[unix-history] / sys / kern / kern_time.c

/*
 * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from: @(#)kern_time.c	7.15 (Berkeley) 3/17/91
 *	$Id: kern_time.c,v 1.4 1993/11/25 01:33:14 wollman Exp $
 */

#include "param.h"
#include "systm.h"
#include "resourcevar.h"
#include "kernel.h"
#include "proc.h"

#include "machine/cpu.h"

/* 
 * Time of day and interval timer support.
 *
 * These routines provide the kernel entry points to get and set
 * the time-of-day and per-process interval timers.  Subroutines
 * here provide support for adding and subtracting timeval structures
 * and decrementing interval timers, optionally reloading the interval
 * timers when they expire.
 */

struct gettimeofday_args {
	struct	timeval *tp;
	struct	timezone *tzp;
};

/* ARGSUSED */
int
gettimeofday(p, uap, retval)
	struct proc *p;
	register struct gettimeofday_args *uap;
	int *retval;
{
	struct timeval atv;
	int error = 0;

	if (uap->tp) {
		microtime(&atv);
		if (error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
		    sizeof (atv)))
			return (error);
	}
	if (uap->tzp)
		error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
		    sizeof (tz));
	return (error);
}

struct settimeofday_args {
	struct	timeval *tv;
	struct	timezone *tzp;
};

/* ARGSUSED */
int
settimeofday(p, uap, retval)
	struct proc *p;
	struct settimeofday_args *uap;
	int *retval;
{
	struct timeval atv;
	struct timezone atz;
	int error, s;

	if (error = suser(p->p_ucred, &p->p_acflag))
		return (error);
	if (uap->tv) {
		if (error = copyin((caddr_t)uap->tv, (caddr_t)&atv,
		    sizeof (struct timeval)))
			return (error);
		/* WHAT DO WE DO ABOUT PENDING REAL-TIME TIMEOUTS??? */
		boottime.tv_sec += atv.tv_sec - time.tv_sec;
		s = splclock();
		time.tv_sec = atv.tv_sec;	/* XXX avoid skew in tv_usec */
		splx(s);
		resettodr();
	}
	if (uap->tzp && (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz,
	    sizeof (atz))) == 0)
		tz = atz;
	return (error);
}

extern	int tickadj;			/* "standard" clock skew, us./tick */
int	tickdelta;			/* current clock skew, us. per tick */
long	timedelta;			/* unapplied time correction, us. */
long	bigadj = 1000000;		/* use 10x skew above bigadj us. */

struct adjtime_args {
		struct timeval *delta;
		struct timeval *olddelta;
};

/* ARGSUSED */
int
adjtime(p, uap, retval)
	struct proc *p;
	register struct adjtime_args *uap;
	int *retval;
{
	struct timeval atv, oatv;
	register long ndelta;
	int s, error;

	if (error = suser(p->p_ucred, &p->p_acflag))
		return (error);
	if (error =
	    copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof (struct timeval)))
		return (error);
	ndelta = atv.tv_sec * 1000000 + atv.tv_usec;
	if (timedelta == 0)
		if (ndelta > bigadj)
			tickdelta = 10 * tickadj;
		else
			tickdelta = tickadj;
	if (ndelta % tickdelta)
		ndelta = ndelta / tickadj * tickadj;

	s = splclock();
	if (uap->olddelta) {
		oatv.tv_sec = timedelta / 1000000;
		oatv.tv_usec = timedelta % 1000000;
	}
	timedelta = ndelta;
	splx(s);

	if (uap->olddelta)
		(void) copyout((caddr_t)&oatv, (caddr_t)uap->olddelta,
			sizeof (struct timeval));
	return (0);
}

