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 1.14 2004/01/30 05:42:17 dillon 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 static void no_lease_updatetime (int); 74 75 static int sleep_hard_us = 100; 76 SYSCTL_INT(_kern, OID_AUTO, sleep_hard_us, CTLFLAG_RW, &sleep_hard_us, 0, "") 77 78 static void 79 no_lease_updatetime(deltat) 80 int deltat; 81 { 82 } 83 84 void (*lease_updatetime) (int) = no_lease_updatetime; 85 86 static int 87 settime(tv) 88 struct timeval *tv; 89 { 90 struct timeval delta, tv1, tv2; 91 static struct timeval maxtime, laststep; 92 struct timespec ts; 93 94 crit_enter(); 95 microtime(&tv1); 96 delta = *tv; 97 timevalsub(&delta, &tv1); 98 99 /* 100 * If the system is secure, we do not allow the time to be 101 * set to a value earlier than 1 second less than the highest 102 * time we have yet seen. The worst a miscreant can do in 103 * this circumstance is "freeze" time. He couldn't go 104 * back to the past. 105 * 106 * We similarly do not allow the clock to be stepped more 107 * than one second, nor more than once per second. This allows 108 * a miscreant to make the clock march double-time, but no worse. 109 */ 110 if (securelevel > 1) { 111 if (delta.tv_sec < 0 || delta.tv_usec < 0) { 112 /* 113 * Update maxtime to latest time we've seen. 114 */ 115 if (tv1.tv_sec > maxtime.tv_sec) 116 maxtime = tv1; 117 tv2 = *tv; 118 timevalsub(&tv2, &maxtime); 119 if (tv2.tv_sec < -1) { 120 tv->tv_sec = maxtime.tv_sec - 1; 121 printf("Time adjustment clamped to -1 second\n"); 122 } 123 } else { 124 if (tv1.tv_sec == laststep.tv_sec) { 125 crit_exit(); 126 return (EPERM); 127 } 128 if (delta.tv_sec > 1) { 129 tv->tv_sec = tv1.tv_sec + 1; 130 printf("Time adjustment clamped to +1 second\n"); 131 } 132 laststep = *tv; 133 } 134 } 135 136 ts.tv_sec = tv->tv_sec; 137 ts.tv_nsec = tv->tv_usec * 1000; 138 set_timeofday(&ts); 139 lease_updatetime(delta.tv_sec); 140 crit_exit(); 141 resettodr(); 142 return (0); 143 } 144 145 /* ARGSUSED */ 146 int 147 clock_gettime(struct clock_gettime_args *uap) 148 { 149 struct timespec ats; 150 151 if (SCARG(uap, clock_id) != CLOCK_REALTIME) 152 return (EINVAL); 153 nanotime(&ats); 154 return (copyout(&ats, SCARG(uap, tp), sizeof(ats))); 155 } 156 157 /* ARGSUSED */ 158 int 159 clock_settime(struct clock_settime_args *uap) 160 { 161 struct thread *td = curthread; 162 struct timeval atv; 163 struct timespec ats; 164 int error; 165 166 if ((error = suser(td)) != 0) 167 return (error); 168 if (SCARG(uap, clock_id) != CLOCK_REALTIME) 169 return (EINVAL); 170 if ((error = copyin(SCARG(uap, tp), &ats, sizeof(ats))) != 0) 171 return (error); 172 if (ats.tv_nsec < 0 || ats.tv_nsec >= 1000000000) 173 return (EINVAL); 174 /* XXX Don't convert nsec->usec and back */ 175 TIMESPEC_TO_TIMEVAL(&atv, &ats); 176 if ((error = settime(&atv))) 177 return (error); 178 return (0); 179 } 180 181 int 182 clock_getres(struct clock_getres_args *uap) 183 { 184 struct timespec ts; 185 int error; 186 187 if (SCARG(uap, clock_id) != CLOCK_REALTIME) 188 return (EINVAL); 189 error = 0; 190 if (SCARG(uap, tp)) { 191 ts.tv_sec = 0; 192 /* 193 * Round up the result of the division cheaply by adding 1. 194 * Rounding up is especially important if rounding down 195 * would give 0. Perfect rounding is unimportant. 