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 #ifdef KTRACE 104 if (KTRPOINT(td, KTR_CSW)) 105 ktrcsw(1, 0); 106 #endif 107 CV_ASSERT(cvp, lock, td); 108 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 109 "Waiting on \"%s\"", cvp->cv_description); 110 WITNESS_SAVE(lock, lock_witness); 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 DROP_GIANT(); 127 lock_state = class->lc_unlock(lock); 128 129 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 130 sleepq_wait(cvp); 131 132 #ifdef KTRACE 133 if (KTRPOINT(td, KTR_CSW)) 134 ktrcsw(0, 0); 135 #endif 136 PICKUP_GIANT(); 137 class->lc_lock(lock, lock_state); 138 WITNESS_RESTORE(lock, lock_witness); 139 } 140 141 /* 142 * Wait on a condition variable. This function differs from cv_wait by 143 * not aquiring the mutex after condition variable was signaled. 144 */ 145 void 146 _cv_wait_unlock(struct cv *cvp, struct lock_object *lock) 147 { 148 struct lock_class *class; 149 struct thread *td; 150 151 td = curthread; 152 #ifdef KTRACE 153 if (KTRPOINT(td, KTR_CSW)) 154 ktrcsw(1, 0); 155 #endif 156 CV_ASSERT(cvp, lock, td); 157 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 158 "Waiting on \"%s\"", cvp->cv_description); 159 class = LOCK_CLASS(lock); 160 161 if (cold || panicstr) { 162 /* 163 * During autoconfiguration, just give interrupts 164 * a chance, then just return. Don't run any other 165 * thread or panic below, in case this is the idle 166 * process and already asleep. 167 */ 168 class->lc_unlock(lock); 169 return; 170 } 171 172 sleepq_lock(cvp); 173 174 cvp->cv_waiters++; 175 DROP_GIANT(); 176 class->lc_unlock(lock); 177 178 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 179 sleepq_wait(cvp); 180 181 #ifdef KTRACE 182 if (KTRPOINT(td, KTR_CSW)) 183 ktrcsw(0, 0); 184 #endif 185 PICKUP_GIANT(); 186 } 187 188 /* 189 * Wait on a condition variable, allowing interruption by signals. Return 0 if 190 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if 191 * a signal was caught. If ERESTART is returned the system call should be 192 * restarted if possible. 193 */ 194 int 195 _cv_wait_sig(struct cv *cvp, struct lock_object *lock) 196 { 197 WITNESS_SAVE_DECL(lock_witness); 198 struct lock_class *class; 199 struct thread *td; 200 struct proc *p; 201 int lock_state, rval; 202 203 td = curthread; 204 p = td->td_proc; 205 #ifdef KTRACE 206 if (KTRPOINT(td, KTR_CSW)) 207 ktrcsw(1, 0); 208 #endif 209 CV_ASSERT(cvp, lock, td); 210 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 211 "Waiting on \"%s\"", cvp->cv_description); 212 WITNESS_SAVE(lock, lock_witness); 213 class = LOCK_CLASS(lock); 214 215 if (cold || panicstr) { 216 /* 217 * After a panic, or during autoconfiguration, just give 218 * interrupts a chance, then just return; don't run any other 219 * procs or panic below, in case this is the idle process and 220 * already asleep. 221 */ 222 return (0); 223 } 224 225 sleepq_lock(cvp); 226 227 cvp->cv_waiters++; 228 DROP_GIANT(); 229 lock_state = class->lc_unlock(lock); 230 231 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 232 SLEEPQ_INTERRUPTIBLE, 0); 233 rval = sleepq_wait_sig(cvp); 234 235 #ifdef KTRACE 236 if (KTRPOINT(td, KTR_CSW)) 237 ktrcsw(0, 0); 238 #endif 239 PICKUP_GIANT(); 240 class->lc_lock(lock, lock_state); 241 WITNESS_RESTORE(lock, lock_witness); 242 243 return (rval); 244 } 245 246 /* 247 * Wait on a condition variable for at most timo/hz seconds. Returns 0 if the 248 * process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout 249 * expires. 