/*
 * Get value of an interval timer.  The process virtual and
 * profiling virtual time timers are kept in the p_stats area, since
 * they can be swapped out.  These are kept internally in the
 * way they are specified externally: in time until they expire.
 *
 * The real time interval timer is kept in the process table slot
 * for the process, and its value (it_value) is kept as an
 * absolute time rather than as a delta, so that it is easy to keep
 * periodic real-time signals from drifting.
 *
 * Virtual time timers are processed in the hardclock() routine of
 * kern_clock.c.  The real time timer is processed by a timeout
 * routine, called from the softclock() routine.  Since a callout
 * may be delayed in real time due to interrupt processing in the system,
 * it is possible for the real time timeout routine (realitexpire, given below),
 * to be delayed in real time past when it is supposed to occur.  It
 * does not suffice, therefore, to reload the real timer .it_value from the
 * real time timers .it_interval.  Rather, we compute the next time in
 * absolute time the timer should go off.
 */

struct getitimer_args {
		u_int	which;
		struct	itimerval *itv;
};

/* ARGSUSED */
int
getitimer(p, uap, retval)
	struct proc *p;
	register struct getitimer_args *uap;
	int *retval;
{
	struct itimerval aitv;
	int s;

	if (uap->which > ITIMER_PROF)
		return (EINVAL);
	s = splclock();
	if (uap->which == ITIMER_REAL) {
		/*
		 * Convert from absoulte to relative time in .it_value
		 * part of real time timer.  If time for real time timer
		 * has passed return 0, else return difference between
		 * current time and time for the timer to go off.
		 */
		aitv = p->p_realtimer;
		if (timerisset(&aitv.it_value))
			if (timercmp(&aitv.it_value, &time, <))
				timerclear(&aitv.it_value);
			else
				timevalsub(&aitv.it_value, &time);
	} else
		aitv = p->p_stats->p_timer[uap->which];
	splx(s);
	return (copyout((caddr_t)&aitv, (caddr_t)uap->itv,
	    sizeof (struct itimerval)));
}

struct setitimer_args {
	u_int	which;
	struct	itimerval *itv, *oitv;
};

/* ARGSUSED */
int
setitimer(p, uap, retval)
	struct proc *p;
	register struct setitimer_args *uap;
	int *retval;
{
	struct itimerval aitv;
	register struct itimerval *itvp;
	int s, error;

	if (uap->which > ITIMER_PROF)
		return (EINVAL);
	itvp = uap->itv;
	if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
	    sizeof(struct itimerval))))
		return (error);
	if ((uap->itv = uap->oitv) && (error = getitimer(p, uap, retval)))
		return (error);
	if (itvp == 0)
		return (0);
	if (itimerfix(&aitv.it_value) || itimerfix(&aitv.it_interval))
		return (EINVAL);
	s = splclock();
	if (uap->which == ITIMER_REAL) {
		untimeout(realitexpire, (caddr_t)p);
		if (timerisset(&aitv.it_value)) {
			timevaladd(&aitv.it_value, &time);
			timeout(realitexpire, (caddr_t)p, hzto(&aitv.it_value));
		}
		p->p_realtimer = aitv;
	} else
		p->p_stats->p_timer[uap->which] = aitv;
	splx(s);
	return (0);
}

/*
 * Real interval timer expired:
 * send process whose timer expired an alarm signal.
 * If time is not set up to reload, then just return.
 * Else compute next time timer should go off which is > current time.
 * This is where delay in processing this timeout causes multiple
 * SIGALRM calls to be compressed into one.
 */
void
realitexpire(caddr_t arg1, int arg2)
{
	register struct proc *p = (struct proc *)arg1;
	int s;

	psignal(p, SIGALRM);
	if (!timerisset(&p->p_realtimer.it_interval)) {
		timerclear(&p->p_realtimer.it_value);
		return;
	}
	for (;;) {
		s = splclock();
		timevaladd(&p->p_realtimer.it_value,
		    &p->p_realtimer.it_interval);
		if (timercmp(&p->p_realtimer.it_value, &time, >)) {
			timeout(realitexpire, (caddr_t)p,
			    hzto(&p->p_realtimer.it_value));
			splx(s);
			return;
		}
		splx(s);
	}
}

/*
 * Check that a proposed value to load into the .it_value or
 * .it_interval part of an interval timer is acceptable, and
 * fix it to have at least minimal value (i.e. if it is less
 * than the resolution of the clock, round it up.)
 */
int
itimerfix(tv)
	struct timeval *tv;
{

	if (tv->tv_sec < 0 || tv->tv_sec > 100000000 ||
	    tv->tv_usec < 0 || tv->tv_usec >= 1000000)
		return (EINVAL);
	if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
		tv->tv_usec = tick;
	return (0);
}

