Add asleep() and await() support. Currently highly experimental. A
small support structure had to be added to the proc structure, and
a few minor conditional panics no longer apply.
This commit is contained in:
dillon
parent
131312c0d6
commit
953800406c
@ -36,7 +36,7 @@
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* SUCH DAMAGE.
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*
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* @(#)kern_synch.c 8.9 (Berkeley) 5/19/95
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* $Id: kern_synch.c,v 1.68 1998/11/26 16:49:55 bde Exp $
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* $Id: kern_synch.c,v 1.69 1998/11/27 11:44:22 dg Exp $
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*/
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#include "opt_ktrace.h"
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@ -407,9 +407,21 @@ tsleep(ident, priority, wmesg, timo)
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if (ident == NULL || p->p_stat != SRUN)
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panic("tsleep");
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/* XXX This is not exhaustive, just the most common case */
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#ifdef NOTDEF
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/*
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* This can happen legitimately now with asleep()/await()
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*/
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if ((p->p_procq.tqe_prev != NULL) && (*p->p_procq.tqe_prev == p))
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panic("sleeping process already on another queue");
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#endif
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#endif
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/*
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* Process may be sitting on a slpque if asleep() was called, remove
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* it before re-adding.
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*/
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if (p->p_wchan != NULL)
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unsleep(p);
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p->p_wchan = ident;
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p->p_wmesg = wmesg;
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p->p_slptime = 0;
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@ -475,7 +487,170 @@ tsleep(ident, priority, wmesg, timo)
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}
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/*
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* Implement timeout for tsleep.
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* asleep() - async sleep call. Place process on wait queue and return
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* immediately without blocking. The process stays runnable until await()
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* is called. If ident is NULL, remove process from wait queue if it is still
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* on one.
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*
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* Only the most recent sleep condition is effective when making successive
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* calls to asleep() or when calling tsleep().
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*
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* The timeout, if any, is not initiated until await() is called. The sleep
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* priority, signal, and timeout is specified in the asleep() call but may be
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* overriden in the await() call.
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*
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* <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>>
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*/
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int
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asleep(void *ident, int priority, const char *wmesg, int timo)
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{
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struct proc *p = curproc;
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int s;
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/*
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* splhigh() while manipulating sleep structures and slpque.
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*
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* Remove preexisting wait condition (if any) and place process
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* on appropriate slpque, but do not put process to sleep.
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*/
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s = splhigh();
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if (p->p_wchan != NULL)
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unsleep(p);
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if (ident) {
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p->p_wchan = ident;
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p->p_wmesg = wmesg;
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p->p_slptime = 0;
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p->p_asleep.as_priority = priority;
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p->p_asleep.as_timo = timo;
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TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_procq);
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}
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splx(s);
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return(0);
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}
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/*
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* await() - wait for async condition to occur. The process blocks until
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* wakeup() is called on the most recent asleep() address. If wakeup is called
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* priority to await(), await() winds up being a NOP.
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*
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* If await() is called more then once (without an intervening asleep() call),
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* await() is still effectively a NOP but it calls mi_switch() to give other
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* processes some cpu before returning. The process is left runnable.
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*
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* <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>>
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*/
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int
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await(int priority, int timo)
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{
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struct proc *p = curproc;
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int s;
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s = splhigh();
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if (p->p_wchan != NULL) {
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struct callout_handle thandle;
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int sig;
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int catch;
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/*
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* The call to await() can override defaults specified in
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* the original asleep().
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*/
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if (priority < 0)
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priority = p->p_asleep.as_priority;
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if (timo < 0)
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timo = p->p_asleep.as_timo;
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/*
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* Install timeout
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*/
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if (timo)
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thandle = timeout(endtsleep, (void *)p, timo);
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sig = 0;
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catch = priority & PCATCH;
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if (catch) {
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p->p_flag |= P_SINTR;
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if ((sig = CURSIG(p))) {
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if (p->p_wchan)
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unsleep(p);
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p->p_stat = SRUN;
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goto resume;
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}
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if (p->p_wchan == NULL) {
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catch = 0;
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goto resume;
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}
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}
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p->p_stat = SSLEEP;
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p->p_stats->p_ru.ru_nvcsw++;
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mi_switch();
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resume:
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curpriority = p->p_usrpri;
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splx(s);
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p->p_flag &= ~P_SINTR;
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if (p->p_flag & P_TIMEOUT) {
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p->p_flag &= ~P_TIMEOUT;
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if (sig == 0) {
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#ifdef KTRACE
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if (KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 0, 0);
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#endif
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return (EWOULDBLOCK);
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}
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} else if (timo)
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untimeout(endtsleep, (void *)p, thandle);
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if (catch && (sig != 0 || (sig = CURSIG(p)))) {
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#ifdef KTRACE
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if (KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 0, 0);
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#endif
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if (p->p_sigacts->ps_sigintr & sigmask(sig))
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return (EINTR);
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return (ERESTART);
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}
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#ifdef KTRACE
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if (KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 0, 0);
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#endif
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} else {
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/*
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* If as_priority is 0, await() has been called without an
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* intervening asleep(). We are still effectively a NOP,
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* but we call mi_switch() for safety.
