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 sleepq_lock(cvp); 82 sq = sleepq_lookup(cvp); 83 sleepq_release(cvp); 84 KASSERT(sq == NULL, ("%s: associated sleep queue non-empty", __func__)); 85 #endif 86 } 87 88 /* 89 * Wait on a condition variable. The current thread is placed on the condition 90 * variable's wait queue and suspended. A cv_signal or cv_broadcast on the same 91 * condition variable will resume the thread. The mutex is released before 92 * sleeping and will be held on return. It is recommended that the mutex be 93 * held when cv_signal or cv_broadcast are called. 94 */ 95 void 96 cv_wait(struct cv *cvp, struct mtx *mp) 97 { 98 WITNESS_SAVE_DECL(mp); 99 100 WITNESS_SAVE(&mp->mtx_object, mp); 101 102 if (cold || panicstr) { 103 /* 104 * During autoconfiguration, just give interrupts 105 * a chance, then just return. Don't run any other 106 * thread or panic below, in case this is the idle 107 * process and already asleep. 108 */ 109 return; 110 } 111 112 cv_wait_unlock(cvp, mp); 113 mtx_lock(mp); 114 WITNESS_RESTORE(&mp->mtx_object, mp); 115 } 116 117 /* 118 * Wait on a condition variable. This function differs from cv_wait by 119 * not aquiring the mutex after condition variable was signaled. 120 */ 121 void 122 cv_wait_unlock(struct cv *cvp, struct mtx *mp) 123 { 124 struct thread *td; 125 126 td = curthread; 127 #ifdef KTRACE 128 if (KTRPOINT(td, KTR_CSW)) 129 ktrcsw(1, 0); 130 #endif 131 CV_ASSERT(cvp, mp, td); 132 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object, 133 "Waiting on \"%s\"", cvp->cv_description); 134 135 if (cold || panicstr) { 136 /* 137 * During autoconfiguration, just give interrupts 138 * a chance, then just return. Don't run any other 139 * thread or panic below, in case this is the idle 140 * process and already asleep. 141 */ 142 mtx_unlock(mp); 143 return; 144 } 145 146 sleepq_lock(cvp); 147 148 cvp->cv_waiters++; 149 DROP_GIANT(); 150 mtx_unlock(mp); 151 152 sleepq_add(cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR); 153 sleepq_wait(cvp); 154 155 PICKUP_GIANT(); 156 } 157 158 /* 159 * Wait on a condition variable, allowing interruption by signals. Return 0 if 160 * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if 161 * a signal was caught. If ERESTART is returned the system call should be 162 * restarted if possible. 163 */ 164 int 165 cv_wait_sig(struct cv *cvp, struct mtx *mp) 166 { 167 struct thread *td; 168 struct proc *p; 169 int rval; 170 WITNESS_SAVE_DECL(mp); 171 172 td = curthread; 173 p = td->td_proc; 174 #ifdef KTRACE 175 if (KTRPOINT(td, KTR_CSW)) 176 ktrcsw(1, 0); 177 #endif 178 CV_ASSERT(cvp, mp, td); 179 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object, 180 "Waiting on \"%s\"", cvp->cv_description); 181 WITNESS_SAVE(&mp->mtx_object, mp); 182 183 if (cold || panicstr) { 184 /* 185 * After a panic, or during autoconfiguration, just give 186 * interrupts a chance, then just return; don't run any other 187 * procs or panic below, in case this is the idle process and 188 * already asleep. 