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 * $FreeBSD: src/sys/kern/kern_timeout.c,v 1.59.2.1 2001/11/13 18:24:52 archie Exp $ 40 * $DragonFly: src/sys/kern/kern_timeout.c,v 1.6 2003/08/26 21:09:02 rob Exp $ 41 */ 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/callout.h> 46 #include <sys/kernel.h> 47 #include <sys/interrupt.h> 48 #include <sys/thread.h> 49 #include <machine/ipl.h> 50 51 /* 52 * TODO: 53 * allocate more timeout table slots when table overflows. 54 */ 55 56 /* Exported to machdep.c and/or kern_clock.c. */ 57 struct callout *callout; 58 struct callout_list callfree; 59 int callwheelsize, callwheelbits, callwheelmask; 60 struct callout_tailq *callwheel; 61 int softticks; /* Like ticks, but for softclock(). */ 62 63 static struct callout *nextsoftcheck; /* Next callout to be checked. */ 64 65 /* 66 * The callout mechanism is based on the work of Adam M. Costello and 67 * George Varghese, published in a technical report entitled "Redesigning 68 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 69 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 70 * used in this implementation was published by G.Varghese and A. Lauck in 71 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 72 * the Efficient Implementation of a Timer Facility" in the Proceedings of 73 * the 11th ACM Annual Symposium on Operating Systems Principles, 74 * Austin, Texas Nov 1987. 75 */ 76 77 /* 78 * Software (low priority) clock interrupt. 79 * Run periodic events from timeout queue. 80 */ 81 static void 82 swi_softclock(void *dummy) 83 { 84 struct callout *c; 85 struct callout_tailq *bucket; 86 int s; 87 int curticks; 88 int steps; /* #steps since we last allowed interrupts */ 89 90 #ifndef MAX_SOFTCLOCK_STEPS 91 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 92 #endif /* MAX_SOFTCLOCK_STEPS */ 93 94 steps = 0; 95 s = splhigh(); 96 while (softticks != ticks) { 97 softticks++; 98 /* 99 * softticks may be modified by hard clock, so cache 100 * it while we work on a given bucket. 101 */ 102 curticks = softticks; 103 bucket = &callwheel[curticks & callwheelmask]; 104 c = TAILQ_FIRST(bucket); 105 while (c) { 106 if (c->c_time != curticks) { 107 c = TAILQ_NEXT(c, c_links.tqe); 108 ++steps; 109 if (steps >= MAX_SOFTCLOCK_STEPS) { 110 nextsoftcheck = c; 111 /* Give interrupts a chance. */ 112 splx(s); 113 s = splhigh(); 114 c = nextsoftcheck; 115 steps = 0; 116 } 117 } else { 118 void (*c_func)(void *); 119 void *c_arg; 120 121 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 122 TAILQ_REMOVE(bucket, c, c_links.tqe); 123 c_func = c->c_func; 124 c_arg = c->c_arg; 125 c->c_func = NULL; 126 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 127 c->c_flags = CALLOUT_LOCAL_ALLOC; 128 SLIST_INSERT_HEAD(&callfree, c, 129 c_links.sle); 130 } else { 131 c->c_flags = 132 (c->c_flags & ~CALLOUT_PENDING); 133 } 134 splx(s); 135 c_func(c_arg); 136 s = splhigh(); 137 steps = 0; 138 c = nextsoftcheck; 139 } 140 } 141 } 142 nextsoftcheck = NULL; 143 splx(s); 144 } 145 146 /* 147 * timeout -- 148 * Execute a function after a specified length of time. 149 * 150 * untimeout -- 151 * Cancel previous timeout function call. 152 * 153 * callout_handle_init -- 154 * Initialize a handle so that using it with untimeout is benign. 155 * 156 * See AT&T BCI Driver Reference Manual for specification. This 157 * implementation differs from that one in that although an 158 * identification value is returned from timeout, the original 159 * arguments to timeout as well as the identifier are used to 160 * identify entries for untimeout. 161 */ 162 struct callout_handle 163 timeout(ftn, arg, to_ticks) 164 timeout_t *ftn; 165 void *arg; 166 int to_ticks; 167 { 168 int s; 169 struct callout *new; 170 struct callout_handle handle; 171 172 s = splhigh(); 173 174 /* Fill in the next free callout structure. */ 175 new = SLIST_FIRST(&callfree); 176 if (new == NULL) 177 /* XXX Attempt to malloc first */ 178 panic("timeout table full"); 179 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 180 181 callout_reset(new, to_ticks, ftn, arg); 182 183 handle.callout = new; 184 splx(s); 185 return (handle); 186 } 187 188 void 189 untimeout(ftn, arg, handle) 190 timeout_t *ftn; 191 void *arg; 192 struct callout_handle handle; 193 { 194 int s; 195 196 /* 197 * Check for a handle that was initialized 198 * by callout_handle_init, but never used 199 * for a real timeout. 200 */ 201 if (handle.callout == NULL) 202 return; 203 204 s = splhigh(); 205 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 206 callout_stop(handle.callout); 207 splx(s); 208 } 209 210 void 211 callout_handle_init(struct callout_handle *handle) 212 { 213 handle->callout = NULL; 214 } 215 216 /* 217 * New interface; clients allocate their own callout structures. 