1 /* 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)kern_time.c 8.1 (Berkeley) 6/10/93 34 * $FreeBSD: src/sys/kern/kern_time.c,v 1.68.2.1 2002/10/01 08:00:41 bde Exp $ 35 * $DragonFly: src/sys/kern/kern_time.c,v 1.40 2008/04/02 14:16:16 sephe Exp $ 36 */ 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/buf.h> 41 #include <sys/sysproto.h> 42 #include <sys/resourcevar.h> 43 #include <sys/signalvar.h> 44 #include <sys/kernel.h> 45 #include <sys/systm.h> 46 #include <sys/sysent.h> 47 #include <sys/sysunion.h> 48 #include <sys/proc.h> 49 #include <sys/time.h> 50 #include <sys/vnode.h> 51 #include <sys/sysctl.h> 52 #include <vm/vm.h> 53 #include <vm/vm_extern.h> 54 #include <sys/msgport2.h> 55 #include <sys/thread2.h> 56 57 struct timezone tz; 58 59 /* 60 * Time of day and interval timer support. 61 * 62 * These routines provide the kernel entry points to get and set 63 * the time-of-day and per-process interval timers. Subroutines 64 * here provide support for adding and subtracting timeval structures 65 * and decrementing interval timers, optionally reloading the interval 66 * timers when they expire. 67 */ 68 69 static int nanosleep1 (struct timespec *rqt, 70 struct timespec *rmt); 71 static int settime (struct timeval *); 72 static void timevalfix (struct timeval *); 73 74 static int sleep_hard_us = 100; 75 SYSCTL_INT(_kern, OID_AUTO, sleep_hard_us, CTLFLAG_RW, &sleep_hard_us, 0, "") 76 77 static int 78 settime(struct timeval *tv) 79 { 80 struct timeval delta, tv1, tv2; 81 static struct timeval maxtime, laststep; 82 struct timespec ts; 83 int origcpu; 84 85 if ((origcpu = mycpu->gd_cpuid) != 0) 86 lwkt_setcpu_self(globaldata_find(0)); 87 88 crit_enter(); 89 microtime(&tv1); 90 delta = *tv; 91 timevalsub(&delta, &tv1); 92 93 /* 94 * If the system is secure, we do not allow the time to be 95 * set to a value earlier than 1 second less than the highest 96 * time we have yet seen. The worst a miscreant can do in 97 * this circumstance is "freeze" time. He couldn't go 98 * back to the past. 99 * 100 * We similarly do not allow the clock to be stepped more 101 * than one second, nor more than once per second. This allows 102 * a miscreant to make the clock march double-time, but no worse. 103 */ 104 if (securelevel > 1) { 105 if (delta.tv_sec < 0 || delta.tv_usec < 0) { 106 /* 107 * Update maxtime to latest time we've seen. 108 */ 109 if (tv1.tv_sec > maxtime.tv_sec) 110 maxtime = tv1; 111 tv2 = *tv; 112 timevalsub(&tv2, &maxtime); 113 if (tv2.tv_sec < -1) { 114 tv->tv_sec = maxtime.tv_sec - 1; 115 kprintf("Time adjustment clamped to -1 second\n"); 116 } 117 } else { 118 if (tv1.tv_sec == laststep.tv_sec) { 119 crit_exit(); 120 return (EPERM); 121 } 122 if (delta.tv_sec > 1) { 123 tv->tv_sec = tv1.tv_sec + 1; 124 kprintf("Time adjustment clamped to +1 second\n"); 125 } 126 laststep = *tv; 127 } 128 } 129 130 ts.tv_sec = tv->tv_sec; 131 ts.tv_nsec = tv->tv_usec * 1000; 132 set_timeofday(&ts); 133 crit_exit(); 134 135 if (origcpu != 0) 136 lwkt_setcpu_self(globaldata_find(origcpu)); 137 138 resettodr(); 139 return (0); 140 } 141 142 /* ARGSUSED */ 143 int 144 sys_clock_gettime(struct clock_gettime_args *uap) 145 { 146 struct timespec ats; 147 148 switch(uap->clock_id) { 149 case CLOCK_REALTIME: 150 nanotime(&ats); 151 return (copyout(&ats, uap->tp, sizeof(ats))); 152 case CLOCK_MONOTONIC: 153 