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 atomic_add_int(&cvp->cv_waiters, 1); 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 atomic_subtract_int(&cvp->cv_waiters, 1); 141 142 #ifdef KTRACE 143 if (KTRPOINT(td, KTR_CSW)) 144 ktrcsw(0, 0, cv_wmesg(cvp)); 145 #endif 146 PICKUP_GIANT(); 147 if (lock != &Giant.lock_object) { 148 class->lc_lock(lock, lock_state); 149 WITNESS_RESTORE(lock, lock_witness); 150 } 151 } 152 153 /* 154 * Wait on a condition variable. This function differs from cv_wait by 155 * not aquiring the mutex after condition variable was signaled. 156 */ 157 void 158 _cv_wait_unlock(struct cv *cvp, struct lock_object *lock) 159 { 160 struct lock_class *class; 161 struct thread *td; 162 163 td = curthread; 164 #ifdef KTRACE 165 if (KTRPOINT(td, KTR_CSW)) 166 ktrcsw(1, 0, cv_wmesg(cvp)); 167 #endif 168 CV_ASSERT(cvp, lock, td); 169 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 170 "Waiting on \"%s\"", cvp->cv_description); 171 KASSERT(lock != &Giant.lock_object, 172 ("cv_wait_unlock cannot be used with Giant")); 173 class = LOCK_CLASS(lock); 174 175 if (cold || panicstr) { 176 /* 177 * During autoconfiguration, just give interrupts 178 * a chance, then just return. Don't run any other 179 * thread or panic below, in case this is the idle 180 * process and already asleep. 181 */ 182 class->lc_unlock(lock); 183 return; 184 } 185 186 sleepq_lock(cvp); 187 188 atomic_add_int(&cvp->cv_waiters, 1); 189 DROP_GIANT(); 190 191 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 192 if (class->lc_flags & LC_SLEEPABLE) 193 sleepq_release(cvp); 194 class->lc_unlock(lock); 195 if (class->lc_flags & LC_SLEEPABLE) 196 sleepq_lock(cvp); 197 sleepq_wait(cvp, 0); 198 atomic_subtract_int(&cvp->cv_waiters, 1); 199 200 #ifdef KTRACE 201 if (KTRPOINT(td, KTR_CSW)) 202 ktrcsw(0, 0, cv_wmesg(cvp)); 203 #endif 204 PICKUP_GIANT(); 205 } 206 207 /* 208 * Wait on a condition variable, allowing interruption by signals. Return 0 if 209 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if 210 * a signal was caught. If ERESTART is returned the system call should be 211 * restarted if possible. 212 */ 213 int 214 _cv_wait_sig(struct cv *cvp, struct lock_object *lock) 215 { 216 WITNESS_SAVE_DECL(lock_witness); 217 struct lock_class *class; 218 struct thread *td; 219 uintptr_t lock_state; 220 int rval; 221 222 td = curthread; 223 lock_state = 0; 224 #ifdef KTRACE 225 if (KTRPOINT(td, KTR_CSW)) 226 ktrcsw(1, 0, cv_wmesg(cvp)); 227 #endif 228 CV_ASSERT(cvp, lock, td); 229 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 230 "Waiting on \"%s\"", cvp->cv_description); 231 class = LOCK_CLASS(lock); 232 233 if (cold || panicstr) { 234 /* 235 * After a panic, or during autoconfiguration, just give 236 * interrupts a chance, then just return; don't run any other 237 * procs or panic below, in case this is the idle process and 238 * already asleep. 239 */ 240 return (0); 241 } 242 243 sleepq_lock(cvp); 244 245 atomic_add_int(&cvp->cv_waiters, 1); 246 if (lock == &Giant.lock_object) 247 mtx_assert(&Giant, MA_OWNED); 248 DROP_GIANT(); 249 250 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 251 SLEEPQ_INTERRUPTIBLE, 0); 252 if (lock != &Giant.lock_object) { 253 if (class->lc_flags & LC_SLEEPABLE) 254 sleepq_release(cvp); 255 WITNESS_SAVE(lock, lock_witness); 256 lock_state = class->lc_unlock(lock); 257 if (class->lc_flags & LC_SLEEPABLE) 258 sleepq_lock(cvp); 259 } 260 rval = sleepq_wait_sig(cvp, 0); 261 atomic_subtract_int(&cvp->cv_waiters, 1); 262 263 #ifdef KTRACE 264 if (KTRPOINT(td, KTR_CSW)) 265 ktrcsw(0, 0, cv_wmesg(cvp)); 266 #endif 267 PICKUP_GIANT(); 268 if (lock != &Giant.lock_object) { 269 class->lc_lock(lock, lock_state); 270 WITNESS_RESTORE(lock, lock_witness); 271 } 272 273 return (rval); 274 } 275 276 /* 277 * Wait on a condition variable for (at most) the value specified in sbt 278 * argument. Returns 0 if the process was resumed by cv_signal or cv_broadcast, 279 * EWOULDBLOCK if the timeout expires. 280 */ 281 int 282 _cv_timedwait_sbt(struct cv *cvp, struct lock_object *lock, sbintime_t sbt, 283 sbintime_t pr, int flags) 284 { 285 WITNESS_SAVE_DECL(lock_witness); 286 struct lock_class *class; 287 struct thread *td; 288 int lock_state, rval; 289 290 td = curthread; 291 lock_state = 0; 292 #ifdef KTRACE 293 if (KTRPOINT(td, KTR_CSW)) 294 ktrcsw(1, 0, cv_wmesg(cvp)); 295 #endif 296 CV_ASSERT(cvp, lock, td); 297 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 298 "Waiting on \"%s\"", cvp->cv_description); 299 class = LOCK_CLASS(lock); 300 301 if (cold || panicstr) { 302 /* 303 * After a panic, or during autoconfiguration, just give 304 * interrupts a chance, then just return; don't run any other 305 * thread or panic below, in case this is the idle process and 306 * already asleep. 