547 lines
13 KiB
C
547 lines
13 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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* $FreeBSD$
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*/
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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/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/mutex.h>
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#include <sys/signalvar.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, p) do { \
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KASSERT((p) != NULL, ("%s: curproc NULL", __FUNCTION__)); \
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KASSERT((p)->p_stat == SRUN, ("%s: not SRUN", __FUNCTION__)); \
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KASSERT((cvp) != NULL, ("%s: cvp NULL", __FUNCTION__)); \
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KASSERT((mp) != NULL, ("%s: mp NULL", __FUNCTION__)); \
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mtx_assert((mp), MA_OWNED | MA_NOTRECURSED); \
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} while (0)
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#ifdef CV_DEBUG
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#define CV_WAIT_VALIDATE(cvp, mp) do { \
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if (TAILQ_EMPTY(&(cvp)->cv_waitq)) { \
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/* Only waiter. */ \
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(cvp)->cv_mtx = (mp); \
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} else { \
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/* \
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* Other waiter; assert that we're using the \
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* same mutex. \
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*/ \
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KASSERT((cvp)->cv_mtx == (mp), \
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("%s: Multiple mutexes", __FUNCTION__)); \
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} \
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} while (0)
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#define CV_SIGNAL_VALIDATE(cvp) do { \
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if (!TAILQ_EMPTY(&(cvp)->cv_waitq)) { \
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KASSERT(mtx_owned((cvp)->cv_mtx), \
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("%s: Mutex not owned", __FUNCTION__)); \
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} \
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} while (0)
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#else
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#define CV_WAIT_VALIDATE(cvp, mp)
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#define CV_SIGNAL_VALIDATE(cvp)
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#endif
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static void cv_timedwait_end(void *arg);
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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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TAILQ_INIT(&cvp->cv_waitq);
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cvp->cv_mtx = NULL;
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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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KASSERT(cv_waitq_empty(cvp), ("%s: cv_waitq non-empty", __FUNCTION__));
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}
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/*
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* Common code for cv_wait* functions. All require sched_lock.
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*/
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/*
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* Switch context.
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*/
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static __inline void
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cv_switch(struct proc *p)
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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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CTR3(KTR_PROC, "cv_switch: resume proc %p (pid %d, %s)", p, p->p_pid,
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p->p_comm);
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}
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/*
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* Switch context, catching signals.
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*/
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static __inline int
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cv_switch_catch(struct proc *p)
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{
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int sig;
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/*
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* We put ourselves on the sleep queue and start our timeout before
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* calling CURSIG, as we could stop there, and a wakeup or a SIGCONT (or
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* both) could occur while we were stopped. A SIGCONT would cause us to
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* be marked as SSLEEP without resuming us, thus we must be ready for
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* sleep when CURSIG is called. If the wakeup happens while we're
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* stopped, p->p_wchan will be 0 upon return from CURSIG.
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*/
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p->p_sflag |= PS_SINTR;
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mtx_exit(&sched_lock, MTX_SPIN);
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sig = CURSIG(p);
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mtx_enter(&sched_lock, MTX_SPIN);
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if (sig != 0) {
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if (p->p_wchan != NULL)
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cv_waitq_remove(p);
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p->p_stat = SRUN;
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} else if (p->p_wchan != NULL) {
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cv_switch(p);
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}
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p->p_sflag &= ~PS_SINTR;
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return sig;
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}
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/*
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* Add a process to the wait queue of a condition variable.
