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PR/8657: z@rentaboat.se: alarm takes more seconds that it can handle.

This is a followup to PR/14558.

    - itimerfix(9) limited the number of seconds to 100M, before I changed
      it to 1000M for PR/14558.
    - nanosleep(2) documents a limit of 1000M seconds.
    - setitimer(2), select(2), and other library functions that indirectly
      use setitimer(2) for example alarm(3) don't specify a limit.

So it only seems appropriate that any positive number of seconds in
struct timeval should be accepted by any code that uses itimerfix(9)
directly, except nanosleep(2) which should check for 1000M seconds
manually. This changes makes the manual pages of select(2), nanosleep(2),
setitimer(2), and alarm(3) consistent with the code.

/*	$NetBSD: kern_time.c,v 1.59 2001/11/13 00:34:21 christos Exp $	*/

/*-
 * Copyright (c) 2000 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christopher G. Demetriou.
 *
 * 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 NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*
 * Copyright (c) 1982, 1986, 1989, 1993
 *	The 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.
 *
 *	@(#)kern_time.c	8.4 (Berkeley) 5/26/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_time.c,v 1.59 2001/11/13 00:34:21 christos Exp $");

#include "fs_nfs.h"
#include "opt_nfs.h"
#include "opt_nfsserver.h"

#include <sys/param.h>
#include <sys/resourcevar.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/signalvar.h>
#include <sys/syslog.h>

#include <sys/mount.h>
#include <sys/syscallargs.h>

#include <uvm/uvm_extern.h>

#if defined(NFS) || defined(NFSSERVER)
#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfs/nfs_var.h>
#endif

#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.
 */

/* This function is used by clock_settime and settimeofday */
int
settime(tv)
	struct timeval *tv;
{
	struct timeval delta;
	struct cpu_info *ci;
	int s;

	/* WHAT DO WE DO ABOUT PENDING REAL-TIME TIMEOUTS??? */
	s = splclock();
	timersub(tv, &time, &delta);
	if ((delta.tv_sec < 0 || delta.tv_usec < 0) && securelevel > 1) {
		splx(s);
		return (EPERM);
	}
#ifdef notyet
	if ((delta.tv_sec < 86400) && securelevel > 0) {
		splx(s);
		return (EPERM);
	}
#endif
	time = *tv;
	(void) spllowersoftclock();
	timeradd(&boottime, &delta, &boottime);
	/*
	 * XXXSMP
	 * This is wrong.  We should traverse a list of all
	 * CPUs and add the delta to the runtime of those
	 * CPUs which have a process on them.
	 */
	ci = curcpu();
	timeradd(&ci->ci_schedstate.spc_runtime, &delta,
	    &ci->ci_schedstate.spc_runtime);
#	if (defined(NFS) && !defined (NFS_V2_ONLY)) || defined(NFSSERVER)
		nqnfs_lease_updatetime(delta.tv_sec);
#	endif
	splx(s);
	resettodr();
	return (0);
}

/* ARGSUSED */
int
sys_clock_gettime(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_clock_gettime_args /* {
		syscallarg(clockid_t) clock_id;
		syscallarg(struct timespec *) tp;
	} */ *uap = v;
	clockid_t clock_id;
	struct timeval atv;
	struct timespec ats;

	clock_id = SCARG(uap, clock_id);
	if (clock_id != CLOCK_REALTIME)
		return (EINVAL);

	microtime(&atv);
	TIMEVAL_TO_TIMESPEC(&atv,&ats);

	return copyout(&ats, SCARG(uap, tp), sizeof(ats));
}

/* ARGSUSED */
int
sys_clock_settime(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_clock_settime_args /* {
		syscallarg(clockid_t) clock_id;
		syscallarg(const struct timespec *) tp;
	} */ *uap = v;
	clockid_t clock_id;
	struct timespec ats;
	int error;

	if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
		return (error);

	clock_id = SCARG(uap, clock_id);

	if ((error = copyin(SCARG(uap, tp), &ats, sizeof(ats))) != 0)
		return (error);

	return (clock_settime1(clock_id, &ats));
}


int
clock_settime1(clock_id, ats)
	clockid_t clock_id;
	struct timespec *ats;
{
	struct timeval atv;
	int error;

	if (clock_id != CLOCK_REALTIME)
		return (EINVAL);

