kern_timeout.c revision 69136
159093Sdfr/*- 259093Sdfr * Copyright (c) 1982, 1986, 1991, 1993 359093Sdfr * The Regents of the University of California. All rights reserved. 459093Sdfr * (c) UNIX System Laboratories, Inc. 559093Sdfr * All or some portions of this file are derived from material licensed 659093Sdfr * to the University of California by American Telephone and Telegraph 759093Sdfr * Co. or Unix System Laboratories, Inc. and are reproduced herein with 859093Sdfr * the permission of UNIX System Laboratories, Inc. 959093Sdfr * 1059093Sdfr * Redistribution and use in source and binary forms, with or without 1159093Sdfr * modification, are permitted provided that the following conditions 1259093Sdfr * are met: 1359093Sdfr * 1. Redistributions of source code must retain the above copyright 1459093Sdfr * notice, this list of conditions and the following disclaimer. 1559093Sdfr * 2. Redistributions in binary form must reproduce the above copyright 1659093Sdfr * notice, this list of conditions and the following disclaimer in the 1759093Sdfr * documentation and/or other materials provided with the distribution. 1859093Sdfr * 3. All advertising materials mentioning features or use of this software 1959093Sdfr * must display the following acknowledgement: 2059093Sdfr * This product includes software developed by the University of 2159093Sdfr * California, Berkeley and its contributors. 2259093Sdfr * 4. Neither the name of the University nor the names of its contributors 2359093Sdfr * may be used to endorse or promote products derived from this software 2459093Sdfr * without specific prior written permission. 2559093Sdfr * 2659093Sdfr * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27116182Sobrien * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28116182Sobrien * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29116182Sobrien * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 3059093Sdfr * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 3159093Sdfr * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 3259093Sdfr * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 3359093Sdfr * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 3459093Sdfr * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 3559093Sdfr * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 3659093Sdfr * SUCH DAMAGE. 3759093Sdfr * 3859093Sdfr * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 3959093Sdfr * $FreeBSD: head/sys/kern/kern_timeout.c 69136 2000-11-25 03:34:49Z jake $ 4059093Sdfr */ 4159093Sdfr 4259093Sdfr#include <sys/param.h> 4359093Sdfr#include <sys/systm.h> 4459093Sdfr#include <sys/callout.h> 4559093Sdfr#include <sys/kernel.h> 4659093Sdfr#include <sys/mutex.h> 4759093Sdfr 4859093Sdfr/* 4959093Sdfr * TODO: 5059093Sdfr * allocate more timeout table slots when table overflows. 5198105Skbyanc */ 5298105Skbyanc 5359093Sdfr/* Exported to machdep.c and/or kern_clock.c. */ 5498105Skbyancstruct callout *callout; 5559093Sdfrstruct callout_list callfree; 5698105Skbyancint callwheelsize, callwheelbits, callwheelmask; 5759093Sdfrstruct callout_tailq *callwheel; 5859093Sdfrint softticks; /* Like ticks, but for softclock(). */ 5959093Sdfrstruct mtx callout_lock; 6059093Sdfr 6159093Sdfrstatic struct callout *nextsoftcheck; /* Next callout to be checked. */ 6259093Sdfr 6359093Sdfr/* 6459093Sdfr * The callout mechanism is based on the work of Adam M. Costello and 6559093Sdfr * George