/*
 * Decrement an interval timer by a specified number
 * of microseconds, which must be less than a second,
 * i.e. < 1000000.  If the timer expires, then reload
 * it.  In this case, carry over (usec - old value) to
 * reducint the value reloaded into the timer so that
 * the timer does not drift.  This routine assumes
 * that it is called in a context where the timers
 * on which it is operating cannot change in value.
 */
int
itimerdecr(itp, usec)
	register struct itimerval *itp;
	int usec;
{

	if (itp->it_value.tv_usec < usec) {
		if (itp->it_value.tv_sec == 0) {
			/* expired, and already in next interval */
			usec -= itp->it_value.tv_usec;
			goto expire;
		}
		itp->it_value.tv_usec += 1000000;
		itp->it_value.tv_sec--;
	}
	itp->it_value.tv_usec -= usec;
	usec = 0;
	if (timerisset(&itp->it_value))
		return (1);
	/* expired, exactly at end of interval */
expire:
	if (timerisset(&itp->it_interval)) {
		itp->it_value = itp->it_interval;
		itp->it_value.tv_usec -= usec;
		if (itp->it_value.tv_usec < 0) {
			itp->it_value.tv_usec += 1000000;
			itp->it_value.tv_sec--;
		}
	} else
		itp->it_value.tv_usec = 0;		/* sec is already 0 */
	return (0);
}

/*
 * Add and subtract routines for timevals.
 * N.B.: subtract routine doesn't deal with
 * results which are before the beginning,
 * it just gets very confused in this case.
 * Caveat emptor.
 */
void
timevaladd(t1, t2)
	struct timeval *t1, *t2;
{

