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 1.9 2003/08/12 02:36:15 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/proc.h> 48 #include <sys/time.h> 49 #include <sys/vnode.h> 50 #include <vm/vm.h> 51 #include <vm/vm_extern.h> 52 #include <sys/msgport2.h> 53 54 struct timezone tz; 55 56 /* 57 * Time of day and interval timer support. 58 * 59 * These routines provide the kernel entry points to get and set 60 * the time-of-day and per-process interval timers. Subroutines 61 * here provide support for adding and subtracting timeval structures 62 * and decrementing interval timers, optionally reloading the interval 63 * timers when they expire. 64 */ 65 66 static int nanosleep1 __P((struct timespec *rqt, 67 struct timespec *rmt)); 68 static int settime __P((struct timeval *)); 69 static void timevalfix __P((struct timeval *)); 70 static void no_lease_updatetime __P((int)); 71 72 static void 73 no_lease_updatetime(deltat) 74 int deltat; 75 { 76 } 77 78 void (*lease_updatetime) __P((int)) = no_lease_updatetime; 79 80 static int 81 settime(tv) 82 struct timeval *tv; 83 { 84 struct timeval delta, tv1, tv2; 85 static struct timeval maxtime, laststep; 86 struct timespec ts; 87 int s; 88 89 s = splclock(); 90 microtime(&tv1); 91 delta = *tv; 92 timevalsub(&delta, &tv1); 93 94 /* 95 * If the system is secure, we do not allow the time to be 96 * set to a value earlier than 1 second less than the highest 97 * time we have yet seen. The worst a miscreant can do in 98 * this circumstance is "freeze" time. He couldn't go 99 * back to the past. 100 * 101 * We similarly do not allow the clock to be stepped more 102 * than one second, nor more than once per second. This allows 103 * a miscreant to make the clock march double-time, but no worse. 104 */ 105 if (securelevel > 1) { 106 if (delta.tv_sec < 0 || delta.tv_usec < 0) { 107 /* 108 * Update maxtime to latest time we've seen. 109 */ 110 if (tv1.tv_sec > maxtime.tv_sec) 111 maxtime = tv1; 112 tv2 = *tv; 113 timevalsub(&tv2, &maxtime); 114 if (tv2.tv_sec < -1) { 115 tv->tv_sec = maxtime.tv_sec - 1; 116 printf("Time adjustment clamped to -1 second\n"); 117 } 118 } else { 119 if (tv1.tv_sec == laststep.tv_sec) { 120 splx(s); 121 return (EPERM); 122 } 123 if (delta.tv_sec > 1) { 124 tv->tv_sec = tv1.tv_sec + 1; 125 printf("Time adjustment clamped to +1 second\n"); 126 } 127 laststep = *tv; 128 } 129 } 130 131 ts.tv_sec = tv->tv_sec; 132 ts.tv_nsec = tv->tv_usec * 1000; 133 set_timecounter(&ts); 134 (void) splsoftclock(); 135 lease_updatetime(delta.tv_sec); 136 splx(s); 137 resettodr(); 138 return (0); 139 } 140 141 /* ARGSUSED */ 142 int 143 clock_gettime(struct clock_gettime_args *uap) 144 { 145 struct timespec ats; 146 147 if (SCARG(uap, clock_id) != CLOCK_REALTIME) 148 return (EINVAL); 149 nanotime(&ats); 150 return (copyout(&ats, SCARG(uap, tp), sizeof(ats))); 151 } 152 153 /* ARGSUSED */ 154 int 155 clock_settime(struct clock_settime_args *uap) 156 { 157 struct thread *td = curthread; 158 struct timeval atv; 159 struct timespec ats; 160 int error; 161 162 if ((error = suser(td)) != 0) 163 return (error); 164 if (SCARG(uap, clock_id) != CLOCK_REALTIME) 165 return (EINVAL); 166 if ((error = copyin(SCARG(uap, tp), &ats, sizeof(ats))) != 0) 167 return (error); 168 if (ats.tv_nsec < 0 || ats.tv_nsec >= 1000000000) 169 return (EINVAL); 170 /* XXX Don't convert nsec->usec and back */ 171 TIMESPEC_TO_TIMEVAL(&atv, &ats); 172 if ((error = settime(&atv))) 173 return (error); 174 return (0); 175 } 176 177 int 178 clock_getres(struct clock_getres_args *uap) 179 { 180 struct timespec ts; 181 int error; 182 183 if (SCARG(uap, clock_id) != CLOCK_REALTIME) 184 return (EINVAL); 185 error = 0; 186 if (SCARG(uap, tp)) { 187 ts.tv_sec = 0; 188 /* 189 * Round up the result of the division cheaply by adding 1. 190 * Rounding up is especially important if rounding down 191 * would give 0. Perfect rounding is unimportant. 192 */ 193 ts.tv_nsec = 1000000000 / timecounter->tc_frequency + 1; 194 error = copyout(&ts, SCARG(uap, tp), sizeof(ts)); 195 } 196 return (error); 197 } 198 199 static int nanowait; 200 201 static int 202 nanosleep1(struct timespec *rqt, struct timespec *rmt) 203 { 204 struct timespec ts, ts2, ts3; 205 struct timeval tv; 206 int error; 207 208 if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000) 209 return (EINVAL); 210 if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0)) 211 return (0); 212 getnanouptime(&ts); 213 timespecadd(&ts, rqt); 214 TIMESPEC_TO_TIMEVAL(&tv, rqt); 215 for (;;) { 216 error = tsleep(&nanowait, PCATCH, "nanslp", 217 tvtohz(&tv)); 218 getnanouptime(&ts2); 219 if (error != EWOULDBLOCK) { 220 if (error == ERESTART) 221 error = EINTR; 222 if (rmt != NULL) { 223 timespecsub(&ts, &ts2); 224 if (ts.tv_sec < 0) 225 timespecclear(&ts); 226 *rmt = ts; 227 } 228 return (error); 229 } 230 if (timespeccmp(&ts2, &ts, >=)) 231 return (0); 232 ts3 = ts; 233 timespecsub(&ts3, &ts2); 234 TIMESPEC_TO_TIMEVAL(&tv, &ts3); 235 } 236 } 237 238 static void nanosleep_done(void *arg); 239 static void nanosleep_return(lwkt_port_t port, lwkt_msg_t msg); 240 241 /* ARGSUSED */ 242 int 243 nanosleep(struct nanosleep_args *uap) 244 { 245 int error; 246 struct sysmsg_sleep *sysmsg = &uap->sysmsg.sm_sleep; 247 248 error = copyin(uap->rqtp, &sysmsg->rqt, sizeof(sysmsg->rqt)); 249 if (error) 250 return (error); 251 /* 252 * YYY clean this up to always use the callout, note that an abort 253 * implementation should record the residual in the async case. 254 */ 255 if (sysmsg->lmsg.ms_flags & MSGF_ASYNC) { 256 quad_t ticks; 257 258 ticks = (quad_t)sysmsg->rqt.tv_nsec * hz / 1000000000LL; 259 if (sysmsg->rqt.tv_sec) 260 ticks += (quad_t)sysmsg->rqt.tv_sec * hz; 261 if (ticks <= 0) { 262 if (ticks == 0) 263 error = 0; 264 else 265 error = EINVAL; 266 } else { 267 sysmsg->lmsg.ms_cleanupmsg = nanosleep_return; 268 callout_init(&sysmsg->timer); 269 callout_reset(&sysmsg->timer, ticks, nanosleep_done, uap); 270 error = EASYNC; 271 } 272 } else { 273 /* 274 * Old synchronous sleep code, copyout the residual if 275 * nanosleep was interrupted. 276 */ 277 error = nanosleep1(&sysmsg->rqt, &sysmsg->rmt); 278 if (error && SCARG(uap, rmtp)) 279 error = copyout(&sysmsg->rmt, SCARG(uap, rmtp), sizeof(sysmsg->rmt)); 280 } 281 return (error); 282 } 283 284 /* 285 * Asynch completion for the nanosleep() syscall. This function may be 286 * called from any context and cannot legally access the originating 287 * thread, proc, or its user space. 