nanouptime(&ats); 154 return (copyout(&ats, uap->tp, sizeof(ats))); 155 default: 156 return (EINVAL); 157 } 158 } 159 160 /* ARGSUSED */ 161 int 162 sys_clock_settime(struct clock_settime_args *uap) 163 { 164 struct thread *td = curthread; 165 struct timeval atv; 166 struct timespec ats; 167 int error; 168 169 if ((error = suser(td)) != 0) 170 return (error); 171 switch(uap->clock_id) { 172 case CLOCK_REALTIME: 173 if ((error = copyin(uap->tp, &ats, sizeof(ats))) != 0) 174 return (error); 175 if (ats.tv_nsec < 0 || ats.tv_nsec >= 1000000000) 176 return (EINVAL); 177 /* XXX Don't convert nsec->usec and back */ 178 TIMESPEC_TO_TIMEVAL(&atv, &ats); 179 error = settime(&atv); 180 return (error); 181 default: 182 return (EINVAL); 183 } 184 } 185 186 int 187 sys_clock_getres(struct clock_getres_args *uap) 188 { 189 struct timespec ts; 190 191 switch(uap->clock_id) { 192 case CLOCK_REALTIME: 193 case CLOCK_MONOTONIC: 194 /* 195 * Round up the result of the division cheaply 196 * by adding 1. Rounding up is especially important 197 * if rounding down would give 0. Perfect rounding 198 * is unimportant. 199 */ 200 ts.tv_sec = 0; 201 ts.tv_nsec = 1000000000 / sys_cputimer->freq + 1; 202 return(copyout(&ts, uap->tp, sizeof(ts))); 203 default: 204 return(EINVAL); 205 } 206 } 207 208 /* 209 * nanosleep1() 210 * 211 * This is a general helper function for nanosleep() (aka sleep() aka 212 * usleep()). 213 * 214 * If there is less then one tick's worth of time left and 215 * we haven't done a yield, or the remaining microseconds is 216 * ridiculously low, do a yield. This avoids having 217 * to deal with systimer overheads when the system is under 218 * heavy loads. If we have done a yield already then use 219 * a systimer and an uninterruptable thread wait. 220 * 221 * If there is more then a tick's worth of time left, 222 * calculate the baseline ticks and use an interruptable 223 * tsleep, then handle the fine-grained delay on the next 224 * loop. This usually results in two sleeps occuring, a long one 225 * and a short one. 226 */ 227 static void 228 ns1_systimer(systimer_t info) 229 { 230 lwkt_schedule(info->data); 231 } 232 233 static int 234 nanosleep1(struct timespec *rqt, struct timespec *rmt) 235 { 236 static int nanowait; 237 struct timespec ts, ts2, ts3; 238 struct timeval tv; 239 int error; 240 int tried_yield; 241 242 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000) 243 return (EINVAL); 244 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0)) 245 return (0); 246 nanouptime(&ts); 247 timespecadd(&ts, rqt); /* ts = target timestamp compare */ 248 TIMESPEC_TO_TIMEVAL(&tv, rqt); /* tv = sleep interval */ 249 tried_yield = 0; 250 251 for (;;) { 252 int ticks; 253 struct systimer info; 254 255 ticks = tv.tv_usec / tick; /* approximate */ 256 257 if (tv.tv_sec == 0 && ticks == 0) { 258 thread_t td = curthread; 259 if (tried_yield || tv.tv_usec < sleep_hard_us) { 260 tried_yield = 0; 261 uio_yield(); 262 } else { 263 crit_enter_quick(td); 264 systimer_init_oneshot(&info, ns1_systimer, 265 td, tv.tv_usec); 266 lwkt_deschedule_self(td); 267 crit_exit_quick(td); 268 lwkt_switch(); 269 systimer_del(&info); /* make sure it's gone */ 270 } 271 error = iscaught(td->td_lwp); 272 } else if (tv.tv_sec == 0) { 273 error = tsleep(&nanowait, PCATCH, "nanslp", ticks); 274 } else { 275 ticks = tvtohz_low(&tv); /* also