Varghese, published in a technical report entitled "Redesigning 6659093Sdfr * the BSD Callout and Timer Facilities" and modified slightly for inclusion 6759093Sdfr * in FreeBSD by Justin T. Gibbs. The original work on the data structures 6859093Sdfr * used in this implementation was published by G.Varghese and A. Lauck in 6959093Sdfr * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 7059093Sdfr * the Efficient Implementation of a Timer Facility" in the Proceedings of 7159093Sdfr * the 11th ACM Annual Symposium on Operating Systems Principles, 7259093Sdfr * Austin, Texas Nov 1987. 7359093Sdfr */ 7459093Sdfr 7559093Sdfr/* 7659093Sdfr * Software (low priority) clock interrupt. 7759093Sdfr * Run periodic events from timeout queue. 7859093Sdfr */ 7959093Sdfrvoid 8059093Sdfrsoftclock(void *dummy) 8165173Sdfr{ 8265173Sdfr register struct callout *c; 8359093Sdfr register struct callout_tailq *bucket; 8459093Sdfr register int s; 8559093Sdfr register int curticks; 8659093Sdfr register int steps; /* #steps since we last allowed interrupts */ 8759093Sdfr 8859093Sdfr#ifndef MAX_SOFTCLOCK_STEPS 8959093Sdfr#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 9059093Sdfr#endif /* MAX_SOFTCLOCK_STEPS */ 9159093Sdfr 9259093Sdfr steps = 0; 9359093Sdfr s = splhigh(); 9459093Sdfr mtx_enter(&callout_lock, MTX_SPIN); 9559093Sdfr while (softticks != ticks) { 9659093Sdfr softticks++; 9759093Sdfr /* 9859093Sdfr * softticks may be modified by hard clock, so cache 9959093Sdfr * it while we work on a given bucket. 10065173Sdfr */ 10159093Sdfr curticks = softticks; 10259093Sdfr bucket = &callwheel[curticks & callwheelmask]; 10359093Sdfr c = TAILQ_FIRST(bucket); 10459093Sdfr while (c) { 10559093Sdfr if (c->c_time != curticks) { 10659093Sdfr c = TAILQ_NEXT(c, c_links.tqe); 10759093Sdfr ++steps; 10865173Sdfr if (steps >= MAX_SOFTCLOCK_STEPS) { 10965173Sdfr nextsoftcheck = c; 11065173Sdfr /* Give interrupts a chance. */ 11165173Sdfr mtx_exit(&callout_lock, MTX_SPIN); 11265173Sdfr splx(s); 11365173Sdfr s = splhigh(); 11465173Sdfr mtx_enter(&callout_lock, MTX_SPIN); 11565173Sdfr c = nextsoftcheck; 11665173Sdfr steps = 0; 11765173Sdfr } 11865173Sdfr } else { 11965173Sdfr void (*c_func)(void *); 12065173Sdfr void *c_arg; 12165173Sdfr int c_flags; 12265173Sdfr 12365173Sdfr nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 12465173Sdfr TAILQ_REMOVE(bucket, c, c_links.tqe); 12565173Sdfr c_func = c->c_func; 12665173Sdfr c_arg = c->c_arg; 12765173Sdfr c_flags = c->c_flags; 12865173Sdfr c->c_func = NULL; 12965173Sdfr if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 13065173Sdfr c->c_flags = CALLOUT_LOCAL_ALLOC; 13165173Sdfr SLIST_INSERT_HEAD(&callfree, c, 13259093Sdfr c_links.sle); 13359093Sdfr } else { 13459093Sdfr c->c_flags = 13559093Sdfr (c->c_flags & ~CALLOUT_PENDING); 13659093Sdfr } 13759093Sdfr mtx_exit(&callout_lock, MTX_SPIN); 13859093Sdfr if (!(c_flags & CALLOUT_MPSAFE)) 13959093Sdfr mtx_enter(&Giant, MTX_DEF); 14059093Sdfr splx(s); 14159093Sdfr c_func(c_arg); 14259093Sdfr s = splhigh(); 14359093Sdfr if (!(c_flags & CALLOUT_MPSAFE)) 14459093Sdfr mtx_exit(&Giant, MTX_DEF); 14559093Sdfr mtx_enter(&callout_lock, MTX_SPIN); 14659093Sdfr steps = 0; 14759093Sdfr c = nextsoftcheck; 14859093Sdfr } 14959093Sdfr } 15059093Sdfr } 15159093Sdfr nextsoftcheck = NULL; 15259093Sdfr mtx_exit(&callout_lock, MTX_SPIN); 15359093Sdfr splx(s); 15459093Sdfr} 15559093Sdfr 15659093Sdfr/* 15759093Sdfr * timeout -- 15859093Sdfr * Execute a function after a specified length of time. 15959093Sdfr * 16059093Sdfr * untimeout -- 16159093Sdfr * Cancel previous timeout function call. 16259093Sdfr * 16359093Sdfr * callout_handle_init -- 16459093Sdfr * Initialize a handle so that using it with untimeout is benign. 