288 * 289 * YYY change the callout interface API so we can simply assign the replymsg 290 * function to it directly. 291 */ 292 static void 293 nanosleep_done(void *arg) 294 { 295 struct nanosleep_args *uap = arg; 296 297 lwkt_replymsg(&uap->sysmsg.lmsg, 0); 298 } 299 300 /* 301 * Asynch return for the nanosleep() syscall, called in the context of the 302 * originating thread when it pulls the message off the reply port. This 303 * function is responsible for any copyouts to userland. Kernel threads 304 * which do their own internal system calls will not usually call the return 305 * function. 306 */ 307 static void 308 nanosleep_return(lwkt_port_t port, lwkt_msg_t msg) 309 { 310 struct nanosleep_args *uap = (void *)msg; 311 struct sysmsg_sleep *sysmsg = &uap->sysmsg.sm_sleep; 312 313 if (sysmsg->lmsg.ms_error && uap->rmtp) { 314 sysmsg->lmsg.ms_error = 315 copyout(&sysmsg->rmt, uap->rmtp, sizeof(sysmsg->rmt)); 316 } 317 } 318 319 /* ARGSUSED */ 320 int 321 gettimeofday(struct gettimeofday_args *uap) 322 { 323 struct timeval atv; 324 int error = 0; 325 326 if (uap->tp) { 327 microtime(&atv); 328 if ((error = copyout((caddr_t)&atv, (caddr_t)uap->tp, 329 sizeof (atv)))) 330 return (error); 331 } 332 if (uap->tzp) 333 error = copyout((caddr_t)&tz, (caddr_t)uap->tzp, 334 sizeof (tz)); 335 return (error); 336 } 337 338 /* ARGSUSED */ 339 int 340 settimeofday(struct settimeofday_args *uap) 341 { 342 struct thread *td = curthread; 343 struct timeval atv; 344 struct timezone atz; 345 int error; 346 347 if ((error = suser(td))) 348 return (error); 349 /* Verify all parameters before changing time. */ 350 if (uap->tv) { 351 if ((error = copyin((caddr_t)uap->tv, (caddr_t)&atv, 352 sizeof(atv)))) 353 return (error); 354 if (atv.tv_usec < 0 || atv.tv_usec >= 1000000) 355 return (EINVAL); 356 } 357 if (uap->tzp && 358 (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz, sizeof(atz)))) 359 return (error); 360 if (uap->tv && (error = settime(&atv))) 361 return (error); 362 if (uap->tzp) 363 tz = atz; 364 return (0); 365 } 366 367 int tickdelta; /* current clock skew, us. per tick */ 368 long timedelta; /* unapplied time correction, us. */ 369 static long bigadj = 1000000; /* use 10x skew above bigadj us. */ 370 371 /* ARGSUSED */ 372 int 373 adjtime(struct adjtime_args *uap) 374 { 375 struct thread *td = curthread; 376 struct timeval atv; 377 long ndelta, ntickdelta, odelta; 378 int s, error; 379 380 if ((error = suser(td))) 381 return (error); 382 if ((error = 383 copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof(struct timeval)))) 384 return (error); 385 386 /* 387 * Compute the total correction and the rate at which to apply it. 388 * Round the adjustment down to a whole multiple of the per-tick 389 * delta, so that after some number of incremental changes in 390 * hardclock(), tickdelta will become zero, lest the correction 391 * overshoot and start taking us away from the desired final time. 392 */ 393 ndelta = atv.tv_sec * 1000000 + atv.tv_usec; 394 if (ndelta > bigadj || ndelta < -bigadj) 395 ntickdelta = 10 * tickadj; 396 else 397 ntickdelta = tickadj; 398 if (ndelta % ntickdelta) 399 ndelta = ndelta / ntickdelta * ntickdelta; 400 401 /* 402 * To make hardclock()'s job easier, make the per-tick delta negative 403 * if we want time to run slower; then hardclock can simply compute 404 * tick + tickdelta, and subtract tickdelta from timedelta. 