b4f65d818d
Previously, calls to *sleep() and cv_*wait*() immediately returned during early boot. Instead, permit threads that request a sleep without a timeout to sleep as wakeup() works during early boot. Sleeps with timeouts are harder to emulate without working timers, so just punt and panic explicitly if any thread tries to use those before timers are working. Any threads that depend on timeouts should either wait until SI_SUB_KICK_SCHEDULER to start or they should use DELAY() until timers are available. Until APs are started earlier this should be a no-op as other kthreads shouldn't get a chance to start running until after timers are working regardless of when they were created. Reviewed by: kib Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D5724
443 lines
11 KiB
C
443 lines
11 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/limits.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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* A bound below which cv_waiters is valid. Once cv_waiters reaches this bound,
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* cv_signal must manually check the wait queue for threads.
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*/
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#define CV_WAITERS_BOUND INT_MAX
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#define CV_WAITERS_INC(cvp) do { \
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if ((cvp)->cv_waiters < CV_WAITERS_BOUND) \
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(cvp)->cv_waiters++; \
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} while (0)
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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, lock, td) do { \
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KASSERT((td) != NULL, ("%s: td 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((lock) != NULL, ("%s: lock NULL", __func__)); \
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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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cvp->cv_waiters = 0;
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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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sleepq_lock(cvp);
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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 lock_object *lock)
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{
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WITNESS_SAVE_DECL(lock_witness);
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struct lock_class *class;
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struct thread *td;
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uintptr_t lock_state;
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td = curthread;
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lock_state = 0;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0, cv_wmesg(cvp));
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#endif
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CV_ASSERT(cvp, lock, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
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"Waiting on \"%s\"", cvp->cv_description);
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class = LOCK_CLASS(lock);
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if (SCHEDULER_STOPPED())
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return;
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sleepq_lock(cvp);
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CV_WAITERS_INC(cvp);
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if (lock == &Giant.lock_object)
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mtx_assert(&Giant, MA_OWNED);
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DROP_GIANT();
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sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
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if (lock != &Giant.lock_object) {
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_release(cvp);
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WITNESS_SAVE(lock, lock_witness);
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lock_state = class->lc_unlock(lock);
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_lock(cvp);
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}
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sleepq_wait(cvp, 0);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0, cv_wmesg(cvp));
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#endif
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PICKUP_GIANT();
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if (lock != &Giant.lock_object) {
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class->lc_lock(lock, lock_state);
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WITNESS_RESTORE(lock, lock_witness);
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}
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}
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/*
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* Wait on a condition variable. This function differs from cv_wait by
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* not aquiring the mutex after condition variable was signaled.
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*/
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void
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_cv_wait_unlock(struct cv *cvp, struct lock_object *lock)
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{
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struct lock_class *class;
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struct thread *td;
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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, cv_wmesg(cvp));
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#endif
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CV_ASSERT(cvp, lock, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
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"Waiting on \"%s\"", cvp->cv_description);
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KASSERT(lock != &Giant.lock_object,
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("cv_wait_unlock cannot be used with Giant"));
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class = LOCK_CLASS(lock);
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if (SCHEDULER_STOPPED()) {
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class->lc_unlock(lock);
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return;
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}
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sleepq_lock(cvp);
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CV_WAITERS_INC(cvp);
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DROP_GIANT();
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sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_release(cvp);
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class->lc_unlock(lock);
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_lock(cvp);
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sleepq_wait(cvp, 0);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0, cv_wmesg(cvp));
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#endif
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PICKUP_GIANT();
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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 lock_object *lock)
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{
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WITNESS_SAVE_DECL(lock_witness);
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struct lock_class *class;
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struct thread *td;
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uintptr_t lock_state;
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int rval;
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td = curthread;
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lock_state = 0;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0, cv_wmesg(cvp));
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#endif
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CV_ASSERT(cvp, lock, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
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"Waiting on \"%s\"", cvp->cv_description);
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class = LOCK_CLASS(lock);
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if (SCHEDULER_STOPPED())
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return (0);
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sleepq_lock(cvp);
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CV_WAITERS_INC(cvp);
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if (lock == &Giant.lock_object)
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mtx_assert(&Giant, MA_OWNED);
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DROP_GIANT();
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sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
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SLEEPQ_INTERRUPTIBLE, 0);
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if (lock != &Giant.lock_object) {
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_release(cvp);
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WITNESS_SAVE(lock, lock_witness);
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lock_state = class->lc_unlock(lock);
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_lock(cvp);
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}
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rval = sleepq_wait_sig(cvp, 0);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0, cv_wmesg(cvp));
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#endif
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PICKUP_GIANT();
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if (lock != &Giant.lock_object) {
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class->lc_lock(lock, lock_state);
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WITNESS_RESTORE(lock, lock_witness);
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}
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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) the value specified in sbt
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* argument. Returns 0 if the process was resumed by cv_signal or cv_broadcast,
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* EWOULDBLOCK if the timeout expires.