16559093Sdfr * 16659093Sdfr * See AT&T BCI Driver Reference Manual for specification. This 16759093Sdfr * implementation differs from that one in that although an 16859093Sdfr * identification value is returned from timeout, the original 16959093Sdfr * arguments to timeout as well as the identifier are used to 17059093Sdfr * identify entries for untimeout. 17159093Sdfr */ 17259093Sdfrstruct callout_handle 17359093Sdfrtimeout(ftn, arg, to_ticks) 17459093Sdfr timeout_t *ftn; 17559093Sdfr void *arg; 17659093Sdfr register int to_ticks; 17759093Sdfr{ 17859093Sdfr int s; 17969781Sdwmalone struct callout *new; 18059093Sdfr struct callout_handle handle; 18159093Sdfr 18259093Sdfr s = splhigh(); 18359093Sdfr mtx_enter(&callout_lock, MTX_SPIN); 18459093Sdfr 18559093Sdfr /* Fill in the next free callout structure. */ 18659093Sdfr new = SLIST_FIRST(&callfree); 18759093Sdfr if (new == NULL) 18859093Sdfr /* XXX Attempt to malloc first */ 18959093Sdfr panic("timeout table full"); 19059093Sdfr SLIST_REMOVE_HEAD(&callfree, c_links.sle); 19159093Sdfr 19259093Sdfr callout_reset(new, to_ticks, ftn, arg); 19359093Sdfr 19459093Sdfr handle.callout = new; 19559093Sdfr mtx_exit(&callout_lock, MTX_SPIN); 19659093Sdfr splx(s); 19759820Sdfr return (handle); 19859093Sdfr} 19959093Sdfr 20059093Sdfrvoid 20159093Sdfruntimeout(ftn, arg, handle) 20259093Sdfr timeout_t *ftn; 20359093Sdfr void *arg; 20459093Sdfr struct callout_handle handle; 20559093Sdfr{ 20659093Sdfr register int s; 20759093Sdfr 20859093Sdfr /* 20959093Sdfr * Check for a handle that was initialized 21059820Sdfr * by callout_handle_init, but never used 21159820Sdfr * for a real timeout. 21259093Sdfr */ 21359093Sdfr if (handle.callout == NULL) 21459093Sdfr return; 21559093Sdfr 21659093Sdfr s = splhigh(); 21759093Sdfr mtx_enter(&callout_lock, MTX_SPIN); 218 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 219 callout_stop(handle.callout); 220 mtx_exit(&callout_lock, MTX_SPIN); 221 splx(s); 222} 223 224void 225callout_handle_init(struct callout_handle *handle) 226{ 227 handle->callout = NULL; 228} 229 230/* 231 * New interface; clients allocate their own callout structures. 232 * 233 * callout_reset() - establish or change a timeout 234 * callout_stop() - disestablish a timeout 235 * callout_init() - initialize a callout structure so that it can 236 * safely be passed to callout_reset() and callout_stop() 237 * 238 * <sys/callout.h> defines three convenience macros: 239 * 240 * callout_active() - returns truth if callout has not been serviced 241 * callout_pending() - returns truth if callout is still waiting for timeout 242 * callout_deactivate() - marks the callout as having been serviced 243 */ 244void 245_callout_reset(c, to_ticks, ftn, arg, flags) 246 struct callout *c; 247 int to_ticks; 248 void (*ftn) __P((void *)); 249 void *arg; 250 int flags; 251{ 252 int s; 253 254 s = splhigh(); 255 mtx_enter(&callout_lock, MTX_SPIN); 256 if (c->c_flags & CALLOUT_PENDING) 257 callout_stop(c); 258 259 /* 260 * We could spl down here and back up at the TAILQ_INSERT_TAIL, 261 * but there's no point since doing this setup doesn't take much 262 * time. 263 */ 264 if (to_ticks <= 0) 265 to_ticks = 1; 266 267 c->c_arg = arg; 268 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING | 269 (flags & CALLOUT_MPSAFE)); 270 c->c_func = ftn; 271 c->c_time = ticks + to_ticks; 272 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 273 c, c_links.tqe); 274 mtx_exit(&callout_lock, MTX_SPIN); 275 splx(s); 276} 277 278void 279callout_stop(c) 280 struct callout *c; 281{ 282 int s; 283 284 s = splhigh(); 285 mtx_enter(&callout_lock, MTX_SPIN); 286 /* 287 * Don't attempt to delete a callout that's not on the queue. 