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kern_time.c revision 1.60
      1 /*	$NetBSD: kern_time.c,v 1.60 2001/12/09 16:10:43 manu Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2000 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Christopher G. Demetriou.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the NetBSD
     21  *	Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 /*
     40  * Copyright (c) 1982, 1986, 1989, 1993
     41  *	The Regents of the University of California.  All rights reserved.
     42  *
     43  * Redistribution and use in source and binary forms, with or without
     44  * modification, are permitted provided that the following conditions
     45  * are met:
     46  * 1. Redistributions of source code must retain the above copyright
     47  *    notice, this list of conditions and the following disclaimer.
     48  * 2. Redistributions in binary form must reproduce the above copyright
     49  *    notice, this list of conditions and the following disclaimer in the
     50  *    documentation and/or other materials provided with the distribution.
     51  * 3. All advertising materials mentioning features or use of this software
     52  *    must display the following acknowledgement:
     53  *	This product includes software developed by the University of
     54  *	California, Berkeley and its contributors.
     55  * 4. Neither the name of the University nor the names of its contributors
     56  *    may be used to endorse or promote products derived from this software
     57  *    without specific prior written permission.
     58  *
     59  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     60  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     61  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     62  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     63  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     64  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     65  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     66  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     67  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     68  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     69  * SUCH DAMAGE.
     70  *
     71  *	@(#)kern_time.c	8.4 (Berkeley) 5/26/95
     72  */
     73 
     74 #include <sys/cdefs.h>
     75 __KERNEL_RCSID(0, "$NetBSD: kern_time.c,v 1.60 2001/12/09 16:10:43 manu Exp $");
     76 
     77 #include "fs_nfs.h"
     78 #include "opt_nfs.h"
     79 #include "opt_nfsserver.h"
     80 
     81 #include <sys/param.h>
     82 #include <sys/resourcevar.h>
     83 #include <sys/kernel.h>
     84 #include <sys/systm.h>
     85 #include <sys/proc.h>
     86 #include <sys/vnode.h>
     87 #include <sys/signalvar.h>
     88 #include <sys/syslog.h>
     89 
     90 #include <sys/mount.h>
     91 #include <sys/syscallargs.h>
     92 
     93 #include <uvm/uvm_extern.h>
     94 
     95 #if defined(NFS) || defined(NFSSERVER)
     96 #include <nfs/rpcv2.h>
     97 #include <nfs/nfsproto.h>
     98 #include <nfs/nfs_var.h>
     99 #endif
    100 
    101 #include <machine/cpu.h>
    102 
    103 /*
    104  * Time of day and interval timer support.
    105  *
    106  * These routines provide the kernel entry points to get and set
    107  * the time-of-day and per-process interval timers.  Subroutines
    108  * here provide support for adding and subtracting timeval structures
    109  * and decrementing interval timers, optionally reloading the interval
    110  * timers when they expire.
    111  */
    112 
    113 /* This function is used by clock_settime and settimeofday */
    114 int
    115 settime(tv)
    116 	struct timeval *tv;
    117 {
    118 	struct timeval delta;
    119 	struct cpu_info *ci;
    120 	int s;
    121 
    122 	/* WHAT DO WE DO ABOUT PENDING REAL-TIME TIMEOUTS??? */
    123 	s = splclock();
    124 	timersub(tv, &time, &delta);
    125 	if ((delta.tv_sec < 0 || delta.tv_usec < 0) && securelevel > 1) {
    126 		splx(s);
    127 		return (EPERM);
    128 	}
    129 #ifdef notyet
    130 	if ((delta.tv_sec < 86400) && securelevel > 0) {
    131 		splx(s);
    132 		return (EPERM);
    133 	}
    134 #endif
    135 	time = *tv;
    136 	(void) spllowersoftclock();
    137 	timeradd(&boottime, &delta, &boottime);
    138 	/*
    139 	 * XXXSMP
    140 	 * This is wrong.  We should traverse a list of all
    141 	 * CPUs and add the delta to the runtime of those
    142 	 * CPUs which have a process on them.
