/*- * Copyright (c) 2000 Jake Burkholder <jake@freebsd.org>. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include "opt_ktrace.h" #include <sys/param.h> #include <sys/systm.h> #include <sys/lock.h> #include <sys/mutex.h> #include <sys/proc.h> #include <sys/kernel.h> #include <sys/ktr.h> #include <sys/condvar.h> #include <sys/sched.h> #include <sys/signalvar.h> #include <sys/sleepqueue.h> #include <sys/resourcevar.h> #ifdef KTRACE #include <sys/uio.h> #include <sys/ktrace.h> #endif /* * Common sanity checks for cv_wait* functions. */ #define CV_ASSERT(cvp, lock, td) do { \ KASSERT((td) != NULL, ("%s: curthread NULL", __func__)); \ KASSERT(TD_IS_RUNNING(td), ("%s: not TDS_RUNNING", __func__)); \ KASSERT((cvp) != NULL, ("%s: cvp NULL", __func__)); \ KASSERT((lock) != NULL, ("%s: lock NULL", __func__)); \ } while (0) /* * Initialize a condition variable. Must be called before use. */ void cv_init(struct cv *cvp, const char *desc) { cvp->cv_description = desc; cvp->cv_waiters = 0; } /* * Destroy a condition variable. The condition variable must be re-initialized * in order to be re-used. */ void cv_destroy(struct cv *cvp) { #ifdef INVARIANTS struct sleepqueue *sq; sleepq_lock(cvp); sq = sleepq_lookup(cvp); sleepq_release(cvp); KASSERT(sq == NULL, ("%s: associated sleep queue non-empty", __func__)); #endif } /* * Wait on a condition variable. The current thread is placed on the condition * variable's wait queue and suspended. A cv_signal or cv_broadcast on the same * condition variable will resume the thread. The mutex is released before * sleeping and will be held on return. It is recommended that the mutex be * held when cv_signal or cv_broadcast are called. */ void _cv_wait(struct cv *cvp, struct lock_object *lock) { WITNESS_SAVE_DECL(lock_witness); struct lock_class *class; struct thread *td; int lock_state; td = curthread; #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(1, 0); #endif CV_ASSERT(cvp, lock, td); WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, "Waiting on \"%s\"", cvp->cv_description); WITNESS_SAVE(lock, lock_witness); class = LOCK_CLASS(lock); if (cold || panicstr) { /* * During autoconfiguration, just give interrupts * a chance, then just return. Don't run any other * thread or panic below, in case this is the idle * process and already asleep. */ return; } sleepq_lock(cvp); cvp->cv_waiters++; DROP_GIANT(); sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); if (class->lc_flags & LC_SLEEPABLE) sleepq_release(cvp); lock_state = class->lc_unlock(lock); if (class->lc_flags & LC_SLEEPABLE) sleepq_lock(cvp); sleepq_wait(cvp); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(0, 0); #endif PICKUP_GIANT(); class->lc_lock(lock, lock_state); WITNESS_RESTORE(lock, lock_witness); } /* * Wait on a condition variable. This function differs from cv_wait by * not aquiring the mutex after condition variable was signaled. */ void _cv_wait_unlock(struct cv *cvp, struct lock_object *lock) { struct lock_class *class; struct thread *td; td = curthread; #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(1, 0); #endif CV_ASSERT(cvp, lock, td); WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, "Waiting on \"%s\"", cvp->cv_description); class = LOCK_CLASS(lock); if (cold || panicstr) { /* * During autoconfiguration, just give interrupts * a chance, then just return. Don't run any other * thread or panic below, in case this is the idle * process and already asleep. */ class->lc_unlock(lock); return; } sleepq_lock(cvp); cvp->cv_waiters++; DROP_GIANT(); sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); if (class->lc_flags & LC_SLEEPABLE) sleepq_release(cvp); class->lc_unlock(lock); if (class->lc_flags & LC_SLEEPABLE) sleepq_lock(cvp); sleepq_wait(cvp); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(0, 0); #endif PICKUP_GIANT(); } /* * Wait on a condition variable, allowing interruption by signals. Return 0 if * the thread was resumed with cv_signal or cv_broadcast, EINTR or ERESTART if * a signal was caught. If ERESTART is returned the system call should be * restarted if possible. */ int _cv_wait_sig(struct cv *cvp, struct lock_object *lock) { WITNESS_SAVE_DECL(lock_witness); struct lock_class *class; struct thread *td; struct proc *p; int lock_state, rval; td = curthread; p = td->td_proc; #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(1, 0); #endif CV_ASSERT(cvp, lock, td); WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, "Waiting on \"%s\"", cvp->cv_description); WITNESS_SAVE(lock, lock_witness); class = LOCK_CLASS(lock); if (cold || panicstr) { /* * After a panic, or during autoconfiguration, just give * interrupts a chance, then just return; don't run any other * procs or panic below, in case this is the idle process and * already asleep. */ return (0); } sleepq_lock(cvp); cvp->cv_waiters++; DROP_GIANT(); sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | SLEEPQ_INTERRUPTIBLE, 0); if (class->lc_flags & LC_SLEEPABLE) sleepq_release(cvp); lock_state = class->lc_unlock(lock); if (class->lc_flags & LC_SLEEPABLE) sleepq_lock(cvp); rval = sleepq_wait_sig(cvp); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(0, 0); #endif PICKUP_GIANT(); class->lc_lock(lock, lock_state); WITNESS_RESTORE(lock, lock_witness); return (rval); } /* * Wait on a condition variable for at most timo/hz seconds. Returns 0 if the * process was resumed by cv_signal or cv_broadcast, EWOULDBLOCK if the timeout * expires. */ int _cv_timedwait(struct cv *cvp, struct lock_object *lock, int timo) { WITNESS_SAVE_DECL(lock_witness); struct lock_class *class; struct thread *td; int lock_state, rval; td = curthread; rval = 0; #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(1, 0); #endif CV_ASSERT(cvp, lock, td); WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, "Waiting on \"%s\"", cvp->cv_description); WITNESS_SAVE(lock, lock_witness); class = LOCK_CLASS(lock); if (cold || panicstr) { /* * After a panic, or during autoconfiguration, just give * interrupts a chance, then just return; don't run any other * thread or panic below, in case this is the idle process and * already asleep. */ return 0; } sleepq_lock(cvp); cvp->cv_waiters++; DROP_GIANT(); sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR, 0); sleepq_set_timeout(cvp, timo); if (class->lc_flags & LC_SLEEPABLE) sleepq_release(cvp); lock_state = class->lc_unlock(lock); if (class->lc_flags & LC_SLEEPABLE) sleepq_lock(cvp); rval = sleepq_timedwait(cvp); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(0, 0); #endif PICKUP_GIANT(); class->lc_lock(lock, lock_state); WITNESS_RESTORE(lock, lock_witness); return (rval); } /* * Wait on a condition variable for at most timo/hz seconds, allowing * interruption by signals. Returns 0 if the thread was resumed by cv_signal * or cv_broadcast, EWOULDBLOCK if the timeout expires, and EINTR or ERESTART if * a signal was caught. */ int _cv_timedwait_sig(struct cv *cvp, struct lock_object *lock, int timo) { WITNESS_SAVE_DECL(lock_witness); struct lock_class *class; struct thread *td; struct proc *p; int lock_state, rval; td = curthread; p = td->td_proc; rval = 0; #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(1, 0); #endif CV_ASSERT(cvp, lock, td); WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock, "Waiting on \"%s\"", cvp->cv_description); WITNESS_SAVE(lock, lock_witness); class = LOCK_CLASS(lock); if (cold || panicstr) { /* * After a panic, or during autoconfiguration, just give * interrupts a chance, then just return; don't run any other * thread or panic below, in case this is the idle process and * already asleep. */ return 0; } sleepq_lock(cvp); cvp->cv_waiters++; DROP_GIANT(); sleepq_add(cvp, lock, cvp->cv_description, SLEEPQ_CONDVAR | SLEEPQ_INTERRUPTIBLE, 0); sleepq_set_timeout(cvp, timo); if (class->lc_flags & LC_SLEEPABLE) sleepq_release(cvp); lock_state = class->lc_unlock(lock); if (class->lc_flags & LC_SLEEPABLE) sleepq_lock(cvp); rval = sleepq_timedwait_sig(cvp); #ifdef KTRACE if (KTRPOINT(td, KTR_CSW)) ktrcsw(0, 0); #endif PICKUP_GIANT(); class->lc_lock(lock, lock_state); WITNESS_RESTORE(lock, lock_witness); return (rval); } /* * Signal a condition variable, wakes up one waiting thread. Will also wakeup * the swapper if the process is not in memory, so that it can bring the * sleeping process in. Note that this may also result in additional threads * being made runnable. Should be called with the same mutex as was passed to * cv_wait held. */ void cv_signal(struct cv *cvp) { sleepq_lock(cvp); if (cvp->cv_waiters > 0) { cvp->cv_waiters--; sleepq_signal(cvp, SLEEPQ_CONDVAR, -1, 0); } sleepq_release(cvp); } /* * Broadcast a signal to a condition variable. Wakes up all waiting threads. * Should be called with the same mutex as was passed to cv_wait held. */ void cv_broadcastpri(struct cv *cvp, int pri) { sleepq_lock(cvp); if (cvp->cv_waiters > 0) { cvp->cv_waiters = 0; sleepq_broadcast(cvp, SLEEPQ_CONDVAR, pri, 0); } else sleepq_release(cvp); }