189 */ 190 return (0); 191 } 192 193 sleepq_lock(cvp); 194 195 cvp->cv_waiters++; 196 DROP_GIANT(); 197 mtx_unlock(mp); 198 199 sleepq_add(cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR | 200 SLEEPQ_INTERRUPTIBLE); 201 rval = sleepq_wait_sig(cvp); 202 203 #ifdef KTRACE 204 if (KTRPOINT(td, KTR_CSW)) 205 ktrcsw(0, 0); 206 #endif 207 PICKUP_GIANT(); 208 mtx_lock(mp); 209 WITNESS_RESTORE(&mp->mtx_object, mp); 210 211 return (rval); 212 } 213 214 /* 215 * Wait on a condition variable for at most timo/hz seconds. Returns 0 if the 216 * process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout 217 * expires. 218 */ 219 int 220 cv_timedwait(struct cv *cvp, struct mtx *mp, int timo) 221 { 222 struct thread *td; 223 int rval; 224 WITNESS_SAVE_DECL(mp); 225 226 td = curthread; 227 rval = 0; 228 #ifdef KTRACE 229 if (KTRPOINT(td, KTR_CSW)) 230 ktrcsw(1, 0); 231 #endif 232 CV_ASSERT(cvp, mp, td); 233 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object, 234 "Waiting on \"%s\"", cvp->cv_description); 235 WITNESS_SAVE(&mp->mtx_object, mp); 236 237 if (cold || panicstr) { 238 /* 239 * After a panic, or during autoconfiguration, just give 240 * interrupts a chance, then just return; don't run any other 241 * thread or panic below, in case this is the idle process and 242 * already asleep. 243 */ 244 return 0; 245 } 246 247 sleepq_lock(cvp); 248 249 cvp->cv_waiters++; 250 DROP_GIANT(); 251 mtx_unlock(mp); 252 253 sleepq_add(cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR); 254 sleepq_set_timeout(cvp, timo); 255 rval = sleepq_timedwait(cvp); 256 257 #ifdef KTRACE 258 if (KTRPOINT(td, KTR_CSW)) 259 ktrcsw(0, 0); 260 #endif 261 PICKUP_GIANT(); 262 mtx_lock(mp); 263 WITNESS_RESTORE(&mp->mtx_object, mp); 264 265 return (rval); 266 } 267 268 /* 269 * Wait on a condition variable for at most timo/hz seconds, allowing 270 * interruption by signals. Returns 0 if the thread was resumed by cv_signal 271 * or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if 272 * a signal was caught. 273 */ 274 int 275 cv_timedwait_sig(struct cv *cvp, struct mtx *mp, int timo) 276 { 277 struct thread *td; 278 struct proc *p; 279 int rval; 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 sleepq_lock(cvp); 305 306 cvp->cv_waiters++; 307 DROP_GIANT(); 308 mtx_unlock(mp); 309 310 sleepq_add(cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR | 311 SLEEPQ_INTERRUPTIBLE); 312 sleepq_set_timeout(cvp, timo); 313 rval = sleepq_timedwait_sig(cvp); 314 315 #ifdef KTRACE 316 if (KTRPOINT(td, KTR_CSW)) 317 ktrcsw(0, 0); 318 #endif 319 PICKUP_GIANT(); 320 mtx_lock(mp); 321 WITNESS_RESTORE(&mp->mtx_object, mp); 322 323 return (rval); 324 } 325 326 /* 327 * Signal a condition variable, wakes up one waiting thread. Will also wakeup 328 * the swapper if the process is not in memory, so that it can bring the 329 * sleeping process in. Note that this may also result in additional threads 330 * being made runnable. Should be called with the same mutex as was passed to 331 * cv_wait held. 332 */ 333 void 334 cv_signal(struct cv *cvp) 335 { 336 337 sleepq_lock(cvp); 338 if (cvp->cv_waiters > 0) { 339 cvp->cv_waiters--; 340 sleepq_signal(cvp, SLEEPQ_CONDVAR, -1); 341 } else 342 sleepq_release(cvp); 343 } 344 345 /* 346 * Broadcast a signal to a condition variable. Wakes up all waiting threads. 347 * Should be called with the same mutex as was passed to cv_wait held. 348 */ 349 void 350 cv_broadcastpri(struct cv *cvp, int pri) 351 { 352 353 sleepq_lock(cvp); 354 if (cvp->cv_waiters > 0) { 355 cvp->cv_waiters = 0; 356 sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri); 357 } else 358 sleepq_release(cvp); 359 } 360