	t1->tv_sec += t2->tv_sec;
	t1->tv_usec += t2->tv_usec;
	timevalfix(t1);
}

void
timevalsub(t1, t2)
	struct timeval *t1, *t2;
{

	t1->tv_sec -= t2->tv_sec;
	t1->tv_usec -= t2->tv_usec;
	timevalfix(t1);
}

void
timevalfix(t1)
	struct timeval *t1;
{

	if (t1->tv_usec < 0) {
		t1->tv_sec--;
		t1->tv_usec += 1000000;
	}
	if (t1->tv_usec >= 1000000) {
		t1->tv_sec++;
		t1->tv_usec -= 1000000;
	}
}
Commit	Line	Data
15637ed4 RG	1	/*
	2	* Copyright (c) 1982, 1986, 1989 Regents of the University of California.
	3	* 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	*
600f7f07	33	* from: @(#)kern_time.c 7.15 (Berkeley) 3/17/91
da6ece2e	34	* $Id: kern_time.c,v 1.4 1993/11/25 01:33:14 wollman Exp $
15637ed4 RG	35	*/
	36
	37	#include "param.h"
4c45483e	38	#include "systm.h"
15637ed4 RG	39	#include "resourcevar.h"
	40	#include "kernel.h"
	41	#include "proc.h"
	42
	43	#include "machine/cpu.h"
	44
	45	/*
	46	* Time of day and interval timer support.
	47	*
	48	* These routines provide the kernel entry points to get and set
	49	* the time-of-day and per-process interval timers. Subroutines
	50	* here provide support for adding and subtracting timeval structures
	51	* and decrementing interval timers, optionally reloading the interval
	52	* timers when they expire.
	53	*/
	54
3c7eb27c DG	55	struct gettimeofday_args {
	56	struct timeval *tp;
	57	struct timezone *tzp;
	58	};
	59
15637ed4	60	/* ARGSUSED */
4c45483e	61	int
15637ed4 RG	62	gettimeofday(p, uap, retval)
15637ed4 RG	63	struct proc *p;
3c7eb27c	64	register struct gettimeofday_args *uap;
15637ed4 RG	65	int *retval;
	66	{
	67	struct timeval atv;
	68	int error = 0;
	69
	70	if (uap->tp) {
	71	microtime(&atv);
	72	if (error = copyout((caddr_t)&atv, (caddr_t)uap->tp,
	73	sizeof (atv)))
	74	return (error);
	75	}
	76	if (uap->tzp)
	77	error = copyout((caddr_t)&tz, (caddr_t)uap->tzp,
	78	sizeof (tz));
	79	return (error);
	80	}
	81
3c7eb27c DG	82	struct settimeofday_args {
	83	struct timeval *tv;
	84	struct timezone *tzp;
	85	};
	86
15637ed4	87	/* ARGSUSED */
4c45483e	88	int
15637ed4 RG	89	settimeofday(p, uap, retval)
15637ed4 RG	90	struct proc *p;
3c7eb27c	91	struct settimeofday_args *uap;
15637ed4 RG	92	int *retval;
	93	{
	94	struct timeval atv;
	95	struct timezone atz;
	96	int error, s;
	97
	98	if (error = suser(p->p_ucred, &p->p_acflag))
	99	return (error);
	100	if (uap->tv) {
	101	if (error = copyin((caddr_t)uap->tv, (caddr_t)&atv,
	102	sizeof (struct timeval)))
	103	return (error);
	104	/* WHAT DO WE DO ABOUT PENDING REAL-TIME TIMEOUTS??? */
	105	boottime.tv_sec += atv.tv_sec - time.tv_sec;
da6ece2e JH	106	s = splclock();
	107	time.tv_sec = atv.tv_sec; /* XXX avoid skew in tv_usec */
	108	splx(s);
15637ed4 RG	109	resettodr();
	110	}
	111	if (uap->tzp && (error = copyin((caddr_t)uap->tzp, (caddr_t)&atz,
	112	sizeof (atz))) == 0)
	113	tz = atz;
	114	return (error);
	115	}
	116
	117	extern int tickadj; /* "standard" clock skew, us./tick */
	118	int tickdelta; /* current clock skew, us. per tick */
	119	long timedelta; /* unapplied time correction, us. */
	120	long bigadj = 1000000; /* use 10x skew above bigadj us. */
	121
3c7eb27c DG	122	struct adjtime_args {
	123	struct timeval *delta;
	124	struct timeval *olddelta;
	125	};
	126
15637ed4	127	/* ARGSUSED */
4c45483e	128	int
15637ed4 RG	129	adjtime(p, uap, retval)
15637ed4 RG	130	struct proc *p;
3c7eb27c	131	register struct adjtime_args *uap;
15637ed4 RG	132	int *retval;
	133	{
	134	struct timeval atv, oatv;
	135	register long ndelta;
	136	int s, error;
	137
	138	if (error = suser(p->p_ucred, &p->p_acflag))
	139	return (error);
	140	if (error =
	141	copyin((caddr_t)uap->delta, (caddr_t)&atv, sizeof (struct timeval)))
	142	return (error);
	143	ndelta = atv.tv_sec * 1000000 + atv.tv_usec;
	144	if (timedelta == 0)
	145	if (ndelta > bigadj)
	146	tickdelta = 10 * tickadj;
	147	else
	148	tickdelta = tickadj;