307 */ 308 return 0; 309 } 310 311 sleepq_lock(cvp); 312 313 atomic_add_int(&cvp->cv_waiters, 1); 314 if (lock == &Giant.lock_object) 315 mtx_assert(&Giant, MA_OWNED); 316 DROP_GIANT(); 317 318 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 319 sleepq_set_timeout_sbt(cvp, sbt, pr, flags); 320 if (lock != &Giant.lock_object) { 321 if (class->lc_flags & LC_SLEEPABLE) 322 sleepq_release(cvp); 323 WITNESS_SAVE(lock, lock_witness); 324 lock_state = class->lc_unlock(lock); 325 if (class->lc_flags & LC_SLEEPABLE) 326 sleepq_lock(cvp); 327 } 328 rval = sleepq_timedwait(cvp, 0); 329 atomic_subtract_int(&cvp->cv_waiters, 1); 330 331 #ifdef KTRACE 332 if (KTRPOINT(td, KTR_CSW)) 333 ktrcsw(0, 0, cv_wmesg(cvp)); 334 #endif 335 PICKUP_GIANT(); 336 if (lock != &Giant.lock_object) { 337 class->lc_lock(lock, lock_state); 338 WITNESS_RESTORE(lock, lock_witness); 339 } 340 341 return (rval); 342 } 343 344 /* 345 * Wait on a condition variable for (at most) the value specified in sbt 346 * argument, allowing interruption by signals. 347 * Returns 0 if the thread was resumed by cv_signal or cv_broadcast, 348 * EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if a signal 349 * was caught. 350 */ 351 int 352 _cv_timedwait_sig_sbt(struct cv *cvp, struct lock_object *lock, 353 sbintime_t sbt, sbintime_t pr, int flags) 354 { 355 WITNESS_SAVE_DECL(lock_witness); 356 struct lock_class *class; 357 struct thread *td; 358 int lock_state, rval; 359 360 td = curthread; 361 lock_state = 0; 362 #ifdef KTRACE 363 if (KTRPOINT(td, KTR_CSW)) 364 ktrcsw(1, 0, cv_wmesg(cvp)); 365 #endif 366 CV_ASSERT(cvp, lock, td); 367 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 368 "Waiting on \"%s\"", cvp->cv_description); 369 class = LOCK_CLASS(lock); 370 371 if (cold || panicstr) { 372 /* 373 * After a panic, or during autoconfiguration, just give 374 * interrupts a chance, then just return; don't run any other 375 * thread or panic below, in case this is the idle process and 376 * already asleep. 377 */ 378 return 0; 379 } 380 381 sleepq_lock(cvp); 382 383 atomic_add_int(&cvp->cv_waiters, 1); 384 if (lock == &Giant.lock_object) 385 mtx_assert(&Giant, MA_OWNED); 386 DROP_GIANT(); 387 388 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 389 SLEEPQ_INTERRUPTIBLE, 0); 390 sleepq_set_timeout_sbt(cvp, sbt, pr, flags); 391 if (lock != &Giant.lock_object) { 392 if (class->lc_flags & LC_SLEEPABLE) 393 sleepq_release(cvp); 394 WITNESS_SAVE(lock, lock_witness); 395 lock_state = class->lc_unlock(lock); 396 if (class->lc_flags & LC_SLEEPABLE) 397 sleepq_lock(cvp); 398 } 399 rval = sleepq_timedwait_sig(cvp, 0); 400 atomic_subtract_int(&cvp->cv_waiters, 1); 401 402 #ifdef KTRACE 403 if (KTRPOINT(td, KTR_CSW)) 404 ktrcsw(0, 0, cv_wmesg(cvp)); 405 #endif 406 PICKUP_GIANT(); 407 if (lock != &Giant.lock_object) { 408 class->lc_lock(lock, lock_state); 409 WITNESS_RESTORE(lock, lock_witness); 410 } 411 412 return (rval); 413 } 414 415 /* 416 * Signal a condition variable, wakes up one waiting thread. Will also wakeup 417 * the swapper if the process is not in memory, so that it can bring the 418 * sleeping process in. Note that this may also result in additional threads 419 * being made runnable. Should be called with the same mutex as was passed to 420 * cv_wait held. 421 */ 422 void 423 cv_signal(struct cv *cvp) 424 { 425 int wakeup_swapper; 426 427 wakeup_swapper = 0; 428 sleepq_lock(cvp); 429 if (cvp->cv_waiters > 0) 430 wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0, 0); 431 sleepq_release(cvp); 432 if (wakeup_swapper) 433 kick_proc0(); 434 } 435 436 /* 437 * Broadcast a signal to a condition variable. Wakes up all waiting threads. 438 * Should be called with the same mutex as was passed to cv_wait held. 439 */ 440 void 441 cv_broadcastpri(struct cv *cvp, int pri) 442 { 443 int wakeup_swapper; 444 445 /* 446 * XXX sleepq_broadcast pri argument changed from -1 meaning 447 * no pri to 0 meaning no pri. 448 */ 449 wakeup_swapper = 0; 450 if (pri == -1) 451 pri = 0; 452 sleepq_lock(cvp); 453 if (cvp->cv_waiters > 0) 454 wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0); 455 sleepq_release(cvp); 456 if (wakeup_swapper) 457 kick_proc0(); 458 } 459