[rtems-libbsd commit] SLEEPQUEUE(9): Import from FreeBSD
Sebastian Huber
sebh at rtems.org
Tue Mar 24 14:28:56 UTC 2015
Module: rtems-libbsd
Branch: master
Commit: 9975839a123ff5c5891760841b8622fb471fa3d4
Changeset: http://git.rtems.org/rtems-libbsd/commit/?id=9975839a123ff5c5891760841b8622fb471fa3d4
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Tue Mar 24 10:02:31 2015 +0100
SLEEPQUEUE(9): Import from FreeBSD
---
freebsd/sys/kern/subr_sleepqueue.c | 1236 ++++++++++++++++++++++++++++++++++++
freebsd/sys/sys/sleepqueue.h | 117 ++++
2 files changed, 1353 insertions(+)
diff --git a/freebsd/sys/kern/subr_sleepqueue.c b/freebsd/sys/kern/subr_sleepqueue.c
new file mode 100644
index 0000000..3774e66
--- /dev/null
+++ b/freebsd/sys/kern/subr_sleepqueue.c
@@ -0,0 +1,1236 @@
+#include <machine/rtems-bsd-kernel-space.h>
+
+/*-
+ * Copyright (c) 2004 John Baldwin <jhb at 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.
+ */
+
+/*
+ * Implementation of sleep queues used to hold queue of threads blocked on
+ * a wait channel. Sleep queues different from turnstiles in that wait
+ * channels are not owned by anyone, so there is no priority propagation.
+ * Sleep queues can also provide a timeout and can also be interrupted by
+ * signals. That said, there are several similarities between the turnstile
+ * and sleep queue implementations. (Note: turnstiles were implemented
+ * first.) For example, both use a hash table of the same size where each
+ * bucket is referred to as a "chain" that contains both a spin lock and
+ * a linked list of queues. An individual queue is located by using a hash
+ * to pick a chain, locking the chain, and then walking the chain searching
+ * for the queue. This means that a wait channel object does not need to
+ * embed it's queue head just as locks do not embed their turnstile queue
+ * head. Threads also carry around a sleep queue that they lend to the
+ * wait channel when blocking. Just as in turnstiles, the queue includes
+ * a free list of the sleep queues of other threads blocked on the same
+ * wait channel in the case of multiple waiters.
+ *
+ * Some additional functionality provided by sleep queues include the
+ * ability to set a timeout. The timeout is managed using a per-thread
+ * callout that resumes a thread if it is asleep. A thread may also
+ * catch signals while it is asleep (aka an interruptible sleep). The
+ * signal code uses sleepq_abort() to interrupt a sleeping thread. Finally,
+ * sleep queues also provide some extra assertions. One is not allowed to
+ * mix the sleep/wakeup and cv APIs for a given wait channel. Also, one
+ * must consistently use the same lock to synchronize with a wait channel,
+ * though this check is currently only a warning for sleep/wakeup due to
+ * pre-existing abuse of that API. The same lock must also be held when
+ * awakening threads, though that is currently only enforced for condition
+ * variables.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <rtems/bsd/local/opt_sleepqueue_profiling.h>
+#include <rtems/bsd/local/opt_ddb.h>
+#include <rtems/bsd/local/opt_kdtrace.h>
+#include <rtems/bsd/local/opt_sched.h>
+
+#include <rtems/bsd/sys/param.h>
+#include <sys/systm.h>
+#include <rtems/bsd/sys/lock.h>
+#include <sys/kernel.h>
+#include <sys/ktr.h>
+#include <sys/mutex.h>
+#include <sys/proc.h>
+#include <sys/sbuf.h>
+#include <sys/sched.h>
+#include <sys/sdt.h>
+#include <sys/signalvar.h>
+#include <sys/sleepqueue.h>
+#include <sys/sysctl.h>
+
+#include <vm/uma.h>
+
+#ifdef DDB
+#include <ddb/ddb.h>
+#endif
+
+/*
+ * Constants for the hash table of sleep queue chains. These constants are
+ * the same ones that 4BSD (and possibly earlier versions of BSD) used.
+ * Basically, we ignore the lower 8 bits of the address since most wait
+ * channel pointers are aligned and only look at the next 7 bits for the
+ * hash. SC_TABLESIZE must be a power of two for SC_MASK to work properly.
