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 int 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 int lock_state, rval; 218 219 td = curthread; 220 lock_state = 0; 221 #ifdef KTRACE 222 if (KTRPOINT(td, KTR_CSW)) 223 ktrcsw(1, 0, cv_wmesg(cvp)); 224 #endif 225 CV_ASSERT(cvp, lock, td); 226 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 227 "Waiting on \"%s\"", cvp->cv_description); 228 class = LOCK_CLASS(lock); 229 230 if (cold || panicstr) { 231 /* 232 * After a panic, or during autoconfiguration, just give 233 * interrupts a chance, then just return; don't run any other 234 * procs or panic below, in case this is the idle process and 235 * already asleep. 236 */ 237 return (0); 238 } 239 240 sleepq_lock(cvp); 241 242 cvp->cv_waiters++; 243 if (lock == &Giant.lock_object) 244 mtx_assert(&Giant, MA_OWNED); 245 DROP_GIANT(); 246 247 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 248 SLEEPQ_INTERRUPTIBLE, 0); 249 if (lock != &Giant.lock_object) { 250 if (class->lc_flags & LC_SLEEPABLE) 251 sleepq_release(cvp); 252 WITNESS_SAVE(lock, lock_witness); 253 lock_state = class->lc_unlock(lock); 254 if (class->lc_flags & LC_SLEEPABLE) 255 sleepq_lock(cvp); 256 } 257 rval = sleepq_wait_sig(cvp, 0); 258 259 #ifdef KTRACE 260 if (KTRPOINT(td, KTR_CSW)) 261 ktrcsw(0, 0, cv_wmesg(cvp)); 262 #endif 263 PICKUP_GIANT(); 264 if (lock != &Giant.lock_object) { 265 class->lc_lock(lock, lock_state); 266 WITNESS_RESTORE(lock, lock_witness); 267 } 268 269 return (rval); 270 } 271 272 /* 273 * Wait on a condition variable for (at most) the value specified in sbt 274 * argument. Returns 0 if the process was resumed by cv_signal or cv_broadcast, 275 * EWOULDBLOCK if the timeout expires. 276 */ 277 int 278 _cv_timedwait_sbt(struct cv *cvp, struct lock_object *lock, sbintime_t sbt, 279 sbintime_t pr, int flags) 280 { 281 WITNESS_SAVE_DECL(lock_witness); 282 struct lock_class *class; 283 struct thread *td; 284 int lock_state, rval; 285 286 td = curthread; 287 lock_state = 0; 288 #ifdef KTRACE 289 if (KTRPOINT(td, KTR_CSW)) 290 ktrcsw(1, 0, cv_wmesg(cvp)); 291 #endif 292 CV_ASSERT(cvp, lock, td); 293 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 294 "Waiting on \"%s\"", cvp->cv_description); 295 class = LOCK_CLASS(lock); 296 297 if (cold || panicstr) { 298 /* 299 * After a panic, or during autoconfiguration, just give 300 * interrupts a chance, then just return; don't run any other 301 * thread or panic below, in case this is the idle process and 302 * already asleep. 303 */ 304 return 0; 305 } 306 307 sleepq_lock(cvp); 308 309 cvp->cv_waiters++; 310 if (lock == &Giant.lock_object) 311 mtx_assert(&Giant, MA_OWNED); 312 DROP_GIANT(); 313 314 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 315 sleepq_set_timeout_sbt(cvp, sbt, pr, flags); 316 if (lock != &Giant.lock_object) { 317 if (class->lc_flags & LC_SLEEPABLE) 318 sleepq_release(cvp); 319 WITNESS_SAVE(lock, lock_witness); 320 lock_state = class->lc_unlock(lock); 321 if (class->lc_flags & LC_SLEEPABLE) 322 sleepq_lock(cvp); 323 } 324 rval = sleepq_timedwait(cvp, 0); 325 326 #ifdef KTRACE 327 if (KTRPOINT(td, KTR_CSW)) 328 ktrcsw(0, 0, cv_wmesg(cvp)); 329 #endif 330 PICKUP_GIANT(); 331 if (lock != &Giant.lock_object) { 332 class->lc_lock(lock, lock_state); 333 WITNESS_RESTORE(lock, lock_witness); 334 } 335 336 return (rval); 337 } 338 339 /* 340 * Wait on a condition variable for (at most) the value specified in sbt 341 * argument, allowing interruption by signals. 