1 /* $OpenBSD: kern_synch.c,v 1.80 2007/05/16 17:27:30 art Exp $ */ 2 /* $NetBSD: kern_synch.c,v 1.37 1996/04/22 01:38:37 christos Exp $ */ 3 4 /* 5 * Copyright (c) 1982, 1986, 1990, 1991, 1993 6 * The Regents of the University of California. All rights reserved. 7 * (c) UNIX System Laboratories, Inc. 8 * All or some portions of this file are derived from material licensed 9 * to the University of California by American Telephone and Telegraph 10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 11 * the permission of UNIX System Laboratories, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)kern_synch.c 8.6 (Berkeley) 1/21/94 38 */ 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/proc.h> 43 #include <sys/kernel.h> 44 #include <sys/buf.h> 45 #include <sys/signalvar.h> 46 #include <sys/resourcevar.h> 47 #include <uvm/uvm_extern.h> 48 #include <sys/sched.h> 49 #include <sys/timeout.h> 50 #include <sys/mount.h> 51 #include <sys/syscallargs.h> 52 #include <sys/pool.h> 53 54 #include <machine/spinlock.h> 55 56 #ifdef KTRACE 57 #include <sys/ktrace.h> 58 #endif 59 60 void updatepri(struct proc *); 61 void endtsleep(void *); 62 63 /* 64 * We're only looking at 7 bits of the address; everything is 65 * aligned to 4, lots of things are aligned to greater powers 66 * of 2. Shift right by 8, i.e. drop the bottom 256 worth. 67 */ 68 #define TABLESIZE 128 69 #define LOOKUP(x) (((long)(x) >> 8) & (TABLESIZE - 1)) 70 struct slpque { 71 struct proc *sq_head; 72 struct proc **sq_tailp; 73 } slpque[TABLESIZE]; 74 75 /* 76 * During autoconfiguration or after a panic, a sleep will simply 77 * lower the priority briefly to allow interrupts, then return. 78 * The priority to be used (safepri) is machine-dependent, thus this 79 * value is initialized and maintained in the machine-dependent layers. 80 * This priority will typically be 0, or the lowest priority 81 * that is safe for use on the interrupt stack; it can be made 82 * higher to block network software interrupts after panics. 83 */ 84 int safepri; 85 86 /* 87 * General sleep call. Suspends the current process until a wakeup is 88 * performed on the specified identifier. The process will then be made 89 * runnable with the specified priority. Sleeps at most timo/hz seconds 90 * (0 means no timeout). If pri includes PCATCH flag, signals are checked 91 * before and after sleeping, else signals are not checked. Returns 0 if 92 * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a 93 * signal needs to be delivered, ERESTART is returned if the current system 94 * call should be restarted if possible, and EINTR is returned if the system 95 * call should be interrupted by the signal (return EINTR). 96 */ 97 int 98 tsleep(void *ident, int priority, const char *wmesg, int timo) 99 { 100 struct sleep_state sls; 101 int error, error1; 102 103 if (cold || panicstr) { 104 int s; 105 /* 106 * After a panic, or during autoconfiguration, 107 * just give interrupts a chance, then just return; 108 * don't run any other procs or panic below, 109 * in case this is the idle process and already asleep. 