+ */
+#define SC_TABLESIZE 128 /* Must be power of 2. */
+#define SC_MASK (SC_TABLESIZE - 1)
+#define SC_SHIFT 8
+#define SC_HASH(wc) (((uintptr_t)(wc) >> SC_SHIFT) & SC_MASK)
+#define SC_LOOKUP(wc) &sleepq_chains[SC_HASH(wc)]
+#define NR_SLEEPQS 2
+/*
+ * There two different lists of sleep queues. Both lists are connected
+ * via the sq_hash entries. The first list is the sleep queue chain list
+ * that a sleep queue is on when it is attached to a wait channel. The
+ * second list is the free list hung off of a sleep queue that is attached
+ * to a wait channel.
+ *
+ * Each sleep queue also contains the wait channel it is attached to, the
+ * list of threads blocked on that wait channel, flags specific to the
+ * wait channel, and the lock used to synchronize with a wait channel.
+ * The flags are used to catch mismatches between the various consumers
+ * of the sleep queue API (e.g. sleep/wakeup and condition variables).
+ * The lock pointer is only used when invariants are enabled for various
+ * debugging checks.
+ *
+ * Locking key:
+ * c - sleep queue chain lock
+ */
+struct sleepqueue {
+ TAILQ_HEAD(, thread) sq_blocked[NR_SLEEPQS]; /* (c) Blocked threads. */
+ u_int sq_blockedcnt[NR_SLEEPQS]; /* (c) N. of blocked threads. */
+ LIST_ENTRY(sleepqueue) sq_hash; /* (c) Chain and free list. */
+ LIST_HEAD(, sleepqueue) sq_free; /* (c) Free queues. */
+ void *sq_wchan; /* (c) Wait channel. */
+ int sq_type; /* (c) Queue type. */
+#ifdef INVARIANTS
+ struct lock_object *sq_lock; /* (c) Associated lock. */
+#endif
+};
+
+struct sleepqueue_chain {
+ LIST_HEAD(, sleepqueue) sc_queues; /* List of sleep queues. */
+ struct mtx sc_lock; /* Spin lock for this chain. */
+#ifdef SLEEPQUEUE_PROFILING
+ u_int sc_depth; /* Length of sc_queues. */
+ u_int sc_max_depth; /* Max length of sc_queues. */
+#endif
+};
+
+#ifdef SLEEPQUEUE_PROFILING
+u_int sleepq_max_depth;
+static SYSCTL_NODE(_debug, OID_AUTO, sleepq, CTLFLAG_RD, 0, "sleepq profiling");
+static SYSCTL_NODE(_debug_sleepq, OID_AUTO, chains, CTLFLAG_RD, 0,
+ "sleepq chain stats");
+SYSCTL_UINT(_debug_sleepq, OID_AUTO, max_depth, CTLFLAG_RD, &sleepq_max_depth,
+ 0, "maxmimum depth achieved of a single chain");
+
+static void sleepq_profile(const char *wmesg);
+static int prof_enabled;
+#endif
+static struct sleepqueue_chain sleepq_chains[SC_TABLESIZE];
+static uma_zone_t sleepq_zone;
+
+/*
+ * Prototypes for non-exported routines.
+ */
+static int sleepq_catch_signals(void *wchan, int pri);
+static int sleepq_check_signals(void);
+static int sleepq_check_timeout(void);
+#ifdef INVARIANTS
+static void sleepq_dtor(void *mem, int size, void *arg);
+#endif
+static int sleepq_init(void *mem, int size, int flags);
+static int sleepq_resume_thread(struct sleepqueue *sq, struct thread *td,
+ int pri);
+static void sleepq_switch(void *wchan, int pri);
+static void sleepq_timeout(void *arg);
+
+SDT_PROBE_DECLARE(sched, , , sleep);
+SDT_PROBE_DECLARE(sched, , , wakeup);
+
+/*
+ * Early initialization of sleep queues that is called from the sleepinit()
+ * SYSINIT.
