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 1.15 2004/04/10 20:55:23 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 thread_t td = curthread; 254 if (tried_yield || tv.tv_usec < sleep_hard_us) { 255 tried_yield = 0; 256 uio_yield(); 257 } else { 258 crit_enter_quick(td); 259 systimer_init_oneshot(&info, ns1_systimer, 260 td, tv.tv_usec); 261 lwkt_deschedule_self(td); 262 crit_exit_quick(td); 263 lwkt_switch(); 264 systimer_del(&info); /* make sure it's gone */ 265 } 266 error = iscaught(td->td_proc); 267 } else if (tv.tv_sec == 0) { 268 error = tsleep(&nanowait, PCATCH, "nanslp", ticks); 269 } else { 270 ticks = tvtohz_low(&tv); /* also handles overflow */ 271 error = tsleep(&nanowait, PCATCH, "nanslp", ticks); 272 } 273 nanouptime(&ts2); 274 if (error && error != EWOULDBLOCK) { 275 if (error == ERESTART) 276 error = EINTR; 277 if (rmt != NULL) { 278 timespecsub(&ts, &ts2); 279 if (ts.tv_sec < 0) 280 timespecclear(&ts); 281 *rmt = ts; 282 } 283 return (error); 284 } 285 if (timespeccmp(&ts2, &ts, >=)) 286 return (0); 287 ts3 = ts; 288 timespecsub(&ts3, &ts2); 289 TIMESPEC_TO_TIMEVAL(&tv, &ts3); 290 } 291 } 292 293 static void nanosleep_done(void *arg); 294 static void nanosleep_copyout(union sysunion *sysun); 295 296 /* ARGSUSED */ 297 int 298 nanosleep(struct nanosleep_args *uap) 299 { 300 int error; 301 struct sysmsg_sleep *smsleep = &uap->sysmsg.sm.sleep; 302 303 error = copyin(uap->rqtp, &smsleep->rqt, sizeof(smsleep->rqt)); 304 if (error) 305 return (error); 306 /* 307 * YYY clean this up to always use the callout, note that an abort 308 * implementation should record the residual in the async case. 309 */ 310 if (uap->sysmsg.lmsg.ms_flags & MSGF_ASYNC) { 311 quad_t ticks; 312 313 ticks = (quad_t)smsleep->rqt.tv_nsec * hz / 1000000000LL; 314 if (smsleep->rqt.tv_sec) 315 ticks += (quad_t)smsleep->rqt.tv_sec * hz; 316 if (ticks <= 0) { 317 if (ticks == 0) 318 error = 0; 319 else 320 error = EINVAL; 321 } else { 322 uap->sysmsg.copyout = nanosleep_copyout; 323 callout_init(&smsleep->timer); 324 callout_reset(&smsleep->timer, ticks, nanosleep_done, uap); 325 error = EASYNC; 326 } 327 } else { 328 /* 329 * Old synchronous sleep code, copyout the residual if 330 * nanosleep was interrupted. 331 */ 332 error = nanosleep1(&smsleep->rqt, &smsleep->rmt); 333 if (error && SCARG(uap, rmtp)) 334 error = copyout(&smsleep->rmt, SCARG(uap, rmtp), sizeof(smsleep->rmt)); 335 } 336 return (error); 337 } 338 339 /* 340 * Asynch completion for the nanosleep() syscall. This function may be 341 * called from any context and cannot legally access the originating 342 * thread, proc, or its user space. 343 * 344 * YYY change the callout interface API so we can simply assign the replymsg 345 * function to it directly. 346 */ 347 static void 348 nanosleep_done(void *arg) 349 { 350 struct nanosleep_args *uap = arg; 351 352 lwkt_replymsg(&uap->sysmsg.lmsg, 0); 353 } 354 355 /* 356 * Asynch return for the nanosleep() syscall, called in the context of the 357 * originating thread when it pulls the message off the reply port. This 358 * function is responsible for any copyouts to userland. Kernel threads 359 * which do their own internal system calls will not usually call the return 360 * function. 361 */ 362 static void 363 nanosleep_copyout(union sysunion *sysun) 364 { 365 struct nanosleep_args *uap = &sysun->nanosleep; 366 struct sysmsg_sleep *smsleep = &uap->sysmsg.sm.sleep; 367 368 if (sysun->lmsg.ms_error && uap->rmtp) { 369 sysun->lmsg.ms_error = 370 copyout(&smsleep->rmt, uap->rmtp, sizeof(smsleep->rmt)); 371 } 372 } 373 374 /* ARGSUSED */ 375 int 376 gettimeofday(struct gettimeofday_args *uap) 377 { 378 struct timeval atv; 379 int error = 0; 380 381 if (uap->tp) { 382 microtime(&atv); 383 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp, 384 sizeof (atv)))) 385 return (error); 386 } 387 if (uap->tzp) 388 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp, 389 sizeof (tz)); 390 return (error); 391 } 392 393 /* ARGSUSED */ 394 int 395 settimeofday(struct settimeofday_args *uap) 396 { 397 struct thread *td = curthread; 398 struct timeval atv; 399 struct timezone atz; 400 int error; 401 402 if ((error = suser(td))) 403 return (error); 404 /* Verify all parameters before changing time. */ 405 if (uap->tv) { 406 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv, 407 sizeof(atv)))) 408 return (error); 409 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000) 410 return (EINVAL); 411 } 412 if (uap->tzp && 413 (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz)))) 414 return (error); 415 if (uap->tv && (error = settime(&atv))) 416 return (error); 417 if (uap->tzp) 418 tz = atz; 419 return (0); 420 } 421 422 int tickdelta; /* current clock skew, us. per tick */ 423 long timedelta; /* unapplied time correction, us. */ 424 static long bigadj = 1000000; /* use 10x skew above bigadj us. */ 425 426 /* ARGSUSED */ 427 int 428 adjtime(struct adjtime_args *uap) 429 { 430 struct thread *td = curthread; 431 struct timeval atv; 432 long ndelta, ntickdelta, odelta; 433 int error; 434 435 if ((error = suser(td))) 436 return (error); 437 if ((error = 438 copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof(struct timeval)))) 439 return (error); 440 441 /* 442 * Compute the total correction and the rate at which to apply it. 443 * Round the adjustment down to a whole multiple of the per-tick 444 * delta, so that after some number of incremental changes in 445 * hardclock(), tickdelta will become zero, lest the correction 446 * overshoot and start taking us away from the desired final time. 447 */ 448 ndelta = atv.tv_sec * 1000000 + atv.tv_usec; 449 if (ndelta > bigadj || ndelta < -bigadj) 450 ntickdelta = 10 * tickadj; 451 else 452 ntickdelta = tickadj; 453 if (ndelta % ntickdelta) 454 ndelta = ndelta / ntickdelta * ntickdelta; 455 456 /* 457 * To make hardclock()'s job easier, make the per-tick delta negative 458 * if we want time to run slower; then hardclock can simply compute 459 * tick + tickdelta, and subtract tickdelta from timedelta. 460 */ 461 if (ndelta < 0) 462 ntickdelta = -ntickdelta; 463 /* 464 * XXX not MP safe , but will probably work anyway. 465 */ 466 crit_enter(); 467 odelta = timedelta; 468 timedelta = ndelta; 469 tickdelta = ntickdelta; 470 crit_exit(); 471 472 if (uap->olddelta) { 473 atv.tv_sec = odelta / 1000000; 474 atv.tv_usec = odelta % 1000000; 475 (void) copyout((caddr_t)&atv, (caddr_t)uap->olddelta, 476 sizeof(struct timeval)); 477 } 478 return (0); 479 } 480 481 /* 482 * Get value of an interval timer. The process virtual and 483 * profiling virtual time timers are kept in the p_stats area, since 484 * they can be swapped out. These are kept internally in the 485 * way they are specified externally: in time until they expire. 486 * 487 * The real time interval timer is kept in the process table slot 488 * for the process, and its value (it_value) is kept as an 489 * absolute time rather than as a delta, so that it is easy to keep 490 * periodic real-time signals from drifting. 491 * 492 * Virtual time timers are processed in the hardclock() routine of 493 * kern_clock.c. The real time timer is processed by a timeout 494 * routine, called from the softclock() routine. Since a callout 495 * may be delayed in real time due to interrupt processing in the system, 496 * it is possible for the real time timeout routine (realitexpire, given below), 497 * to be delayed in real time past when it is supposed to occur. It 498 * does not suffice, therefore, to reload the real timer .it_value from the 499 * real time timers .it_interval. Rather, we compute the next time in 500 * absolute time the timer should go off. 501 */ 502 /* ARGSUSED */ 