405 */ 406 if (ndelta < 0) 407 ntickdelta = -ntickdelta; 408 s = splclock(); 409 odelta = timedelta; 410 timedelta = ndelta; 411 tickdelta = ntickdelta; 412 splx(s); 413 414 if (uap->olddelta) { 415 atv.tv_sec = odelta / 1000000; 416 atv.tv_usec = odelta % 1000000; 417 (void) copyout((caddr_t)&atv, (caddr_t)uap->olddelta, 418 sizeof(struct timeval)); 419 } 420 return (0); 421 } 422 423 /* 424 * Get value of an interval timer. The process virtual and 425 * profiling virtual time timers are kept in the p_stats area, since 426 * they can be swapped out. These are kept internally in the 427 * way they are specified externally: in time until they expire. 428 * 429 * The real time interval timer is kept in the process table slot 430 * for the process, and its value (it_value) is kept as an 431 * absolute time rather than as a delta, so that it is easy to keep 432 * periodic real-time signals from drifting. 433 * 434 * Virtual time timers are processed in the hardclock() routine of 435 * kern_clock.c. The real time timer is processed by a timeout 436 * routine, called from the softclock() routine. Since a callout 437 * may be delayed in real time due to interrupt processing in the system, 438 * it is possible for the real time timeout routine (realitexpire, given below), 439 * to be delayed in real time past when it is supposed to occur. It 440 * does not suffice, therefore, to reload the real timer .it_value from the 441 * real time timers .it_interval. Rather, we compute the next time in 442 * absolute time the timer should go off. 443 */ 444 /* ARGSUSED */ 445 int 446 getitimer(struct getitimer_args *uap) 447 { 448 struct proc *p = curproc; 449 struct timeval ctv; 450 struct itimerval aitv; 451 int s; 452 453 if (uap->which > ITIMER_PROF) 454 return (EINVAL); 455 s = splclock(); /* XXX still needed ? */ 456 if (uap->which == ITIMER_REAL) { 457 /* 458 * Convert from absolute to relative time in .it_value 459 * part of real time timer. If time for real time timer 460 * has passed return 0, else return difference between 461 * current time and time for the timer to go off. 462 */ 463 aitv = p->p_realtimer; 464 if (timevalisset(&aitv.it_value)) { 465 getmicrouptime(&ctv); 466 if (timevalcmp(&aitv.it_value, &ctv, <)) 467 timevalclear(&aitv.it_value); 468 else 469 timevalsub(&aitv.it_value, &ctv); 470 } 471 } else 472 aitv = p->p_stats->p_timer[uap->which]; 473 splx(s); 474 return (copyout((caddr_t)&aitv, (caddr_t)uap->itv, 475 sizeof (struct itimerval))); 476 } 477 478 /* ARGSUSED */ 479 int 480 setitimer(struct setitimer_args *uap) 481 { 482 struct itimerval aitv; 483 struct timeval ctv; 484 struct itimerval *itvp; 485 struct proc *p = curproc; 486 int s, error; 487 488 if (uap->which > ITIMER_PROF) 489 return (EINVAL); 490 itvp = uap->itv; 491 if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv, 492 sizeof(struct itimerval)))) 493 return (error); 494 if ((uap->itv = uap->oitv) && 495 (error = getitimer((struct getitimer_args *)uap))) 496 return (error); 497 if (itvp == 0) 498 return (0); 499 if (itimerfix(&aitv.it_value)) 500 return (EINVAL); 501 if (!timevalisset(&aitv.it_value)) 502 timevalclear(&aitv.it_interval); 503 else if (itimerfix(&aitv.it_interval)) 504 return (EINVAL); 505 s = splclock(); /* XXX: still needed ? */ 506 if (uap->which == ITIMER_REAL) { 507 if (timevalisset(&p->p_realtimer.it_value)) 508 untimeout(realitexpire, (caddr_t)p, p->p_ithandle); 509 if (timevalisset(&aitv.it_value)) 510 p->p_ithandle = timeout(realitexpire, (caddr_t)p, 511 tvtohz(&aitv.it_value)); 512 getmicrouptime(&ctv); 513 timevaladd(&aitv.it_value, &ctv); 514 p->p_realtimer = aitv; 515 } else 516 p->p_stats->p_timer[uap->which] = aitv; 517 splx(s); 518 return (0); 519 } 520 521 /* 522 * Real interval timer expired: 523 * send process whose timer expired an alarm signal. 524 * If time is not set up to reload, then just return. 525 * Else compute next time timer should go off which is > current time. 526 * This is where delay in processing this timeout causes multiple 527 * SIGALRM calls to be compressed into one. 528 * tvtohz() always adds 1 to allow for the time until the next clock 529 * interrupt being strictly less than 1 clock tick, but we don't want 530 * that here since we want to appear to be in sync with the clock 531 * interrupt even when we're delayed. 532 */ 533 void 534 realitexpire(arg) 535 void *arg; 536 { 537 struct proc *p; 538 struct timeval ctv, ntv; 539 int s; 540 541 p = (struct proc *)arg; 542 psignal(p, SIGALRM); 543 if (!timevalisset(&p->p_realtimer.it_interval)) { 544 timevalclear(&p->p_realtimer.it_value); 545 return; 546 } 547 for (;;) { 548 s = splclock(); /* XXX: still neeeded ? */ 549 timevaladd(&p->p_realtimer.it_value, 550 &p->p_realtimer.it_interval); 551 getmicrouptime(&ctv); 552 if (timevalcmp(&p->p_realtimer.it_value, &ctv, >)) { 553 ntv = p->p_realtimer.it_value; 554 timevalsub(&ntv, &ctv); 555 p->p_ithandle = timeout(realitexpire, (caddr_t)p, 556 tvtohz(&ntv) - 1); 557 splx(s); 558 return; 559 } 560 splx(s); 561 } 562 } 563 564 /* 565 * Check that a proposed value to load into the .it_value or 566 * .it_interval part of an interval timer is acceptable, and 567 * fix it to have at least minimal value (i.e. if it is less 568 * than the resolution of the clock, round it up.) 569 */ 570 int 571 itimerfix(tv) 572 struct timeval *tv; 573 { 574 575 if (tv->tv_sec < 0 || tv->tv_sec > 100000000 || 576 tv->tv_usec < 0 || tv->tv_usec >= 1000000) 577 return (EINVAL); 578 if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick) 579 tv->tv_usec = tick; 580 return (0); 581 } 582 583 /* 584 * Decrement an interval timer by a specified number 585 * of microseconds, which must be less than a second, 586 * i.e. < 1000000. If the timer expires, then reload 587 * it. In this case, carry over (usec - old value) to 588 * reduce the value reloaded into the timer so that 589 * the timer does not drift. This routine assumes 590 * that it is called in a context where the timers 591 * on which it is operating cannot change in value. 