+ */
+void
+init_sleepqueues(void)
+{
+#ifdef SLEEPQUEUE_PROFILING
+ struct sysctl_oid *chain_oid;
+ char chain_name[10];
+#endif
+ int i;
+
+ for (i = 0; i < SC_TABLESIZE; i++) {
+ LIST_INIT(&sleepq_chains[i].sc_queues);
+ mtx_init(&sleepq_chains[i].sc_lock, "sleepq chain", NULL,
+ MTX_SPIN | MTX_RECURSE);
+#ifdef SLEEPQUEUE_PROFILING
+ snprintf(chain_name, sizeof(chain_name), "%d", i);
+ chain_oid = SYSCTL_ADD_NODE(NULL,
+ SYSCTL_STATIC_CHILDREN(_debug_sleepq_chains), OID_AUTO,
+ chain_name, CTLFLAG_RD, NULL, "sleepq chain stats");
+ SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
+ "depth", CTLFLAG_RD, &sleepq_chains[i].sc_depth, 0, NULL);
+ SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
+ "max_depth", CTLFLAG_RD, &sleepq_chains[i].sc_max_depth, 0,
+ NULL);
+#endif
+ }
+ sleepq_zone = uma_zcreate("SLEEPQUEUE", sizeof(struct sleepqueue),
+#ifdef INVARIANTS
+ NULL, sleepq_dtor, sleepq_init, NULL, UMA_ALIGN_CACHE, 0);
+#else
+ NULL, NULL, sleepq_init, NULL, UMA_ALIGN_CACHE, 0);
+#endif
+
+ thread0.td_sleepqueue = sleepq_alloc();
+}
+
+/*
+ * Get a sleep queue for a new thread.
+ */
+struct sleepqueue *
+sleepq_alloc(void)
+{
+
+ return (uma_zalloc(sleepq_zone, M_WAITOK));
+}
+
+/*
+ * Free a sleep queue when a thread is destroyed.
+ */
+void
+sleepq_free(struct sleepqueue *sq)
+{
+
+ uma_zfree(sleepq_zone, sq);
+}
+
+/*
+ * Lock the sleep queue chain associated with the specified wait channel.
+ */
+void
+sleepq_lock(void *wchan)
+{
+ struct sleepqueue_chain *sc;
+
+ sc = SC_LOOKUP(wchan);
+ mtx_lock_spin(&sc->sc_lock);
+}
+
+/*
+ * Look up the sleep queue associated with a given wait channel in the hash
+ * table locking the associated sleep queue chain. If no queue is found in
+ * the table, NULL is returned.
+ */
+struct sleepqueue *
+sleepq_lookup(void *wchan)
+{
+ struct sleepqueue_chain *sc;
+ struct sleepqueue *sq;
+
+ KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
+ sc = SC_LOOKUP(wchan);
+ mtx_assert(&sc->sc_lock, MA_OWNED);
+ LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
+ if (sq->sq_wchan == wchan)
+ return (sq);
+ return (NULL);
+}
+
+/*
+ * Unlock the sleep queue chain associated with a given wait channel.
+ */
+void
+sleepq_release(void *wchan)
+{
+ struct sleepqueue_chain *sc;
+
+ sc = SC_LOOKUP(wchan);
+ mtx_unlock_spin(&sc->sc_lock);
+}
+
+/*
+ * Places the current thread on the sleep queue for the specified wait
+ * channel. If INVARIANTS is enabled, then it associates the passed in
+ * lock with the sleepq to make sure it is held when that sleep queue is
+ * woken up.
+ */
+void
+sleepq_add(void *wchan, struct lock_object *lock, const char *wmesg, int flags,
+ int queue)
+{
+ struct sleepqueue_chain *sc;
+ struct sleepqueue *sq;
+ struct thread *td;
+
+ td = curthread;
+ sc = SC_LOOKUP(wchan);
+ mtx_assert(&sc->sc_lock, MA_OWNED);
+ MPASS(td->td_sleepqueue != NULL);
+ MPASS(wchan != NULL);
+ MPASS((queue >= 0) && (queue < NR_SLEEPQS));
+
+ /* If this thread is not allowed to sleep, die a horrible death. */
+ KASSERT(!(td->td_pflags & TDP_NOSLEEPING),
+ ("Trying sleep, but thread marked as sleeping prohibited"));
+
+ /* Look up the sleep queue associated with the wait channel 'wchan'. */
+ sq = sleepq_lookup(wchan);
+
+ /*
+ * If the wait channel does not already have a sleep queue, use
+ * this thread's sleep queue. Otherwise, insert the current thread
+ * into the sleep queue already in use by this wait channel.