218 * 219 * callout_reset() - establish or change a timeout 220 * callout_stop() - disestablish a timeout 221 * callout_init() - initialize a callout structure so that it can 222 * safely be passed to callout_reset() and callout_stop() 223 * 224 * <sys/callout.h> defines three convenience macros: 225 * 226 * callout_active() - returns truth if callout has not been serviced 227 * callout_pending() - returns truth if callout is still waiting for timeout 228 * callout_deactivate() - marks the callout as having been serviced 229 */ 230 void 231 callout_reset(c, to_ticks, ftn, arg) 232 struct callout *c; 233 int to_ticks; 234 void (*ftn) (void *); 235 void *arg; 236 { 237 int s; 238 239 s = splhigh(); 240 if (c->c_flags & CALLOUT_PENDING) 241 callout_stop(c); 242 243 /* 244 * We could spl down here and back up at the TAILQ_INSERT_TAIL, 245 * but there's no point since doing this setup doesn't take much 246 * time. 247 */ 248 if (to_ticks <= 0) 249 to_ticks = 1; 250 251 c->c_arg = arg; 252 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 253 c->c_func = ftn; 254 c->c_time = ticks + to_ticks; 255 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 256 c, c_links.tqe); 257 splx(s); 258 259 } 260 261 int 262 callout_stop(c) 263 struct callout *c; 264 { 265 int s; 266 267 s = splhigh(); 268 /* 269 * Don't attempt to delete a callout that's not on the queue. 270 */ 271 if (!(c->c_flags & CALLOUT_PENDING)) { 272 c->c_flags &= ~CALLOUT_ACTIVE; 273 splx(s); 274 return (0); 275 } 276 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 277 278 if (nextsoftcheck == c) { 279 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 280 } 281 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 282 c->c_func = NULL; 283 284 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 285 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 286 } 287 splx(s); 288 return (1); 289 } 290 291 void 292 callout_init(c) 293 struct callout *c; 294 { 295 bzero(c, sizeof *c); 296 } 297 298 static void 299 swi_softclock_setup(void *arg) 300 { 301 register_swi(SWI_CLOCK, swi_softclock, NULL, "swi_sftclk"); 302 swi_setpriority(SWI_CLOCK, TDPRI_SOFT_TIMER); 303 } 304 305 SYSINIT(vm_setup, SI_SUB_CPU, SI_ORDER_ANY, swi_softclock_setup, NULL); 306 307 #ifdef APM_FIXUP_CALLTODO 308 /* 309 * Adjust the kernel calltodo timeout list. This routine is used after 310 * an APM resume to recalculate the calltodo timer list values with the 311 * number of hz's we have been sleeping. The next hardclock() will detect 312 * that there are fired timers and run softclock() to execute them. 313 * 314 * Please note, I have not done an exhaustive analysis of what code this 315 * might break. I am motivated to have my select()'s and alarm()'s that 316 * have expired during suspend firing upon resume so that the applications 317 * which set the timer can do the maintanence the timer was for as close 318 * as possible to the originally intended time. Testing this code for a 319 * week showed that resuming from a suspend resulted in 22 to 25 timers 320 * firing, which seemed independant on whether the suspend was 2 hours or 321 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 322 */ 323 void 324 adjust_timeout_calltodo(time_change) 325 struct timeval *time_change; 326 { 327 struct callout *p; 328 unsigned long delta_ticks; 329 int s; 330 331 /* 332 * How many ticks were we asleep? 333 * (stolen from tvtohz()). 334 */ 335 336 /* Don't do anything */ 337 if (time_change->tv_sec < 0) 338 return; 339 else if (time_change->tv_sec <= LONG_MAX / 1000000) 340 delta_ticks = (time_change->tv_sec * 1000000 + 341 time_change->tv_usec + (tick - 1)) / tick + 1; 342 else if (time_change->tv_sec <= LONG_MAX / hz) 343 delta_ticks = time_change->tv_sec * hz + 344 (time_change->tv_usec + (tick - 1)) / tick + 1; 345 else 346 delta_ticks = LONG_MAX; 347 348 if (delta_ticks > INT_MAX) 349 delta_ticks = INT_MAX; 350 351 /* 352 * Now rip through the timer calltodo list looking for timers 353 * to expire. 354 */ 355 356 /* don't collide with softclock() */ 357 s = splhigh(); 358 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 359 p->c_time -= delta_ticks; 360 361 /* Break if the timer had more time on it than delta_ticks */ 362 if (p->c_time > 0) 363 break; 364 365 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 366 delta_ticks = -p->c_time; 367 } 368 splx(s); 369 370 return; 371 } 372 #endif /* APM_FIXUP_CALLTODO */ 373