196 */ 197 ts.tv_nsec = 1000000000 / cputimer_freq + 1; 198 error = copyout(&ts, SCARG(uap, tp), sizeof(ts)); 199 } 200 return (error); 201 } 202 203 /* 204 * nanosleep1() 205 * 206 * This is a general helper function for nanosleep() (aka sleep() aka 207 * usleep()). 208 * 209 * If there is less then one tick's worth of time left and 210 * we haven't done a yield, or the remaining microseconds is 211 * ridiculously low, do a yield. This avoids having 212 * to deal with systimer overheads when the system is under 213 * heavy loads. If we have done a yield already then use 214 * a systimer and an uninterruptable thread wait. 215 * 216 * If there is more then a tick's worth of time left, 217 * calculate the baseline ticks and use an interruptable 218 * tsleep, then handle the fine-grained delay on the next 219 * loop. This usually results in two sleeps occuring, a long one 220 * and a short one. 221 */ 222 static void 223 ns1_systimer(systimer_t info) 224 { 225 lwkt_schedule(info->data); 226 } 227 228 static int 229 nanosleep1(struct timespec *rqt, struct timespec *rmt) 230 { 231 static int nanowait; 232 struct timespec ts, ts2, ts3; 233 struct timeval tv; 234 int error; 235 int tried_yield; 236 237 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000) 238 return (EINVAL); 239 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0)) 240 return (0); 241 nanouptime(&ts); 242 timespecadd(&ts, rqt); /* ts = target timestamp compare */ 243 TIMESPEC_TO_TIMEVAL(&tv, rqt); /* tv = sleep interval */ 244 tried_yield = 0; 245 246 for (;;) { 247 int ticks; 248 struct systimer info; 249 250 ticks = tv.tv_usec / tick; /* approximate */ 251 252 if (tv.tv_sec == 0 && ticks == 0) { 253 if (tried_yield || tv.tv_usec < sleep_hard_us) { 254 tried_yield = 0; 255 uio_yield(); 256 } else { 257 crit_enter(); 258 systimer_init_oneshot(&info, ns1_systimer, 259 curthread, tv.tv_usec); 260 lwkt_deschedule_self(); 261 crit_exit(); 262 lwkt_switch(); 263 systimer_del(&info); /* make sure it's gone */ 264 } 265 error = iscaught(curproc); 266 } else if (tv.tv_sec == 0) { 267 error = tsleep(&nanowait, PCATCH, "nanslp", ticks); 268 } else { 269 ticks = tvtohz_low(&tv); /* also handles overflow */ 270 error = tsleep(&nanowait, PCATCH, "nanslp", ticks); 271 } 272 nanouptime(&ts2); 273 if (error && error != EWOULDBLOCK) { 274 if (error == ERESTART) 275 error = EINTR; 276 if (rmt != NULL) { 277 timespecsub(&ts, &ts2); 278 if (ts.tv_sec < 0) 279 timespecclear(&ts); 280 *rmt = ts; 281 } 282 return (error); 283 } 284 if (timespeccmp(&ts2, &ts, >=)) 285 return (0); 286 ts3 = ts; 287 timespecsub(&ts3, &ts2); 288 TIMESPEC_TO_TIMEVAL(&tv, &ts3); 289 } 290 } 291 292 static void nanosleep_done(void *arg); 293 static void nanosleep_copyout(union sysunion *sysun); 294 295 /* ARGSUSED */ 296 int 297 nanosleep(struct nanosleep_args *uap) 298 { 299 int error; 300 struct sysmsg_sleep *smsleep = &uap->sysmsg.sm.sleep; 301 302 error = copyin(uap->rqtp, &smsleep->rqt, sizeof(smsleep->rqt)); 303 if (error) 304 return (error); 305 /* 306 * YYY clean this up to always use the callout, note that an abort 307 * implementation should record the residual in the async case. 308 */ 309 if (uap->sysmsg.lmsg.ms_flags & MSGF_ASYNC) { 310 quad_t ticks; 311 312 ticks = (quad_t)smsleep->rqt.tv_nsec * hz / 1000000000LL; 313 if (smsleep->rqt.tv_sec) 314 ticks += (quad_t)smsleep->rqt.tv_sec * hz; 315 if (ticks <= 0) { 316 if (ticks == 0) 317 error = 0; 318 else 319 error = EINVAL; 320 } else { 321 uap->sysmsg.copyout = nanosleep_copyout; 322 callout_init(&smsleep->timer); 323 callout_reset(&smsleep->timer, ticks, nanosleep_done, uap); 324 error = EASYNC; 325 } 326 } else { 327 /* 328 * Old synchronous sleep code, copyout the residual if 329 * nanosleep was interrupted. 