+ */
+ if (sq == NULL) {
+#ifdef INVARIANTS
+ int i;
+
+ sq = td->td_sleepqueue;
+ for (i = 0; i < NR_SLEEPQS; i++) {
+ KASSERT(TAILQ_EMPTY(&sq->sq_blocked[i]),
+ ("thread's sleep queue %d is not empty", i));
+ KASSERT(sq->sq_blockedcnt[i] == 0,
+ ("thread's sleep queue %d count mismatches", i));
+ }
+ KASSERT(LIST_EMPTY(&sq->sq_free),
+ ("thread's sleep queue has a non-empty free list"));
+ KASSERT(sq->sq_wchan == NULL, ("stale sq_wchan pointer"));
+ sq->sq_lock = lock;
+#endif
+#ifdef SLEEPQUEUE_PROFILING
+ sc->sc_depth++;
+ if (sc->sc_depth > sc->sc_max_depth) {
+ sc->sc_max_depth = sc->sc_depth;
+ if (sc->sc_max_depth > sleepq_max_depth)
+ sleepq_max_depth = sc->sc_max_depth;
+ }
+#endif
+ sq = td->td_sleepqueue;
+ LIST_INSERT_HEAD(&sc->sc_queues, sq, sq_hash);
+ sq->sq_wchan = wchan;
+ sq->sq_type = flags & SLEEPQ_TYPE;
+ } else {
+ MPASS(wchan == sq->sq_wchan);
+ MPASS(lock == sq->sq_lock);
+ MPASS((flags & SLEEPQ_TYPE) == sq->sq_type);
+ LIST_INSERT_HEAD(&sq->sq_free, td->td_sleepqueue, sq_hash);
+ }
+ thread_lock(td);
+ TAILQ_INSERT_TAIL(&sq->sq_blocked[queue], td, td_slpq);
+ sq->sq_blockedcnt[queue]++;
+ td->td_sleepqueue = NULL;
+ td->td_sqqueue = queue;
+ td->td_wchan = wchan;
+ td->td_wmesg = wmesg;
+ if (flags & SLEEPQ_INTERRUPTIBLE) {
+ td->td_flags |= TDF_SINTR;
+ td->td_flags &= ~TDF_SLEEPABORT;
+ }
+ thread_unlock(td);
+}
+
+/*
+ * Sets a timeout that will remove the current thread from the specified
+ * sleep queue after timo ticks if the thread has not already been awakened.
+ */
+void
+sleepq_set_timeout(void *wchan, int timo)
+{
+ struct sleepqueue_chain *sc;
+ struct thread *td;
+
+ td = curthread;
+ sc = SC_LOOKUP(wchan);
+ mtx_assert(&sc->sc_lock, MA_OWNED);
+ MPASS(TD_ON_SLEEPQ(td));
+ MPASS(td->td_sleepqueue == NULL);
+ MPASS(wchan != NULL);
+ callout_reset_curcpu(&td->td_slpcallout, timo, sleepq_timeout, td);
+}
+
+/*
+ * Return the number of actual sleepers for the specified queue.
+ */
+u_int
+sleepq_sleepcnt(void *wchan, int queue)
+{
+ struct sleepqueue *sq;
+
+ KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
+ MPASS((queue >= 0) && (queue < NR_SLEEPQS));
+ sq = sleepq_lookup(wchan);
+ if (sq == NULL)
+ return (0);
+ return (sq->sq_blockedcnt[queue]);
+}
+
+/*
+ * Marks the pending sleep of the current thread as interruptible and
+ * makes an initial check for pending signals before putting a thread
+ * to sleep. Enters and exits with the thread lock held. Thread lock
+ * may have transitioned from the sleepq lock to a run lock.
+ */
+static int
+sleepq_catch_signals(void *wchan, int pri)
+{
+ struct sleepqueue_chain *sc;
+ struct sleepqueue *sq;
+ struct thread *td;
+ struct proc *p;
+ struct sigacts *ps;
+ int sig, ret, stop_allowed;
+
+ td = curthread;
+ p = curproc;
+ sc = SC_LOOKUP(wchan);
+ mtx_assert(&sc->sc_lock, MA_OWNED);
+ MPASS(wchan != NULL);
+ if ((td->td_pflags & TDP_WAKEUP) != 0) {
+ td->td_pflags &= ~TDP_WAKEUP;
+ ret = EINTR;
+ thread_lock(td);
+ goto out;
+ }
+
+ /*
+ * See if there are any pending signals for this thread. If not
+ * we can switch immediately. Otherwise do the signal processing
+ * directly.