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*/
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static __inline void
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cv_waitq_add(struct cv *cvp, struct proc *p)
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{
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/*
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* Process may be sitting on a slpque if asleep() was called, remove it
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* 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_sflag |= PS_CVWAITQ;
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p->p_wchan = cvp;
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p->p_wmesg = cvp->cv_description;
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p->p_slptime = 0;
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p->p_nativepri = p->p_priority;
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CTR3(KTR_PROC, "cv_waitq_add: proc %p (pid %d, %s)", p, p->p_pid,
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p->p_comm);
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TAILQ_INSERT_TAIL(&cvp->cv_waitq, p, p_slpq);
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}
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/*
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* Wait on a condition variable. The current process 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 process. 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 proc *p;
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WITNESS_SAVE_DECL(mp);
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p = CURPROC;
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#ifdef KTRACE
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if (p && KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 1, 0);
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#endif
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CV_ASSERT(cvp, mp, p);
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WITNESS_SLEEP(0, mp);
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WITNESS_SAVE(mp, mp);
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mtx_enter(&sched_lock, MTX_SPIN);
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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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mtx_exit(&sched_lock, MTX_SPIN);
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return;
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}
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CV_WAIT_VALIDATE(cvp, mp);
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DROP_GIANT_NOSWITCH();
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mtx_exit(mp, MTX_DEF | MTX_NOSWITCH);
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cv_waitq_add(cvp, p);
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cv_switch(p);
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curpriority = p->p_usrpri;
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mtx_exit(&sched_lock, MTX_SPIN);
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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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PICKUP_GIANT();
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mtx_enter(mp, MTX_DEF);
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WITNESS_RESTORE(mp, 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 process 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 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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p = CURPROC;
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rval = 0;
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#ifdef KTRACE
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if (p && KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 1, 0);
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#endif
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CV_ASSERT(cvp, mp, p);
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WITNESS_SLEEP(0, mp);
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WITNESS_SAVE(mp, mp);
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mtx_enter(&sched_lock, MTX_SPIN);
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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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mtx_exit(&sched_lock, MTX_SPIN);
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return 0;
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}
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CV_WAIT_VALIDATE(cvp, mp);
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DROP_GIANT_NOSWITCH();
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mtx_exit(mp, MTX_DEF | MTX_NOSWITCH);
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cv_waitq_add(cvp, p);
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sig = cv_switch_catch(p);
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curpriority = p->p_usrpri;
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mtx_exit(&sched_lock, MTX_SPIN);
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PICKUP_GIANT();
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/* proc_lock(p); */
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if (sig == 0)
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sig = CURSIG(p);
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if (sig != 0) {
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if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
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rval = EINTR;
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else
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rval = ERESTART;
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}
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/* proc_unlock(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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mtx_enter(mp, MTX_DEF);
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WITNESS_RESTORE(mp, 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 proc *p;
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int rval;
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WITNESS_SAVE_DECL(mp);
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p = CURPROC;
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rval = 0;
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#ifdef KTRACE
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if (p && KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 1, 0);
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#endif
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CV_ASSERT(cvp, mp, p);
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WITNESS_SLEEP(0, mp);
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WITNESS_SAVE(mp, mp);
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mtx_enter(&sched_lock, MTX_SPIN);
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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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mtx_exit(&sched_lock, MTX_SPIN);
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return 0;
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}
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CV_WAIT_VALIDATE(cvp, mp);
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DROP_GIANT_NOSWITCH();
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mtx_exit(mp, MTX_DEF | MTX_NOSWITCH);
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cv_waitq_add(cvp, p);
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callout_reset(&p->p_slpcallout, timo, cv_timedwait_end, p);
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cv_switch(p);
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curpriority = p->p_usrpri;
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if (p->p_sflag & PS_TIMEOUT) {
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p->p_sflag &= ~PS_TIMEOUT;
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rval = EWOULDBLOCK;
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} else
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callout_stop(&p->p_slpcallout);
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mtx_exit(&sched_lock, MTX_SPIN);
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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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PICKUP_GIANT();
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mtx_enter(mp, MTX_DEF);
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WITNESS_RESTORE(mp, 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 process 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 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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p = CURPROC;
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rval = 0;
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#ifdef KTRACE
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if (p && KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 1, 0);
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#endif
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CV_ASSERT(cvp, mp, p);
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WITNESS_SLEEP(0, mp);
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WITNESS_SAVE(mp, mp);
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mtx_enter(&sched_lock, MTX_SPIN);
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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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mtx_exit(&sched_lock, MTX_SPIN);
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return 0;
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}
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CV_WAIT_VALIDATE(cvp, mp);
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DROP_GIANT_NOSWITCH();
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mtx_exit(mp, MTX_DEF | MTX_NOSWITCH);
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cv_waitq_add(cvp, p);
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callout_reset(&p->p_slpcallout, timo, cv_timedwait_end, p);
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sig = cv_switch_catch(p);
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curpriority = p->p_usrpri;
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if (p->p_sflag & PS_TIMEOUT) {
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p->p_sflag &= ~PS_TIMEOUT;
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rval = EWOULDBLOCK;
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} else
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callout_stop(&p->p_slpcallout);
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mtx_exit(&sched_lock, MTX_SPIN);
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PICKUP_GIANT();
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/* proc_lock(p); */
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if (sig == 0)
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sig = CURSIG(p);
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if (sig != 0) {
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if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
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rval = EINTR;
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else
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rval = ERESTART;
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}
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/* proc_unlock(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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mtx_enter(mp, MTX_DEF);
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WITNESS_RESTORE(mp, mp);
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return (rval);
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}
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/*
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* Common code for signal and broadcast. Assumes waitq is not empty. Must be
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* called with sched_lock held.