    143 	 */
    144 	ci = curcpu();
    145 	timeradd(&ci->ci_schedstate.spc_runtime, &delta,
    146 	    &ci->ci_schedstate.spc_runtime);
    147 #	if (defined(NFS) && !defined (NFS_V2_ONLY)) || defined(NFSSERVER)
    148 		nqnfs_lease_updatetime(delta.tv_sec);
    149 #	endif
    150 	splx(s);
    151 	resettodr();
    152 	return (0);
    153 }
    154 
    155 /* ARGSUSED */
    156 int
    157 sys_clock_gettime(p, v, retval)
    158 	struct proc *p;
    159 	void *v;
    160 	register_t *retval;
    161 {
    162 	struct sys_clock_gettime_args /* {
    163 		syscallarg(clockid_t) clock_id;
    164 		syscallarg(struct timespec *) tp;
    165 	} */ *uap = v;
    166 	clockid_t clock_id;
    167 	struct timeval atv;
    168 	struct timespec ats;
    169 
    170 	clock_id = SCARG(uap, clock_id);
    171 	if (clock_id != CLOCK_REALTIME)
    172 		return (EINVAL);
    173 
    174 	microtime(&atv);
    175 	TIMEVAL_TO_TIMESPEC(&atv,&ats);
    176 
    177 	return copyout(&ats, SCARG(uap, tp), sizeof(ats));
    178 }
    179 
    180 /* ARGSUSED */
    181 int
    182 sys_clock_settime(p, v, retval)
    183 	struct proc *p;
    184 	void *v;
    185 	register_t *retval;
    186 {
    187 	struct sys_clock_settime_args /* {
    188 		syscallarg(clockid_t) clock_id;
    189 		syscallarg(const struct timespec *) tp;
    190 	} */ *uap = v;
    191 	int error;
    192 
    193 	if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
    194 		return (error);
    195 
    196 	return (clock_settime1(SCARG(uap, clock_id), SCARG(uap, tp)));
    197 }
    198 
    199 
    200 int
    201 clock_settime1(clock_id, tp)
    202 	clockid_t clock_id;
    203 	const struct timespec *tp;
    204 {
    205 	struct timespec ats;
    206 	struct timeval atv;
    207 	int error;
    208 
    209 	if ((error = copyin(tp, &ats, sizeof(ats))) != 0)
    210 		return (error);
    211 
    212 	if (clock_id != CLOCK_REALTIME)
    213 		return (EINVAL);
    214 
    215 	TIMESPEC_TO_TIMEVAL(&atv, &ats);
    216 	if ((error = settime(&atv)) != 0)
    217 		return (error);
    218 
    219 	return 0;
    220 }
    221 
    222 int
    223 sys_clock_getres(p, v, retval)
    224 	struct proc *p;
    225 	void *v;
    226 	register_t *retval;
    227 {
    228 	struct sys_clock_getres_args /* {
    229 		syscallarg(clockid_t) clock_id;
    230 		syscallarg(struct timespec *) tp;
    231 	} */ *uap = v;
    232 	clockid_t clock_id;
    233 	struct timespec ts;
    234 	int error = 0;
    235 
    236 	clock_id = SCARG(uap, clock_id);
    237 	if (clock_id != CLOCK_REALTIME)
    238 		return (EINVAL);
    239 
    240 	if (SCARG(uap, tp)) {