330 */ 331 error = nanosleep1(&smsleep->rqt, &smsleep->rmt); 332 if (error && SCARG(uap, rmtp)) 333 error = copyout(&smsleep->rmt, SCARG(uap, rmtp), sizeof(smsleep->rmt)); 334 } 335 return (error); 336 } 337 338 /* 339 * Asynch completion for the nanosleep() syscall. This function may be 340 * called from any context and cannot legally access the originating 341 * thread, proc, or its user space. 342 * 343 * YYY change the callout interface API so we can simply assign the replymsg 344 * function to it directly. 345 */ 346 static void 347 nanosleep_done(void *arg) 348 { 349 struct nanosleep_args *uap = arg; 350 351 lwkt_replymsg(&uap->sysmsg.lmsg, 0); 352 } 353 354 /* 355 * Asynch return for the nanosleep() syscall, called in the context of the 356 * originating thread when it pulls the message off the reply port. This 357 * function is responsible for any copyouts to userland. Kernel threads 358 * which do their own internal system calls will not usually call the return 359 * function. 360 */ 361 static void 362 nanosleep_copyout(union sysunion *sysun) 363 { 364 struct nanosleep_args *uap = &sysun->nanosleep; 365 struct sysmsg_sleep *smsleep = &uap->sysmsg.sm.sleep; 366 367 if (sysun->lmsg.ms_error && uap->rmtp) { 368 sysun->lmsg.ms_error = 369 copyout(&smsleep->rmt, uap->rmtp, sizeof(smsleep->rmt)); 370 } 371 } 372 373 /* ARGSUSED */ 374 int 375 gettimeofday(struct gettimeofday_args *uap) 376 { 377 struct timeval atv; 378 int error = 0; 379 380 if (uap->tp) { 381 microtime(&atv); 382 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp, 383 sizeof (atv)))) 384 return (error); 385 } 386 if (uap->tzp) 387 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp, 388 sizeof (tz)); 389 return (error); 390 } 391 392 /* ARGSUSED */ 393 int 394 settimeofday(struct settimeofday_args *uap) 395 { 396 struct thread *td = curthread; 397 struct timeval atv; 398 struct timezone atz; 399 int error; 400 401 if ((error = suser(td))) 402 return (error); 403 /* Verify all parameters before changing time. */ 404 if (uap->tv) { 405 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv, 406 sizeof(atv)))) 407 return (error); 408 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000) 409 return (EINVAL); 410 } 411 if (uap->tzp && 412 (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz)))) 413 return (error); 414 if (uap->tv && (error = settime(&atv))) 415 return (error); 416 if (uap->tzp) 417 tz = atz; 418 return (0); 419 } 420 421 int tickdelta; /* current clock skew, us. per tick */ 422 long timedelta; /* unapplied time correction, us. */ 423 static long bigadj = 1000000; /* use 10x skew above bigadj us. */ 424 425 /* ARGSUSED */ 426 int 427 adjtime(struct adjtime_args *uap) 428 { 429 struct thread *td = curthread; 430 struct timeval atv; 431 long ndelta, ntickdelta, odelta; 432 int error; 433 434 if ((error = suser(td))) 435 return (error); 436 if ((error = 437 copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof(struct timeval)))) 438 return (error); 439 440 /* 441 * Compute the total correction and the