1 /* $NetBSD: kern_sleepq.c,v 1.30 2008/05/26 12:08:38 ad Exp $ */ 2 3 /*- 4 * Copyright (c) 2006, 2007, 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Andrew Doran. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * Sleep queue implementation, used by turnstiles and general sleep/wakeup 34 * interfaces. 35 */ 36 37 #include <sys/cdefs.h> 38 __KERNEL_RCSID(0, "$NetBSD: kern_sleepq.c,v 1.30 2008/05/26 12:08:38 ad Exp $"); 39 40 #include <sys/param.h> 41 #include <sys/kernel.h> 42 #include <sys/cpu.h> 43 #include <sys/pool.h> 44 #include <sys/proc.h> 45 #include <sys/resourcevar.h> 46 #include <sys/sched.h> 47 #include <sys/systm.h> 48 #include <sys/sleepq.h> 49 #include <sys/ktrace.h> 50 51 #include <uvm/uvm_extern.h> 52 53 int sleepq_sigtoerror(lwp_t *, int); 54 55 /* General purpose sleep table, used by ltsleep() and condition variables. */ 56 sleeptab_t sleeptab; 57 58 /* 59 * sleeptab_init: 60 * 61 * Initialize a sleep table. 62 */ 63 void 64 sleeptab_init(sleeptab_t *st) 65 { 66 sleepq_t *sq; 67 int i; 68 69 for (i = 0; i < SLEEPTAB_HASH_SIZE; i++) { 70 sq = &st->st_queues[i].st_queue; 71 mutex_init(&st->st_queues[i].st_mutex, MUTEX_DEFAULT, 72 IPL_SCHED); 73 sleepq_init(sq); 74 } 75 } 76 77 /* 78 * sleepq_init: 79 * 80 * Prepare a sleep queue for use. 81 */ 82 void 83 sleepq_init(sleepq_t *sq) 84 { 85 86 TAILQ_INIT(sq); 87 } 88 89 /* 90 * sleepq_remove: 91 * 92 * Remove an LWP from a sleep queue and wake it up. Return non-zero if 93 * the LWP is swapped out; if so the caller needs to awaken the swapper 94 * to bring the LWP into memory. 95 */ 96 int 97 sleepq_remove(sleepq_t *sq, lwp_t *l) 98 { 99 struct schedstate_percpu *spc; 100 struct cpu_info *ci; 101 102 KASSERT(lwp_locked(l, NULL)); 103 104 TAILQ_REMOVE(sq, l, l_sleepchain); 105 l->l_syncobj = &sched_syncobj; 106 l->l_wchan = NULL; 107 l->l_sleepq = NULL; 108 l->l_flag &= ~LW_SINTR; 109 110 ci = l->l_cpu; 111 spc = &ci->ci_schedstate; 112 113 /* 114 * If not sleeping, the LWP must have been suspended. Let whoever 115 * holds it stopped set it running again. 116 */ 117 if (l->l_stat != LSSLEEP) { 118 KASSERT(l->l_stat == LSSTOP || l->l_stat == LSSUSPENDED); 119 lwp_setlock(l, spc->spc_lwplock); 120 return 0; 121 } 122 123 /* 124 * If the LWP is still on the CPU, mark it as LSONPROC. It may be 125 * about to call mi_switch(), in which case it will yield. 126 */ 127 if ((l->l_flag & LW_RUNNING) != 0) { 128 l->l_stat = LSONPROC; 129 l->l_slptime = 0; 130 lwp_setlock(l, spc->spc_lwplock); 131 return 0; 132 } 133 134 /* Update sleep time delta, call the wake-up handler of scheduler */ 135 l->l_slpticksum += (hardclock_ticks - l->l_slpticks); 136 sched_wakeup(l); 137 138 /* Look for a CPU to wake up */ 139 l->l_cpu = sched_takecpu(l); 140 ci = l->l_cpu; 141 spc = &ci->ci_schedstate; 142 143 /* 144 * Set it running. 145 */ 146 spc_lock(ci); 147 lwp_setlock(l, spc->spc_mutex); 148 sched_setrunnable(l); 149 l->l_stat = LSRUN; 150 l->l_slptime = 0; 151 if ((l->l_flag & LW_INMEM) != 0) { 152 sched_enqueue(l, false); 153 spc_unlock(ci); 154 return 0; 155 } 156 spc_unlock(ci); 157 return 1; 158 } 159 160 /* 161 * sleepq_insert: 162 * 163 * Insert an LWP into the sleep queue, optionally sorting by priority. 