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/lock.h> 47 #include <sys/mutex.h> 48 49 /* 50 * TODO: 51 * allocate more timeout table slots when table overflows. 52 */ 53 54 /* Exported to machdep.c and/or kern_clock.c. */ 55 struct callout *callout; 56 struct callout_list callfree; 57 int callwheelsize, callwheelbits, callwheelmask; 58 struct callout_tailq *callwheel; 59 int softticks; /* Like ticks, but for softclock(). */ 60 struct mtx callout_lock; 61 62 static struct callout *nextsoftcheck; /* Next callout to be checked. */ 63 64 /* 65 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization 66 * 67 * This code is called very early in the kernel initialization sequence, 68 * and may be called more then once. 69 */ 70 caddr_t 71 kern_timeout_callwheel_alloc(caddr_t v) 72 { 73 /* 74 * Calculate callout wheel size 75 */ 76 for (callwheelsize = 1, callwheelbits = 0; 77 callwheelsize < ncallout; 78 callwheelsize <<= 1, ++callwheelbits) 79 ; 80 callwheelmask = callwheelsize - 1; 81 82 callout = (struct callout *)v; 83 v = (caddr_t)(callout + ncallout); 84 callwheel = (struct callout_tailq *)v; 85 v = (caddr_t)(callwheel + callwheelsize); 86 return(v); 87 } 88 89 /* 90 * kern_timeout_callwheel_init() - initialize previously reserved callwheel 91 * space. 92 * 93 * This code is called just once, after the space reserved for the 94 * callout wheel has been finalized. 95 */ 96 void 97 kern_timeout_callwheel_init(void) 98 { 99 int i; 100 101 SLIST_INIT(&callfree); 102 for (i = 0; i < ncallout; i++) { 103 callout_init(&callout[i], 0); 104 callout[i].c_flags = CALLOUT_LOCAL_ALLOC; 105 SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle); 106 } 107 for (i = 0; i < callwheelsize; i++) { 108 TAILQ_INIT(&callwheel[i]); 109 } 110 mtx_init(&callout_lock, "callout", MTX_SPIN | MTX_RECURSE); 111 } 112 113 /* 114 * The callout mechanism is based on the work of Adam M. Costello and 115 * George Varghese, published in a technical report entitled "Redesigning 116 * the BSD Callout and Timer Facilities" and modified slightly for inclusion 117 * in FreeBSD by Justin T. Gibbs. The original work on the data structures 118 * used in this implementation was published by G.Varghese and A. Lauck in 119 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for 120 * the Efficient Implementation of a Timer Facility" in the Proceedings of 121 * the 11th ACM Annual Symposium on Operating Systems Principles, 122 * Austin, Texas Nov 1987. 123 */ 124 125 /* 126 * Software (low priority) clock interrupt. 127 * Run periodic events from timeout queue. 128 */ 129 void 130 softclock(void *dummy) 131 { 132 register struct callout *c; 133 register struct callout_tailq *bucket; 134 register int curticks; 135 register int steps; /* #steps since we last allowed interrupts */ 136 137 #ifndef MAX_SOFTCLOCK_STEPS 138 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ 139 #endif /* MAX_SOFTCLOCK_STEPS */ 140 141 steps = 0; 142 mtx_lock_spin(&callout_lock); 143 while (softticks != ticks) { 144 softticks++; 145 /* 146 * softticks may be modified by hard clock, so cache 147 * it while we work on a given bucket. 