rate at which to apply it. 442 * Round the adjustment down to a whole multiple of the per-tick 443 * delta, so that after some number of incremental changes in 444 * hardclock(), tickdelta will become zero, lest the correction 445 * overshoot and start taking us away from the desired final time. 446 */ 447 ndelta = atv.tv_sec * 1000000 + atv.tv_usec; 448 if (ndelta > bigadj || ndelta < -bigadj) 449 ntickdelta = 10 * tickadj; 450 else 451 ntickdelta = tickadj; 452 if (ndelta % ntickdelta) 453 ndelta = ndelta / ntickdelta * ntickdelta; 454 455 /* 456 * To make hardclock()'s job easier, make the per-tick delta negative 457 * if we want time to run slower; then hardclock can simply compute 458 * tick + tickdelta, and subtract tickdelta from timedelta. 459 */ 460 if (ndelta < 0) 461 ntickdelta = -ntickdelta; 462 /* 463 * XXX not MP safe , but will probably work anyway. 464 */ 465 crit_enter(); 466 odelta = timedelta; 467 timedelta = ndelta; 468 tickdelta = ntickdelta; 469 crit_exit(); 470 471 if (uap->olddelta) { 472 atv.tv_sec = odelta / 1000000; 473 atv.tv_usec = odelta % 1000000; 474 (void) copyout((caddr_t)&atv, (caddr_t)uap->olddelta, 475 sizeof(struct timeval)); 476 } 477 return (0); 478 } 479 480 /* 481 * Get value of an interval timer. The process virtual and 482 * profiling virtual time timers are kept in the p_stats area, since 483 * they can be swapped out. These are kept internally in the 484 * way they are specified externally: in time until they expire. 485 * 486 * The real time interval timer is kept in the process table slot 487 * for the process, and its value (it_value) is kept as an 488 * absolute time rather than as a delta, so that it is easy to keep 489 * periodic real-time signals from drifting. 490 * 491 * Virtual time timers are processed in the hardclock() routine of 492 * kern_clock.c. The real time timer is processed by a timeout 493 * routine, called from the softclock() routine. Since a callout 494 * may be delayed in real time due to interrupt processing in the system, 495 * it is possible for the real time timeout routine (realitexpire, given below), 496 * to be delayed in real time past when it is supposed to occur. It 497 * does not suffice, therefore, to reload the real timer .it_value from the 498 * real time timers .it_interval. Rather, we compute the next time in 499 * absolute time the timer should go off. 500 */ 501 /* ARGSUSED */ 502 int 503 getitimer(struct getitimer_args *uap) 504 { 505 struct proc *p = curproc; 506 struct timeval ctv; 507 struct itimerval aitv; 508 509 if (uap->which > ITIMER_PROF) 510 return (EINVAL); 511 crit_enter(); 512 if (uap->which == ITIMER_REAL) { 513 /* 514 * Convert from absolute to relative time in .it_value 515 * part of real time timer. If time for real time timer 516 * has passed return 0, else return difference between 517 * current time and time for the timer to go off. 518 */ 519 aitv = p->p_realtimer; 520 if (timevalisset(&aitv.it_value)) { 521 getmicrouptime(&ctv); 522 if (timevalcmp(&aitv.it_value, &ctv, <)) 523 timevalclear(&aitv.it_value); 524 else 525 timevalsub(&aitv.it_value, &ctv); 526 } 527 } else { 528 aitv = p->p_stats->p_timer[uap->which]; 529 } 530 crit_exit(); 531 return (copyout((caddr_t)&aitv, (caddr_t)uap->itv, 532 sizeof (struct itimerval))); 533 } 534 535 /* ARGSUSED */ 536 int 537 setitimer(struct setitimer_args *uap) 