    241 		ts.tv_sec = 0;
    242 		ts.tv_nsec = 1000000000 / hz;
    243 
    244 		error = copyout(&ts, SCARG(uap, tp), sizeof(ts));
    245 	}
    246 
    247 	return error;
    248 }
    249 
    250 /* ARGSUSED */
    251 int
    252 sys_nanosleep(p, v, retval)
    253 	struct proc *p;
    254 	void *v;
    255 	register_t *retval;
    256 {
    257 	static int nanowait;
    258 	struct sys_nanosleep_args/* {
    259 		syscallarg(struct timespec *) rqtp;
    260 		syscallarg(struct timespec *) rmtp;
    261 	} */ *uap = v;
    262 	struct timespec rqt;
    263 	struct timespec rmt;
    264 	struct timeval atv, utv;
    265 	int error, s, timo;
    266 
    267 	error = copyin((caddr_t)SCARG(uap, rqtp), (caddr_t)&rqt,
    268 		       sizeof(struct timespec));
    269 	if (error)
    270 		return (error);
    271 
    272 	TIMESPEC_TO_TIMEVAL(&atv,&rqt)
    273 	if (itimerfix(&atv) || atv.tv_sec > 1000000000)
    274 		return (EINVAL);
    275 
    276 	s = splclock();
    277 	timeradd(&atv,&time,&atv);
    278 	timo = hzto(&atv);
    279 	/*
    280 	 * Avoid inadvertantly sleeping forever
    281 	 */
    282 	if (timo == 0)
    283 		timo = 1;
    284 	splx(s);
    285 
    286 	error = tsleep(&nanowait, PWAIT | PCATCH, "nanosleep", timo);
    287 	if (error == ERESTART)
    288 		error = EINTR;
    289 	if (error == EWOULDBLOCK)
    290 		error = 0;
    291 
    292 	if (SCARG(uap, rmtp)) {
    293 		int error;
    294 
    295 		s = splclock();
    296 		utv = time;
    297 		splx(s);
    298 
    299 		timersub(&atv, &utv, &utv);
    300 		if (utv.tv_sec < 0)
    301 			timerclear(&utv);
    302 
    303 		TIMEVAL_TO_TIMESPEC(&utv,&rmt);
    304 		error = copyout((caddr_t)&rmt, (caddr_t)SCARG(uap,rmtp),
    305 			sizeof(rmt));
    306 		if (error)
    307 			return (error);
    308 	}
    309 
    310 	return error;
    311 }
    312 
    313 /* ARGSUSED */
    314 int
    315 sys_gettimeofday(p, v, retval)
    316 	struct proc *p;
    317 	void *v;
    318 	register_t *retval;
    319 {
    320 	struct sys_gettimeofday_args /* {
    321 		syscallarg(struct timeval *) tp;
    322 		syscallarg(struct timezone *) tzp;
    323 	} */ *uap = v;
    324 	struct timeval atv;
    325 	int error = 0;
    326 	struct timezone tzfake;
    327 
    328 	if (SCARG(uap, tp)) {
    329 		microtime(&atv);
    330 		error = copyout(&atv, SCARG(uap, tp), sizeof(atv));
    331 		if (error)
    332 			return (error);
    333 	}
    334 	if (SCARG(uap, tzp)) {
    335 		/*
    336 		 * NetBSD has no kernel notion of time zone, so we just
    337 		 * fake up a timezone struct and return it if demanded.
