d25301c858
sleep queue interface: - Sleep queues attempt to merge some of the benefits of both sleep queues and condition variables. Having sleep qeueus in a hash table avoids having to allocate a queue head for each wait channel. Thus, struct cv has shrunk down to just a single char * pointer now. However, the hash table does not hold threads directly, but queue heads. This means that once you have located a queue in the hash bucket, you no longer have to walk the rest of the hash chain looking for threads. Instead, you have a list of all the threads sleeping on that wait channel. - Outside of the sleepq code and the sleep/cv code the kernel no longer differentiates between cv's and sleep/wakeup. For example, calls to abortsleep() and cv_abort() are replaced with a call to sleepq_abort(). Thus, the TDF_CVWAITQ flag is removed. Also, calls to unsleep() and cv_waitq_remove() have been replaced with calls to sleepq_remove(). - The sched_sleep() function no longer accepts a priority argument as sleep's no longer inherently bump the priority. Instead, this is soley a propery of msleep() which explicitly calls sched_prio() before blocking. - The TDF_ONSLEEPQ flag has been dropped as it was never used. The associated TDF_SET_ONSLEEPQ and TDF_CLR_ON_SLEEPQ macros have also been dropped and replaced with a single explicit clearing of td_wchan. TD_SET_ONSLEEPQ() would really have only made sense if it had taken the wait channel and message as arguments anyway. Now that that only happens in one place, a macro would be overkill.
357 lines
8.9 KiB
C
357 lines
8.9 KiB
C
/*-
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* Copyright (c) 2000 Jake Burkholder <jake@freebsd.org>.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_ktrace.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/kernel.h>
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#include <sys/ktr.h>
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#include <sys/condvar.h>
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#include <sys/sched.h>
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#include <sys/signalvar.h>
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#include <sys/sleepqueue.h>
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#include <sys/resourcevar.h>
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#ifdef KTRACE
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#include <sys/uio.h>
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#include <sys/ktrace.h>
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#endif
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/*
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* Common sanity checks for cv_wait* functions.
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*/
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#define CV_ASSERT(cvp, mp, td) do { \
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KASSERT((td) != NULL, ("%s: curthread NULL", __func__)); \
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KASSERT(TD_IS_RUNNING(td), ("%s: not TDS_RUNNING", __func__)); \
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KASSERT((cvp) != NULL, ("%s: cvp NULL", __func__)); \
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KASSERT((mp) != NULL, ("%s: mp NULL", __func__)); \
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mtx_assert((mp), MA_OWNED | MA_NOTRECURSED); \
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} while (0)
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/*
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* Initialize a condition variable. Must be called before use.
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*/
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void
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cv_init(struct cv *cvp, const char *desc)
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{
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cvp->cv_description = desc;
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}
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/*
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* Destroy a condition variable. The condition variable must be re-initialized
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* in order to be re-used.
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*/
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void
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cv_destroy(struct cv *cvp)
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{
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#ifdef INVARIANTS
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struct sleepqueue *sq;
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sq = sleepq_lookup(cvp);
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sleepq_release(cvp);
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KASSERT(sq == NULL, ("%s: associated sleep queue non-empty", __func__));
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#endif
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}
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/*
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* Wait on a condition variable. The current thread is placed on the condition
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* variable's wait queue and suspended. A cv_signal or cv_broadcast on the same
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* condition variable will resume the thread. The mutex is released before
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* sleeping and will be held on return. It is recommended that the mutex be
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* held when cv_signal or cv_broadcast are called.
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*/
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void
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cv_wait(struct cv *cvp, struct mtx *mp)
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{
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struct sleepqueue *sq;
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struct thread *td;
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WITNESS_SAVE_DECL(mp);
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td = curthread;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0);
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#endif
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CV_ASSERT(cvp, mp, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
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"Waiting on \"%s\"", cvp->cv_description);
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WITNESS_SAVE(&mp->mtx_object, mp);
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if (cold || panicstr) {
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/*
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* During autoconfiguration, just give interrupts
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* a chance, then just return. Don't run any other
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* thread or panic below, in case this is the idle
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* process and already asleep.
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*/
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return;
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}
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sq = sleepq_lookup(cvp);
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DROP_GIANT();
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mtx_unlock(mp);
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sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR);
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sleepq_wait(cvp);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0);
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#endif
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PICKUP_GIANT();
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mtx_lock(mp);
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WITNESS_RESTORE(&mp->mtx_object, mp);
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}
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/*
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* Wait on a condition variable, allowing interruption by signals. Return 0 if
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* the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if
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* a signal was caught. If ERESTART is returned the system call should be
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* restarted if possible.
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*/
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int
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cv_wait_sig(struct cv *cvp, struct mtx *mp)
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{
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struct sleepqueue *sq;
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struct thread *td;
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struct proc *p;
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int rval, sig;
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WITNESS_SAVE_DECL(mp);
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td = curthread;
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p = td->td_proc;
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rval = 0;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0);
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#endif
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CV_ASSERT(cvp, mp, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
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"Waiting on \"%s\"", cvp->cv_description);
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WITNESS_SAVE(&mp->mtx_object, mp);
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if (cold || panicstr) {
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/*
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* After a panic, or during autoconfiguration, just give
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* interrupts a chance, then just return; don't run any other
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* procs or panic below, in case this is the idle process and
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* already asleep.
