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, mp, 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((mp) != NULL, ("%s: mp NULL", __func__)); \ 57 mtx_assert((mp), MA_OWNED | MA_NOTRECURSED); \ 58 } while (0) 59 60 /* 61 * Initialize a condition variable. Must be called before use. 62 */ 63 void 64 cv_init(struct cv *cvp, const char *desc) 65 { 66 67 cvp->cv_description = desc; 68 cvp->cv_waiters = 0; 69 } 70 71 /* 72 * Destroy a condition variable. The condition variable must be re-initialized 73 * in order to be re-used. 74 */ 75 void 76 cv_destroy(struct cv *cvp) 77 { 78 #ifdef INVARIANTS 79 struct sleepqueue *sq; 80 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 mtx *mp) 96 { 97 struct sleepqueue *sq; 98 struct thread *td; 99 WITNESS_SAVE_DECL(mp); 100 101 td = curthread; 102 #ifdef KTRACE 103 if (KTRPOINT(td, KTR_CSW)) 104 ktrcsw(1, 0); 105 #endif 106 CV_ASSERT(cvp, mp, td); 107 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object, 108 "Waiting on \"%s\"", cvp->cv_description); 109 WITNESS_SAVE(&mp->mtx_object, mp); 110 111 if (cold || panicstr) { 112 /* 113 * During autoconfiguration, just give interrupts 114 * a chance, then just return. Don't run any other 115 * thread or panic below, in case this is the idle 116 * process and already asleep. 117 */ 118 return; 119 } 120 121 sq = sleepq_lookup(cvp); 122 123 cvp->cv_waiters++; 124 DROP_GIANT(); 125 mtx_unlock(mp); 126 127 sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR); 128 sleepq_wait(cvp); 129 130 #ifdef KTRACE 131 if (KTRPOINT(td, KTR_CSW)) 132 ktrcsw(0, 0); 133 #endif 134 PICKUP_GIANT(); 135 mtx_lock(mp); 136 WITNESS_RESTORE(&mp->mtx_object, mp); 137 } 138 139 /* 140 * Wait on a condition variable, allowing interruption by signals. Return 0 if 141 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if 142 * a signal was caught. If ERESTART is returned the system call should be 143 * restarted if possible. 144 */ 145 int 146 cv_wait_sig(struct cv *cvp, struct mtx *mp) 147 { 148 struct sleepqueue *sq; 149 struct thread *td; 150 struct proc *p; 151 int rval, sig; 152 WITNESS_SAVE_DECL(mp); 153 154 td = curthread; 155 p = td->td_proc; 156 #ifdef KTRACE 157 if (KTRPOINT(td, KTR_CSW)) 158 ktrcsw(1, 0); 159 #endif 160 CV_ASSERT(cvp, mp, td); 161 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object, 162 "Waiting on \"%s\"", cvp->cv_description); 163 WITNESS_SAVE(&mp->mtx_object, mp); 164 165 if (cold || panicstr) { 166 /* 167 * After a panic, or during autoconfiguration, just give 168 * interrupts a chance, then just return; don't run any other 169 * procs or panic below, in case this is the idle process and 170 * already asleep. 171 */ 172 return (0); 173 } 174 175 sq = sleepq_lookup(cvp); 176 177 /* 178 * Don't bother sleeping if we are exiting and not the exiting 179 * thread or if our thread is marked as interrupted. 180 */ 181 mtx_lock_spin(&sched_lock); 182 rval = thread_sleep_check(td); 183 mtx_unlock_spin(&sched_lock); 184 if (rval != 0) { 185 sleepq_release(cvp); 186 return (rval); 187 } 188 189 cvp->cv_waiters++; 190 DROP_GIANT(); 191 mtx_unlock(mp); 192 193 sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR | 194 SLEEPQ_INTERRUPTIBLE); 195 sig = sleepq_catch_signals(cvp); 196 rval = sleepq_wait_sig(cvp); 197 if (rval == 0) 198 rval = sleepq_calc_signal_retval(sig); 199 200 #ifdef KTRACE 201 if (KTRPOINT(td, KTR_CSW)) 202 ktrcsw(0, 0); 203 #endif 204 PICKUP_GIANT(); 205 mtx_lock(mp); 206 WITNESS_RESTORE(&mp->mtx_object, mp); 207 208 return (rval); 209 } 210 211 /* 212 * Wait on a condition variable for at most timo/hz seconds. Returns 0 if the 213 * process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout 214 * expires. 