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 * $FreeBSD$ 40 */ 41 42 #include <sys/param.h> 43 #include <sys/systm.h> 44 #include <sys/callout.h> 45 #include <sys/kernel.h> 46 #include <sys/mutex.h> 47 48 /* 49 * TODO: 50 * allocate more timeout table slots when table overflows. 51 */ 52 53 /* Exported to machdep.c and/or kern_clock.c. */ 54 struct callout *callout; 55 struct callout_list callfree; 56 int callwheelsize, callwheelbits, callwheelmask; 57 struct callout_tailq *callwheel; 58 int softticks; /* Like ticks, but for softclock(). */ 59 struct mtx callout_lock; 60 61 static struct callout *nextsoftcheck; /* Next callout to be checked. */ 62 63 /* 64 * The callout mechanism is based on the work of Adam M. Costello and 65 * George Varghese, published in a technical report entitled "Redesigning 66 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 67 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 68 * used in this implementation was published by G.Varghese and A. Lauck in 69 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 70 * the Efficient Implementation of a Timer Facility" in the Proceedings of 71 * the 11th ACM Annual Symposium on Operating Systems Principles, 72 * Austin, Texas Nov 1987. 73 */ 74 75 /* 76 * Software (low priority) clock interrupt. 77 * Run periodic events from timeout queue. 78 */ 79 void 80 softclock(void *dummy) 81 { 82 register struct callout *c; 83 register struct callout_tailq *bucket; 84 register int s; 85 register int curticks; 86 register int steps; /* #steps since we last allowed interrupts */ 87 88 #ifndef MAX_SOFTCLOCK_STEPS 89 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 90 #endif /* MAX_SOFTCLOCK_STEPS */ 91 92 steps = 0; 93 s = splhigh(); 94 mtx_enter(&callout_lock, MTX_SPIN); 95 while (softticks != ticks) { 96 softticks++; 97 /* 98 * softticks may be modified by hard clock, so cache 99 * it while we work on a given bucket. 100 */ 101 curticks = softticks; 102 bucket = &callwheel[curticks & callwheelmask]; 103 c = TAILQ_FIRST(bucket); 104 while (c) { 105 if (c->c_time != curticks) { 106 c = TAILQ_NEXT(c, c_links.tqe); 107 ++steps; 108 if (steps >= MAX_SOFTCLOCK_STEPS) { 109 nextsoftcheck = c; 110 /* Give interrupts a chance. */ 111 mtx_exit(&callout_lock, MTX_SPIN); 112 splx(s); 113 s = splhigh(); 114 mtx_enter(&callout_lock, MTX_SPIN); 115 c = nextsoftcheck; 116 steps = 0; 117 } 118 } else { 119 void (*c_func)(void *); 120 void *c_arg; 121 int c_flags; 122 123 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 124 TAILQ_REMOVE(bucket, c, c_links.tqe); 125 c_func = c->c_func; 126 c_arg = c->c_arg; 127 c_flags = c->c_flags; 128 c->c_func = NULL; 129 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 130 c->c_flags = CALLOUT_LOCAL_ALLOC; 131 SLIST_INSERT_HEAD(&callfree, c, 132 c_links.sle); 133 } else { 134 c->c_flags = 135 (c->c_flags & ~CALLOUT_PENDING); 136 } 137 mtx_exit(&callout_lock, MTX_SPIN); 138 if (!(c_flags & CALLOUT_MPSAFE)) 139 mtx_enter(&Giant, MTX_DEF); 140 splx(s); 141 c_func(c_arg); 142 s = splhigh(); 143 if (!(c_flags & CALLOUT_MPSAFE)) 144 mtx_exit(&Giant, MTX_DEF); 145 mtx_enter(&callout_lock, MTX_SPIN); 146 steps = 0; 147 c = nextsoftcheck; 148 } 149 } 150 } 151 nextsoftcheck = NULL; 152 mtx_exit(&callout_lock, MTX_SPIN); 153 splx(s); 154 } 155 156 /* 157 * timeout -- 158 * Execute a function after a specified length of time. 159 * 160 * untimeout -- 161 * Cancel previous timeout function call. 162 * 163 * callout_handle_init -- 164 * Initialize a handle so that using it with untimeout is benign. 165 * 166 * See AT&T BCI Driver Reference Manual for specification. This 167 * implementation differs from that one in that although an 168 * identification value is returned from timeout, the original 169 * arguments to timeout as well as the identifier are used to 170 * identify entries for untimeout. 171 */ 172 struct callout_handle 173 timeout(ftn, arg, to_ticks) 174 timeout_t *ftn; 175 void *arg; 176 int to_ticks; 177 { 178 int s; 179 struct callout *new; 180 struct callout_handle handle; 181 182 s = splhigh(); 183 mtx_enter(&callout_lock, MTX_SPIN); 184 185 /* Fill in the next free callout structure. */ 186 new = SLIST_FIRST(&callfree); 187 if (new == NULL) 188 /* XXX Attempt to malloc first */ 189 panic("timeout table full"); 190 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 191 192 callout_reset(new, to_ticks, ftn, arg); 193 194 handle.callout = new; 195 mtx_exit(&callout_lock, MTX_SPIN); 196 splx(s); 197 return (handle); 198 } 199 200 void 201 untimeout(ftn, arg, handle) 202 timeout_t *ftn; 203 void *arg; 204 struct callout_handle handle; 205 { 206 register int s; 207 208 /* 209 * Check for a handle that was initialized 210 * by callout_handle_init, but never used 211 * for a real timeout. 