    338 		 */
    339 		tzfake.tz_minuteswest = 0;
    340 		tzfake.tz_dsttime = 0;
    341 		error = copyout(&tzfake, SCARG(uap, tzp), sizeof(tzfake));
    342 	}
    343 	return (error);
    344 }
    345 
    346 /* ARGSUSED */
    347 int
    348 sys_settimeofday(p, v, retval)
    349 	struct proc *p;
    350 	void *v;
    351 	register_t *retval;
    352 {
    353 	struct sys_settimeofday_args /* {
    354 		syscallarg(const struct timeval *) tv;
    355 		syscallarg(const struct timezone *) tzp;
    356 	} */ *uap = v;
    357 	int error;
    358 
    359 	if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
    360 		return (error);
    361 
    362 	return settimeofday1(SCARG(uap, tv), SCARG(uap, tzp), p);
    363 }
    364 
    365 int
    366 settimeofday1(utv, utzp, p)
    367 	const struct timeval *utv;
    368 	const struct timezone *utzp;
    369 	struct proc *p;
    370 {
    371 	struct timeval atv;
    372 	struct timezone atz;
    373 	struct timeval *tv = NULL;
    374 	struct timezone *tzp = NULL;
    375 	int error;
    376 
    377 	/* Verify all parameters before changing time. */
    378 	if (utv) {
    379 		if ((error = copyin(utv, &atv, sizeof(atv))) != 0)
    380 			return (error);
    381 		tv = &atv;
    382 	}
    383 	/* XXX since we don't use tz, probably no point in doing copyin. */
    384 	if (utzp) {
    385 		if ((error = copyin(utzp, &atz, sizeof(atz))) != 0)
    386 			return (error);
    387 		tzp = &atz;
    388 	}
    389 
    390 	if (tv)
    391 		if ((error = settime(tv)) != 0)
    392 			return (error);
    393 	/*
    394 	 * NetBSD has no kernel notion of time zone, and only an
    395 	 * obsolete program would try to set it, so we log a warning.
    396 	 */
    397 	if (tzp)
    398 		log(LOG_WARNING, "pid %d attempted to set the "
    399 		    "(obsolete) kernel time zone\n", p->p_pid);
    400 	return (0);
    401 }
    402 
    403 int	tickdelta;			/* current clock skew, us. per tick */
    404 long	timedelta;			/* unapplied time correction, us. */
    405 long	bigadj = 1000000;		/* use 10x skew above bigadj us. */
    406 
    407 /* ARGSUSED */
    408 int
    409 sys_adjtime(p, v, retval)
    410 	struct proc *p;
    411 	void *v;
    412 	register_t *retval;
    413 {
    414 	struct sys_adjtime_args /* {
    415 		syscallarg(const struct timeval *) delta;
    416 		syscallarg(struct timeval *) olddelta;
    417 	} */ *uap = v;
    418 	int error;
    419 
    420 	if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
    421 		return (error);
    422 
    423 	return adjtime1(SCARG(uap, delta), SCARG(uap, olddelta), p);
    424 }
    425 
    426 int
    427 adjtime1(delta, olddelta, p)
    428 	const struct timeval *delta;
    429 	struct timeval *olddelta;
    430 	struct proc *p;
    431 {
    432 	struct timeval atv;
    433 	struct timeval *oatv = NULL;
    434 	long ndelta, ntickdelta, odelta;
    435 	int error;
    436 	int s;
    437 
    438 	error = copyin(delta, &atv, sizeof(struct timeval));
    439 	if (error)
    440 		return (error);
    441 
    442 	if (olddelta != NULL) {
    443 		if (uvm_useracc((caddr_t)olddelta,
    444 		    sizeof(struct timeval), B_WRITE) == FALSE)
    445 			return (EFAULT);
    446 		oatv = olddelta;
    447 	}
    448 
    449 	/*
    450 	 * Compute the total correction and the rate at which to apply it.
    451 	 * Round the adjustment down to a whole multiple of the per-tick
    452 	 * delta, so that after some number of incremental changes in
    453 	 * hardclock(), tickdelta will become zero, lest the correction
    454 	 * overshoot and start taking us away from the desired final time.
    455 	 */
    456 	ndelta = atv.tv_sec * 1000000 + atv.tv_usec;
    457 	if (ndelta > bigadj || ndelta < -bigadj)
    458 		ntickdelta = 10 * tickadj;
    459 	else
    460 		ntickdelta = tickadj;
    461 	if (ndelta % ntickdelta)
    462 		ndelta = ndelta / ntickdelta * ntickdelta;
    463 
    464 	/*
    465 	 * To make hardclock()'s job easier, make the per-tick delta negative
    466 	 * if we want time to run slower; then hardclock can simply compute
    467 	 * tick + tickdelta, and subtract tickdelta from timedelta.
