1 /* $OpenBSD: kern_timeout.c,v 1.42 2015/03/14 03:38:50 jsg Exp $ */ 2 /* 3 * Copyright (c) 2001 Thomas Nordin <nordin@openbsd.org> 4 * Copyright (c) 2000-2001 Artur Grabowski <art@openbsd.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 17 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 18 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 19 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 20 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include <sys/param.h> 29 #include <sys/systm.h> 30 #include <sys/lock.h> 31 #include <sys/timeout.h> 32 #include <sys/mutex.h> 33 #include <sys/kernel.h> 34 #include <sys/queue.h> /* _Q_INVALIDATE */ 35 36 #ifdef DDB 37 #include <machine/db_machdep.h> 38 #include <ddb/db_interface.h> 39 #include <ddb/db_sym.h> 40 #include <ddb/db_output.h> 41 #endif 42 43 /* 44 * Timeouts are kept in a hierarchical timing wheel. The to_time is the value 45 * of the global variable "ticks" when the timeout should be called. There are 46 * four levels with 256 buckets each. See 'Scheme 7' in 47 * "Hashed and Hierarchical Timing Wheels: Efficient Data Structures for 48 * Implementing a Timer Facility" by George Varghese and Tony Lauck. 49 */ 50 #define BUCKETS 1024 51 #define WHEELSIZE 256 52 #define WHEELMASK 255 53 #define WHEELBITS 8 54 55 struct circq timeout_wheel[BUCKETS]; /* Queues of timeouts */ 56 struct circq timeout_todo; /* Worklist */ 57 58 #define MASKWHEEL(wheel, time) (((time) >> ((wheel)*WHEELBITS)) & WHEELMASK) 59 60 #define BUCKET(rel, abs) \ 61 (timeout_wheel[ \ 62 ((rel) <= (1 << (2*WHEELBITS))) \ 63 ? ((rel) <= (1 << WHEELBITS)) \ 64 ? MASKWHEEL(0, (abs)) \ 65 : MASKWHEEL(1, (abs)) + WHEELSIZE \ 66 : ((rel) <= (1 << (3*WHEELBITS))) \ 67 ? MASKWHEEL(2, (abs)) + 2*WHEELSIZE \ 68 : MASKWHEEL(3, (abs)) + 3*WHEELSIZE]) 69 70 #define MOVEBUCKET(wheel, time) \ 71 CIRCQ_APPEND(&timeout_todo, \ 72 &timeout_wheel[MASKWHEEL((wheel), (time)) + (wheel)*WHEELSIZE]) 73 74 /* 75 * The first thing in a struct timeout is its struct circq, so we 76 * can get back from a pointer to the latter to a pointer to the 77 * whole timeout with just a cast. 78 */ 79 static __inline struct timeout * 80 timeout_from_circq(struct circq *p) 81 { 82 return ((struct timeout *)(p)); 83 } 84 85 /* 86 * All wheels are locked with the same mutex. 87 * 88 * We need locking since the timeouts are manipulated from hardclock that's 89 * not behind the big lock. 90 */ 91 struct mutex timeout_mutex = MUTEX_INITIALIZER(IPL_HIGH); 92 93 /* 94 * Circular queue definitions. 95 */ 96 97 #define CIRCQ_INIT(elem) do { \ 98 (elem)->next = (elem); \ 99 (elem)->prev = (elem); \ 100 } while (0) 101 102 #define CIRCQ_INSERT(elem, list) do { \ 103 (elem)->prev = (list)->prev; \ 104 (elem)->next = (list); \ 105 (list)->prev->next = (elem); \ 106 (list)->prev = (elem); \ 107 } while (0) 108 109 #define CIRCQ_APPEND(fst, snd) do { \ 110 if (!CIRCQ_EMPTY(snd)) { \ 111 (fst)->prev->next = (snd)->next;\ 112 (snd)->next->prev = (fst)->prev;\ 113 (snd)->prev->next = (fst); \ 114 (fst)->prev = (snd)->prev; \ 115 CIRCQ_INIT(snd); \ 116 } \ 117 } while (0) 118 119 #define CIRCQ_REMOVE(elem) do { \ 120 (elem)->next->prev = (elem)->prev; \ 121 (elem)->prev->next = (elem)->next; \ 122 _Q_INVALIDATE((elem)->prev); \ 123 _Q_INVALIDATE((elem)->next); \ 124 } while (0) 125 126 #define CIRCQ_FIRST(elem) ((elem)->next) 127 128 #define CIRCQ_EMPTY(elem) (CIRCQ_FIRST(elem) == (elem)) 129 130 /* 131 * Some of the "math" in here is a bit tricky. 