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Annotation of src/sys/kern/kern_time.c, Revision 1.1.1.1

1.1       cgd         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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