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: curthread 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); 107 #endif 108 CV_ASSERT(cvp, lock, td); 109 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 110 "Waiting on \"%s\"", cvp->cv_description); 111 WITNESS_SAVE(lock, lock_witness); 112 class = LOCK_CLASS(lock); 113 114 if (cold || panicstr) { 115 /* 116 * During autoconfiguration, just give interrupts 117 * a chance, then just return. Don't run any other 118 * thread or panic below, in case this is the idle 119 * process and already asleep. 120 */ 121 return; 122 } 123 124 sleepq_lock(cvp); 125 126 cvp->cv_waiters++; 127 DROP_GIANT(); 128 129 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 130 if (lock != &Giant.lock_object) { 131 if (class->lc_flags & LC_SLEEPABLE) 132 sleepq_release(cvp); 133 lock_state = class->lc_unlock(lock); 134 if (class->lc_flags & LC_SLEEPABLE) 135 sleepq_lock(cvp); 136 } 137 sleepq_wait(cvp, 0); 138 139 #ifdef KTRACE 140 if (KTRPOINT(td, KTR_CSW)) 141 ktrcsw(0, 0); 142 #endif 143 PICKUP_GIANT(); 144 if (lock != &Giant.lock_object) { 145 class->lc_lock(lock, lock_state); 146 WITNESS_RESTORE(lock, lock_witness); 147 } 148 } 149 150 /* 151 * Wait on a condition variable. This function differs from cv_wait by 152 * not aquiring the mutex after condition variable was signaled. 153 */ 154 void 155 _cv_wait_unlock(struct cv *cvp, struct lock_object *lock) 156 { 157 struct lock_class *class; 158 struct thread *td; 159 160 td = curthread; 161 #ifdef KTRACE 162 if (KTRPOINT(td, KTR_CSW)) 163 ktrcsw(1, 0); 164 #endif 165 CV_ASSERT(cvp, lock, td); 166 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 167 "Waiting on \"%s\"", cvp->cv_description); 168 KASSERT(lock != &Giant.lock_object, 169 ("cv_wait_unlock cannot be used with Giant")); 170 class = LOCK_CLASS(lock); 171 172 if (cold || panicstr) { 173 /* 174 * During autoconfiguration, just give interrupts 175 * a chance, then just return. Don't run any other 176 * thread or panic below, in case this is the idle 177 * process and already asleep. 178 */ 179 class->lc_unlock(lock); 180 return; 181 } 182 183 sleepq_lock(cvp); 184 185 cvp->cv_waiters++; 186 DROP_GIANT(); 187 188 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 189 if (class->lc_flags & LC_SLEEPABLE) 190 sleepq_release(cvp); 191 class->lc_unlock(lock); 192 if (class->lc_flags & LC_SLEEPABLE) 193 sleepq_lock(cvp); 194 sleepq_wait(cvp, 0); 195 196 #ifdef KTRACE 197 if (KTRPOINT(td, KTR_CSW)) 198 ktrcsw(0, 0); 199 #endif 200 PICKUP_GIANT(); 201 } 202 203 /* 204 * Wait on a condition variable, allowing interruption by signals. Return 0 if 205 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if 206 * a signal was caught. If ERESTART is returned the system call should be 207 * restarted if possible. 208 */ 209 int 210 _cv_wait_sig(struct cv *cvp, struct lock_object *lock) 211 { 212 WITNESS_SAVE_DECL(lock_witness); 213 struct lock_class *class; 214 struct thread *td; 215 struct proc *p; 216 int lock_state, rval; 217 218 td = curthread; 219 p = td->td_proc; 220 lock_state = 0; 221 #ifdef KTRACE 222 if (KTRPOINT(td, KTR_CSW)) 223 ktrcsw(1, 0); 224 #endif 225 CV_ASSERT(cvp, lock, td); 226 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 227 "Waiting on \"%s\"", cvp->cv_description); 228 WITNESS_SAVE(lock, lock_witness); 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 DROP_GIANT(); 245 246 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 247 SLEEPQ_INTERRUPTIBLE, 0); 248 if (lock != &Giant.lock_object) { 249 if (class->lc_flags & LC_SLEEPABLE) 250 sleepq_release(cvp); 251 lock_state = class->lc_unlock(lock); 252 if (class->lc_flags & LC_SLEEPABLE) 253 sleepq_lock(cvp); 254 } 255 rval = sleepq_wait_sig(cvp, 0); 256 257 #ifdef KTRACE 258 if (KTRPOINT(td, KTR_CSW)) 259 ktrcsw(0, 0); 260 #endif 261 PICKUP_GIANT(); 262 if (lock != &Giant.lock_object) { 263 class->lc_lock(lock, lock_state); 264 WITNESS_RESTORE(lock, lock_witness); 265 } 266 267 return (rval); 268 } 269 270 /* 271 * Wait on a condition variable for at most timo/hz seconds. Returns 0 if the 272 * process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout 273 * expires. 