132 * 133 * We have to beware of wrapping ints. 134 * We use the fact that any element added to the queue must be added with a 135 * positive time. That means that any element `to' on the queue cannot be 136 * scheduled to timeout further in time than INT_MAX, but to->to_time can 137 * be positive or negative so comparing it with anything is dangerous. 138 * The only way we can use the to->to_time value in any predictable way 139 * is when we calculate how far in the future `to' will timeout - 140 * "to->to_time - ticks". The result will always be positive for future 141 * timeouts and 0 or negative for due timeouts. 142 */ 143 extern int ticks; /* XXX - move to sys/X.h */ 144 145 void 146 timeout_startup(void) 147 { 148 int b; 149 150 CIRCQ_INIT(&timeout_todo); 151 for (b = 0; b < nitems(timeout_wheel); b++) 152 CIRCQ_INIT(&timeout_wheel[b]); 153 } 154 155 void 156 timeout_set(struct timeout *new, void (*fn)(void *), void *arg) 157 { 158 new->to_func = fn; 159 new->to_arg = arg; 160 new->to_flags = TIMEOUT_INITIALIZED; 161 } 162 163 164 int 165 timeout_add(struct timeout *new, int to_ticks) 166 { 167 int old_time; 168 int ret = 1; 169 170 #ifdef DIAGNOSTIC 171 if (!(new->to_flags & TIMEOUT_INITIALIZED)) 172 panic("timeout_add: not initialized"); 173 if (to_ticks < 0) 174 panic("timeout_add: to_ticks (%d) < 0", to_ticks); 175 #endif 176 177 mtx_enter(&timeout_mutex); 178 /* Initialize the time here, it won't change. */ 179 old_time = new->to_time; 180 new->to_time = to_ticks + ticks; 181 new->to_flags &= ~TIMEOUT_TRIGGERED; 182 183 /* 184 * If this timeout already is scheduled and now is moved 185 * earlier, reschedule it now. Otherwise leave it in place 186 * and let it be rescheduled later. 187 */ 188 if (new->to_flags & TIMEOUT_ONQUEUE) { 189 if (new->to_time - ticks < old_time - ticks) { 190 CIRCQ_REMOVE(&new->to_list); 191 CIRCQ_INSERT(&new->to_list, &timeout_todo); 192 } 193 ret = 0; 194 } else { 195 new->to_flags |= TIMEOUT_ONQUEUE; 196 CIRCQ_INSERT(&new->to_list, &timeout_todo); 197 } 198 mtx_leave(&timeout_mutex); 199 200 return (ret); 201 } 202 203 int 204 timeout_add_tv(struct timeout *to, const struct timeval *tv) 205 { 206 long long to_ticks; 207 208 to_ticks = (long long)hz * tv->tv_sec + tv->tv_usec / tick; 209 if (to_ticks > INT_MAX) 210 to_ticks = INT_MAX; 211 212 return (timeout_add(to, (int)to_ticks)); 213 } 214 215 int 216 timeout_add_ts(struct timeout *to, const struct timespec *ts) 217 { 218 long long to_ticks; 219 220 to_ticks = (long long)hz * ts->tv_sec + ts->tv_nsec / (tick * 1000); 221 if (to_ticks > INT_MAX) 222 to_ticks = INT_MAX; 223 224 return (timeout_add(to, (int)to_ticks)); 225 } 226 227 int 228 timeout_add_bt(struct timeout *to, const struct bintime *bt) 229 { 230 long long to_ticks; 231 232 to_ticks = (long long)hz * bt->sec + (long)(((uint64_t)1000000 * 233 (uint32_t)(bt->frac >> 32)) >> 32) / tick; 234 if (to_ticks > INT_MAX) 235 to_ticks = INT_MAX; 236 237 return (timeout_add(to, (int)to_ticks)); 238 } 239 240 int 241 timeout_add_sec(struct timeout *to, int secs) 242 { 243 long long to_ticks; 244 245 to_ticks = (long long)hz * secs; 246 if (to_ticks > INT_MAX) 247 to_ticks = INT_MAX; 248 249 return (timeout_add(to, (int)to_ticks)); 250 } 251 252 int 253 timeout_add_msec(struct timeout *to, int msecs) 254 { 255 long long to_ticks; 256 257 to_ticks = (long long)msecs * 1000 / tick; 258 if (to_ticks > INT_MAX) 259 to_ticks = INT_MAX; 260 261 return (timeout_add(to, (int)to_ticks)); 262 } 263 264 int 265 timeout_add_usec(struct timeout *to, int usecs) 266 { 267 int to_ticks = usecs / tick; 268 269 return (timeout_add(to, to_ticks)); 270 } 271 272 int 273 timeout_add_nsec(struct