handles overflow */ 276 error = tsleep(&nanowait, PCATCH, "nanslp", ticks); 277 } 278 nanouptime(&ts2); 279 if (error && error != EWOULDBLOCK) { 280 if (error == ERESTART) 281 error = EINTR; 282 if (rmt != NULL) { 283 timespecsub(&ts, &ts2); 284 if (ts.tv_sec < 0) 285 timespecclear(&ts); 286 *rmt = ts; 287 } 288 return (error); 289 } 290 if (timespeccmp(&ts2, &ts, >=)) 291 return (0); 292 ts3 = ts; 293 timespecsub(&ts3, &ts2); 294 TIMESPEC_TO_TIMEVAL(&tv, &ts3); 295 } 296 } 297 298 /* ARGSUSED */ 299 int 300 sys_nanosleep(struct nanosleep_args *uap) 301 { 302 int error; 303 struct timespec rqt; 304 struct timespec rmt; 305 306 error = copyin(uap->rqtp, &rqt, sizeof(rqt)); 307 if (error) 308 return (error); 309 310 error = nanosleep1(&rqt, &rmt); 311 312 /* 313 * copyout the residual if nanosleep was interrupted. 314 */ 315 if (error && uap->rmtp) 316 error = copyout(&rmt, uap->rmtp, sizeof(rmt)); 317 return (error); 318 } 319 320 /* ARGSUSED */ 321 int 322 sys_gettimeofday(struct gettimeofday_args *uap) 323 { 324 struct timeval atv; 325 int error = 0; 326 327 if (uap->tp) { 328 microtime(&atv); 329 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp, 330 sizeof (atv)))) 331 return (error); 332 } 333 if (uap->tzp) 334 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp, 335 sizeof (tz)); 336 return (error); 337 } 338 339 /* ARGSUSED */ 340 int 341 sys_settimeofday(struct settimeofday_args *uap) 342 { 343 struct thread *td = curthread; 344 struct timeval atv; 345 struct timezone atz; 346 int error; 347 348 if ((error = suser(td))) 349 return (error); 350 /* Verify all parameters before changing time. */ 351 if (uap->tv) { 352 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv, 353 sizeof(atv)))) 354 return (error); 355 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000) 356 return (EINVAL); 357 } 358 if (uap->tzp && 359 (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz)))) 360 return (error); 361 if (uap->tv && (error = settime(&atv))) 362 return (error); 363 if (uap->tzp) 364 tz = atz; 365 return (0); 366 } 367 368 static void 369 kern_adjtime_common(void) 370 { 371 if ((ntp_delta >= 0 && ntp_delta < ntp_default_tick_delta) || 372 (ntp_delta < 0 && ntp_delta > -ntp_default_tick_delta)) 373 ntp_tick_delta = ntp_delta; 374 else if (ntp_delta > ntp_big_delta) 375 ntp_tick_delta = 10 * ntp_default_tick_delta; 376 else if (ntp_delta < -ntp_big_delta) 377 ntp_tick_delta = -10 * ntp_default_tick_delta; 378 else if (ntp_delta > 0) 379 ntp_tick_delta = ntp_default_tick_delta; 380 else 381 ntp_tick_delta = -ntp_default_tick_delta; 382 } 383 384 void 385 kern_adjtime(int64_t delta, int64_t *odelta) 386 { 387 int origcpu; 388 389 if ((origcpu = mycpu->gd_cpuid) != 0) 390 lwkt_setcpu_self(globaldata_find(0)); 391 392 crit_enter(); 393 *odelta = ntp_delta; 394 ntp_delta = delta; 395 kern_adjtime_common(); 396 crit_exit(); 397 398 if (origcpu != 0) 399 lwkt_setcpu_self(globaldata_find(origcpu)); 400 } 401 402 static void 403 kern_get_ntp_delta(int64_t *delta) 404 { 405 int origcpu; 406 407 if ((origcpu = mycpu->gd_cpuid) != 0) 408 lwkt_setcpu_self(globaldata_find(0)); 409 410 crit_enter(); 411 *delta = ntp_delta; 412 crit_exit(); 413 414 if (origcpu != 0) 415 lwkt_setcpu_self(globaldata_find(origcpu)); 416 } 417 418 void 419 kern_reladjtime(int64_t delta) 420 { 421 int origcpu; 