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Annotation of Net2/kern/kern_time.c, revision 1.1

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

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