    468 	 */
    469 	if (ndelta < 0)
    470 		ntickdelta = -ntickdelta;
    471 	s = splclock();
    472 	odelta = timedelta;
    473 	timedelta = ndelta;
    474 	tickdelta = ntickdelta;
    475 	splx(s);
    476 
    477 	if (olddelta) {
    478 		atv.tv_sec = odelta / 1000000;
    479 		atv.tv_usec = odelta % 1000000;
    480 		(void) copyout(&atv, olddelta, sizeof(struct timeval));
    481 	}
    482 	return (0);
    483 }
    484 
    485 /*
    486  * Get value of an interval timer.  The process virtual and
    487  * profiling virtual time timers are kept in the p_stats area, since
    488  * they can be swapped out.  These are kept internally in the
    489  * way they are specified externally: in time until they expire.
    490  *
    491  * The real time interval timer is kept in the process table slot
    492  * for the process, and its value (it_value) is kept as an
    493  * absolute time rather than as a delta, so that it is easy to keep
    494  * periodic real-time signals from drifting.
    495  *
    496  * Virtual time timers are processed in the hardclock() routine of
    497  * kern_clock.c.  The real time timer is processed by a timeout
    498  * routine, called from the softclock() routine.  Since a callout
    499  * may be delayed in real time due to interrupt processing in the system,
    500  * it is possible for the real time timeout routine (realitexpire, given below),
    501  * to be delayed in real time past when it is supposed to occur.  It
    502  * does not suffice, therefore, to reload the real timer .it_value from the
    503  * real time timers .it_interval.  Rather, we compute the next time in
    504  * absolute time the timer should go off.
    505  */
    506 /* ARGSUSED */
    507 int
    508 sys_getitimer(p, v, retval)
    509 	struct proc *p;
    510 	void *v;
    511 	register_t *retval;
    512 {
    513 	struct sys_getitimer_args /* {
    514 		syscallarg(int) which;
    515 		syscallarg(struct itimerval *) itv;
    516 	} */ *uap = v;
    517 	int which = SCARG(uap, which);
    518 	struct itimerval aitv;
    519 	int s;
    520 
    521 	if ((u_int)which > ITIMER_PROF)
    522 		return (EINVAL);
    523 	s = splclock();
    524 	if (which == ITIMER_REAL) {
    525 		/*
    526 		 * Convert from absolute to relative time in .it_value
    527 		 * part of real time timer.  If time for real time timer
    528 		 * has passed return 0, else return difference between
    529 		 * current time and time for the timer to go off.
    530 		 */
    531 		aitv = p->p_realtimer;
    532 		if (timerisset(&aitv.it_value)) {
    533 			if (timercmp(&aitv.it_value, &time, <))
    534 				timerclear(&aitv.it_value);
    535 			else
    536 				timersub(&aitv.it_value, &time, &aitv.it_value);
    537 		}
    538 	} else
    539 		aitv = p->p_stats->p_timer[which];
    540 	splx(s);
    541 	return (copyout(&aitv, SCARG(uap, itv), sizeof(struct itimerval)));
    542 }
    543 
    544 /* ARGSUSED */
    545 int
    546 sys_setitimer(p, v, retval)
    547 	struct proc *p;
    548 	void *v;
    549 	register_t *retval;
    550 {
    551 	struct sys_setitimer_args /* {
    552 		syscallarg(int) which;
    553 		syscallarg(const struct itimerval *) itv;
    554 		syscallarg(struct itimerval *) oitv;
    555 	} */ *uap = v;
    556 	int which = SCARG(uap, which);
    557 	struct sys_getitimer_args getargs;
    558 	struct itimerval aitv;
    559 	const struct itimerval *itvp;
    560 	int s, error;
    561 
    562 	if ((u_int)which > ITIMER_PROF)
    563 		return (EINVAL);
    564 	itvp = SCARG(uap, itv);
    565 	if (itvp &&
    566 	    (error = copyin(itvp, &aitv, sizeof(struct itimerval)) != 0))
    567 		return (error);
    568 	if (SCARG(uap, oitv) != NULL) {
    569 		SCARG(&getargs, which) = which;
    570 		SCARG(&getargs, itv) = SCARG(uap, oitv);
    571 		if ((error = sys_getitimer(p, &getargs, retval)) != 0)
    572 			return (error);
    573 	}
    574 	if (itvp == 0)
    575 		return (0);
    576 	if (itimerfix(&aitv.it_value) || itimerfix(&aitv.it_interval))
    577 		return (EINVAL);
    578 	s = splclock();
    579 	if (which == ITIMER_REAL) {
    580 		callout_stop(&p->p_realit_ch);
    581 		if (timerisset(&aitv.it_value)) {
    582 			/*
    583 			 * Don't need to check hzto() return value, here.