503 int 504 getitimer(struct getitimer_args *uap) 505 { 506 struct proc *p = curproc; 507 struct timeval ctv; 508 struct itimerval aitv; 509 510 if (uap->which > ITIMER_PROF) 511 return (EINVAL); 512 crit_enter(); 513 if (uap->which == ITIMER_REAL) { 514 /* 515 * Convert from absolute to relative time in .it_value 516 * part of real time timer. If time for real time timer 517 * has passed return 0, else return difference between 518 * current time and time for the timer to go off. 519 */ 520 aitv = p->p_realtimer; 521 if (timevalisset(&aitv.it_value)) { 522 getmicrouptime(&ctv); 523 if (timevalcmp(&aitv.it_value, &ctv, <)) 524 timevalclear(&aitv.it_value); 525 else 526 timevalsub(&aitv.it_value, &ctv); 527 } 528 } else { 529 aitv = p->p_stats->p_timer[uap->which]; 530 } 531 crit_exit(); 532 return (copyout((caddr_t)&aitv, (caddr_t)uap->itv, 533 sizeof (struct itimerval))); 534 } 535 536 /* ARGSUSED */ 537 int 538 setitimer(struct setitimer_args *uap) 539 { 540 struct itimerval aitv; 541 struct timeval ctv; 542 struct itimerval *itvp; 543 struct proc *p = curproc; 544 int error; 545 546 if (uap->which > ITIMER_PROF) 547 return (EINVAL); 548 itvp = uap->itv; 549 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv, 550 sizeof(struct itimerval)))) 551 return (error); 552 if ((uap->itv = uap->oitv) && 553 (error = getitimer((struct getitimer_args *)uap))) 554 return (error); 555 if (itvp == 0) 556 return (0); 557 if (itimerfix(&aitv.it_value)) 558 return (EINVAL); 559 if (!timevalisset(&aitv.it_value)) 560 timevalclear(&aitv.it_interval); 561 else if (itimerfix(&aitv.it_interval)) 562 return (EINVAL); 563 crit_enter(); 564 if (uap->which == ITIMER_REAL) { 565 if (timevalisset(&p->p_realtimer.it_value)) 566 untimeout(realitexpire, (caddr_t)p, p->p_ithandle); 567 if (timevalisset(&aitv.it_value)) 568 p->p_ithandle = timeout(realitexpire, (caddr_t)p, 569 tvtohz_high(&aitv.it_value)); 570 getmicrouptime(&ctv); 571 timevaladd(&aitv.it_value, &ctv); 572 p->p_realtimer = aitv; 573 } else { 574 p->p_stats->p_timer[uap->which] = aitv; 575 } 576 crit_exit(); 577 return (0); 578 } 579 580 /* 581 * Real interval timer expired: 582 * send process whose timer expired an alarm signal. 583 * If time is not set up to reload, then just return. 584 * Else compute next time timer should go off which is > current time. 585 * This is where delay in processing this timeout causes multiple 586 * SIGALRM calls to be compressed into one. 587 * tvtohz_high() always adds 1 to allow for the time until the next clock 588 * interrupt being strictly less than 1 clock tick, but we don't want 589 * that here since we want to appear to be in sync with the clock 590 * interrupt even when we're delayed. 591 */ 592 void 593 realitexpire(arg) 594 void *arg; 595 { 596 struct proc *p; 597 struct timeval ctv, ntv; 598 599 p = (struct proc *)arg; 600 psignal(p, SIGALRM); 601 if (!timevalisset(&p->p_realtimer.it_interval)) { 602 timevalclear(&p->p_realtimer.it_value); 603 return; 604 } 605 for (;;) { 606 crit_enter(); 607 timevaladd(&p->p_realtimer.it_value, 608 &p->p_realtimer.it_interval); 609 getmicrouptime(&ctv); 610 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) { 611 ntv = p->p_realtimer.it_value; 612 timevalsub(&ntv, &ctv); 613 p->p_ithandle = timeout(realitexpire, (caddr_t)p, 614 tvtohz_low(&ntv)); 615 crit_exit(); 616 return; 617 } 618 crit_exit(); 619 } 620 } 621 622 /* 623 * Check that a proposed value to load into the .it_value or 624 * .it_interval part of an interval timer is acceptable, and 625 * fix it to have at least minimal value (i.e. if it is less 626 * than the resolution of the clock, round it up.) 627 */ 628 int 629 itimerfix(tv) 630 struct timeval *tv; 631 { 632 633 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 || 634 tv->tv_usec < 0 || tv->tv_usec >= 1000000) 635 return (EINVAL); 636 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick) 637 tv->tv_usec = tick; 638 return (0); 639 } 640 641 /* 642 * Decrement an interval timer by a specified number 643 * of microseconds, which must be less than a second, 644 * i.e. < 1000000. If the timer expires, then reload 645 * it. In this case, carry over (usec - old value) to 646 * reduce the value reloaded into the timer so that 647 * the timer does not drift. This routine assumes 648 * that it is called in a context where the timers 649 * on which it is operating cannot change in value. 