538 { 539 struct itimerval aitv; 540 struct timeval ctv; 541 struct itimerval *itvp; 542 struct proc *p = curproc; 543 int error; 544 545 if (uap->which > ITIMER_PROF) 546 return (EINVAL); 547 itvp = uap->itv; 548 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv, 549 sizeof(struct itimerval)))) 550 return (error); 551 if ((uap->itv = uap->oitv) && 552 (error = getitimer((struct getitimer_args *)uap))) 553 return (error); 554 if (itvp == 0) 555 return (0); 556 if (itimerfix(&aitv.it_value)) 557 return (EINVAL); 558 if (!timevalisset(&aitv.it_value)) 559 timevalclear(&aitv.it_interval); 560 else if (itimerfix(&aitv.it_interval)) 561 return (EINVAL); 562 crit_enter(); 563 if (uap->which == ITIMER_REAL) { 564 if (timevalisset(&p->p_realtimer.it_value)) 565 untimeout(realitexpire, (caddr_t)p, p->p_ithandle); 566 if (timevalisset(&aitv.it_value)) 567 p->p_ithandle = timeout(realitexpire, (caddr_t)p, 568 tvtohz_high(&aitv.it_value)); 569 getmicrouptime(&ctv); 570 timevaladd(&aitv.it_value, &ctv); 571 p->p_realtimer = aitv; 572 } else { 573 p->p_stats->p_timer[uap->which] = aitv; 574 } 575 crit_exit(); 576 return (0); 577 } 578 579 /* 580 * Real interval timer expired: 581 * send process whose timer expired an alarm signal. 582 * If time is not set up to reload, then just return. 583 * Else compute next time timer should go off which is > current time. 584 * This is where delay in processing this timeout causes multiple 585 * SIGALRM calls to be compressed into one. 586 * tvtohz_high() always adds 1 to allow for the time until the next clock 587 * interrupt being strictly less than 1 clock tick, but we don't want 588 * that here since we want to appear to be in sync with the clock 589 * interrupt even when we're delayed. 590 */ 591 void 592 realitexpire(arg) 593 void *arg; 594 { 595 struct proc *p; 596 struct timeval ctv, ntv; 597 598 p = (struct proc *)arg; 599 psignal(p, SIGALRM); 600 if (!timevalisset(&p->p_realtimer.it_interval)) { 601 timevalclear(&p->p_realtimer.it_value); 602 return; 603 } 604 for (;;) { 605 crit_enter(); 606 timevaladd(&p->p_realtimer.it_value, 607 &p->p_realtimer.it_interval); 608 getmicrouptime(&ctv); 609 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) { 610 ntv = p->p_realtimer.it_value; 611 timevalsub(&ntv, &ctv); 612 p->p_ithandle = timeout(realitexpire, (caddr_t)p, 613 tvtohz_low(&ntv)); 614 crit_exit(); 615 return; 616 } 617 crit_exit(); 618 } 619 } 620 621 /* 622 * Check that a proposed value to load into the .it_value or 623 * .it_interval part of an interval timer is acceptable, and 624 * fix it to have at least minimal value (i.e. if it is less 625 * than the resolution of the clock, round it up.) 626 */ 627 int 628 itimerfix(tv) 629 struct timeval *tv; 630 { 631 632 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 || 633 tv->tv_usec < 0 || tv->tv_usec >= 1000000) 634 return (EINVAL); 635 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick) 636 tv->tv_usec = tick; 637 return (0); 638 } 639 640 /* 641 * Decrement an interval timer by a specified number 642 * of microseconds, which must be less than a second, 643 * i.e. < 1000000. If the timer expires, then reload 644 * it. In this case, carry over (usec - old value) to 645 * reduce the value reloaded into the timer so that 646 * the timer does not drift. This routine assumes 647 * that it is called in a context where the timers 648 * on which it is operating cannot change in value. 