timeout *to, int nsecs) 274 { 275 int to_ticks = nsecs / (tick * 1000); 276 277 return (timeout_add(to, to_ticks)); 278 } 279 280 int 281 timeout_del(struct timeout *to) 282 { 283 int ret = 0; 284 285 mtx_enter(&timeout_mutex); 286 if (to->to_flags & TIMEOUT_ONQUEUE) { 287 CIRCQ_REMOVE(&to->to_list); 288 to->to_flags &= ~TIMEOUT_ONQUEUE; 289 ret = 1; 290 } 291 to->to_flags &= ~TIMEOUT_TRIGGERED; 292 mtx_leave(&timeout_mutex); 293 294 return (ret); 295 } 296 297 /* 298 * This is called from hardclock() once every tick. 299 * We return !0 if we need to schedule a softclock. 300 */ 301 int 302 timeout_hardclock_update(void) 303 { 304 int ret; 305 306 mtx_enter(&timeout_mutex); 307 308 ticks++; 309 310 MOVEBUCKET(0, ticks); 311 if (MASKWHEEL(0, ticks) == 0) { 312 MOVEBUCKET(1, ticks); 313 if (MASKWHEEL(1, ticks) == 0) { 314 MOVEBUCKET(2, ticks); 315 if (MASKWHEEL(2, ticks) == 0) 316 MOVEBUCKET(3, ticks); 317 } 318 } 319 ret = !CIRCQ_EMPTY(&timeout_todo); 320 mtx_leave(&timeout_mutex); 321 322 return (ret); 323 } 324 325 void 326 softclock(void *arg) 327 { 328 struct timeout *to; 329 void (*fn)(void *); 330 331 mtx_enter(&timeout_mutex); 332 while (!CIRCQ_EMPTY(&timeout_todo)) { 333 334 to = timeout_from_circq(CIRCQ_FIRST(&timeout_todo)); 335 CIRCQ_REMOVE(&to->to_list); 336 337 /* If due run it, otherwise insert it into the right bucket. */ 338 if (to->to_time - ticks > 0) { 339 CIRCQ_INSERT(&to->to_list, 340 &BUCKET((to->to_time - ticks), to->to_time)); 341 } else { 342 #ifdef DEBUG 343 if (to->to_time - ticks < 0) 344 printf("timeout delayed %d\n", to->to_time - 345 ticks); 346 #endif 347 to->to_flags &= ~TIMEOUT_ONQUEUE; 348 to->to_flags |= TIMEOUT_TRIGGERED; 349 350 fn = to->to_func; 351 arg = to->to_arg; 352 353 mtx_leave(&timeout_mutex); 354 fn(arg); 355 mtx_enter(&timeout_mutex); 356 } 357 } 358 mtx_leave(&timeout_mutex); 359 } 360 361 #ifndef SMALL_KERNEL 362 void 363 timeout_adjust_ticks(int adj) 364 { 365 struct timeout *to; 366 struct circq *p; 367 int new_ticks, b; 368 369 /* adjusting the monotonic clock backwards would be a Bad Thing */ 370 if (adj <= 0) 371 return; 372 373 mtx_enter(&timeout_mutex); 374 new_ticks = ticks + adj; 375 for (b = 0; b < nitems(timeout_wheel); b++) { 376 p = CIRCQ_FIRST(&timeout_wheel[b]); 377 while (p != &timeout_wheel[b]) { 378 to = timeout_from_circq(p); 379 p = CIRCQ_FIRST(p); 380 381 /* when moving a timeout forward need to reinsert it */ 382 if (to->to_time - ticks < adj) 383 to->to_time = new_ticks; 384 CIRCQ_REMOVE(&to->to_list); 385 CIRCQ_INSERT(&to->to_list, &timeout_todo); 386 } 387 } 388 ticks = new_ticks; 389 mtx_leave(&timeout_mutex); 390 } 391 #endif 392 393 #ifdef DDB 394 void db_show_callout_bucket(struct circq *); 395 396 void 397 db_show_callout_bucket(struct circq *bucket) 398 { 399 struct timeout *to; 400 struct circq *p; 401 db_expr_t offset; 402 char *name; 403 404 for (p = CIRCQ_FIRST(bucket); p != bucket; p = CIRCQ_FIRST(p)) { 405 to = timeout_from_circq(p); 406 db_find_sym_and_offset((db_addr_t)to->to_func, &name, &offset); 407 name = name ? name : "?"; 408 db_printf("%9d %2td/%-4td %p %s\n", to->to_time - ticks, 409 (bucket - timeout_wheel) / WHEELSIZE, 410 bucket - timeout_wheel, to->to_arg, name); 411 } 412 } 413 414 void 415 db_show_callout(db_expr_t addr, int haddr, db_expr_t count, char *modif) 416 { 417 int b; 418 419 db_printf("ticks now: %d\n", ticks); 420 db_printf(" ticks wheel arg func\n"); 421 422 db_show_callout_bucket(&timeout_todo); 423 for (b = 0; b < nitems(timeout_wheel); b++) 424 db_show_callout_bucket(&timeout_wheel[b]); 425 } 426 #endif 427