    584 			 * callout_reset() does it for us.
    585 			 */
    586 			timeradd(&aitv.it_value, &time, &aitv.it_value);
    587 			callout_reset(&p->p_realit_ch, hzto(&aitv.it_value),
    588 			    realitexpire, p);
    589 		}
    590 		p->p_realtimer = aitv;
    591 	} else
    592 		p->p_stats->p_timer[which] = aitv;
    593 	splx(s);
    594 	return (0);
    595 }
    596 
    597 /*
    598  * Real interval timer expired:
    599  * send process whose timer expired an alarm signal.
    600  * If time is not set up to reload, then just return.
    601  * Else compute next time timer should go off which is > current time.
    602  * This is where delay in processing this timeout causes multiple
    603  * SIGALRM calls to be compressed into one.
    604  */
    605 void
    606 realitexpire(arg)
    607 	void *arg;
    608 {
    609 	struct proc *p;
    610 	int s;
    611 
    612 	p = (struct proc *)arg;
    613 	psignal(p, SIGALRM);
    614 	if (!timerisset(&p->p_realtimer.it_interval)) {
    615 		timerclear(&p->p_realtimer.it_value);
    616 		return;
    617 	}
    618 	for (;;) {
    619 		s = splclock();
    620 		timeradd(&p->p_realtimer.it_value,
    621 		    &p->p_realtimer.it_interval, &p->p_realtimer.it_value);
    622 		if (timercmp(&p->p_realtimer.it_value, &time, >)) {
    623 			/*
    624 			 * Don't need to check hzto() return value, here.
    625 			 * callout_reset() does it for us.
    626 			 */
    627 			callout_reset(&p->p_realit_ch,
    628 			    hzto(&p->p_realtimer.it_value), realitexpire, p);
    629 			splx(s);
    630 			return;
    631 		}
    632 		splx(s);
    633 	}
    634 }
    635 
    636 /*
    637  * Check that a proposed value to load into the .it_value or
    638  * .it_interval part of an interval timer is acceptable, and
    639  * fix it to have at least minimal value (i.e. if it is less
    640  * than the resolution of the clock, round it up.)
    641  */
    642 int
    643 itimerfix(tv)
    644 	struct timeval *tv;
    645 {
    646 
    647 	if (tv->tv_sec < 0 || tv->tv_usec < 0 || tv->tv_usec >= 1000000)
    648 		return (EINVAL);
    649 	if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
    650 		tv->tv_usec = tick;
    651 	return (0);
    652 }
    653 
    654 /*
    655  * Decrement an interval timer by a specified number
    656  * of microseconds, which must be less than a second,
    657  * i.e. < 1000000.  If the timer expires, then reload
    658  * it.  In this case, carry over (usec - old value) to
    659  * reduce the value reloaded into the timer so that
    660  * the timer does not drift.  This routine assumes
    661  * that it is called in a context where the timers
    662  * on which it is operating cannot change in value.