+ */
+ thread_lock(td);
+ if ((td->td_flags & (TDF_NEEDSIGCHK | TDF_NEEDSUSPCHK)) == 0) {
+ sleepq_switch(wchan, pri);
+ return (0);
+ }
+ stop_allowed = (td->td_flags & TDF_SBDRY) ? SIG_STOP_NOT_ALLOWED :
+ SIG_STOP_ALLOWED;
+ thread_unlock(td);
+ mtx_unlock_spin(&sc->sc_lock);
+ CTR3(KTR_PROC, "sleepq catching signals: thread %p (pid %ld, %s)",
+ (void *)td, (long)p->p_pid, td->td_name);
+ PROC_LOCK(p);
+ ps = p->p_sigacts;
+ mtx_lock(&ps->ps_mtx);
+ sig = cursig(td, stop_allowed);
+ if (sig == 0) {
+ mtx_unlock(&ps->ps_mtx);
+ ret = thread_suspend_check(1);
+ MPASS(ret == 0 || ret == EINTR || ret == ERESTART);
+ } else {
+ if (SIGISMEMBER(ps->ps_sigintr, sig))
+ ret = EINTR;
+ else
+ ret = ERESTART;
+ mtx_unlock(&ps->ps_mtx);
+ }
+ /*
+ * Lock the per-process spinlock prior to dropping the PROC_LOCK
+ * to avoid a signal delivery race. PROC_LOCK, PROC_SLOCK, and
+ * thread_lock() are currently held in tdsendsignal().
+ */
+ PROC_SLOCK(p);
+ mtx_lock_spin(&sc->sc_lock);
+ PROC_UNLOCK(p);
+ thread_lock(td);
+ PROC_SUNLOCK(p);
+ if (ret == 0) {
+ sleepq_switch(wchan, pri);
+ return (0);
+ }
+out:
+ /*
+ * There were pending signals and this thread is still
+ * on the sleep queue, remove it from the sleep queue.
+ */
+ if (TD_ON_SLEEPQ(td)) {
+ sq = sleepq_lookup(wchan);
+ if (sleepq_resume_thread(sq, td, 0)) {
+#ifdef INVARIANTS
+ /*
+ * This thread hasn't gone to sleep yet, so it
+ * should not be swapped out.
+ */
+ panic("not waking up swapper");
+#endif
+ }
+ }
+ mtx_unlock_spin(&sc->sc_lock);
+ MPASS(td->td_lock != &sc->sc_lock);
+ return (ret);
+}
+
+/*
+ * Switches to another thread if we are still asleep on a sleep queue.
+ * Returns with thread lock.
+ */
+static void
+sleepq_switch(void *wchan, int pri)
+{
+ struct sleepqueue_chain *sc;
+ struct sleepqueue *sq;
+ struct thread *td;
+
+ td = curthread;
+ sc = SC_LOOKUP(wchan);
+ mtx_assert(&sc->sc_lock, MA_OWNED);
+ THREAD_LOCK_ASSERT(td, MA_OWNED);
+
+ /*
+ * If we have a sleep queue, then we've already been woken up, so
+ * just return.
+ */
+ if (td->td_sleepqueue != NULL) {
+ mtx_unlock_spin(&sc->sc_lock);
+ return;
+ }
+
+ /*
+ * If TDF_TIMEOUT is set, then our sleep has been timed out
+ * already but we are still on the sleep queue, so dequeue the
+ * thread and return.
+ */
+ if (td->td_flags & TDF_TIMEOUT) {
+ MPASS(TD_ON_SLEEPQ(td));
+ sq = sleepq_lookup(wchan);
+ if (sleepq_resume_thread(sq, td, 0)) {
+#ifdef INVARIANTS
+ /*
+ * This thread hasn't gone to sleep yet, so it
+ * should not be swapped out.
+ */
+ panic("not waking up swapper");
+#endif
+ }
+ mtx_unlock_spin(&sc->sc_lock);
+ return;
+ }
+#ifdef SLEEPQUEUE_PROFILING
+ if (prof_enabled)
+ sleepq_profile(td->td_wmesg);
+#endif
+ MPASS(td->td_sleepqueue == NULL);
+ sched_sleep(td, pri);
+ thread_lock_set(td, &sc->sc_lock);
+ SDT_PROBE0(sched, , , sleep);
+ TD_SET_SLEEPING(td);
+ mi_switch(SW_VOL | SWT_SLEEPQ, NULL);
+ KASSERT(TD_IS_RUNNING(td), ("running but not TDS_RUNNING"));
+ CTR3(KTR_PROC, "sleepq resume: thread %p (pid %ld, %s)",
+ (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
+}
+
+/*
+ * Check to see if we timed out.