274 */ 275 int 276 _cv_timedwait(struct cv *cvp, struct lock_object *lock, int timo) 277 { 278 WITNESS_SAVE_DECL(lock_witness); 279 struct lock_class *class; 280 struct thread *td; 281 int lock_state, rval; 282 283 td = curthread; 284 rval = 0; 285 lock_state = 0; 286 #ifdef KTRACE 287 if (KTRPOINT(td, KTR_CSW)) 288 ktrcsw(1, 0); 289 #endif 290 CV_ASSERT(cvp, lock, td); 291 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 292 "Waiting on \"%s\"", cvp->cv_description); 293 WITNESS_SAVE(lock, lock_witness); 294 class = LOCK_CLASS(lock); 295 296 if (cold || panicstr) { 297 /* 298 * After a panic, or during autoconfiguration, just give 299 * interrupts a chance, then just return; don't run any other 300 * thread or panic below, in case this is the idle process and 301 * already asleep. 302 */ 303 return 0; 304 } 305 306 sleepq_lock(cvp); 307 308 cvp->cv_waiters++; 309 DROP_GIANT(); 310 311 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 312 sleepq_set_timeout(cvp, timo); 313 if (lock != &Giant.lock_object) { 314 if (class->lc_flags & LC_SLEEPABLE) 315 sleepq_release(cvp); 316 lock_state = class->lc_unlock(lock); 317 if (class->lc_flags & LC_SLEEPABLE) 318 sleepq_lock(cvp); 319 } 320 rval = sleepq_timedwait(cvp, 0); 321 322 #ifdef KTRACE 323 if (KTRPOINT(td, KTR_CSW)) 324 ktrcsw(0, 0); 325 #endif 326 PICKUP_GIANT(); 327 if (lock != &Giant.lock_object) { 328 class->lc_lock(lock, lock_state); 329 WITNESS_RESTORE(lock, lock_witness); 330 } 331 332 return (rval); 333 } 334 335 /* 336 * Wait on a condition variable for at most timo/hz seconds, allowing 337 * interruption by signals. Returns 0 if the thread was resumed by cv_signal 338 * or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if 339 * a signal was caught. 340 */ 341 int 342 _cv_timedwait_sig(struct cv *cvp, struct lock_object *lock, int timo) 343 { 344 WITNESS_SAVE_DECL(lock_witness); 345 struct lock_class *class; 346 struct thread *td; 347 struct proc *p; 348 int lock_state, rval; 349 350 td = curthread; 351 p = td->td_proc; 352 rval = 0; 353 lock_state = 0; 354 #ifdef KTRACE 355 if (KTRPOINT(td, KTR_CSW)) 356 ktrcsw(1, 0); 357 #endif 358 CV_ASSERT(cvp, lock, td); 359 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 360 "Waiting on \"%s\"", cvp->cv_description); 361 WITNESS_SAVE(lock, lock_witness); 362 class = LOCK_CLASS(lock); 363 364 if (cold || panicstr) { 365 /* 366 * After a panic, or during autoconfiguration, just give 367 * interrupts a chance, then just return; don't run any other 368 * thread or panic below, in case this is the idle process and 369 * already asleep. 370 */ 371 return 0; 372 } 373 374 sleepq_lock(cvp); 375 376 cvp->cv_waiters++; 377 DROP_GIANT(); 378 379 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 380 SLEEPQ_INTERRUPTIBLE, 0); 381 sleepq_set_timeout(cvp, timo); 382 if (lock != &Giant.lock_object) { 383 if (class->lc_flags & LC_SLEEPABLE) 384 sleepq_release(cvp); 385 lock_state = class->lc_unlock(lock); 386 if (class->lc_flags & LC_SLEEPABLE) 387 sleepq_lock(cvp); 388 } 389 rval = sleepq_timedwait_sig(cvp, 0); 390 391 #ifdef KTRACE 392 if (KTRPOINT(td, KTR_CSW)) 393 ktrcsw(0, 0); 394 #endif 395 PICKUP_GIANT(); 396 if (lock != &Giant.lock_object) { 397 class->lc_lock(lock, lock_state); 398 WITNESS_RESTORE(lock, lock_witness); 399 } 400 401 return (rval); 402 } 403 404 /* 405 * Signal a condition variable, wakes up one waiting thread. Will also wakeup 406 * the swapper if the process is not in memory, so that it can bring the 407 * sleeping process in. Note that this may also result in additional threads 408 * being made runnable. Should be called with the same mutex as was passed to 409 * cv_wait held. 410 */ 411 void 412 cv_signal(struct cv *cvp) 413 { 414 int wakeup_swapper; 415 416 wakeup_swapper = 0; 417 sleepq_lock(cvp); 418 if (cvp->cv_waiters > 0) { 419 cvp->cv_waiters--; 420 wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0, 0); 421 } 422 sleepq_release(cvp); 423 if (wakeup_swapper) 424 kick_proc0(); 425 } 426 427 /* 428 * Broadcast a signal to a condition variable. Wakes up all waiting threads. 429 * Should be called with the same mutex as was passed to cv_wait held. 430 */ 431 void 432 cv_broadcastpri(struct cv *cvp, int pri) 433 { 434 int wakeup_swapper; 435 436 /* 437 * XXX sleepq_broadcast pri argument changed from -1 meaning 438 * no pri to 0 meaning no pri. 439 */ 440 wakeup_swapper = 0; 441 if (pri == -1) 442 pri = 0; 443 sleepq_lock(cvp); 444 if (cvp->cv_waiters > 0) { 445 cvp->cv_waiters = 0; 446 wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0); 447 } 448 sleepq_release(cvp); 449 if (wakeup_swapper) 450 kick_proc0(); 451 } 452