	TIMESPEC_TO_TIMEVAL(&atv, ats);
	if ((error = settime(&atv)) != 0)
		return (error);

	return 0;
}

int
sys_clock_getres(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_clock_getres_args /* {
		syscallarg(clockid_t) clock_id;
		syscallarg(struct timespec *) tp;
	} */ *uap = v;
	clockid_t clock_id;
	struct timespec ts;
	int error = 0;

	clock_id = SCARG(uap, clock_id);
	if (clock_id != CLOCK_REALTIME)
		return (EINVAL);

	if (SCARG(uap, tp)) {
		ts.tv_sec = 0;
		ts.tv_nsec = 1000000000 / hz;

		error = copyout(&ts, SCARG(uap, tp), sizeof(ts));
	}

	return error;
}

/* ARGSUSED */
int
sys_nanosleep(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	static int nanowait;
	struct sys_nanosleep_args/* {
		syscallarg(struct timespec *) rqtp;
		syscallarg(struct timespec *) rmtp;
	} */ *uap = v;
	struct timespec rqt;
	struct timespec rmt;
	struct timeval atv, utv;
	int error, s, timo;

	error = copyin((caddr_t)SCARG(uap, rqtp), (caddr_t)&rqt,
		       sizeof(struct timespec));
	if (error)
		return (error);

	TIMESPEC_TO_TIMEVAL(&atv,&rqt)
	if (itimerfix(&atv) || atv.tv_sec > 1000000000)
		return (EINVAL);

	s = splclock();
	timeradd(&atv,&time,&atv);
	timo = hzto(&atv);
	/* 
	 * Avoid inadvertantly sleeping forever
	 */
	if (timo == 0)
		timo = 1;
	splx(s);

	error = tsleep(&nanowait, PWAIT | PCATCH, "nanosleep", timo);
	if (error == ERESTART)
		error = EINTR;
	if (error == EWOULDBLOCK)
		error = 0;

	if (SCARG(uap, rmtp)) {
		int error;

		s = splclock();
		utv = time;
		splx(s);

		timersub(&atv, &utv, &utv);
		if (utv.tv_sec < 0)
			timerclear(&utv);

		TIMEVAL_TO_TIMESPEC(&utv,&rmt);
		error = copyout((caddr_t)&rmt, (caddr_t)SCARG(uap,rmtp),
			sizeof(rmt));
		if (error)
			return (error);
	}

	return error;
}

/* ARGSUSED */
int
sys_gettimeofday(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_gettimeofday_args /* {
		syscallarg(struct timeval *) tp;
		syscallarg(struct timezone *) tzp;
	} */ *uap = v;
	struct timeval atv;
	int error = 0;
	struct timezone tzfake;

	if (SCARG(uap, tp)) {
		microtime(&atv);
		error = copyout(&atv, SCARG(uap, tp), sizeof(atv));
		if (error)
			return (error);
	}
	if (SCARG(uap, tzp)) {
		/*
		 * NetBSD has no kernel notion of time zone, so we just
		 * fake up a timezone struct and return it if demanded.
		 */
		tzfake.tz_minuteswest = 0;
		tzfake.tz_dsttime = 0;
		error = copyout(&tzfake, SCARG(uap, tzp), sizeof(tzfake));
	}
	return (error);
}

/* ARGSUSED */
int
sys_settimeofday(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_settimeofday_args /* {
		syscallarg(const struct timeval *) tv;
		syscallarg(const struct timezone *) tzp;
	} */ *uap = v;
	struct timeval atv;
	struct timezone atz;
	struct timeval *tv = NULL;
	struct timezone *tzp = NULL;
	int error;

	if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
		return (error);