	149	if (ndelta % tickdelta)
	150	ndelta = ndelta / tickadj * tickadj;
	151
	152	s = splclock();
	153	if (uap->olddelta) {
	154	oatv.tv_sec = timedelta / 1000000;
	155	oatv.tv_usec = timedelta % 1000000;
	156	}
	157	timedelta = ndelta;
	158	splx(s);
	159
	160	if (uap->olddelta)
	161	(void) copyout((caddr_t)&oatv, (caddr_t)uap->olddelta,
	162	sizeof (struct timeval));
	163	return (0);
	164	}
	165
	166	/*
	167	* Get value of an interval timer. The process virtual and
	168	* profiling virtual time timers are kept in the p_stats area, since
	169	* they can be swapped out. These are kept internally in the
	170	* way they are specified externally: in time until they expire.
	171	*
	172	* The real time interval timer is kept in the process table slot
	173	* for the process, and its value (it_value) is kept as an
	174	* absolute time rather than as a delta, so that it is easy to keep
	175	* periodic real-time signals from drifting.
	176	*
	177	* Virtual time timers are processed in the hardclock() routine of
	178	* kern_clock.c. The real time timer is processed by a timeout
	179	* routine, called from the softclock() routine. Since a callout
	180	* may be delayed in real time due to interrupt processing in the system,
	181	* it is possible for the real time timeout routine (realitexpire, given below),
	182	* to be delayed in real time past when it is supposed to occur. It
	183	* does not suffice, therefore, to reload the real timer .it_value from the
	184	* real time timers .it_interval. Rather, we compute the next time in
	185	* absolute time the timer should go off.
	186	*/
3c7eb27c DG	187
	188	struct getitimer_args {
	189	u_int which;
	190	struct itimerval *itv;
	191	};
	192
15637ed4	193	/* ARGSUSED */
4c45483e	194	int
15637ed4 RG	195	getitimer(p, uap, retval)
15637ed4 RG	196	struct proc *p;
3c7eb27c	197	register struct getitimer_args *uap;
15637ed4 RG	198	int *retval;
	199	{
	200	struct itimerval aitv;
	201	int s;
	202
	203	if (uap->which > ITIMER_PROF)
	204	return (EINVAL);
	205	s = splclock();
	206	if (uap->which == ITIMER_REAL) {
	207	/*
	208	* Convert from absoulte to relative time in .it_value
	209	* part of real time timer. If time for real time timer
	210	* has passed return 0, else return difference between
	211	* current time and time for the timer to go off.
	212	*/
	213	aitv = p->p_realtimer;
	214	if (timerisset(&aitv.it_value))
	215	if (timercmp(&aitv.it_value, &time, <))
	216	timerclear(&aitv.it_value);
	217	else
	218	timevalsub(&aitv.it_value, &time);
	219	} else
	220	aitv = p->p_stats->p_timer[uap->which];
	221	splx(s);
	222	return (copyout((caddr_t)&aitv, (caddr_t)uap->itv,
	223	sizeof (struct itimerval)));
	224	}
	225
3c7eb27c DG	226	struct setitimer_args {
	227	u_int which;
	228	struct itimerval itv, oitv;
	229	};
	230
15637ed4	231	/* ARGSUSED */
4c45483e	232	int
15637ed4 RG	233	setitimer(p, uap, retval)
15637ed4 RG	234	struct proc *p;
3c7eb27c	235	register struct setitimer_args *uap;
15637ed4 RG	236	int *retval;
	237	{
	238	struct itimerval aitv;
	239	register struct itimerval *itvp;
	240	int s, error;
	241
	242	if (uap->which > ITIMER_PROF)
	243	return (EINVAL);
	244	itvp = uap->itv;
	245	if (itvp && (error = copyin((caddr_t)itvp, (caddr_t)&aitv,
	246	sizeof(struct itimerval))))
	247	return (error);
	248	if ((uap->itv = uap->oitv) && (error = getitimer(p, uap, retval)))
	249	return (error);
	250	if (itvp == 0)
	251	return (0);
	252	if (itimerfix(&aitv.it_value) \|\| itimerfix(&aitv.it_interval))
	253	return (EINVAL);
	254	s = splclock();
	255	if (uap->which == ITIMER_REAL) {
	256	untimeout(realitexpire, (caddr_t)p);
	257	if (timerisset(&aitv.it_value)) {
	258	timevaladd(&aitv.it_value, &time);
	259	timeout(realitexpire, (caddr_t)p, hzto(&aitv.it_value));
	260	}
	261	p->p_realtimer = aitv;
	262	} else
	263	p->p_stats->p_timer[uap->which] = aitv;