342 * Returns 0 if the thread was resumed by cv_signal or cv_broadcast, 343 * EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if a signal 344 * was caught. 345 */ 346 int 347 _cv_timedwait_sig_sbt(struct cv *cvp, struct lock_object *lock, 348 sbintime_t sbt, sbintime_t pr, int flags) 349 { 350 WITNESS_SAVE_DECL(lock_witness); 351 struct lock_class *class; 352 struct thread *td; 353 int lock_state, rval; 354 355 td = curthread; 356 lock_state = 0; 357 #ifdef KTRACE 358 if (KTRPOINT(td, KTR_CSW)) 359 ktrcsw(1, 0, cv_wmesg(cvp)); 360 #endif 361 CV_ASSERT(cvp, lock, td); 362 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 363 "Waiting on \"%s\"", cvp->cv_description); 364 class = LOCK_CLASS(lock); 365 366 if (cold || panicstr) { 367 /* 368 * After a panic, or during autoconfiguration, just give 369 * interrupts a chance, then just return; don't run any other 370 * thread or panic below, in case this is the idle process and 371 * already asleep. 372 */ 373 return 0; 374 } 375 376 sleepq_lock(cvp); 377 378 cvp->cv_waiters++; 379 if (lock == &Giant.lock_object) 380 mtx_assert(&Giant, MA_OWNED); 381 DROP_GIANT(); 382 383 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 384 SLEEPQ_INTERRUPTIBLE, 0); 385 sleepq_set_timeout_sbt(cvp, sbt, pr, flags); 386 if (lock != &Giant.lock_object) { 387 if (class->lc_flags & LC_SLEEPABLE) 388 sleepq_release(cvp); 389 WITNESS_SAVE(lock, lock_witness); 390 lock_state = class->lc_unlock(lock); 391 if (class->lc_flags & LC_SLEEPABLE) 392 sleepq_lock(cvp); 393 } 394 rval = sleepq_timedwait_sig(cvp, 0); 395 396 #ifdef KTRACE 397 if (KTRPOINT(td, KTR_CSW)) 398 ktrcsw(0, 0, cv_wmesg(cvp)); 399 #endif 400 PICKUP_GIANT(); 401 if (lock != &Giant.lock_object) { 402 class->lc_lock(lock, lock_state); 403 WITNESS_RESTORE(lock, lock_witness); 404 } 405 406 return (rval); 407 } 408 409 /* 410 * Signal a condition variable, wakes up one waiting thread. Will also wakeup 411 * the swapper if the process is not in memory, so that it can bring the 412 * sleeping process in. Note that this may also result in additional threads 413 * being made runnable. Should be called with the same mutex as was passed to 414 * cv_wait held. 415 */ 416 void 417 cv_signal(struct cv *cvp) 418 { 419 int wakeup_swapper; 420 421 wakeup_swapper = 0; 422 sleepq_lock(cvp); 423 if (cvp->cv_waiters > 0) { 424 cvp->cv_waiters--; 425 wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0, 0); 426 } 427 sleepq_release(cvp); 428 if (wakeup_swapper) 429 kick_proc0(); 430 } 431 432 /* 433 * Broadcast a signal to a condition variable. Wakes up all waiting threads. 434 * Should be called with the same mutex as was passed to cv_wait held. 435 */ 436 void 437 cv_broadcastpri(struct cv *cvp, int pri) 438 { 439 int wakeup_swapper; 440 441 /* 442 * XXX sleepq_broadcast pri argument changed from -1 meaning 443 * no pri to 0 meaning no pri. 444 */ 445 wakeup_swapper = 0; 446 if (pri == -1) 447 pri = 0; 448 sleepq_lock(cvp); 449 if (cvp->cv_waiters > 0) { 450 cvp->cv_waiters = 0; 451 wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0); 452 } 453 sleepq_release(cvp); 454 if (wakeup_swapper) 455 kick_proc0(); 456 } 457