lock != &Giant.lock_object) { 403 class->lc_lock(lock, lock_state); 404 WITNESS_RESTORE(lock, lock_witness); 405 } 406 407 return (rval); 408 } 409 410 /* 411 * Signal a condition variable, wakes up one waiting thread. Will also wakeup 412 * the swapper if the process is not in memory, so that it can bring the 413 * sleeping process in. Note that this may also result in additional threads 414 * being made runnable. Should be called with the same mutex as was passed to 415 * cv_wait held. 416 */ 417 void 418 cv_signal(struct cv *cvp) 419 { 420 int wakeup_swapper; 421 422 wakeup_swapper = 0; 423 sleepq_lock(cvp); 424 if (cvp->cv_waiters > 0) { 425 cvp->cv_waiters--; 426 wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0, 0); 427 } 428 sleepq_release(cvp); 429 if (wakeup_swapper) 430 kick_proc0(); 431 } 432 433 /* 434 * Broadcast a signal to a condition variable. Wakes up all waiting threads. 435 * Should be called with the same mutex as was passed to cv_wait held. 436 */ 437 void 438 cv_broadcastpri(struct cv *cvp, int pri) 439 { 440 int wakeup_swapper; 441 442 /* 443 * XXX sleepq_broadcast pri argument changed from -1 meaning 444 * no pri to 0 meaning no pri. 445 */ 446 wakeup_swapper = 0; 447 if (pri == -1) 448 pri = 0; 449 sleepq_lock(cvp); 450 if (cvp->cv_waiters > 0) { 451 cvp->cv_waiters = 0; 452 wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0); 453 } 454 sleepq_release(cvp); 455 if (wakeup_swapper) 456 kick_proc0(); 457 } 458