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*/
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if (p->p_asleep.as_priority == 0) {
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p->p_stats->p_ru.ru_nvcsw++;
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mi_switch();
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}
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splx(s);
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}
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/*
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* clear p_asleep.as_priority as an indication that await() has been
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* called. If await() is called again without an intervening asleep(),
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* await() is still effectively a NOP but the above mi_switch() code
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* is triggered as a safety.
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*/
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p->p_asleep.as_priority = 0;
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return (0);
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}
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/*
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* Implement timeout for tsleep or asleep()/await()
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*
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* If process hasn't been awakened (wchan non-zero),
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* set timeout flag and undo the sleep. If proc
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* is stopped, just unsleep so it will remain stopped.
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@ -532,8 +707,14 @@ wakeup(ident)
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restart:
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for (p = qp->tqh_first; p != NULL; p = p->p_procq.tqe_next) {
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#ifdef DIAGNOSTIC
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#ifdef NOTDEF
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/*
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* The process can legitimately be running now with
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* asleep()/await().
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*/
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if (p->p_stat != SSLEEP && p->p_stat != SSTOP)
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panic("wakeup");
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#endif
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#endif
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if (p->p_wchan == ident) {
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TAILQ_REMOVE(qp, p, p_procq);
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@ -577,8 +758,14 @@ wakeup_one(ident)
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for (p = qp->tqh_first; p != NULL; p = p->p_procq.tqe_next) {
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#ifdef DIAGNOSTIC
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#ifdef NOTDEF
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/*
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* The process can legitimately be running now with
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* asleep()/await().
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*/
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if (p->p_stat != SSLEEP && p->p_stat != SSTOP)
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panic("wakeup_one");
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#endif
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#endif
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if (p->p_wchan == ident) {
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TAILQ_REMOVE(qp, p, p_procq);
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@ -36,7 +36,7 @@
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* SUCH DAMAGE.
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*
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* @(#)proc.h 8.15 (Berkeley) 5/19/95
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* $Id: proc.h,v 1.62 1998/11/13 17:53:55 dg Exp $
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* $Id: proc.h,v 1.63 1998/12/19 02:55:34 julian Exp $
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*/
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#ifndef _SYS_PROC_H_
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@ -94,6 +94,18 @@ struct procsig {
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};
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#endif /* COMPAT_LINUX_THREADS */
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/*
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* pasleep structure, used by asleep() syscall to hold requested priority and
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* timeout values for await().
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*/
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struct pasleep {
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int as_priority; /* async priority */
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int as_timo; /* async timeout */
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} pasleep;
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/*
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* Description of a process.
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*
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@ -232,6 +244,7 @@ struct proc {
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int p_wakeup; /* thread id */
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struct proc *p_peers;
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struct proc *p_leader;
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struct pasleep p_asleep; /* used by asleep()/await() */
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};
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#define p_session p_pgrp->pg_session
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@ -36,7 +36,7 @@
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* SUCH DAMAGE.
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*
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* @(#)systm.h 8.7 (Berkeley) 3/29/95
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* $Id: systm.h,v 1.78 1998/10/30 05:41:15 msmith Exp $
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* $Id: systm.h,v 1.79 1998/12/03 04:45:57 archie Exp $
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*/
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#ifndef _SYS_SYSTM_H_
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@ -295,6 +295,8 @@ extern watchdog_tickle_fn wdog_tickler;
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* less often.
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*/
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int tsleep __P((void *chan, int pri, const char *wmesg, int timo));
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int asleep __P((void *chan, int pri, const char *wmesg, int timo));
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int await __P((int pri, int timo));
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void wakeup __P((void *chan));
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#endif /* !_SYS_SYSTM_H_ */
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