148 */ 149 curticks = softticks; 150 bucket = &callwheel[curticks & callwheelmask]; 151 c = TAILQ_FIRST(bucket); 152 while (c) { 153 if (c->c_time != curticks) { 154 c = TAILQ_NEXT(c, c_links.tqe); 155 ++steps; 156 if (steps >= MAX_SOFTCLOCK_STEPS) { 157 nextsoftcheck = c; 158 /* Give interrupts a chance. */ 159 mtx_unlock_spin(&callout_lock); 160 ; /* nothing */ 161 mtx_lock_spin(&callout_lock); 162 c = nextsoftcheck; 163 steps = 0; 164 } 165 } else { 166 void (*c_func)(void *); 167 void *c_arg; 168 int c_flags; 169 170 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 171 TAILQ_REMOVE(bucket, c, c_links.tqe); 172 c_func = c->c_func; 173 c_arg = c->c_arg; 174 c_flags = c->c_flags; 175 c->c_func = NULL; 176 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 177 c->c_flags = CALLOUT_LOCAL_ALLOC; 178 SLIST_INSERT_HEAD(&callfree, c, 179 c_links.sle); 180 } else { 181 c->c_flags = 182 (c->c_flags & ~CALLOUT_PENDING); 183 } 184 mtx_unlock_spin(&callout_lock); 185 if (!(c_flags & CALLOUT_MPSAFE)) 186 mtx_lock(&Giant); 187 c_func(c_arg); 188 if (!(c_flags & CALLOUT_MPSAFE)) 189 mtx_unlock(&Giant); 190 mtx_lock_spin(&callout_lock); 191 steps = 0; 192 c = nextsoftcheck; 193 } 194 } 195 } 196 nextsoftcheck = NULL; 197 mtx_unlock_spin(&callout_lock); 198 } 199 200 /* 201 * timeout -- 202 * Execute a function after a specified length of time. 203 * 204 * untimeout -- 205 * Cancel previous timeout function call. 206 * 207 * callout_handle_init -- 208 * Initialize a handle so that using it with untimeout is benign. 209 * 210 * See AT&T BCI Driver Reference Manual for specification. This 211 * implementation differs from that one in that although an 212 * identification value is returned from timeout, the original 213 * arguments to timeout as well as the identifier are used to 214 * identify entries for untimeout. 215 */ 216 struct callout_handle 217 timeout(ftn, arg, to_ticks) 218 timeout_t *ftn; 219 void *arg; 220 int to_ticks; 221 { 222 struct callout *new; 223 struct callout_handle handle; 224 225 mtx_lock_spin(&callout_lock); 226 227 /* Fill in the next free callout structure. */ 228 new = SLIST_FIRST(&callfree); 229 if (new == NULL) 230 /* XXX Attempt to malloc first */ 231 panic("timeout table full"); 232 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 233 234 callout_reset(new, to_ticks, ftn, arg); 235 236 handle.callout = new; 237 mtx_unlock_spin(&callout_lock); 238 return (handle); 239 } 240 241 void 242 untimeout(ftn, arg, handle) 243 timeout_t *ftn; 244 void *arg; 245 struct callout_handle handle; 246 { 247 248 /* 249 * Check for a handle that was initialized 250 * by callout_handle_init, but never used 251 * for a real timeout. 252 */ 253 if (handle.callout == NULL) 254 return; 255 256 mtx_lock_spin(&callout_lock); 257 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) 258 callout_stop(handle.callout); 259 mtx_unlock_spin(&callout_lock); 260 } 261 262 void 263 callout_handle_init(struct callout_handle *handle) 264 { 265 handle->callout = NULL; 266 } 267 268 /* 269 * New interface; clients allocate their own callout structures. 270 * 271 * callout_reset() - establish or change a timeout 272 * callout_stop() - disestablish a timeout 273 * callout_init() - initialize a callout structure so that it can 274 * safely be passed to callout_reset() and callout_stop() 275 * 276 * <sys/callout.h> defines three convenience macros: 277 * 278 * callout_active() - returns truth if callout has not been serviced 279 * callout_pending() - returns truth if callout is still waiting for timeout 280 * callout_deactivate() - marks the callout as having been serviced 281 */ 282 void 283 callout_reset(c, to_ticks, ftn, arg) 284 struct callout *c; 285 int to_ticks; 286 void (*ftn) __P((void *)); 287 void *arg; 288 { 289 290 mtx_lock_spin(&callout_lock); 291 if (c->c_flags & CALLOUT_PENDING) 292 callout_stop(c); 293 294 /* 295 * We could unlock callout_lock here and lock it again