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b89bc9e62b
td_wmesg field in the thread structure points to the description string of the condition variable or mutex. If the condvar or the mutex had been initialized from a loadable module that was unloaded in the meantime, td_wmesg may now point to invalid memory. Retrieving the process table now may panic the kernel (or access junk). Setting the td_wmesg field to NULL after unblocking on the condvar/mutex prevents this panic. PR: kern/47408 Approved by: jake (mentor)
588 lines
14 KiB
C
588 lines
14 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/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/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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#ifdef INVARIANTS
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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", __func__)); \
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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", __func__)); \
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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", __func__));
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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 thread *td)
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{
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TD_SET_SLEEPING(td);
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td->td_proc->p_stats->p_ru.ru_nvcsw++;
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mi_switch();
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CTR3(KTR_PROC, "cv_switch: resume thread %p (pid %d, %s)", td,
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td->td_proc->p_pid, td->td_proc->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 thread *td)
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{
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struct proc *p;
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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 TDS_SLP 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, td->td_wchan will be 0 upon return from cursig,
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* and TD_ON_SLEEPQ() will return false.
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*/
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td->td_flags |= TDF_SINTR;
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mtx_unlock_spin(&sched_lock);
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p = td->td_proc;
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PROC_LOCK(p);
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sig = cursig(td);
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if (thread_suspend_check(1))
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sig = SIGSTOP;
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mtx_lock_spin(&sched_lock);
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PROC_UNLOCK(p);
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if (sig != 0) {
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if (TD_ON_SLEEPQ(td))
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cv_waitq_remove(td);
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TD_SET_RUNNING(td);
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} else if (TD_ON_SLEEPQ(td)) {
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cv_switch(td);
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}
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td->td_flags &= ~TDF_SINTR;
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return sig;
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}
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/*
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* Add a thread 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 thread *td)
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{
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td->td_flags |= TDF_CVWAITQ;
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TD_SET_ON_SLEEPQ(td);
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td->td_wchan = cvp;
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td->td_wmesg = cvp->cv_description;
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CTR3(KTR_PROC, "cv_waitq_add: thread %p (pid %d, %s)", td,
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td->td_proc->p_pid, td->td_proc->p_comm);
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TAILQ_INSERT_TAIL(&cvp->cv_waitq, td, td_slpq);
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sched_sleep(td, td->td_priority);
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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 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_SLEEP(0, &mp->mtx_object);
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WITNESS_SAVE(&mp->mtx_object, mp);
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if (cold ) {
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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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mtx_lock_spin(&sched_lock);
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CV_WAIT_VALIDATE(cvp, mp);
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DROP_GIANT();
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mtx_unlock(mp);
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cv_waitq_add(cvp, td);
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cv_switch(td);
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mtx_unlock_spin(&sched_lock);
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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 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_SLEEP(0, &mp->mtx_object);
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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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mtx_lock_spin(&sched_lock);
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CV_WAIT_VALIDATE(cvp, mp);
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DROP_GIANT();
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mtx_unlock(mp);
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cv_waitq_add(cvp, td);
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sig = cv_switch_catch(td);
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mtx_unlock_spin(&sched_lock);
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PROC_LOCK(p);
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if (sig == 0)
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sig = cursig(td); /* XXXKSE */
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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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if (p->p_flag & P_WEXIT)
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rval = EINTR;
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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 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_SLEEP(0, &mp->mtx_object);
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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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mtx_lock_spin(&sched_lock);
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CV_WAIT_VALIDATE(cvp, mp);
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DROP_GIANT();
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mtx_unlock(mp);
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cv_waitq_add(cvp, td);
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callout_reset(&td->td_slpcallout, timo, cv_timedwait_end, td);
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cv_switch(td);
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if (td->td_flags & TDF_TIMEOUT) {
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td->td_flags &= ~TDF_TIMEOUT;
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rval = EWOULDBLOCK;
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} else if (td->td_flags & TDF_TIMOFAIL)
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td->td_flags &= ~TDF_TIMOFAIL;
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else if (callout_stop(&td->td_slpcallout) == 0) {
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/*
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* Work around race with cv_timedwait_end similar to that
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* between msleep and endtsleep.
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* Go back to sleep.