649 */ 650 int 651 itimerdecr(itp, usec) 652 struct itimerval *itp; 653 int usec; 654 { 655 656 if (itp->it_value.tv_usec < usec) { 657 if (itp->it_value.tv_sec == 0) { 658 /* expired, and already in next interval */ 659 usec -= itp->it_value.tv_usec; 660 goto expire; 661 } 662 itp->it_value.tv_usec += 1000000; 663 itp->it_value.tv_sec--; 664 } 665 itp->it_value.tv_usec -= usec; 666 usec = 0; 667 if (timevalisset(&itp->it_value)) 668 return (1); 669 /* expired, exactly at end of interval */ 670 expire: 671 if (timevalisset(&itp->it_interval)) { 672 itp->it_value = itp->it_interval; 673 itp->it_value.tv_usec -= usec; 674 if (itp->it_value.tv_usec < 0) { 675 itp->it_value.tv_usec += 1000000; 676 itp->it_value.tv_sec--; 677 } 678 } else 679 itp->it_value.tv_usec = 0; /* sec is already 0 */ 680 return (0); 681 } 682 683 /* 684 * Add and subtract routines for timevals. 685 * N.B.: subtract routine doesn't deal with 686 * results which are before the beginning, 687 * it just gets very confused in this case. 688 * Caveat emptor. 689 */ 690 void 691 timevaladd(t1, t2) 692 struct timeval *t1, *t2; 693 { 694 695 t1->tv_sec += t2->tv_sec; 696 t1->tv_usec += t2->tv_usec; 697 timevalfix(t1); 698 } 699 700 void 701 timevalsub(t1, t2) 702 struct timeval *t1, *t2; 703 { 704 705 t1->tv_sec -= t2->tv_sec; 706 t1->tv_usec -= t2->tv_usec; 707 timevalfix(t1); 708 } 709 710 static void 711 timevalfix(t1) 712 struct timeval *t1; 713 { 714 715 if (t1->tv_usec < 0) { 716 t1->tv_sec--; 717 t1->tv_usec += 1000000; 718 } 719 if (t1->tv_usec >= 1000000) { 720 t1->tv_sec++; 721 t1->tv_usec -= 1000000; 722 } 723 } 724 725 /* 726 * ratecheck(): simple time-based rate-limit checking. 727 */ 728 int 729 ratecheck(struct timeval *lasttime, const struct timeval *mininterval) 730 { 731 struct timeval tv, delta; 732 int rv = 0; 733 734 getmicrouptime(&tv); /* NB: 10ms precision */ 735 delta = tv; 736 timevalsub(&delta, lasttime); 737 738 /* 739 * check for 0,0 is so that the message will be seen at least once, 740 * even if interval is huge. 741 */ 742 if (timevalcmp(&delta, mininterval, >=) || 743 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) { 744 *lasttime = tv; 745 rv = 1; 746 } 747 748 return (rv); 749 } 750 751 /* 752 * ppsratecheck(): packets (or events) per second limitation. 753 * 754 * Return 0 if the limit is to be enforced (e.g. the caller 755 * should drop a packet because of the rate limitation). 756 * 757 * maxpps of 0 always causes zero to be returned. maxpps of -1 758 * always causes 1 to be returned; this effectively defeats rate 759 * limiting. 760 * 761 * Note that we maintain the struct timeval for compatibility 762 * with other bsd systems. We reuse the storage and just monitor 763 * clock ticks for minimal overhead. 764 */ 765 int 766 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps) 767 { 768 int now; 769 770 /* 771 * Reset the last time and counter if this is the first call 772 * or more than a second has passed since the last update of 773 * lasttime. 774 */ 775 now = ticks; 776 if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) { 777 lasttime->tv_sec = now; 778 *curpps = 1; 779 return (maxpps != 0); 780 } else { 781 (*curpps)++; /* NB: ignore potential overflow */ 782 return (maxpps < 0 || *curpps < maxpps); 783 } 784 } 785 786