422 423 if ((origcpu = mycpu->gd_cpuid) != 0) 424 lwkt_setcpu_self(globaldata_find(0)); 425 426 crit_enter(); 427 ntp_delta += delta; 428 kern_adjtime_common(); 429 crit_exit(); 430 431 if (origcpu != 0) 432 lwkt_setcpu_self(globaldata_find(origcpu)); 433 } 434 435 static void 436 kern_adjfreq(int64_t rate) 437 { 438 int origcpu; 439 440 if ((origcpu = mycpu->gd_cpuid) != 0) 441 lwkt_setcpu_self(globaldata_find(0)); 442 443 crit_enter(); 444 ntp_tick_permanent = rate; 445 crit_exit(); 446 447 if (origcpu != 0) 448 lwkt_setcpu_self(globaldata_find(origcpu)); 449 } 450 451 /* ARGSUSED */ 452 int 453 sys_adjtime(struct adjtime_args *uap) 454 { 455 struct thread *td = curthread; 456 struct timeval atv; 457 int64_t ndelta, odelta; 458 int error; 459 460 if ((error = suser(td))) 461 return (error); 462 if ((error = 463 copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof(struct timeval)))) 464 return (error); 465 466 /* 467 * Compute the total correction and the rate at which to apply it. 468 * Round the adjustment down to a whole multiple of the per-tick 469 * delta, so that after some number of incremental changes in 470 * hardclock(), tickdelta will become zero, lest the correction 471 * overshoot and start taking us away from the desired final time. 472 */ 473 ndelta = (int64_t)atv.tv_sec * 1000000000 + atv.tv_usec * 1000; 474 kern_adjtime(ndelta, &odelta); 475 476 if (uap->olddelta) { 477 atv.tv_sec = odelta / 1000000000; 478 atv.tv_usec = odelta % 1000000000 / 1000; 479 (void) copyout((caddr_t)&atv, (caddr_t)uap->olddelta, 480 sizeof(struct timeval)); 481 } 482 return (0); 483 } 484 485 static int 486 sysctl_adjtime(SYSCTL_HANDLER_ARGS) 487 { 488 int64_t delta; 489 int error; 490 491 if (req->newptr != NULL) { 492 if (suser(curthread)) 493 return (EPERM); 494 error = SYSCTL_IN(req, &delta, sizeof(delta)); 495 if (error) 496 return (error); 497 kern_reladjtime(delta); 498 } 499 500 if (req->oldptr) 501 kern_get_ntp_delta(&delta); 502 error = SYSCTL_OUT(req, &delta, sizeof(delta)); 503 return (error); 504 } 505 506 /* 507 * delta is in nanoseconds. 508 */ 509 static int 510 sysctl_delta(SYSCTL_HANDLER_ARGS) 511 { 512 int64_t delta, old_delta; 513 int error; 514 515 if (req->newptr != NULL) { 516 if (suser(curthread)) 517 return (EPERM); 518 error = SYSCTL_IN(req, &delta, sizeof(delta)); 519 if (error) 520 return (error); 521 kern_adjtime(delta, &old_delta); 522 } 523 524 if (req->oldptr != NULL) 525 kern_get_ntp_delta(&old_delta); 526 error = SYSCTL_OUT(req, &old_delta, sizeof(old_delta)); 527 return (error); 528 } 529 530 /* 531 * frequency is in nanoseconds per second shifted left 32. 532 * kern_adjfreq() needs it in nanoseconds per tick shifted left 32. 533 */ 534 static int 535 sysctl_adjfreq(SYSCTL_HANDLER_ARGS) 536 { 537 int64_t freqdelta; 538 int error; 539 540 if (req->newptr != NULL) { 541 if (suser(curthread)) 542 return (EPERM); 543 error = SYSCTL_IN(req, &freqdelta, sizeof(freqdelta)); 544 if (error) 545 return (error); 546 547 freqdelta /= hz; 548 kern_adjfreq(freqdelta); 549 } 550 551 if (req->oldptr != NULL) 552 freqdelta = ntp_tick_permanent * hz; 553 error = SYSCTL_OUT(req, &freqdelta, sizeof(freqdelta)); 554 if (error) 555 return (error); 556 557 return (0); 558 } 559 560 SYSCTL_NODE(_kern, OID_AUTO, ntp, CTLFLAG_RW, 0, "NTP related controls"); 561 