250 */ 251 int 252 _cv_timedwait(struct cv *cvp, struct lock_object *lock, int timo) 253 { 254 WITNESS_SAVE_DECL(lock_witness); 255 struct lock_class *class; 256 struct thread *td; 257 int lock_state, rval; 258 259 td = curthread; 260 rval = 0; 261 #ifdef KTRACE 262 if (KTRPOINT(td, KTR_CSW)) 263 ktrcsw(1, 0); 264 #endif 265 CV_ASSERT(cvp, lock, td); 266 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 267 "Waiting on \"%s\"", cvp->cv_description); 268 WITNESS_SAVE(lock, lock_witness); 269 class = LOCK_CLASS(lock); 270 271 if (cold || panicstr) { 272 /* 273 * After a panic, or during autoconfiguration, just give 274 * interrupts a chance, then just return; don't run any other 275 * thread or panic below, in case this is the idle process and 276 * already asleep. 277 */ 278 return 0; 279 } 280 281 sleepq_lock(cvp); 282 283 cvp->cv_waiters++; 284 DROP_GIANT(); 285 lock_state = class->lc_unlock(lock); 286 287 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); 288 sleepq_set_timeout(cvp, timo); 289 rval = sleepq_timedwait(cvp); 290 291 #ifdef KTRACE 292 if (KTRPOINT(td, KTR_CSW)) 293 ktrcsw(0, 0); 294 #endif 295 PICKUP_GIANT(); 296 class->lc_lock(lock, lock_state); 297 WITNESS_RESTORE(lock, lock_witness); 298 299 return (rval); 300 } 301 302 /* 303 * Wait on a condition variable for at most timo/hz seconds, allowing 304 * interruption by signals. Returns 0 if the thread was resumed by cv_signal 305 * or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if 306 * a signal was caught. 307 */ 308 int 309 _cv_timedwait_sig(struct cv *cvp, struct lock_object *lock, int timo) 310 { 311 WITNESS_SAVE_DECL(lock_witness); 312 struct lock_class *class; 313 struct thread *td; 314 struct proc *p; 315 int lock_state, rval; 316 317 td = curthread; 318 p = td->td_proc; 319 rval = 0; 320 #ifdef KTRACE 321 if (KTRPOINT(td, KTR_CSW)) 322 ktrcsw(1, 0); 323 #endif 324 CV_ASSERT(cvp, lock, td); 325 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, 326 "Waiting on \"%s\"", cvp->cv_description); 327 WITNESS_SAVE(lock, lock_witness); 328 class = LOCK_CLASS(lock); 329 330 if (cold || panicstr) { 331 /* 332 * After a panic, or during autoconfiguration, just give 333 * interrupts a chance, then just return; don't run any other 334 * thread or panic below, in case this is the idle process and 335 * already asleep. 336 */ 337 return 0; 338 } 339 340 sleepq_lock(cvp); 341 342 cvp->cv_waiters++; 343 DROP_GIANT(); 344 lock_state = class->lc_unlock(lock); 345 346 sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | 347 SLEEPQ_INTERRUPTIBLE, 0); 348 sleepq_set_timeout(cvp, timo); 349 rval = sleepq_timedwait_sig(cvp); 350 351 #ifdef KTRACE 352 if (KTRPOINT(td, KTR_CSW)) 353 ktrcsw(0, 0); 354 #endif 355 PICKUP_GIANT(); 356 class->lc_lock(lock, lock_state); 357 WITNESS_RESTORE(lock, lock_witness); 358 359 return (rval); 360 } 361 362 /* 363 * Signal a condition variable, wakes up one waiting thread. Will also wakeup 364 * the swapper if the process is not in memory, so that it can bring the 365 * sleeping process in. Note that this may also result in additional threads 366 * being made runnable. Should be called with the same mutex as was passed to 367 * cv_wait held. 368 */ 369 void 370 cv_signal(struct cv *cvp) 371 { 372 373 sleepq_lock(cvp); 374 if (cvp->cv_waiters > 0) { 375 cvp->cv_waiters--; 376 sleepq_signal(cvp, SLEEPQ_CONDVAR, -1, 0); 377 } else 378 sleepq_release(cvp); 379 } 380 381 /* 382 * Broadcast a signal to a condition variable. Wakes up all waiting threads. 383 * Should be called with the same mutex as was passed to cv_wait held. 384 */ 385 void 386 cv_broadcastpri(struct cv *cvp, int pri) 387 { 388 389 sleepq_lock(cvp); 390 if (cvp->cv_waiters > 0) { 391 cvp->cv_waiters = 0; 392 sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0); 393 } else 394 sleepq_release(cvp); 395 } 396