1 /*- 2 * Copyright (c) 1982, 1986, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * (c) UNIX System Laboratories, Inc. 5 * All or some portions of this file are derived from material licensed 6 * to the University of California by American Telephone and Telegraph 7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 8 * the permission of UNIX System Laboratories, Inc. 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 * 38 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 39 * $Id: kern_timeout.c,v 1.56 1999/03/06 04:46:19 wollman Exp $ 40 */ 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/callout.h> 45 #include <sys/kernel.h> 46 47 /* 48 * TODO: 49 * allocate more timeout table slots when table overflows. 50 */ 51 52 /* Exported to machdep.c and/or kern_clock.c. */ 53 struct callout *callout; 54 struct callout_list callfree; 55 int callwheelsize, callwheelbits, callwheelmask; 56 struct callout_tailq *callwheel; 57 int softticks; /* Like ticks, but for softclock(). */ 58 59 static struct callout *nextsoftcheck; /* Next callout to be checked. */ 60 61 /* 62 * The callout mechanism is based on the work of Adam M. Costello and 63 * George Varghese, published in a technical report entitled "Redesigning 64 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 65 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 66 * used in this implementation was published by G.Varghese and A. Lauck in 67 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 68 * the Efficient Implementation of a Timer Facility" in the Proceedings of 69 * the 11th ACM Annual Symposium on Operating Systems Principles, 70 * Austin, Texas Nov 1987. 71 */ 72 73 /* 74 * Software (low priority) clock interrupt. 75 * Run periodic events from timeout queue. 76 */ 77 void 78 softclock() 79 { 80 register struct callout *c; 81 register struct callout_tailq *bucket; 82 register int s; 83 register int curticks; 84 register int steps; /* #steps since we last allowed interrupts */ 85 86 #ifndef MAX_SOFTCLOCK_STEPS 87 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 88 #endif /* MAX_SOFTCLOCK_STEPS */ 89 90 steps = 0; 91 s = splhigh(); 92 while (softticks != ticks) { 93 softticks++; 94 /* 95 * softticks may be modified by hard clock, so cache 96 * it while we work on a given bucket. 97 */ 98 curticks = softticks; 99 bucket = &callwheel[curticks & callwheelmask]; 100 c = TAILQ_FIRST(bucket); 101 while (c) { 102 if (c->c_time != curticks) { 103 c = TAILQ_NEXT(c, c_links.tqe); 104 ++steps; 105 if (steps >= MAX_SOFTCLOCK_STEPS) { 106 nextsoftcheck = c; 107 /* Give interrupts a chance. */ 108 splx(s); 109 s = splhigh(); 110 c = nextsoftcheck; 111 steps = 0; 112 } 113 } else { 114 void (*c_func)(void *); 115 void *c_arg; 116 117 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 118 TAILQ_REMOVE(bucket, c, c_links.tqe); 119 c_func = c->c_func; 120 c_arg = c->c_arg; 121 c->c_func = NULL; 122 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 123 c->c_flags = CALLOUT_LOCAL_ALLOC; 124 SLIST_INSERT_HEAD(&callfree, c, 125 c_links.sle); 126 } else { 127 c->c_flags = 128 (c->c_flags & ~CALLOUT_PENDING) 129 | CALLOUT_FIRED; 130 } 131 splx(s); 132 c_func(c_arg); 133 s = splhigh(); 134 steps = 0; 135 c = nextsoftcheck; 136 } 137 } 138 } 139 nextsoftcheck = NULL; 140 splx(s); 141 } 142 143 /* 144 * timeout -- 145 * Execute a function after a specified length of time. 146 * 147 * untimeout -- 148 * Cancel previous timeout function call. 149 * 150 * callout_handle_init -- 151 * Initialize a handle so that using it with untimeout is benign. 152 * 153 * See AT&T BCI Driver Reference Manual for specification. This 154 * implementation differs from that one in that although an 155 * identification value is returned from timeout, the original 156 * arguments to timeout as well as the identifier are used to 157 * identify entries for untimeout. 158 */ 159 struct callout_handle 160 timeout(ftn, arg, to_ticks) 161 timeout_t *ftn; 162 void *arg; 163 register int to_ticks; 164 { 165 int s; 166 struct callout *new; 167 struct callout_handle handle; 168 169 s = splhigh(); 170 171 /* Fill in the next free callout structure. */ 172 new = SLIST_FIRST(&callfree); 173 if (new == NULL) 174 /* XXX Attempt to malloc first */ 175 panic("timeout table full"); 176 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 177 178 callout_reset(new, to_ticks, ftn, arg); 179 180 handle.callout = new; 181 splx(s); 182 return (handle); 183 } 184 185 void 186 untimeout(ftn, arg, handle) 187 timeout_t *ftn; 188 void *arg; 189 struct callout_handle handle; 190 { 191 register int s; 192 193 /* 194 * Check for a handle that was initialized 195 * by callout_handle_init, but never used 196 * for a real timeout. 