SYSCTL_PROC(_kern_ntp, OID_AUTO, permanent, 562 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0, 563 sysctl_adjfreq, "Q", "permanent correction per second"); 564 SYSCTL_PROC(_kern_ntp, OID_AUTO, delta, 565 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0, 566 sysctl_delta, "Q", "one-time delta"); 567 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, big_delta, CTLFLAG_RD, 568 &ntp_big_delta, sizeof(ntp_big_delta), "Q", 569 "threshold for fast adjustment"); 570 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, tick_delta, CTLFLAG_RD, 571 &ntp_tick_delta, sizeof(ntp_tick_delta), "LU", 572 "per-tick adjustment"); 573 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, default_tick_delta, CTLFLAG_RD, 574 &ntp_default_tick_delta, sizeof(ntp_default_tick_delta), "LU", 575 "default per-tick adjustment"); 576 SYSCTL_OPAQUE(_kern_ntp, OID_AUTO, next_leap_second, CTLFLAG_RW, 577 &ntp_leap_second, sizeof(ntp_leap_second), "LU", 578 "next leap second"); 579 SYSCTL_INT(_kern_ntp, OID_AUTO, insert_leap_second, CTLFLAG_RW, 580 &ntp_leap_insert, 0, "insert or remove leap second"); 581 SYSCTL_PROC(_kern_ntp, OID_AUTO, adjust, 582 CTLTYPE_QUAD|CTLFLAG_RW, 0, 0, 583 sysctl_adjtime, "Q", "relative adjust for delta"); 584 585 /* 586 * Get value of an interval timer. The process virtual and 587 * profiling virtual time timers are kept in the p_stats area, since 588 * they can be swapped out. These are kept internally in the 589 * way they are specified externally: in time until they expire. 590 * 591 * The real time interval timer is kept in the process table slot 592 * for the process, and its value (it_value) is kept as an 593 * absolute time rather than as a delta, so that it is easy to keep 594 * periodic real-time signals from drifting. 595 * 596 * Virtual time timers are processed in the hardclock() routine of 597 * kern_clock.c. The real time timer is processed by a timeout 598 * routine, called from the softclock() routine. Since a callout 599 * may be delayed in real time due to interrupt processing in the system, 600 * it is possible for the real time timeout routine (realitexpire, given below), 601 * to be delayed in real time past when it is supposed to occur. It 602 * does not suffice, therefore, to reload the real timer .it_value from the 603 * real time timers .it_interval. Rather, we compute the next time in 604 * absolute time the timer should go off. 605 */ 606 /* ARGSUSED */ 607 int 608 sys_getitimer(struct getitimer_args *uap) 609 { 610 struct proc *p = curproc; 611 struct timeval ctv; 612 struct itimerval aitv; 613 614 if (uap->which > ITIMER_PROF) 615 return (EINVAL); 616 crit_enter(); 617 if (uap->which == ITIMER_REAL) { 618 /* 619 * Convert from absolute to relative time in .it_value 620 * part of real time timer. If time for real time timer 621 * has passed return 0, else return difference between 622 * current time and time for the timer to go off. 623 */ 624 aitv = p->p_realtimer; 625 if (timevalisset(&aitv.it_value)) { 626 getmicrouptime(&ctv); 627 if (timevalcmp(&aitv.it_value, &ctv, <)) 628 timevalclear(&aitv.it_value); 629 else 630 timevalsub(&aitv.it_value, &ctv); 631 } 632 } else { 633 aitv = p->p_timer[uap->which]; 634 } 635 crit_exit(); 636 return (copyout((caddr_t)&aitv, (caddr_t)uap->itv, 637 sizeof (struct itimerval))); 638 } 639 640 /* ARGSUSED */ 641 int 642 sys_setitimer(struct