+ */
+static int
+sleepq_check_timeout(void)
+{
+ struct thread *td;
+
+ td = curthread;
+ THREAD_LOCK_ASSERT(td, MA_OWNED);
+
+ /*
+ * If TDF_TIMEOUT is set, we timed out.
+ */
+ if (td->td_flags & TDF_TIMEOUT) {
+ td->td_flags &= ~TDF_TIMEOUT;
+ return (EWOULDBLOCK);
+ }
+
+ /*
+ * If TDF_TIMOFAIL is set, the timeout ran after we had
+ * already been woken up.
+ */
+ if (td->td_flags & TDF_TIMOFAIL)
+ td->td_flags &= ~TDF_TIMOFAIL;
+
+ /*
+ * If callout_stop() fails, then the timeout is running on
+ * another CPU, so synchronize with it to avoid having it
+ * accidentally wake up a subsequent sleep.
+ */
+ else if (callout_stop(&td->td_slpcallout) == 0) {
+ td->td_flags |= TDF_TIMEOUT;
+ TD_SET_SLEEPING(td);
+ mi_switch(SW_INVOL | SWT_SLEEPQTIMO, NULL);
+ }
+ return (0);
+}
+
+/*
+ * Check to see if we were awoken by a signal.
+ */
+static int
+sleepq_check_signals(void)
+{
+ struct thread *td;
+
+ td = curthread;
+ THREAD_LOCK_ASSERT(td, MA_OWNED);
+
+ /* We are no longer in an interruptible sleep. */
+ if (td->td_flags & TDF_SINTR)
+ td->td_flags &= ~TDF_SINTR;
+
+ if (td->td_flags & TDF_SLEEPABORT) {
+ td->td_flags &= ~TDF_SLEEPABORT;
+ return (td->td_intrval);
+ }
+
+ return (0);
+}
+
+/*
+ * Block the current thread until it is awakened from its sleep queue.
+ */
+void
+sleepq_wait(void *wchan, int pri)
+{
+ struct thread *td;
+
+ td = curthread;
+ MPASS(!(td->td_flags & TDF_SINTR));
+ thread_lock(td);
+ sleepq_switch(wchan, pri);
+ thread_unlock(td);
+}
+
+/*
+ * Block the current thread until it is awakened from its sleep queue
+ * or it is interrupted by a signal.
+ */
+int
+sleepq_wait_sig(void *wchan, int pri)
+{
+ int rcatch;
+ int rval;
+
+ rcatch = sleepq_catch_signals(wchan, pri);
+ rval = sleepq_check_signals();
+ thread_unlock(curthread);
+ if (rcatch)
+ return (rcatch);
+ return (rval);
+}
+
+/*
+ * Block the current thread until it is awakened from its sleep queue
+ * or it times out while waiting.
+ */
+int
+sleepq_timedwait(void *wchan, int pri)
+{
+ struct thread *td;
+ int rval;
+
+ td = curthread;
+ MPASS(!(td->td_flags & TDF_SINTR));
+ thread_lock(td);
+ sleepq_switch(wchan, pri);
+ rval = sleepq_check_timeout();
+ thread_unlock(td);
+
+ return (rval);
+}
+
+/*
+ * Block the current thread until it is awakened from its sleep queue,
+ * it is interrupted by a signal, or it times out waiting to be awakened.
+ */
+int
+sleepq_timedwait_sig(void *wchan, int pri)
+{
+ int rcatch, rvalt, rvals;
+
+ rcatch = sleepq_catch_signals(wchan, pri);
+ rvalt = sleepq_check_timeout();
+ rvals = sleepq_check_signals();
+ thread_unlock(curthread);
+ if (rcatch)
+ return (rcatch);
+ if (rvals)
+ return (rvals);
+ return (rvalt);
+}
+
+/*
+ * Returns the type of sleepqueue given a waitchannel.
+ */
+int
+sleepq_type(void *wchan)
+{
+ struct sleepqueue *sq;
+ int type;
+
+ MPASS(wchan != NULL);
+
+ sleepq_lock(wchan);
+ sq = sleepq_lookup(wchan);
+ if (sq == NULL) {
+ sleepq_release(wchan);
+ return (-1);
+ }
+ type = sq->sq_type;
+ sleepq_release(wchan);
+ return (type);
+}
+
+/*
+ * Removes a thread from a sleep queue and makes it
+ * runnable.