110 */ 111 s = splhigh(); 112 splx(safepri); 113 splx(s); 114 return (0); 115 } 116 117 sleep_setup(&sls, ident, priority, wmesg); 118 sleep_setup_timeout(&sls, timo); 119 sleep_setup_signal(&sls, priority); 120 121 sleep_finish(&sls, 1); 122 error1 = sleep_finish_timeout(&sls); 123 error = sleep_finish_signal(&sls); 124 125 /* Signal errors are higher priority than timeouts. */ 126 if (error == 0 && error1 != 0) 127 error = error1; 128 129 return (error); 130 } 131 132 void 133 sleep_setup(struct sleep_state *sls, void *ident, int prio, const char *wmesg) 134 { 135 struct proc *p = curproc; 136 struct slpque *qp; 137 138 #ifdef DIAGNOSTIC 139 if (ident == NULL) 140 panic("tsleep: no ident"); 141 if (p->p_stat != SONPROC) 142 panic("tsleep: not SONPROC"); 143 if (p->p_back != NULL) 144 panic("tsleep: p_back not NULL"); 145 #endif 146 147 #ifdef KTRACE 148 if (KTRPOINT(p, KTR_CSW)) 149 ktrcsw(p, 1, 0); 150 #endif 151 152 sls->sls_catch = 0; 153 sls->sls_do_sleep = 1; 154 sls->sls_sig = 1; 155 156 SCHED_LOCK(sls->sls_s); 157 158 p->p_wchan = ident; 159 p->p_wmesg = wmesg; 160 p->p_slptime = 0; 161 p->p_priority = prio & PRIMASK; 162 qp = &slpque[LOOKUP(ident)]; 163 if (qp->sq_head == 0) 164 qp->sq_head = p; 165 else 166 *qp->sq_tailp = p; 167 *(qp->sq_tailp = &p->p_forw) = NULL; 168 } 169 170 void 171 sleep_finish(struct sleep_state *sls, int do_sleep) 172 { 173 struct proc *p = curproc; 174 175 if (sls->sls_do_sleep && do_sleep) { 176 p->p_stat = SSLEEP; 177 p->p_stats->p_ru.ru_nvcsw++; 178 SCHED_ASSERT_LOCKED(); 179 mi_switch(); 180 } else if (!do_sleep) { 181 unsleep(p); 182 #ifdef DIAGNOSTIC 183 if (p->p_stat != SONPROC) 184 panic("sleep_finish !SONPROC"); 185 #endif 186 } 187 188 p->p_cpu->ci_schedstate.spc_curpriority = p->p_usrpri; 189 SCHED_UNLOCK(sls->sls_s); 190 191 /* 192 * Even though this belongs to the signal handling part of sleep, 193 * we need to clear it before the ktrace. 194 */ 195 atomic_clearbits_int(&p->p_flag, P_SINTR); 196 197 #ifdef KTRACE 198 if (KTRPOINT(p, KTR_CSW)) 199 ktrcsw(p, 0, 0); 200 #endif 201 } 202 203 void 204 sleep_setup_timeout(struct sleep_state *sls, int timo) 205 { 206 if (timo) 207 timeout_add(&curproc->p_sleep_to, timo); 208 } 209 210 int 211 sleep_finish_timeout(struct sleep_state *sls) 212 { 213 struct proc *p = curproc; 214 215 if (p->p_flag & P_TIMEOUT) { 216 atomic_clearbits_int(&p->p_flag, P_TIMEOUT); 217 return (EWOULDBLOCK); 218 } else if (timeout_pending(&p->p_sleep_to)) { 219 timeout_del(&p->p_sleep_to); 220 } 221 222 return (0); 223 } 224 225 void 226 sleep_setup_signal(struct sleep_state *sls, int prio) 227 { 228 struct proc *p = curproc; 229 230 if ((sls->sls_catch = (prio & PCATCH)) == 0) 231 return; 232 233 /* 234 * We put ourselves on the sleep queue and start our timeout 235 * before calling CURSIG, as we could stop there, and a wakeup 236 * or a SIGCONT (or both) could occur while we were stopped. 237 * A SIGCONT would cause us to be marked as SSLEEP 238 * without resuming us, thus we must be ready for sleep 239 * when CURSIG is called. If the wakeup happens while we're 240 * stopped, p->p_wchan will be 0 upon return from CURSIG. 241 */ 242 atomic_setbits_int(&p->p_flag, P_SINTR); 243 if ((sls->sls_sig = CURSIG(p)) != 0) { 244 if (p->p_wchan) 245 unsleep(p); 246 p->p_stat = SONPROC; 247 sls->sls_do_sleep = 0; 248 } else if (p->p_wchan == 0) { 249 sls->sls_catch = 0; 250 sls->sls_do_sleep = 0; 251 } 252 } 253 254 int 255 sleep_finish_signal(struct sleep_state *sls) 256 { 257 struct proc *p = curproc; 258 259 if (sls->sls_catch != 0) { 260 if (sls->sls_sig != 0 || (sls->sls_sig = CURSIG(p)) != 0) { 261 if (p->p_sigacts->ps_sigintr & sigmask(sls->sls_sig)) 262 return (EINTR); 263 return (ERESTART); 264 } 265 } 266 267 return (0); 268 } 269 270 /* 271 * Implement timeout for tsleep. 272 * If process hasn't been awakened (wchan non-zero), 273 * set timeout flag and undo the sleep. If proc 274 * is stopped, just unsleep so it will remain stopped. 