650 */ 651 int 652 itimerdecr(itp, usec) 653 struct itimerval *itp; 654 int usec; 655 { 656 657 if (itp->it_value.tv_usec < usec) { 658 if (itp->it_value.tv_sec == 0) { 659 /* expired, and already in next interval */ 660 usec -= itp->it_value.tv_usec; 661 goto expire; 662 } 663 itp->it_value.tv_usec += 1000000; 664 itp->it_value.tv_sec--; 665 } 666 itp->it_value.tv_usec -= usec; 667 usec = 0; 668 if (timevalisset(&itp->it_value)) 669 return (1); 670 /* expired, exactly at end of interval */ 671 expire: 672 if (timevalisset(&itp->it_interval)) { 673 itp->it_value = itp->it_interval; 674 itp->it_value.tv_usec -= usec; 675 if (itp->it_value.tv_usec < 0) { 676 itp->it_value.tv_usec += 1000000; 677 itp->it_value.tv_sec--; 678 } 679 } else 680 itp->it_value.tv_usec = 0; /* sec is already 0 */ 681 return (0); 682 } 683 684 /* 685 * Add and subtract routines for timevals. 686 * N.B.: subtract routine doesn't deal with 687 * results which are before the beginning, 688 * it just gets very confused in this case. 689 * Caveat emptor. 690 */ 691 void 692 timevaladd(t1, t2) 693 struct timeval *t1, *t2; 694 { 695 696 t1->tv_sec += t2->tv_sec; 697 t1->tv_usec += t2->tv_usec; 698 timevalfix(t1); 699 } 700 701 void 702 timevalsub(t1, t2) 703 struct timeval *t1, *t2; 704 { 705 706 t1->tv_sec -= t2->tv_sec; 707 t1->tv_usec -= t2->tv_usec; 708 timevalfix(t1); 709 } 710 711 static void 712 timevalfix(t1) 713 struct timeval *t1; 714 { 715 716 if (t1->tv_usec < 0) { 717 t1->tv_sec--; 718 t1->tv_usec += 1000000; 719 } 720 if (t1->tv_usec >= 1000000) { 721 t1->tv_sec++; 722 t1->tv_usec -= 1000000; 723 } 724 } 725 726 /* 727 * ratecheck(): simple time-based rate-limit checking. 728 */ 729 int 730 ratecheck(struct timeval *lasttime, const struct timeval *mininterval) 731 { 732 struct timeval tv, delta; 733 int rv = 0; 734 735 getmicrouptime(&tv); /* NB: 10ms precision */ 736 delta = tv; 737 timevalsub(&delta, lasttime); 738 739 /* 740 * check for 0,0 is so that the message will be seen at least once, 741 * even if interval is huge. 742 */ 743 if (timevalcmp(&delta, mininterval, >=) || 744 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) { 745 *lasttime = tv; 746 rv = 1; 747 } 748 749 return (rv); 750 } 751 752 /* 753 * ppsratecheck(): packets (or events) per second limitation. 754 * 755 * Return 0 if the limit is to be enforced (e.g. the caller 756 * should drop a packet because of the rate limitation). 757 * 758 * maxpps of 0 always causes zero to be returned. maxpps of -1 759 * always causes 1 to be returned; this effectively defeats rate 760 * limiting. 761 * 762 * Note that we maintain the struct timeval for compatibility 763 * with other bsd systems. We reuse the storage and just monitor 764 * clock ticks for minimal overhead. 765 */ 766 int 767 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps) 768 { 769 int now; 770 771 /* 772 * Reset the last time and counter if this is the first call 773 * or more than a second has passed since the last update of 774 * lasttime. 775 */ 776 now = ticks; 777 if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) { 778 lasttime->tv_sec = now; 779 *curpps = 1; 780 return (maxpps != 0); 781 } else { 782 (*curpps)++; /* NB: ignore potential overflow */ 783 return (maxpps < 0 || *curpps < maxpps); 784 } 785 } 786 787