592 */ 593 int 594 itimerdecr(itp, usec) 595 struct itimerval *itp; 596 int usec; 597 { 598 599 if (itp->it_value.tv_usec < usec) { 600 if (itp->it_value.tv_sec == 0) { 601 /* expired, and already in next interval */ 602 usec -= itp->it_value.tv_usec; 603 goto expire; 604 } 605 itp->it_value.tv_usec += 1000000; 606 itp->it_value.tv_sec--; 607 } 608 itp->it_value.tv_usec -= usec; 609 usec = 0; 610 if (timevalisset(&itp->it_value)) 611 return (1); 612 /* expired, exactly at end of interval */ 613 expire: 614 if (timevalisset(&itp->it_interval)) { 615 itp->it_value = itp->it_interval; 616 itp->it_value.tv_usec -= usec; 617 if (itp->it_value.tv_usec < 0) { 618 itp->it_value.tv_usec += 1000000; 619 itp->it_value.tv_sec--; 620 } 621 } else 622 itp->it_value.tv_usec = 0; /* sec is already 0 */ 623 return (0); 624 } 625 626 /* 627 * Add and subtract routines for timevals. 628 * N.B.: subtract routine doesn't deal with 629 * results which are before the beginning, 630 * it just gets very confused in this case. 631 * Caveat emptor. 632 */ 633 void 634 timevaladd(t1, t2) 635 struct timeval *t1, *t2; 636 { 637 638 t1->tv_sec += t2->tv_sec; 639 t1->tv_usec += t2->tv_usec; 640 timevalfix(t1); 641 } 642 643 void 644 timevalsub(t1, t2) 645 struct timeval *t1, *t2; 646 { 647 648 t1->tv_sec -= t2->tv_sec; 649 t1->tv_usec -= t2->tv_usec; 650 timevalfix(t1); 651 } 652 653 static void 654 timevalfix(t1) 655 struct timeval *t1; 656 { 657 658 if (t1->tv_usec < 0) { 659 t1->tv_sec--; 660 t1->tv_usec += 1000000; 661 } 662 if (t1->tv_usec >= 1000000) { 663 t1->tv_sec++; 664 t1->tv_usec -= 1000000; 665 } 666 } 667 668 /* 669 * ratecheck(): simple time-based rate-limit checking. 670 */ 671 int 672 ratecheck(struct timeval *lasttime, const struct timeval *mininterval) 673 { 674 struct timeval tv, delta; 675 int rv = 0; 676 677 getmicrouptime(&tv); /* NB: 10ms precision */ 678 delta = tv; 679 timevalsub(&delta, lasttime); 680 681 /* 682 * check for 0,0 is so that the message will be seen at least once, 683 * even if interval is huge. 684 */ 685 if (timevalcmp(&delta, mininterval, >=) || 686 (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) { 687 *lasttime = tv; 688 rv = 1; 689 } 690 691 return (rv); 692 } 693 694 /* 695 * ppsratecheck(): packets (or events) per second limitation. 696 * 697 * Return 0 if the limit is to be enforced (e.g. the caller 698 * should drop a packet because of the rate limitation). 699 * 700 * maxpps of 0 always causes zero to be returned. maxpps of -1 701 * always causes 1 to be returned; this effectively defeats rate 702 * limiting. 703 * 704 * Note that we maintain the struct timeval for compatibility 705 * with other bsd systems. We reuse the storage and just monitor 706 * clock ticks for minimal overhead. 707 */ 708 int 709 ppsratecheck(struct timeval *lasttime, int *curpps, int maxpps) 710 { 711 int now; 712 713 /* 714 * Reset the last time and counter if this is the first call 715 * or more than a second has passed since the last update of 716 * lasttime. 717 */ 718 now = ticks; 719 if (lasttime->tv_sec == 0 || (u_int)(now - lasttime->tv_sec) >= hz) { 720 lasttime->tv_sec = now; 721 *curpps = 1; 722 return (maxpps != 0); 723 } else { 724 (*curpps)++; /* NB: ignore potential overflow */ 725 return (maxpps < 0 || *curpps < maxpps); 726 } 727 } 728 729