    663  */
    664 int
    665 itimerdecr(itp, usec)
    666 	struct itimerval *itp;
    667 	int usec;
    668 {
    669 
    670 	if (itp->it_value.tv_usec < usec) {
    671 		if (itp->it_value.tv_sec == 0) {
    672 			/* expired, and already in next interval */
    673 			usec -= itp->it_value.tv_usec;
    674 			goto expire;
    675 		}
    676 		itp->it_value.tv_usec += 1000000;
    677 		itp->it_value.tv_sec--;
    678 	}
    679 	itp->it_value.tv_usec -= usec;
    680 	usec = 0;
    681 	if (timerisset(&itp->it_value))
    682 		return (1);
    683 	/* expired, exactly at end of interval */
    684 expire:
    685 	if (timerisset(&itp->it_interval)) {
    686 		itp->it_value = itp->it_interval;
    687 		itp->it_value.tv_usec -= usec;
    688 		if (itp->it_value.tv_usec < 0) {
    689 			itp->it_value.tv_usec += 1000000;
    690 			itp->it_value.tv_sec--;
    691 		}
    692 	} else
    693 		itp->it_value.tv_usec = 0;		/* sec is already 0 */
    694 	return (0);
    695 }
    696 
    697 /*
    698  * ratecheck(): simple time-based rate-limit checking.  see ratecheck(9)
    699  * for usage and rationale.
    700  */
    701 int
    702 ratecheck(lasttime, mininterval)
    703 	struct timeval *lasttime;
    704 	const struct timeval *mininterval;
    705 {
    706 	struct timeval tv, delta;
    707 	int s, rv = 0;
    708 
    709 	s = splclock();
    710 	tv = mono_time;
    711 	splx(s);
    712 
    713 	timersub(&tv, lasttime, &delta);
    714 
    715 	/*
    716 	 * check for 0,0 is so that the message will be seen at least once,
    717 	 * even if interval is huge.
    718 	 */
    719 	if (timercmp(&delta, mininterval, >=) ||
    720 	    (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
    721 		*lasttime = tv;
    722 		rv = 1;
    723 	}
    724 
    725 	return (rv);
    726 }
    727 
    728 /*
    729  * ppsratecheck(): packets (or events) per second limitation.
    730  */
    731 int
    732 ppsratecheck(lasttime, curpps, maxpps)
    733 	struct timeval *lasttime;
    734 	int *curpps;
    735 	int maxpps;	/* maximum pps allowed */
    736 {
    737 	struct timeval tv, delta;
    738 	int s, rv;
    739 
    740 	s = splclock();
    741 	tv = mono_time;
    742 	splx(s);
    743 
    744 	timersub(&tv, lasttime, &delta);
    745 
    746 	/*
    747 	 * check for 0,0 is so that the message will be seen at least once.
    748 	 * if more than one second have passed since the last update of
    749 	 * lasttime, reset the counter.
    750 	 *
    751 	 * we do increment *curpps even in *curpps < maxpps case, as some may
    752 	 * try to use *curpps for stat purposes as well.
    753 	 */
    754 	if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) ||
    755 	    delta.tv_sec >= 1) {
    756 		*lasttime = tv;
    757 		*curpps = 0;
    758 		rv = 1;
    759 	} else if (maxpps < 0)
    760 		rv = 1;
    761 	else if (*curpps < maxpps)
    762 		rv = 1;
    763 	else
    764 		rv = 0;
    765 
    766 #if 1 /*DIAGNOSTIC?*/
    767 	/* be careful about wrap-around */
    768 	if (*curpps + 1 > *curpps)
    769 		*curpps = *curpps + 1;
    770 #else
    771 	/*
    772 	 * assume that there's not too many calls to this function.
    773 	 * not sure if the assumption holds, as it depends on *caller's*
    774 	 * behavior, not the behavior of this function.
    775 	 * IMHO it is wrong to make assumption on the caller's behavior,
    776 	 * so the above #if is #if 1, not #ifdef DIAGNOSTIC.
    777 	 */
    778 	*curpps = *curpps + 1;
    779 #endif
    780 
    781 	return (rv);
    782 }
    783