before the 296 * TAILQ_INSERT_TAIL, but there's no point since doing this setup 297 * doesn't take much time. 298 */ 299 if (to_ticks <= 0) 300 to_ticks = 1; 301 302 c->c_arg = arg; 303 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); 304 c->c_func = ftn; 305 c->c_time = ticks + to_ticks; 306 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 307 c, c_links.tqe); 308 mtx_unlock_spin(&callout_lock); 309 } 310 311 int 312 callout_stop(c) 313 struct callout *c; 314 { 315 316 mtx_lock_spin(&callout_lock); 317 /* 318 * Don't attempt to delete a callout that's not on the queue. 319 */ 320 if (!(c->c_flags & CALLOUT_PENDING)) { 321 c->c_flags &= ~CALLOUT_ACTIVE; 322 mtx_unlock_spin(&callout_lock); 323 return (0); 324 } 325 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); 326 327 if (nextsoftcheck == c) { 328 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); 329 } 330 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); 331 c->c_func = NULL; 332 333 if (c->c_flags & CALLOUT_LOCAL_ALLOC) { 334 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 335 } 336 mtx_unlock_spin(&callout_lock); 337 return (1); 338 } 339 340 void 341 callout_init(c, mpsafe) 342 struct callout *c; 343 int mpsafe; 344 { 345 bzero(c, sizeof *c); 346 if (mpsafe) 347 c->c_flags |= CALLOUT_MPSAFE; 348 } 349 350 #ifdef APM_FIXUP_CALLTODO 351 /* 352 * Adjust the kernel calltodo timeout list. This routine is used after 353 * an APM resume to recalculate the calltodo timer list values with the 354 * number of hz's we have been sleeping. The next hardclock() will detect 355 * that there are fired timers and run softclock() to execute them. 356 * 357 * Please note, I have not done an exhaustive analysis of what code this 358 * might break. I am motivated to have my select()'s and alarm()'s that 359 * have expired during suspend firing upon resume so that the applications 360 * which set the timer can do the maintanence the timer was for as close 361 * as possible to the originally intended time. Testing this code for a 362 * week showed that resuming from a suspend resulted in 22 to 25 timers 363 * firing, which seemed independant on whether the suspend was 2 hours or 364 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 365 */ 366 void 367 adjust_timeout_calltodo(time_change) 368 struct timeval *time_change; 369 { 370 register struct callout *p; 371 unsigned long delta_ticks; 372 373 /* 374 * How many ticks were we asleep? 375 * (stolen from tvtohz()). 376 */ 377 378 /* Don't do anything */ 379 if (time_change->tv_sec < 0) 380 return; 381 else if (time_change->tv_sec <= LONG_MAX / 1000000) 382 delta_ticks = (time_change->tv_sec * 1000000 + 383 time_change->tv_usec + (tick - 1)) / tick + 1; 384 else if (time_change->tv_sec <= LONG_MAX / hz) 385 delta_ticks = time_change->tv_sec * hz + 386 (time_change->tv_usec + (tick - 1)) / tick + 1; 387 else 388 delta_ticks = LONG_MAX; 389 390 if (delta_ticks > INT_MAX) 391 delta_ticks = INT_MAX; 392 393 /* 394 * Now rip through the timer calltodo list looking for timers 395 * to expire. 396 */ 397 398 /* don't collide with softclock() */ 399 mtx_lock_spin(&callout_lock); 400 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 401 p->c_time -= delta_ticks; 402 403 /* Break if the timer had more time on it than delta_ticks */ 404 if (p->c_time > 0) 405 break; 406 407 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 408 delta_ticks = -p->c_time; 409 } 410 mtx_unlock_spin(&callout_lock); 411 412 return; 413 } 414 #endif /* APM_FIXUP_CALLTODO */ 415