	/* Verify all parameters before changing time. */
	if (SCARG(uap, tv)) {
		if ((error = copyin(SCARG(uap, tv), &atv, sizeof(atv))) != 0)
			return (error);
		tv = &atv;
	}
	/* XXX since we don't use tz, probably no point in doing copyin. */
	if (SCARG(uap, tzp)) {
		if ((error = copyin(SCARG(uap, tzp), &atz, sizeof(atz))) != 0)
			return (error);
		tzp = &atz;
	}

	return settimeofday1(tv, tzp, p);
}

int
settimeofday1(tv, tzp, p)
	struct timeval *tv;
	struct timezone *tzp;
	struct proc *p;
{
	int error;

	if (tv)
		if ((error = settime(tv)) != 0)
			return (error);
	/*
	 * NetBSD has no kernel notion of time zone, and only an
	 * obsolete program would try to set it, so we log a warning.
	 */
	if (tzp)
		log(LOG_WARNING, "pid %d attempted to set the "
		    "(obsolete) kernel time zone\n", p->p_pid); 
	return (0);
}

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

/* ARGSUSED */
int
sys_adjtime(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_adjtime_args /* {
		syscallarg(const struct timeval *) delta;
		syscallarg(struct timeval *) olddelta;
	} */ *uap = v;
	struct timeval atv;
	struct timeval *oatv = NULL;
	int error;

	if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
		return (error);

	error = copyin(SCARG(uap, delta), &atv, sizeof(struct timeval));
	if (error)
		return (error);

	if (SCARG(uap, olddelta) != NULL) {
		if (uvm_useracc((caddr_t)SCARG(uap, olddelta), 
		    sizeof(struct timeval), B_WRITE) == FALSE)
			return (EFAULT);
		oatv = SCARG(uap, olddelta);
	}

	return adjtime1(&atv, oatv, p);
}

int
adjtime1(delta, olddelta, p)
	struct timeval *delta;
	struct timeval *olddelta;
	struct proc *p;
{
	long ndelta, ntickdelta, odelta;
	int s;

	/*
	 * Compute the total correction and the rate at which to apply it.
	 * Round the adjustment down to a whole multiple of the per-tick
	 * delta, so that after some number of incremental changes in
	 * hardclock(), tickdelta will become zero, lest the correction
	 * overshoot and start taking us away from the desired final time.
	 */
	ndelta = delta->tv_sec * 1000000 + delta->tv_usec;
	if (ndelta > bigadj || ndelta < -bigadj)
		ntickdelta = 10 * tickadj;
	else
		ntickdelta = tickadj;
	if (ndelta % ntickdelta)
		ndelta = ndelta / ntickdelta * ntickdelta;

	/*
	 * To make hardclock()'s job easier, make the per-tick delta negative
	 * if we want time to run slower; then hardclock can simply compute
	 * tick + tickdelta, and subtract tickdelta from timedelta.
	 */
	if (ndelta < 0)
		ntickdelta = -ntickdelta;
	s = splclock();
	odelta = timedelta;
	timedelta = ndelta;
	tickdelta = ntickdelta;
	splx(s);

	if (olddelta) {
		delta->tv_sec = odelta / 1000000;
		delta->tv_usec = odelta % 1000000;
		(void) copyout(delta, 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.
 */
/* ARGSUSED */
int
sys_getitimer(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_getitimer_args /* {
		syscallarg(int) which;
		syscallarg(struct itimerval *) itv;
	} */ *uap = v;
	int which = SCARG(uap, which);
	struct itimerval aitv;
	int s;

	if ((u_int)which > ITIMER_PROF)
		return (EINVAL);
	s = splclock();
	if (which == ITIMER_REAL) {
		/*
		 * Convert from absolute 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
				timersub(&aitv.it_value, &time, &aitv.it_value);
		}
	} else
		aitv = p->p_stats->p_timer[which];
	splx(s);
	return (copyout(&aitv, SCARG(uap, itv), sizeof(struct itimerval)));
}

/* ARGSUSED */
int
sys_setitimer(p, v, retval)
	struct proc *p;
	void *v;
	register_t *retval;
{
	struct sys_setitimer_args /* {
		syscallarg(int) which;
		syscallarg(const struct itimerval *) itv;
		syscallarg(struct itimerval *) oitv;
	} */ *uap = v;
	int which = SCARG(uap, which);
	struct sys_getitimer_args getargs;
	struct itimerval aitv;
	const struct itimerval *itvp;
	int s, error;