275 */ 276 void 277 endtsleep(void *arg) 278 { 279 struct proc *p = arg; 280 int s; 281 282 SCHED_LOCK(s); 283 if (p->p_wchan) { 284 if (p->p_stat == SSLEEP) 285 setrunnable(p); 286 else 287 unsleep(p); 288 atomic_setbits_int(&p->p_flag, P_TIMEOUT); 289 } 290 SCHED_UNLOCK(s); 291 } 292 293 /* 294 * Remove a process from its wait queue 295 */ 296 void 297 unsleep(struct proc *p) 298 { 299 struct slpque *qp; 300 struct proc **hp; 301 302 if (p->p_wchan) { 303 hp = &(qp = &slpque[LOOKUP(p->p_wchan)])->sq_head; 304 while (*hp != p) 305 hp = &(*hp)->p_forw; 306 *hp = p->p_forw; 307 if (qp->sq_tailp == &p->p_forw) 308 qp->sq_tailp = hp; 309 p->p_wchan = 0; 310 } 311 } 312 313 /* 314 * Make a number of processes sleeping on the specified identifier runnable. 315 */ 316 void 317 wakeup_n(void *ident, int n) 318 { 319 struct slpque *qp; 320 struct proc *p, **q; 321 int s; 322 323 SCHED_LOCK(s); 324 qp = &slpque[LOOKUP(ident)]; 325 restart: 326 for (q = &qp->sq_head; (p = *q) != NULL; ) { 327 #ifdef DIAGNOSTIC 328 if (p->p_back) 329 panic("wakeup: p_back not NULL"); 330 if (p->p_stat != SSLEEP && p->p_stat != SSTOP) 331 panic("wakeup: p_stat is %d", (int)p->p_stat); 332 #endif 333 if (p->p_wchan == ident) { 334 --n; 335 p->p_wchan = 0; 336 *q = p->p_forw; 337 if (qp->sq_tailp == &p->p_forw) 338 qp->sq_tailp = q; 339 if (p->p_stat == SSLEEP) { 340 /* OPTIMIZED EXPANSION OF setrunnable(p); */ 341 if (p->p_slptime > 1) 342 updatepri(p); 343 p->p_slptime = 0; 344 p->p_stat = SRUN; 345 346 /* 347 * Since curpriority is a user priority, 348 * p->p_priority is always better than 349 * curpriority on the last CPU on 350 * which it ran. 351 * 352 * XXXSMP See affinity comment in 353 * resched_proc(). 354 */ 355 setrunqueue(p); 356 KASSERT(p->p_cpu != NULL); 357 need_resched(p->p_cpu); 358 /* END INLINE EXPANSION */ 359 360 if (n != 0) 361 goto restart; 362 else 363 break; 364 } 365 } else 366 q = &p->p_forw; 367 } 368 SCHED_UNLOCK(s); 369 } 370 371 /* 372 * Make all processes sleeping on the specified identifier runnable. 373 */ 374 void 375 wakeup(void *chan) 376 { 377 wakeup_n(chan, -1); 378 } 379 380 int 381 sys_sched_yield(struct proc *p, void *v, register_t *retval) 382 { 383 yield(); 384 return (0); 385 } 386 387 #ifdef RTHREADS 388 389 int 390 sys_thrsleep(struct proc *p, void *v, register_t *revtal) 391 { 392 struct sys_thrsleep_args *uap = v; 393 long ident = (long)SCARG(uap, ident); 394 int timo = SCARG(uap, timeout); 395 _spinlock_lock_t *lock = SCARG(uap, lock); 396 _spinlock_lock_t unlocked = _SPINLOCK_UNLOCKED; 397 int error; 398 399 p->p_thrslpid = ident; 400 401 if (lock) 402 copyout(&unlocked, lock, sizeof(unlocked)); 403 if (hz > 1000) 404 timo = timo * (hz / 1000); 405 else 406 timo = timo / (1000 / hz); 407 if (timo < 0) 408 timo = 0; 409 error = tsleep(&p->p_thrslpid, PUSER | PCATCH, "thrsleep", timo); 410 411 if (error == ERESTART) 412 error = EINTR; 413 414 return (error); 415 416 } 417 418 int 419 sys_thrwakeup(struct proc *p, void *v, register_t *retval) 420 { 421 struct sys_thrwakeup_args *uap = v; 422 long ident = (long)SCARG(uap, ident); 423 int n = SCARG(uap, n); 424 struct proc *q; 425 int found = 0; 426 427 TAILQ_FOREACH(q, &p->p_p->ps_threads, p_thr_link) { 428 if (q->p_thrslpid == ident) { 429 wakeup(&q->p_thrslpid); 430 q->p_thrslpid = 0; 431 if (++found == n) 432 return (0); 433 } 434 } 435 if (!found) 436 return (ESRCH); 437 438 return (0); 439 } 440 #endif 441