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*/
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int
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_cv_timedwait_sbt(struct cv *cvp, struct lock_object *lock, sbintime_t sbt,
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sbintime_t pr, int flags)
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{
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WITNESS_SAVE_DECL(lock_witness);
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struct lock_class *class;
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struct thread *td;
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int lock_state, rval;
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td = curthread;
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lock_state = 0;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0, cv_wmesg(cvp));
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#endif
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CV_ASSERT(cvp, lock, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
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"Waiting on \"%s\"", cvp->cv_description);
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class = LOCK_CLASS(lock);
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if (SCHEDULER_STOPPED())
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return (0);
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sleepq_lock(cvp);
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CV_WAITERS_INC(cvp);
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if (lock == &Giant.lock_object)
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mtx_assert(&Giant, MA_OWNED);
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DROP_GIANT();
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sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0);
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sleepq_set_timeout_sbt(cvp, sbt, pr, flags);
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if (lock != &Giant.lock_object) {
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_release(cvp);
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WITNESS_SAVE(lock, lock_witness);
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lock_state = class->lc_unlock(lock);
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_lock(cvp);
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}
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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, cv_wmesg(cvp));
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#endif
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PICKUP_GIANT();
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if (lock != &Giant.lock_object) {
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class->lc_lock(lock, lock_state);
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WITNESS_RESTORE(lock, lock_witness);
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}
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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) the value specified in sbt
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* argument, allowing interruption by signals.
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* Returns 0 if the thread was resumed by cv_signal or cv_broadcast,
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* EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if a signal
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* was caught.
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*/
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int
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_cv_timedwait_sig_sbt(struct cv *cvp, struct lock_object *lock,
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sbintime_t sbt, sbintime_t pr, int flags)
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{
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WITNESS_SAVE_DECL(lock_witness);
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struct lock_class *class;
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struct thread *td;
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int lock_state, rval;
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td = curthread;
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lock_state = 0;
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(1, 0, cv_wmesg(cvp));
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#endif
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CV_ASSERT(cvp, lock, td);
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WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
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"Waiting on \"%s\"", cvp->cv_description);
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class = LOCK_CLASS(lock);
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if (SCHEDULER_STOPPED())
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return (0);
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sleepq_lock(cvp);
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CV_WAITERS_INC(cvp);
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if (lock == &Giant.lock_object)
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mtx_assert(&Giant, MA_OWNED);
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DROP_GIANT();
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sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR |
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SLEEPQ_INTERRUPTIBLE, 0);
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sleepq_set_timeout_sbt(cvp, sbt, pr, flags);
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if (lock != &Giant.lock_object) {
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_release(cvp);
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WITNESS_SAVE(lock, lock_witness);
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lock_state = class->lc_unlock(lock);
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if (class->lc_flags & LC_SLEEPABLE)
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sleepq_lock(cvp);
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}
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rval = sleepq_timedwait_sig(cvp, 0);
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#ifdef KTRACE
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if (KTRPOINT(td, KTR_CSW))
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ktrcsw(0, 0, cv_wmesg(cvp));
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#endif
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PICKUP_GIANT();
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if (lock != &Giant.lock_object) {
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class->lc_lock(lock, lock_state);
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WITNESS_RESTORE(lock, lock_witness);
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}
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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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int wakeup_swapper;
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wakeup_swapper = 0;
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sleepq_lock(cvp);
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if (cvp->cv_waiters > 0) {
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if (cvp->cv_waiters == CV_WAITERS_BOUND &&
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sleepq_lookup(cvp) == NULL) {
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cvp->cv_waiters = 0;
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} else {
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if (cvp->cv_waiters < CV_WAITERS_BOUND)
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cvp->cv_waiters--;
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wakeup_swapper = sleepq_signal(cvp, SLEEPQ_CONDVAR, 0,
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0);
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}
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}
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sleepq_release(cvp);
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if (wakeup_swapper)
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kick_proc0();
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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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int wakeup_swapper;
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/*
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* XXX sleepq_broadcast pri argument changed from -1 meaning
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* no pri to 0 meaning no pri.
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*/
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wakeup_swapper = 0;
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if (pri == -1)
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pri = 0;
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sleepq_lock(cvp);
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if (cvp->cv_waiters > 0) {
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cvp->cv_waiters = 0;
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wakeup_swapper = sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0);
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}
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sleepq_release(cvp);
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if (wakeup_swapper)
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kick_proc0();
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}
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