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*/
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return 0;
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}
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sq = sleepq_lookup(cvp);
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/* XXX: Missing the threading checks from msleep! */
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DROP_GIANT();
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mtx_unlock(mp);
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sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR);
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sig = sleepq_catch_signals(cvp);
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/*
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* XXX: Missing magic return value handling for no signal
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* caught but thread woken up during check.
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*/
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rval = sleepq_wait_sig(cvp);
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if (rval == 0)
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rval = sleepq_calc_signal_retval(sig);
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/* XXX: Part of missing threading checks? */
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PROC_LOCK(p);
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if (p->p_flag & P_WEXIT)
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rval = EINTR;
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PROC_UNLOCK(p);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0);
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#endif
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PICKUP_GIANT();
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mtx_lock(mp);
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WITNESS_RESTORE(&mp->mtx_object, mp);
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return (rval);
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}
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/*
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* Wait on a condition variable for at most timo/hz seconds. Returns 0 if the
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* process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout
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* expires.
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*/
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int
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cv_timedwait(struct cv *cvp, struct mtx *mp, int timo)
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{
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struct sleepqueue *sq;
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struct thread *td;
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int rval;
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WITNESS_SAVE_DECL(mp);
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td = curthread;
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rval = 0;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0);
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#endif
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CV_ASSERT(cvp, mp, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
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"Waiting on \"%s\"", cvp->cv_description);
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WITNESS_SAVE(&mp->mtx_object, mp);
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if (cold || panicstr) {
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/*
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* After a panic, or during autoconfiguration, just give
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* interrupts a chance, then just return; don't run any other
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* thread or panic below, in case this is the idle process and
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* already asleep.
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*/
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return 0;
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}
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sq = sleepq_lookup(cvp);
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DROP_GIANT();
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mtx_unlock(mp);
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sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR);
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sleepq_set_timeout(sq, cvp, timo);
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rval = sleepq_timedwait(cvp, 0);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0);
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#endif
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PICKUP_GIANT();
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mtx_lock(mp);
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WITNESS_RESTORE(&mp->mtx_object, mp);
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return (rval);
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}
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/*
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* Wait on a condition variable for at most timo/hz seconds, allowing
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* interruption by signals. Returns 0 if the thread was resumed by cv_signal
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* or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if
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* a signal was caught.
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*/
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int
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cv_timedwait_sig(struct cv *cvp, struct mtx *mp, int timo)
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{
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struct sleepqueue *sq;
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struct thread *td;
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struct proc *p;
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int rval;
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int sig;
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WITNESS_SAVE_DECL(mp);
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td = curthread;
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p = td->td_proc;
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rval = 0;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0);
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#endif
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CV_ASSERT(cvp, mp, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &mp->mtx_object,
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"Waiting on \"%s\"", cvp->cv_description);
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WITNESS_SAVE(&mp->mtx_object, mp);
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if (cold || panicstr) {
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/*
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* After a panic, or during autoconfiguration, just give
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* interrupts a chance, then just return; don't run any other
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* thread or panic below, in case this is the idle process and
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* already asleep.
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*/
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return 0;
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}
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sq = sleepq_lookup(cvp);
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DROP_GIANT();
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mtx_unlock(mp);
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sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR);
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sleepq_set_timeout(sq, cvp, timo);
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sig = sleepq_catch_signals(cvp);
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/*
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* XXX: Missing magic return value handling for no signal
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* caught but thread woken up during check.
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*/
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rval = sleepq_timedwait_sig(cvp, sig != 0);
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if (rval == 0)
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rval = sleepq_calc_signal_retval(sig);
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/* XXX: Part of missing threading checks? */
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PROC_LOCK(p);
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if (p->p_flag & P_WEXIT)
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rval = EINTR;
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PROC_UNLOCK(p);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0);
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#endif
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PICKUP_GIANT();
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mtx_lock(mp);
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WITNESS_RESTORE(&mp->mtx_object, mp);
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return (rval);
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}
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/*
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* Signal a condition variable, wakes up one waiting thread. Will also wakeup
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* the swapper if the process is not in memory, so that it can bring the
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* sleeping process in. Note that this may also result in additional threads
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* being made runnable. Should be called with the same mutex as was passed to
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* cv_wait held.
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*/
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void
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cv_signal(struct cv *cvp)
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{
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sleepq_signal(cvp, SLEEPQ_CONDVAR, -1);
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}
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/*
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* Broadcast a signal to a condition variable. Wakes up all waiting threads.
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* Should be called with the same mutex as was passed to cv_wait held.
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*/
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void
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cv_broadcastpri(struct cv *cvp, int pri)
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{
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sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri);
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}
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