	if ((u_int)which > ITIMER_PROF)
		return (EINVAL);
	itvp = SCARG(uap, itv);
	if (itvp && 
	    (error = copyin(itvp, &aitv, sizeof(struct itimerval)) != 0))
		return (error);
	if (SCARG(uap, oitv) != NULL) {
		SCARG(&getargs, which) = which;
		SCARG(&getargs, itv) = SCARG(uap, oitv);
		if ((error = sys_getitimer(p, &getargs, retval)) != 0)
			return (error);
	}
	if (itvp == 0)
		return (0);
	if (itimerfix(&aitv.it_value) || itimerfix(&aitv.it_interval))
		return (EINVAL);
	s = splclock();
	if (which == ITIMER_REAL) {
		callout_stop(&p->p_realit_ch);
		if (timerisset(&aitv.it_value)) {
			/*
			 * Don't need to check hzto() return value, here.
			 * callout_reset() does it for us.
			 */
			timeradd(&aitv.it_value, &time, &aitv.it_value);
			callout_reset(&p->p_realit_ch, hzto(&aitv.it_value),
			    realitexpire, p);
		}
		p->p_realtimer = aitv;
	} else
		p->p_stats->p_timer[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(arg)
	void *arg;
{
	struct proc *p;
	int s;

	p = (struct proc *)arg;
	psignal(p, SIGALRM);
	if (!timerisset(&p->p_realtimer.it_interval)) {
		timerclear(&p->p_realtimer.it_value);
		return;
	}
	for (;;) {
		s = splclock();
		timeradd(&p->p_realtimer.it_value,
		    &p->p_realtimer.it_interval, &p->p_realtimer.it_value);
		if (timercmp(&p->p_realtimer.it_value, &time, >)) {
			/*
			 * Don't need to check hzto() return value, here.
			 * callout_reset() does it for us.
			 */
			callout_reset(&p->p_realit_ch,
			    hzto(&p->p_realtimer.it_value), realitexpire, p);
			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_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
 * reduce 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)
	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);
}

/*
 * ratecheck(): simple time-based rate-limit checking.  see ratecheck(9)
 * for usage and rationale.
 */
int
ratecheck(lasttime, mininterval)
	struct timeval *lasttime;
	const struct timeval *mininterval;
{
	struct timeval tv, delta;
	int s, rv = 0;

	s = splclock(); 
	tv = mono_time;
	splx(s);

	timersub(&tv, lasttime, &delta);

	/*
	 * check for 0,0 is so that the message will be seen at least once,
	 * even if interval is huge.
	 */
	if (timercmp(&delta, mininterval, >=) ||
	    (lasttime->tv_sec == 0 && lasttime->tv_usec == 0)) {
		*lasttime = tv;
		rv = 1;
	}

	return (rv);
}

/*
 * ppsratecheck(): packets (or events) per second limitation.
 */
int
ppsratecheck(lasttime, curpps, maxpps)
	struct timeval *lasttime;
	int *curpps;
	int maxpps;	/* maximum pps allowed */
{
	struct timeval tv, delta;
	int s, rv;

	s = splclock(); 
	tv = mono_time;
	splx(s);

	timersub(&tv, lasttime, &delta);

	/*
	 * check for 0,0 is so that the message will be seen at least once.
	 * if more than one second have passed since the last update of
	 * lasttime, reset the counter.
	 *
	 * we do increment *curpps even in *curpps < maxpps case, as some may
	 * try to use *curpps for stat purposes as well.
	 */
	if ((lasttime->tv_sec == 0 && lasttime->tv_usec == 0) ||
	    delta.tv_sec >= 1) {
		*lasttime = tv;
		*curpps = 0;
		rv = 1;
	} else if (maxpps < 0)
		rv = 1;
	else if (*curpps < maxpps)
		rv = 1;
	else
		rv = 0;

#if 1 /*DIAGNOSTIC?*/
	/* be careful about wrap-around */
	if (*curpps + 1 > *curpps)
		*curpps = *curpps + 1;
#else
	/*
	 * assume that there's not too many calls to this function.
	 * not sure if the assumption holds, as it depends on *caller's*
	 * behavior, not the behavior of this function.
	 * IMHO it is wrong to make assumption on the caller's behavior,
	 * so the above #if is #if 1, not #ifdef DIAGNOSTIC.
	 */
	*curpps = *curpps + 1;
#endif

	return (rv);
}