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*/
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TD_SET_SLEEPING(td);
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td->td_proc->p_stats->p_ru.ru_nivcsw++;
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mi_switch();
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td->td_flags &= ~TDF_TIMOFAIL;
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}
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if (td->td_proc->p_flag & P_WEXIT)
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rval = EWOULDBLOCK;
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mtx_unlock_spin(&sched_lock);
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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 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_SLEEP(0, &mp->mtx_object);
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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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mtx_lock_spin(&sched_lock);
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CV_WAIT_VALIDATE(cvp, mp);
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DROP_GIANT();
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mtx_unlock(mp);
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cv_waitq_add(cvp, td);
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callout_reset(&td->td_slpcallout, timo, cv_timedwait_end, td);
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sig = cv_switch_catch(td);
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if (td->td_flags & TDF_TIMEOUT) {
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td->td_flags &= ~TDF_TIMEOUT;
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rval = EWOULDBLOCK;
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} else if (td->td_flags & TDF_TIMOFAIL)
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td->td_flags &= ~TDF_TIMOFAIL;
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else if (callout_stop(&td->td_slpcallout) == 0) {
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/*
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* Work around race with cv_timedwait_end similar to that
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* between msleep and endtsleep.
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* Go back to sleep.
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*/
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TD_SET_SLEEPING(td);
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td->td_proc->p_stats->p_ru.ru_nivcsw++;
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mi_switch();
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td->td_flags &= ~TDF_TIMOFAIL;
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}
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mtx_unlock_spin(&sched_lock);
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PROC_LOCK(p);
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if (sig == 0)
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sig = cursig(td);
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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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if (p->p_flag & P_WEXIT)
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rval = EINTR;
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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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* 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 thread *td;
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mtx_assert(&sched_lock, MA_OWNED);
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td = TAILQ_FIRST(&cvp->cv_waitq);
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KASSERT(td->td_wchan == cvp, ("%s: bogus wchan", __func__));
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KASSERT(td->td_flags & TDF_CVWAITQ, ("%s: not on waitq", __func__));
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cv_waitq_remove(td);
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TD_CLR_SLEEPING(td);
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setrunnable(td);
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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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KASSERT(cvp != NULL, ("%s: cvp NULL", __func__));
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mtx_lock_spin(&sched_lock);
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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_unlock_spin(&sched_lock);
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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.
|
|
*/
|
|
void
|
|
cv_broadcast(struct cv *cvp)
|
|
{
|
|
|
|
KASSERT(cvp != NULL, ("%s: cvp NULL", __func__));
|
|
mtx_lock_spin(&sched_lock);
|
|
CV_SIGNAL_VALIDATE(cvp);
|
|
while (!TAILQ_EMPTY(&cvp->cv_waitq))
|
|
cv_wakeup(cvp);
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|
|
/*
|
|
* Remove a thread from the wait queue of its condition variable. This may be
|
|
* called externally.
|
|
*/
|
|
void
|
|
cv_waitq_remove(struct thread *td)
|
|
{
|
|
struct cv *cvp;
|
|
|
|
mtx_assert(&sched_lock, MA_OWNED);
|
|
if ((cvp = td->td_wchan) != NULL && td->td_flags & TDF_CVWAITQ) {
|
|
TAILQ_REMOVE(&cvp->cv_waitq, td, td_slpq);
|
|
td->td_flags &= ~TDF_CVWAITQ;
|
|
td->td_wmesg = NULL;
|
|
TD_CLR_ON_SLEEPQ(td);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Timeout function for cv_timedwait. Put the thread on the runqueue and set
|
|
* its timeout flag.
|
|
*/
|
|
static void
|
|
cv_timedwait_end(void *arg)
|
|
{
|
|
struct thread *td;
|
|
|
|
td = arg;
|
|
CTR3(KTR_PROC, "cv_timedwait_end: thread %p (pid %d, %s)",
|
|
td, td->td_proc->p_pid, td->td_proc->p_comm);
|
|
mtx_lock_spin(&sched_lock);
|
|
if (TD_ON_SLEEPQ(td)) {
|
|
cv_waitq_remove(td);
|
|
td->td_flags |= TDF_TIMEOUT;
|
|
} else {
|
|
td->td_flags |= TDF_TIMOFAIL;
|
|
}
|
|
TD_CLR_SLEEPING(td);
|
|
setrunnable(td);
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|
|
/*
|
|
* For now only abort interruptable waits.
|
|
* The others will have to either complete on their own or have a timeout.
|
|
*/
|
|
void
|
|
cv_abort(struct thread *td)
|
|
{
|
|
|
|
CTR3(KTR_PROC, "cv_abort: thread %p (pid %d, %s)", td,
|
|
td->td_proc->p_pid, td->td_proc->p_comm);
|
|
mtx_lock_spin(&sched_lock);
|
|
if ((td->td_flags & (TDF_SINTR|TDF_TIMEOUT)) == TDF_SINTR) {
|
|
if (TD_ON_SLEEPQ(td)) {
|
|
cv_waitq_remove(td);
|
|
}
|
|
TD_CLR_SLEEPING(td);
|
|
setrunnable(td);
|
|
}
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|