288 */ 289 if (!(c->c_flags & CALLOUT_PENDING)) { 290 c->c_flags &= ~CALLOUT_ACTIVE; 291 mtx_exit(&callout_lock, MTX_SPIN); 292 splx(s); 293 return; 294 } 295 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 296 297 if (nextsoftcheck == c) { 298 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 299 } 300 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 301 c->c_func = NULL; 302 303 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 304 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 305 } 306 mtx_exit(&callout_lock, MTX_SPIN); 307 splx(s); 308} 309 310void 311callout_init(c) 312 struct callout *c; 313{ 314 bzero(c, sizeof *c); 315} 316 317#ifdef APM_FIXUP_CALLTODO 318/* 319 * Adjust the kernel calltodo timeout list. This routine is used after 320 * an APM resume to recalculate the calltodo timer list values with the 321 * number of hz's we have been sleeping. The next hardclock() will detect 322 * that there are fired timers and run softclock() to execute them. 323 * 324 * Please note, I have not done an exhaustive analysis of what code this 325 * might break. I am motivated to have my select()'s and alarm()'s that 326 * have expired during suspend firing upon resume so that the applications 327 * which set the timer can do the maintanence the timer was for as close 328 * as possible to the originally intended time. Testing this code for a 329 * week showed that resuming from a suspend resulted in 22 to 25 timers 330 * firing, which seemed independant on whether the suspend was 2 hours or 331 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 332 */ 333void 334adjust_timeout_calltodo(time_change) 335 struct timeval *time_change; 336{ 337 register struct callout *p; 338 unsigned long delta_ticks; 339 int s; 340 341 /* 342 * How many ticks were we asleep? 343 * (stolen from tvtohz()). 344 */ 345 346 /* Don't do anything */ 347 if (time_change->tv_sec < 0) 348 return; 349 else if (time_change->tv_sec <= LONG_MAX / 1000000) 350 delta_ticks = (time_change->tv_sec * 1000000 + 351 time_change->tv_usec + (tick - 1)) / tick + 1; 352 else if (time_change->tv_sec <= LONG_MAX / hz) 353 delta_ticks = time_change->tv_sec * hz + 354 (time_change->tv_usec + (tick - 1)) / tick + 1; 355 else 356 delta_ticks = LONG_MAX; 357 358 if (delta_ticks > INT_MAX) 359 delta_ticks = INT_MAX; 360 361 /* 362 * Now rip through the timer calltodo list looking for timers 363 * to expire. 364 */ 365 366 /* don't collide with softclock() */ 367 s = splhigh(); 368 mtx_enter(&callout_lock, MTX_SPIN); 369 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 370 p->c_time -= delta_ticks; 371 372 /* Break if the timer had more time on it than delta_ticks */ 373 if (p->c_time > 0) 374 break; 375 376 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 377 delta_ticks = -p->c_time; 378 } 379 mtx_exit(&callout_lock, MTX_SPIN); 380 splx(s); 381 382 return; 383} 384#endif /* APM_FIXUP_CALLTODO */ 385