212 */ 213 if (handle.callout == NULL) 214 return; 215 216 s = splhigh(); 217 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 } 223 224 void 225 callout_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 */ 244 void 245 callout_reset(c, to_ticks, ftn, arg) 246 struct callout *c; 247 int to_ticks; 248 void (*ftn) __P((void *)); 249 void *arg; 250 { 251 int s; 252 253 s = splhigh(); 254 mtx_enter(&callout_lock, MTX_SPIN); 255 if (c->c_flags & CALLOUT_PENDING) 256 callout_stop(c); 257 258 /* 259 * We could spl down here and back up at the TAILQ_INSERT_TAIL, 260 * but there's no point since doing this setup doesn't take much 261 * time. 262 */ 263 if (to_ticks <= 0) 264 to_ticks = 1; 265 266 c->c_arg = arg; 267 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 268 c->c_func = ftn; 269 c->c_time = ticks + to_ticks; 270 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 271 c, c_links.tqe); 272 mtx_exit(&callout_lock, MTX_SPIN); 273 splx(s); 274 } 275 276 void 277 callout_stop(c) 278 struct callout *c; 279 { 280 int s; 281 282 s = splhigh(); 283 mtx_enter(&callout_lock, MTX_SPIN); 284 /* 285 * Don't attempt to delete a callout that's not on the queue. 286 */ 287 if (!(c->c_flags & CALLOUT_PENDING)) { 288 c->c_flags &= ~CALLOUT_ACTIVE; 289 mtx_exit(&callout_lock, MTX_SPIN); 290 splx(s); 291 return; 292 } 293 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 294 295 if (nextsoftcheck == c) { 296 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 297 } 298 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 299 c->c_func = NULL; 300 301 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 302 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 303 } 304 mtx_exit(&callout_lock, MTX_SPIN); 305 splx(s); 306 } 307 308 void 309 callout_init(c, mpsafe) 310 struct callout *c; 311 int mpsafe; 312 { 313 bzero(c, sizeof *c); 314 if (mpsafe) 315 c->c_flags |= CALLOUT_MPSAFE; 316 } 317 318 #ifdef APM_FIXUP_CALLTODO 319 /* 320 * Adjust the kernel calltodo timeout list. This routine is used after 321 * an APM resume to recalculate the calltodo timer list values with the 322 * number of hz's we have been sleeping. The next hardclock() will detect 323 * that there are fired timers and run softclock() to execute them. 324 * 325 * Please note, I have not done an exhaustive analysis of what code this 326 * might break. I am motivated to have my select()'s and alarm()'s that 327 * have expired during suspend firing upon resume so that the applications 328 * which set the timer can do the maintanence the timer was for as close 329 * as possible to the originally intended time. Testing this code for a 330 * week showed that resuming from a suspend resulted in 22 to 25 timers 331 * firing, which seemed independant on whether the suspend was 2 hours or 332 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 333 */ 334 void 335 adjust_timeout_calltodo(time_change) 336 struct timeval *time_change; 337 { 338 register struct callout *p; 339 unsigned long delta_ticks; 340 int s; 341 342 /* 343 * How many ticks were we asleep? 344 * (stolen from tvtohz()). 345 */ 346 347 /* Don't do anything */ 348 if (time_change->tv_sec < 0) 349 return; 350 else if (time_change->tv_sec <= LONG_MAX / 1000000) 351 delta_ticks = (time_change->tv_sec * 1000000 + 352 time_change->tv_usec + (tick - 1)) / tick + 1; 353 else if (time_change->tv_sec <= LONG_MAX / hz) 354 delta_ticks = time_change->tv_sec * hz + 355 (time_change->tv_usec + (tick - 1)) / tick + 1; 356 else 357 delta_ticks = LONG_MAX; 358 359 if (delta_ticks > INT_MAX) 360 delta_ticks = INT_MAX; 361 362 /* 363 * Now rip through the timer calltodo list looking for timers 364 * to expire. 365 */ 366 367 /* don't collide with softclock() */ 368 s = splhigh(); 369 mtx_enter(&callout_lock, MTX_SPIN); 370 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 371 p->c_time -= delta_ticks; 372 373 /* Break if the timer had more time on it than delta_ticks */ 374 if (p->c_time > 0) 375 break; 376 377 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 378 delta_ticks = -p->c_time; 379 } 380 mtx_exit(&callout_lock, MTX_SPIN); 381 splx(s); 382 383 return; 384 } 385 #endif /* APM_FIXUP_CALLTODO */ 386