setitimer_args *uap) 643 { 644 struct itimerval aitv; 645 struct timeval ctv; 646 struct itimerval *itvp; 647 struct proc *p = curproc; 648 int error; 649 650 if (uap->which > ITIMER_PROF) 651 return (EINVAL); 652 itvp = uap->itv; 653 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv, 654 sizeof(struct itimerval)))) 655 return (error); 656 if ((uap->itv = uap->oitv) && 657 (error = sys_getitimer((struct getitimer_args *)uap))) 658 return (error); 659 if (itvp == 0) 660 return (0); 661 if (itimerfix(&aitv.it_value)) 662 return (EINVAL); 663 if (!timevalisset(&aitv.it_value)) 664 timevalclear(&aitv.it_interval); 665 else if (itimerfix(&aitv.it_interval)) 666 return (EINVAL); 667 crit_enter(); 668 if (uap->which == ITIMER_REAL) { 669 if (timevalisset(&p->p_realtimer.it_value)) 670 callout_stop(&p->p_ithandle); 671 if (timevalisset(&aitv.it_value)) 672 callout_reset(&p->p_ithandle, 673 tvtohz_high(&aitv.it_value), realitexpire, p); 674 getmicrouptime(&ctv); 675 timevaladd(&aitv.it_value, &ctv); 676 p->p_realtimer = aitv; 677 } else { 678 p->p_timer[uap->which] = aitv; 679 } 680 crit_exit(); 681 return (0); 682 } 683 684 /* 685 * Real interval timer expired: 686 * send process whose timer expired an alarm signal. 687 * If time is not set up to reload, then just return. 688 * Else compute next time timer should go off which is > current time. 689 * This is where delay in processing this timeout causes multiple 690 * SIGALRM calls to be compressed into one. 691 * tvtohz_high() always adds 1 to allow for the time until the next clock 692 * interrupt being strictly less than 1 clock tick, but we don't want 693 * that here since we want to appear to be in sync with the clock 694 * interrupt even when we're delayed. 695 */ 696 void 697 realitexpire(void *arg) 698 { 699 struct proc *p; 700 struct timeval ctv, ntv; 701 702 p = (struct proc *)arg; 703 ksignal(p, SIGALRM); 704 if (!timevalisset(&p->p_realtimer.it_interval)) { 705 timevalclear(&p->p_realtimer.it_value); 706 return; 707 } 708 for (;;) { 709 crit_enter(); 710 timevaladd(&p->p_realtimer.it_value, 711 &p->p_realtimer.it_interval); 712 getmicrouptime(&ctv); 713 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) { 714 ntv = p->p_realtimer.it_value; 715 timevalsub(&ntv, &ctv); 716 callout_reset(&p->p_ithandle, tvtohz_low(&ntv), 717 realitexpire, p); 718 crit_exit(); 719 return; 720 } 721 crit_exit(); 722 } 723 } 724 725 /* 726 * Check that a proposed value to load into the .it_value or 727 * .it_interval part of an interval timer is acceptable, and 728 * fix it to have at least minimal value (i.e. if it is less 729 * than the resolution of the clock, round it up.) 730 */ 731 int 732 itimerfix(struct timeval *tv) 733 { 734 735 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 || 736 tv->tv_usec < 0 || tv->tv_usec >= 1000000) 737 return (EINVAL); 738 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick) 739 tv->tv_usec = tick; 740 return (0); 741 } 742 743 /* 744 * Decrement an interval timer by a specified number 745 * of microseconds, which must be less than a second, 746 * i.e. < 1000000. If the timer expires, then reload 747 * it. In this case, carry over (usec - old value) to 748 * reduce the value reloaded into the timer so that 749 * the timer does not drift. This routine assumes 750 * that it is called in a context where the timers 751 * on which it is operating cannot change in value. 