+ */
+static int
+sleepq_resume_thread(struct sleepqueue *sq, struct thread *td, int pri)
+{
+ struct sleepqueue_chain *sc;
+
+ MPASS(td != NULL);
+ MPASS(sq->sq_wchan != NULL);
+ MPASS(td->td_wchan == sq->sq_wchan);
+ MPASS(td->td_sqqueue < NR_SLEEPQS && td->td_sqqueue >= 0);
+ THREAD_LOCK_ASSERT(td, MA_OWNED);
+ sc = SC_LOOKUP(sq->sq_wchan);
+ mtx_assert(&sc->sc_lock, MA_OWNED);
+
+ SDT_PROBE2(sched, , , wakeup, td, td->td_proc);
+
+ /* Remove the thread from the queue. */
+ sq->sq_blockedcnt[td->td_sqqueue]--;
+ TAILQ_REMOVE(&sq->sq_blocked[td->td_sqqueue], td, td_slpq);
+
+ /*
+ * Get a sleep queue for this thread. If this is the last waiter,
+ * use the queue itself and take it out of the chain, otherwise,
+ * remove a queue from the free list.
+ */
+ if (LIST_EMPTY(&sq->sq_free)) {
+ td->td_sleepqueue = sq;
+#ifdef INVARIANTS
+ sq->sq_wchan = NULL;
+#endif
+#ifdef SLEEPQUEUE_PROFILING
+ sc->sc_depth--;
+#endif
+ } else
+ td->td_sleepqueue = LIST_FIRST(&sq->sq_free);
+ LIST_REMOVE(td->td_sleepqueue, sq_hash);
+
+ td->td_wmesg = NULL;
+ td->td_wchan = NULL;
+ td->td_flags &= ~TDF_SINTR;
+
+ CTR3(KTR_PROC, "sleepq_wakeup: thread %p (pid %ld, %s)",
+ (void *)td, (long)td->td_proc->p_pid, td->td_name);
+
+ /* Adjust priority if requested. */
+ MPASS(pri == 0 || (pri >= PRI_MIN && pri <= PRI_MAX));
+ if (pri != 0 && td->td_priority > pri &&
+ PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
+ sched_prio(td, pri);
+
+ /*
+ * Note that thread td might not be sleeping if it is running
+ * sleepq_catch_signals() on another CPU or is blocked on its
+ * proc lock to check signals. There's no need to mark the
+ * thread runnable in that case.
+ */
+ if (TD_IS_SLEEPING(td)) {
+ TD_CLR_SLEEPING(td);
+ return (setrunnable(td));
+ }
+ return (0);
+}
+
+#ifdef INVARIANTS
+/*
+ * UMA zone item deallocator.
+ */
+static void
+sleepq_dtor(void *mem, int size, void *arg)
+{
+ struct sleepqueue *sq;
+ int i;
+
+ sq = mem;
+ for (i = 0; i < NR_SLEEPQS; i++) {
+ MPASS(TAILQ_EMPTY(&sq->sq_blocked[i]));
+ MPASS(sq->sq_blockedcnt[i] == 0);
+ }
+}
+#endif
+
+/*
+ * UMA zone item initializer.
+ */
+static int
+sleepq_init(void *mem, int size, int flags)
+{
+ struct sleepqueue *sq;
+ int i;
+
+ bzero(mem, size);
+ sq = mem;
+ for (i = 0; i < NR_SLEEPQS; i++) {
+ TAILQ_INIT(&sq->sq_blocked[i]);
+ sq->sq_blockedcnt[i] = 0;
+ }
+ LIST_INIT(&sq->sq_free);
+ return (0);
+}
+
+/*
+ * Find the highest priority thread sleeping on a wait channel and resume it.
+ */
+int
+sleepq_signal(void *wchan, int flags, int pri, int queue)
+{
+ struct sleepqueue *sq;
+ struct thread *td, *besttd;
+ int wakeup_swapper;
+
+ CTR2(KTR_PROC, "sleepq_signal(%p, %d)", wchan, flags);
+ KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
+ MPASS((queue >= 0) && (queue < NR_SLEEPQS));
+ sq = sleepq_lookup(wchan);
+ if (sq == NULL)
+ return (0);
+ KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE),
+ ("%s: mismatch between sleep/wakeup and cv_*", __func__));
+
+ /*
+ * Find the highest priority thread on the queue. If there is a
+ * tie, use the thread that first appears in the queue as it has
+ * been sleeping the longest since threads are always added to
+ * the tail of sleep queues.