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*/
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static __inline void
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cv_wakeup(struct cv *cvp)
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{
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struct proc *p;
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mtx_assert(&sched_lock, MA_OWNED);
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p = TAILQ_FIRST(&cvp->cv_waitq);
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KASSERT(p->p_wchan == cvp, ("%s: bogus wchan", __FUNCTION__));
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KASSERT(p->p_sflag & PS_CVWAITQ, ("%s: not on waitq", __FUNCTION__));
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TAILQ_REMOVE(&cvp->cv_waitq, p, p_slpq);
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p->p_sflag &= ~PS_CVWAITQ;
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p->p_wchan = 0;
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if (p->p_stat == SSLEEP) {
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/* OPTIMIZED EXPANSION OF setrunnable(p); */
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CTR3(KTR_PROC, "cv_signal: proc %p (pid %d, %s)",
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p, p->p_pid, p->p_comm);
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if (p->p_slptime > 1)
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updatepri(p);
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p->p_slptime = 0;
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p->p_stat = SRUN;
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if (p->p_sflag & PS_INMEM) {
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setrunqueue(p);
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maybe_resched(p);
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} else {
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p->p_sflag |= PS_SWAPINREQ;
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wakeup(&proc0);
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}
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/* END INLINE EXPANSION */
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}
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}
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/*
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* Signal a condition variable, wakes up one waiting process. 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 processes
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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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KASSERT(cvp != NULL, ("%s: cvp NULL", __FUNCTION__));
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mtx_enter(&sched_lock, MTX_SPIN);
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if (!TAILQ_EMPTY(&cvp->cv_waitq)) {
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CV_SIGNAL_VALIDATE(cvp);
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cv_wakeup(cvp);
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}
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mtx_exit(&sched_lock, MTX_SPIN);
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}
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/*
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* Broadcast a signal to a condition variable. Wakes up all waiting processes.
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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_broadcast(struct cv *cvp)
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{
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KASSERT(cvp != NULL, ("%s: cvp NULL", __FUNCTION__));
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mtx_enter(&sched_lock, MTX_SPIN);
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CV_SIGNAL_VALIDATE(cvp);
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while (!TAILQ_EMPTY(&cvp->cv_waitq))
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cv_wakeup(cvp);
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mtx_exit(&sched_lock, MTX_SPIN);
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}
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/*
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* Remove a process from the wait queue of its condition variable. This may be
|
|
* called externally.
|
|
*/
|
|
void
|
|
cv_waitq_remove(struct proc *p)
|
|
{
|
|
struct cv *cvp;
|
|
|
|
mtx_enter(&sched_lock, MTX_SPIN);
|
|
if ((cvp = p->p_wchan) != NULL && p->p_sflag & PS_CVWAITQ) {
|
|
TAILQ_REMOVE(&cvp->cv_waitq, p, p_slpq);
|
|
p->p_sflag &= ~PS_CVWAITQ;
|
|
p->p_wchan = NULL;
|
|
}
|
|
mtx_exit(&sched_lock, MTX_SPIN);
|
|
}
|
|
|
|
/*
|
|
* Timeout function for cv_timedwait. Put the process on the runqueue and set
|
|
* its timeout flag.
|
|
*/
|
|
static void
|
|
cv_timedwait_end(void *arg)
|
|
{
|
|
struct proc *p;
|
|
|
|
p = arg;
|
|
CTR3(KTR_PROC, "cv_timedwait_end: proc %p (pid %d, %s)", p, p->p_pid,
|
|
p->p_comm);
|
|
mtx_enter(&sched_lock, MTX_SPIN);
|
|
if (p->p_wchan != NULL) {
|
|
if (p->p_stat == SSLEEP)
|
|
setrunnable(p);
|
|
else
|
|
cv_waitq_remove(p);
|
|
p->p_sflag |= PS_TIMEOUT;
|
|
}
|
|
mtx_exit(&sched_lock, MTX_SPIN);
|
|
}
|