164 */ 165 inline void 166 sleepq_insert(sleepq_t *sq, lwp_t *l, syncobj_t *sobj) 167 { 168 lwp_t *l2; 169 const int pri = lwp_eprio(l); 170 171 if ((sobj->sobj_flag & SOBJ_SLEEPQ_SORTED) != 0) { 172 TAILQ_FOREACH(l2, sq, l_sleepchain) { 173 if (lwp_eprio(l2) < pri) { 174 TAILQ_INSERT_BEFORE(l2, l, l_sleepchain); 175 return; 176 } 177 } 178 } 179 180 if ((sobj->sobj_flag & SOBJ_SLEEPQ_LIFO) != 0) 181 TAILQ_INSERT_HEAD(sq, l, l_sleepchain); 182 else 183 TAILQ_INSERT_TAIL(sq, l, l_sleepchain); 184 } 185 186 /* 187 * sleepq_enqueue: 188 * 189 * Enter an LWP into the sleep queue and prepare for sleep. The sleep 190 * queue must already be locked, and any interlock (such as the kernel 191 * lock) must have be released (see sleeptab_lookup(), sleepq_enter()). 192 */ 193 void 194 sleepq_enqueue(sleepq_t *sq, wchan_t wchan, const char *wmesg, syncobj_t *sobj) 195 { 196 lwp_t *l = curlwp; 197 198 KASSERT(lwp_locked(l, NULL)); 199 KASSERT(l->l_stat == LSONPROC); 200 KASSERT(l->l_wchan == NULL && l->l_sleepq == NULL); 201 202 l->l_syncobj = sobj; 203 l->l_wchan = wchan; 204 l->l_sleepq = sq; 205 l->l_wmesg = wmesg; 206 l->l_slptime = 0; 207 l->l_stat = LSSLEEP; 208 l->l_sleeperr = 0; 209 210 sleepq_insert(sq, l, sobj); 211 212 /* Save the time when thread has slept */ 213 l->l_slpticks = hardclock_ticks; 214 sched_slept(l); 215 } 216 217 /* 218 * sleepq_block: 219 * 220 * After any intermediate step such as releasing an interlock, switch. 221 * sleepq_block() may return early under exceptional conditions, for 222 * example if the LWP's containing process is exiting. 223 */ 224 int 225 sleepq_block(int timo, bool catch) 226 { 227 int error = 0, sig; 228 struct proc *p; 229 lwp_t *l = curlwp; 230 bool early = false; 231 232 ktrcsw(1, 0); 233 234 /* 235 * If sleeping interruptably, check for pending signals, exits or 236 * core dump events. 237 */ 238 if (catch) { 239 l->l_flag |= LW_SINTR; 240 if ((l->l_flag & (LW_CANCELLED|LW_WEXIT|LW_WCORE)) != 0) { 241 l->l_flag &= ~LW_CANCELLED; 242 error = EINTR; 243 early = true; 244 } else if ((l->l_flag & LW_PENDSIG) != 0 && sigispending(l, 0)) 245 early = true; 246 } 247 248 if (early) { 249 /* lwp_unsleep() will release the lock */ 250 lwp_unsleep(l, true); 251 } else { 252 if (timo) 253 callout_schedule(&l->l_timeout_ch, timo); 254 mi_switch(l); 255 256 /* The LWP and sleep queue are now unlocked. */ 257 if (timo) { 258 /* 259 * Even if the callout appears to have fired, we need to 260 * stop it in order to synchronise with other CPUs. 261 */ 262 if (callout_halt(&l->l_timeout_ch, NULL)) 263 error = EWOULDBLOCK; 264 } 265 } 266 267 if (catch && error == 0) { 268 p = l->l_proc; 269 if ((l->l_flag & (LW_CANCELLED | LW_WEXIT | LW_WCORE)) != 0) 270 error = EINTR; 271 else if ((l->l_flag & LW_PENDSIG) != 0) { 272 mutex_enter(p->p_lock); 273 if ((sig = issignal(l)) != 0) 274 error = sleepq_sigtoerror(l, sig); 275 mutex_exit(p->p_lock); 276 } 277 } 278 279 ktrcsw(0, 0); 280 if (__predict_false(l->l_biglocks != 0)) { 281 KERNEL_LOCK(l->l_biglocks, NULL); 282 } 283 return error; 284 } 285 286 /* 287 * sleepq_wake: 288 * 289 * Wake zero or more LWPs blocked on a single wait channel. 290 */ 291 lwp_t * 292 sleepq_wake(sleepq_t *sq, wchan_t wchan, u_int expected, kmutex_t *mp) 293 { 294 lwp_t *l, *next; 295 int swapin = 0; 296 297 KASSERT(mutex_owned(mp)); 298 299 for (l = TAILQ_FIRST(sq); l != NULL; l = next) { 300 KASSERT(l->l_sleepq == sq); 301 KASSERT(l->l_mutex == mp); 302 next = TAILQ_NEXT(l, l_sleepchain); 303 if (l->l_wchan != wchan) 304 continue; 305 swapin |= sleepq_remove(sq, l); 306 if (--expected == 0) 307 break; 308 } 309 310 mutex_spin_exit(mp); 311 312 /* 313 * If there are newly awakend threads that need to be swapped in, 314 * then kick the swapper into action. 