197 */ 198 if (handle.callout == NULL) 199 return; 200 201 s = splhigh(); 202 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 203 callout_stop(handle.callout); 204 splx(s); 205 } 206 207 void 208 callout_handle_init(struct callout_handle *handle) 209 { 210 handle->callout = NULL; 211 } 212 213 /* 214 * New interface; clients allocate their own callout structures. 215 * 216 * callout_reset() - establish or change a timeout 217 * callout_stop() - disestablish a timeout 218 * callout_init() - initialize a callout structure so that it can 219 * safely be passed to callout_reset() and callout_stop() 220 * 221 * <sys/callout.h> defines two convenience macros: 222 * 223 * callout_pending() - returns number of ticks until callout fires, or 0 224 * if not scheduled 225 * callout_fired() - returns truth if callout has already been fired 226 */ 227 void 228 callout_reset(c, to_ticks, ftn, arg) 229 struct callout *c; 230 int to_ticks; 231 void (*ftn) __P((void *)); 232 void *arg; 233 { 234 int s; 235 236 s = splhigh(); 237 if (c->c_flags & CALLOUT_PENDING) 238 callout_stop(c); 239 240 /* 241 * We could spl down here and back up at the TAILQ_INSERT_TAIL, 242 * but there's no point since doing this setup doesn't take much 243 ^ time. 244 */ 245 if (to_ticks <= 0) 246 to_ticks = 1; 247 248 c->c_arg = arg; 249 c->c_flags = (c->c_flags & ~CALLOUT_FIRED) | CALLOUT_PENDING; 250 c->c_func = ftn; 251 c->c_time = ticks + to_ticks; 252 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 253 c, c_links.tqe); 254 splx(s); 255 256 } 257 258 void 259 callout_stop(c) 260 struct callout *c; 261 { 262 int s; 263 264 s = splhigh(); 265 /* 266 * Don't attempt to delete a callout that's not on the queue. 267 */ 268 if (!(c->c_flags & CALLOUT_PENDING)) { 269 splx(s); 270 return; 271 } 272 c->c_flags &= ~CALLOUT_PENDING; 273 274 if (nextsoftcheck == c) { 275 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 276 } 277 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 278 c->c_func = NULL; 279 280 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 281 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 282 } 283 splx(s); 284 } 285 286 void 287 callout_init(c) 288 struct callout *c; 289 { 290 bzero(c, sizeof *c); 291 } 292 293 #ifdef APM_FIXUP_CALLTODO 294 /* 295 * Adjust the kernel calltodo timeout list. This routine is used after 296 * an APM resume to recalculate the calltodo timer list values with the 297 * number of hz's we have been sleeping. The next hardclock() will detect 298 * that there are fired timers and run softclock() to execute them. 299 * 300 * Please note, I have not done an exhaustive analysis of what code this 301 * might break. I am motivated to have my select()'s and alarm()'s that 302 * have expired during suspend firing upon resume so that the applications 303 * which set the timer can do the maintanence the timer was for as close 304 * as possible to the originally intended time. Testing this code for a 305 * week showed that resuming from a suspend resulted in 22 to 25 timers 306 * firing, which seemed independant on whether the suspend was 2 hours or 307 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 308 */ 309 void 310 adjust_timeout_calltodo(time_change) 311 struct timeval *time_change; 312 { 313 register struct callout *p; 314 unsigned long delta_ticks; 315 int s; 316 317 /* 318 * How many ticks were we asleep? 319 * (stolen from tvtohz()). 320 */ 321 322 /* Don't do anything */ 323 if (time_change->tv_sec < 0) 324 return; 325 else if (time_change->tv_sec <= LONG_MAX / 1000000) 326 delta_ticks = (time_change->tv_sec * 1000000 + 327 time_change->tv_usec + (tick - 1)) / tick + 1; 328 else if (time_change->tv_sec <= LONG_MAX / hz) 329 delta_ticks = time_change->tv_sec * hz + 330 (time_change->tv_usec + (tick - 1)) / tick + 1; 331 else 332 delta_ticks = LONG_MAX; 333 334 if (delta_ticks > INT_MAX) 335 delta_ticks = INT_MAX; 336 337 /* 338 * Now rip through the timer calltodo list looking for timers 339 * to expire. 340 */ 341 342 /* don't collide with softclock() */ 343 s = splhigh(); 344 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 345 p->c_time -= delta_ticks; 346 347 /* Break if the timer had more time on it than delta_ticks */ 348 if (p->c_time > 0) 349 break; 350 351 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 352 delta_ticks = -p->c_time; 353 } 354 splx(s); 355 356 return; 357 } 358 #endif /* APM_FIXUP_CALLTODO */ 359