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 * @(#)kern_clock.c 8.5 (Berkeley) 1/21/94 39 * $Id: kern_timeout.c,v 1.54 1998/02/25 06:13:32 bde 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 SLIST_INSERT_HEAD(&callfree, c, c_links.sle); 123 splx(s); 124 c_func(c_arg); 125 s = splhigh(); 126 steps = 0; 127 c = nextsoftcheck; 128 } 129 } 130 } 131 nextsoftcheck = NULL; 132 splx(s); 133 } 134 135 /* 136 * timeout -- 137 * Execute a function after a specified length of time. 138 * 139 * untimeout -- 140 * Cancel previous timeout function call. 141 * 142 * callout_handle_init -- 143 * Initialize a handle so that using it with untimeout is benign. 144 * 145 * See AT&T BCI Driver Reference Manual for specification. This 146 * implementation differs from that one in that although an 147 * identification value is returned from timeout, the original 148 * arguments to timeout as well as the identifier are used to 149 * identify entries for untimeout. 150 */ 151 struct callout_handle 152 timeout(ftn, arg, to_ticks) 153 timeout_t *ftn; 154 void *arg; 155 register int to_ticks; 156 { 157 int s; 158 struct callout *new; 159 struct callout_handle handle; 160 161 if (to_ticks <= 0) 162 to_ticks = 1; 163 164 /* Lock out the clock. */ 165 s = splhigh(); 166 167 /* Fill in the next free callout structure. */ 168 new = SLIST_FIRST(&callfree); 169 if (new == NULL) 170 /* XXX Attempt to malloc first */ 171 panic("timeout table full"); 172 173 SLIST_REMOVE_HEAD(&callfree, c_links.sle); 174 new->c_arg = arg; 175 new->c_func = ftn; 176 new->c_time = ticks + to_ticks; 177 TAILQ_INSERT_TAIL(&callwheel[new->c_time & callwheelmask], 178 new, c_links.tqe); 179 180 splx(s); 181 handle.callout = new; 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) 203 && (handle.callout->c_arg == arg)) { 204 if (nextsoftcheck == handle.callout) { 205 nextsoftcheck = TAILQ_NEXT(handle.callout, c_links.tqe); 206 } 207 TAILQ_REMOVE(&callwheel[handle.callout->c_time & callwheelmask], 208 handle.callout, c_links.tqe); 209 handle.callout->c_func = NULL; 210 SLIST_INSERT_HEAD(&callfree, handle.callout, c_links.sle); 211 } 212 splx(s); 213 } 214 215 void 216 callout_handle_init(struct callout_handle *handle) 217 { 218 handle->callout = NULL; 219 } 220 221 #ifdef APM_FIXUP_CALLTODO 222 /* 223 * Adjust the kernel calltodo timeout list. This routine is used after 224 * an APM resume to recalculate the calltodo timer list values with the 225 * number of hz's we have been sleeping. The next hardclock() will detect 226 * that there are fired timers and run softclock() to execute them. 227 * 228 * Please note, I have not done an exhaustive analysis of what code this 229 * might break. I am motivated to have my select()'s and alarm()'s that 230 * have expired during suspend firing upon resume so that the applications 231 * which set the timer can do the maintanence the timer was for as close 232 * as possible to the originally intended time. Testing this code for a 233 * week showed that resuming from a suspend resulted in 22 to 25 timers 234 * firing, which seemed independant on whether the suspend was 2 hours or 235 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> 236 */ 237 void 238 adjust_timeout_calltodo(time_change) 239 struct timeval *time_change; 240 { 241 register struct callout *p; 242 unsigned long delta_ticks; 243 int s; 244 245 /* 246 * How many ticks were we asleep? 247 * (stolen from tvtohz()). 248 */ 249 250 /* Don't do anything */ 251 if (time_change->tv_sec < 0) 252 return; 253 else if (time_change->tv_sec <= LONG_MAX / 1000000) 254 delta_ticks = (time_change->tv_sec * 1000000 + 255 time_change->tv_usec + (tick - 1)) / tick + 1; 256 else if (time_change->tv_sec <= LONG_MAX / hz) 257 delta_ticks = time_change->tv_sec * hz + 258 (time_change->tv_usec + (tick - 1)) / tick + 1; 259 else 260 delta_ticks = LONG_MAX; 261 262 if (delta_ticks > INT_MAX) 263 delta_ticks = INT_MAX; 264 265 /* 266 * Now rip through the timer calltodo list looking for timers 267 * to expire. 268 */ 269 270 /* don't collide with softclock() */ 271 s = splhigh(); 272 for (p = calltodo.c_next; p != NULL; p = p->c_next) { 273 p->c_time -= delta_ticks; 274 275 /* Break if the timer had more time on it than delta_ticks */ 276 if (p->c_time > 0) 277 break; 278 279 /* take back the ticks the timer didn't use (p->c_time <= 0) */ 280 delta_ticks = -p->c_time; 281 } 282 splx(s); 283 284 return; 285 } 286 #endif /* APM_FIXUP_CALLTODO */ 287