315 */ 316 if (swapin) 317 uvm_kick_scheduler(); 318 319 return l; 320 } 321 322 /* 323 * sleepq_unsleep: 324 * 325 * Remove an LWP from its sleep queue and set it runnable again. 326 * sleepq_unsleep() is called with the LWP's mutex held, and will 327 * always release it. 328 */ 329 u_int 330 sleepq_unsleep(lwp_t *l, bool cleanup) 331 { 332 sleepq_t *sq = l->l_sleepq; 333 kmutex_t *mp = l->l_mutex; 334 int swapin; 335 336 KASSERT(lwp_locked(l, mp)); 337 KASSERT(l->l_wchan != NULL); 338 339 swapin = sleepq_remove(sq, l); 340 341 if (cleanup) { 342 mutex_spin_exit(mp); 343 if (swapin) 344 uvm_kick_scheduler(); 345 } 346 347 return swapin; 348 } 349 350 /* 351 * sleepq_timeout: 352 * 353 * Entered via the callout(9) subsystem to time out an LWP that is on a 354 * sleep queue. 355 */ 356 void 357 sleepq_timeout(void *arg) 358 { 359 lwp_t *l = arg; 360 361 /* 362 * Lock the LWP. Assuming it's still on the sleep queue, its 363 * current mutex will also be the sleep queue mutex. 364 */ 365 lwp_lock(l); 366 367 if (l->l_wchan == NULL) { 368 /* Somebody beat us to it. */ 369 lwp_unlock(l); 370 return; 371 } 372 373 lwp_unsleep(l, true); 374 } 375 376 /* 377 * sleepq_sigtoerror: 378 * 379 * Given a signal number, interpret and return an error code. 380 */ 381 int 382 sleepq_sigtoerror(lwp_t *l, int sig) 383 { 384 struct proc *p = l->l_proc; 385 int error; 386 387 KASSERT(mutex_owned(p->p_lock)); 388 389 /* 390 * If this sleep was canceled, don't let the syscall restart. 391 */ 392 if ((SIGACTION(p, sig).sa_flags & SA_RESTART) == 0) 393 error = EINTR; 394 else 395 error = ERESTART; 396 397 return error; 398 } 399 400 /* 401 * sleepq_abort: 402 * 403 * After a panic or during autoconfiguration, lower the interrupt 404 * priority level to give pending interrupts a chance to run, and 405 * then return. Called if sleepq_dontsleep() returns non-zero, and 406 * always returns zero. 407 */ 408 int 409 sleepq_abort(kmutex_t *mtx, int unlock) 410 { 411 extern int safepri; 412 int s; 413 414 s = splhigh(); 415 splx(safepri); 416 splx(s); 417 if (mtx != NULL && unlock != 0) 418 mutex_exit(mtx); 419 420 return 0; 421 } 422 423 /* 424 * sleepq_changepri: 425 * 426 * Adjust the priority of an LWP residing on a sleepq. This method 427 * will only alter the user priority; the effective priority is 428 * assumed to have been fixed at the time of insertion into the queue. 429 */ 430 void 431 sleepq_changepri(lwp_t *l, pri_t pri) 432 { 433 sleepq_t *sq = l->l_sleepq; 434 pri_t opri; 435 436 KASSERT(lwp_locked(l, NULL)); 437 438 opri = lwp_eprio(l); 439 l->l_priority = pri; 440 if (lwp_eprio(l) != opri) { 441 TAILQ_REMOVE(sq, l, l_sleepchain); 442 sleepq_insert(sq, l, l->l_syncobj); 443 } 444 } 445 446 void 447 sleepq_lendpri(lwp_t *l, pri_t pri) 448 { 449 sleepq_t *sq = l->l_sleepq; 450 pri_t opri; 451 452 KASSERT(lwp_locked(l, NULL)); 453 454 opri = lwp_eprio(l); 455 l->l_inheritedprio = pri; 456 457 if (lwp_eprio(l) != opri && 458 (l->l_syncobj->sobj_flag & SOBJ_SLEEPQ_SORTED) != 0) { 459 TAILQ_REMOVE(sq, l, l_sleepchain); 460 sleepq_insert(sq, l, l->l_syncobj); 461 } 462 } 463