752 */ 753 int 754 itimerdecr(struct itimerval *itp, int usec) 755 { 756 757 if (itp->it_value.tv_usec < usec) { 758 if (itp->it_value.tv_sec == 0) { 759 /* expired, and already in next interval */ 760 usec -= itp->it_value.tv_usec; 761 goto expire; 762 } 763 itp->it_value.tv_usec += 1000000; 764 itp->it_value.tv_sec--; 765 } 766 itp->it_value.tv_usec -= usec; 767 usec = 0; 768 if (timevalisset(&itp->it_value)) 769 return (1); 770 /* expired, exactly at end of interval */ 771 expire: 772 if (timevalisset(&itp->it_interval)) { 773 itp->it_value = itp->it_interval; 774 itp->it_value.tv_usec -= usec; 775 if (itp->it_value.tv_usec < 0) { 776 itp->it_value.tv_usec += 1000000; 777 itp->it_value.tv_sec--; 778 } 779 } else 780 itp->it_value.tv_usec = 0; /* sec is already 0 */ 781 return (0); 782 } 783 784 /* 785 * Add and subtract routines for timevals. 786 * N.B.: subtract routine doesn't deal with 787 * results which are before the beginning, 788 * it just gets very confused in this case. 789 * Caveat emptor. 790 */ 791 void 792 timevaladd(struct timeval *t1, const struct timeval *t2) 793 { 794 795 t1->tv_sec += t2->tv_sec; 796 t1->tv_usec += t2->tv_usec; 797 timevalfix(t1); 798 } 799 800 void 801 timevalsub(struct timeval *t1, const struct timeval *t2) 802 { 803 804 t1->tv_sec -= t2->tv_sec; 805 t1->tv_usec -= t2->tv_usec; 806 timevalfix(t1); 807 } 808 809 static void 810 timevalfix(struct timeval *t1) 811 { 812 813 if (t1->tv_usec < 0) { 814 t1->tv_sec--; 815 t1->tv_usec += 1000000; 816 } 817 if (t1->tv_usec >= 1000000) { 818 t1->tv_sec++; 819 t1->tv_usec -= 1000000; 820 } 821 } 822 823 /* 824 * ratecheck(): simple time-based rate-limit checking. 825 */ 826 int 827 ratecheck(struct timeval *lasttime, const struct timeval *mininterval) 828 { 829 struct timeval tv, delta; 830 int rv = 0; 831 832 getmicrouptime(&tv); /* NB: 10ms precision */ 833 delta = tv; 834 timevalsub(&delta, lasttime); 835 836 /* 837 * check for 0,0 is so that the message will be seen at least once, 838 * even if interval is huge. 839 */ 840 if (timevalcmp(&delta, mininterval, >=) || 841 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) { 842 *lasttime = tv; 843 rv = 1; 844 } 845 846 return (rv); 847 } 848 849 /* 850 * ppsratecheck(): packets (or events) per second limitation. 851 * 852 * Return 0 if the limit is to be enforced (e.g. the caller 853 * should drop a packet because of the rate limitation). 854 * 855 * maxpps of 0 always causes zero to be returned. maxpps of -1 856 * always causes 1 to be returned; this effectively defeats rate 857 * limiting. 858 * 859 * Note that we maintain the struct timeval for compatibility 860 * with other bsd systems. We reuse the storage and just monitor 861 * clock ticks for minimal overhead. 862 */ 863 int 864 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps) 865 { 866 int now; 867 868 /* 869 * Reset the last time and counter if this is the first call 870 * or more than a second has passed since the last update of 871 * lasttime. 872 */ 873 now = ticks; 874 if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) { 875 lasttime->tv_sec = now; 876 *curpps = 1; 877 return (maxpps != 0); 878 } else { 879 (*curpps)++; /* NB: ignore potential overflow */ 880 return (maxpps < 0 || *curpps < maxpps); 881 } 882 } 883 884