	264	splx(s);
	265	return (0);
	266	}
	267
	268	/*
	269	* Real interval timer expired:
	270	* send process whose timer expired an alarm signal.
	271	* If time is not set up to reload, then just return.
	272	* Else compute next time timer should go off which is > current time.
	273	* This is where delay in processing this timeout causes multiple
	274	* SIGALRM calls to be compressed into one.
	275	*/
4c45483e GW	276	void
4c45483e GW	277	realitexpire(caddr_t arg1, int arg2)
15637ed4	278	{
4c45483e	279	register struct proc p = (struct proc )arg1;
15637ed4 RG	280	int s;
	281
	282	psignal(p, SIGALRM);
	283	if (!timerisset(&p->p_realtimer.it_interval)) {
	284	timerclear(&p->p_realtimer.it_value);
	285	return;
	286	}
	287	for (;;) {
	288	s = splclock();
	289	timevaladd(&p->p_realtimer.it_value,
	290	&p->p_realtimer.it_interval);
	291	if (timercmp(&p->p_realtimer.it_value, &time, >)) {
	292	timeout(realitexpire, (caddr_t)p,
	293	hzto(&p->p_realtimer.it_value));
	294	splx(s);
	295	return;
	296	}
	297	splx(s);
	298	}
	299	}
	300
	301	/*
	302	* Check that a proposed value to load into the .it_value or
	303	* .it_interval part of an interval timer is acceptable, and
	304	* fix it to have at least minimal value (i.e. if it is less
	305	* than the resolution of the clock, round it up.)
	306	*/
4c45483e	307	int
15637ed4 RG	308	itimerfix(tv)
	309	struct timeval *tv;
	310	{
	311
	312	if (tv->tv_sec < 0 \|\| tv->tv_sec > 100000000 \|\|
	313	tv->tv_usec < 0 \|\| tv->tv_usec >= 1000000)
	314	return (EINVAL);
	315	if (tv->tv_sec == 0 && tv->tv_usec != 0 && tv->tv_usec < tick)
	316	tv->tv_usec = tick;
	317	return (0);
	318	}
	319
	320	/*
	321	* Decrement an interval timer by a specified number
	322	* of microseconds, which must be less than a second,
	323	* i.e. < 1000000. If the timer expires, then reload
	324	* it. In this case, carry over (usec - old value) to
	325	* reducint the value reloaded into the timer so that
	326	* the timer does not drift. This routine assumes
	327	* that it is called in a context where the timers
	328	* on which it is operating cannot change in value.
	329	*/
4c45483e	330	int
15637ed4 RG	331	itimerdecr(itp, usec)
	332	register struct itimerval *itp;
	333	int usec;
	334	{
	335
	336	if (itp->it_value.tv_usec < usec) {
	337	if (itp->it_value.tv_sec == 0) {
	338	/* expired, and already in next interval */
	339	usec -= itp->it_value.tv_usec;
	340	goto expire;
	341	}
	342	itp->it_value.tv_usec += 1000000;
	343	itp->it_value.tv_sec--;
	344	}
	345	itp->it_value.tv_usec -= usec;
	346	usec = 0;
	347	if (timerisset(&itp->it_value))
	348	return (1);
	349	/* expired, exactly at end of interval */
	350	expire:
	351	if (timerisset(&itp->it_interval)) {
	352	itp->it_value = itp->it_interval;
	353	itp->it_value.tv_usec -= usec;
	354	if (itp->it_value.tv_usec < 0) {
	355	itp->it_value.tv_usec += 1000000;
	356	itp->it_value.tv_sec--;
	357	}
	358	} else
	359	itp->it_value.tv_usec = 0; /* sec is already 0 */
	360	return (0);
	361	}
	362
	363	/*
	364	* Add and subtract routines for timevals.
	365	* N.B.: subtract routine doesn't deal with
	366	* results which are before the beginning,
	367	* it just gets very confused in this case.
	368	* Caveat emptor.
	369	*/
4c45483e	370	void
15637ed4 RG	371	timevaladd(t1, t2)
	372	struct timeval t1, t2;
	373	{
	374
	375	t1->tv_sec += t2->tv_sec;
	376	t1->tv_usec += t2->tv_usec;
	377	timevalfix(t1);
	378	}
	379
4c45483e	380	void
15637ed4 RG	381	timevalsub(t1, t2)
	382	struct timeval t1, t2;
	383	{
	384
	385	t1->tv_sec -= t2->tv_sec;
	386	t1->tv_usec -= t2->tv_usec;
	387	timevalfix(t1);
	388	}
	389
4c45483e	390	void
15637ed4 RG	391	timevalfix(t1)
	392	struct timeval *t1;
	393	{
	394
	395	if (t1->tv_usec < 0) {
	396	t1->tv_sec--;
	397	t1->tv_usec += 1000000;
	398	}
	399	if (t1->tv_usec >= 1000000) {
	400	t1->tv_sec++;
	401	t1->tv_usec -= 1000000;
	402	}
	403	}