215 */ 216 int 217 cv_timedwait(struct cv *cvp, struct mtx *mp, int timo) 218 { 219 struct sleepqueue *sq; 220 struct thread *td; 221 int rval; 222 WITNESS_SAVE_DECL(mp); 223 224 td = curthread; 225 rval = 0; 226 #ifdef KTRACE 227 if (KTRPOINT(td, KTR_CSW)) 228 ktrcsw(1, 0); 229 #endif 230 CV_ASSERT(cvp, mp, td); 231 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object, 232 "Waiting on \"%s\"", cvp->cv_description); 233 WITNESS_SAVE(&mp->mtx_object, mp); 234 235 if (cold || panicstr) { 236 /* 237 * After a panic, or during autoconfiguration, just give 238 * interrupts a chance, then just return; don't run any other 239 * thread or panic below, in case this is the idle process and 240 * already asleep. 241 */ 242 return 0; 243 } 244 245 sq = sleepq_lookup(cvp); 246 247 cvp->cv_waiters++; 248 DROP_GIANT(); 249 mtx_unlock(mp); 250 251 sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR); 252 sleepq_set_timeout(cvp, timo); 253 rval = sleepq_timedwait(cvp); 254 255 #ifdef KTRACE 256 if (KTRPOINT(td, KTR_CSW)) 257 ktrcsw(0, 0); 258 #endif 259 PICKUP_GIANT(); 260 mtx_lock(mp); 261 WITNESS_RESTORE(&mp->mtx_object, mp); 262 263 return (rval); 264 } 265 266 /* 267 * Wait on a condition variable for at most timo/hz seconds, allowing 268 * interruption by signals. Returns 0 if the thread was resumed by cv_signal 269 * or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if 270 * a signal was caught. 271 */ 272 int 273 cv_timedwait_sig(struct cv *cvp, struct mtx *mp, int timo) 274 { 275 struct sleepqueue *sq; 276 struct thread *td; 277 struct proc *p; 278 int rval; 279 int sig; 280 WITNESS_SAVE_DECL(mp); 281 282 td = curthread; 283 p = td->td_proc; 284 rval = 0; 285 #ifdef KTRACE 286 if (KTRPOINT(td, KTR_CSW)) 287 ktrcsw(1, 0); 288 #endif 289 CV_ASSERT(cvp, mp, td); 290 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object, 291 "Waiting on \"%s\"", cvp->cv_description); 292 WITNESS_SAVE(&mp->mtx_object, mp); 293 294 if (cold || panicstr) { 295 /* 296 * After a panic, or during autoconfiguration, just give 297 * interrupts a chance, then just return; don't run any other 298 * thread or panic below, in case this is the idle process and 299 * already asleep. 300 */ 301 return 0; 302 } 303 304 sq = sleepq_lookup(cvp); 305 306 /* 307 * Don't bother sleeping if we are exiting and not the exiting 308 * thread or if our thread is marked as interrupted. 309 */ 310 mtx_lock_spin(&sched_lock); 311 rval = thread_sleep_check(td); 312 mtx_unlock_spin(&sched_lock); 313 if (rval != 0) { 314 sleepq_release(cvp); 315 return (rval); 316 } 317 318 cvp->cv_waiters++; 319 DROP_GIANT(); 320 mtx_unlock(mp); 321 322 sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR | 323 SLEEPQ_INTERRUPTIBLE); 324 sleepq_set_timeout(cvp, timo); 325 sig = sleepq_catch_signals(cvp); 326 rval = sleepq_timedwait_sig(cvp, sig != 0); 327 if (rval == 0) 328 rval = sleepq_calc_signal_retval(sig); 329 330 #ifdef KTRACE 331 if (KTRPOINT(td, KTR_CSW)) 332 ktrcsw(0, 0); 333 #endif 334 PICKUP_GIANT(); 335 mtx_lock(mp); 336 WITNESS_RESTORE(&mp->mtx_object, mp); 337 338 return (rval); 339 } 340 341 /* 342 * Signal a condition variable, wakes up one waiting thread. Will also wakeup 343 * the swapper if the process is not in memory, so that it can bring the 344 * sleeping process in. Note that this may also result in additional threads 345 * being made runnable. Should be called with the same mutex as was passed to 346 * cv_wait held. 347 */ 348 void 349 cv_signal(struct cv *cvp) 350 { 351 352 if (cvp->cv_waiters > 0) { 353 cvp->cv_waiters--; 354 sleepq_signal(cvp, SLEEPQ_CONDVAR, -1); 355 } 356 } 357 358 /* 359 * Broadcast a signal to a condition variable. Wakes up all waiting threads. 360 * Should be called with the same mutex as was passed to cv_wait held. 361 */ 362 void 363 cv_broadcastpri(struct cv *cvp, int pri) 364 { 365 366 if (cvp->cv_waiters > 0) { 367 cvp->cv_waiters = 0; 368 sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri); 369 } 370 } 371