+ */
+ besttd = NULL;
+ TAILQ_FOREACH(td, &sq->sq_blocked[queue], td_slpq) {
+ if (besttd == NULL || td->td_priority < besttd->td_priority)
+ besttd = td;
+ }
+ MPASS(besttd != NULL);
+ thread_lock(besttd);
+ wakeup_swapper = sleepq_resume_thread(sq, besttd, pri);
+ thread_unlock(besttd);
+ return (wakeup_swapper);
+}
+
+/*
+ * Resume all threads sleeping on a specified wait channel.
+ */
+int
+sleepq_broadcast(void *wchan, int flags, int pri, int queue)
+{
+ struct sleepqueue *sq;
+ struct thread *td, *tdn;
+ int wakeup_swapper;
+
+ CTR2(KTR_PROC, "sleepq_broadcast(%p, %d)", wchan, flags);
+ KASSERT(wchan != NULL, ("%s: invalid NULL wait channel", __func__));
+ MPASS((queue >= 0) && (queue < NR_SLEEPQS));
+ sq = sleepq_lookup(wchan);
+ if (sq == NULL)
+ return (0);
+ KASSERT(sq->sq_type == (flags & SLEEPQ_TYPE),
+ ("%s: mismatch between sleep/wakeup and cv_*", __func__));
+
+ /* Resume all blocked threads on the sleep queue. */
+ wakeup_swapper = 0;
+ TAILQ_FOREACH_SAFE(td, &sq->sq_blocked[queue], td_slpq, tdn) {
+ thread_lock(td);
+ if (sleepq_resume_thread(sq, td, pri))
+ wakeup_swapper = 1;
+ thread_unlock(td);
+ }
+ return (wakeup_swapper);
+}
+
+/*
+ * Time sleeping threads out. When the timeout expires, the thread is
+ * removed from the sleep queue and made runnable if it is still asleep.
+ */
+static void
+sleepq_timeout(void *arg)
+{
+ struct sleepqueue_chain *sc;
+ struct sleepqueue *sq;
+ struct thread *td;
+ void *wchan;
+ int wakeup_swapper;
+
+ td = arg;
+ wakeup_swapper = 0;
+ CTR3(KTR_PROC, "sleepq_timeout: thread %p (pid %ld, %s)",
+ (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
+
+ /*
+ * First, see if the thread is asleep and get the wait channel if
+ * it is.
+ */
+ thread_lock(td);
+ if (TD_IS_SLEEPING(td) && TD_ON_SLEEPQ(td)) {
+ wchan = td->td_wchan;
+ sc = SC_LOOKUP(wchan);
+ THREAD_LOCKPTR_ASSERT(td, &sc->sc_lock);
+ sq = sleepq_lookup(wchan);
+ MPASS(sq != NULL);
+ td->td_flags |= TDF_TIMEOUT;
+ wakeup_swapper = sleepq_resume_thread(sq, td, 0);
+ thread_unlock(td);
+ if (wakeup_swapper)
+ kick_proc0();
+ return;
+ }
+
+ /*
+ * If the thread is on the SLEEPQ but isn't sleeping yet, it
+ * can either be on another CPU in between sleepq_add() and
+ * one of the sleepq_*wait*() routines or it can be in
+ * sleepq_catch_signals().
+ */
+ if (TD_ON_SLEEPQ(td)) {
+ td->td_flags |= TDF_TIMEOUT;
+ thread_unlock(td);
+ return;
+ }
+
+ /*
+ * Now check for the edge cases. First, if TDF_TIMEOUT is set,
+ * then the other thread has already yielded to us, so clear
+ * the flag and resume it. If TDF_TIMEOUT is not set, then the
+ * we know that the other thread is not on a sleep queue, but it
+ * hasn't resumed execution yet. In that case, set TDF_TIMOFAIL
+ * to let it know that the timeout has already run and doesn't
+ * need to be canceled.
+ */
+ if (td->td_flags & TDF_TIMEOUT) {
+ MPASS(TD_IS_SLEEPING(td));
+ td->td_flags &= ~TDF_TIMEOUT;
+ TD_CLR_SLEEPING(td);
+ wakeup_swapper = setrunnable(td);
+ } else
+ td->td_flags |= TDF_TIMOFAIL;
+ thread_unlock(td);
+ if (wakeup_swapper)
+ kick_proc0();
+}
+
+/*
+ * Resumes a specific thread from the sleep queue associated with a specific
+ * wait channel if it is on that queue.
+ */
+void
+sleepq_remove(struct thread *td, void *wchan)
+{
+ struct sleepqueue *sq;
+ int wakeup_swapper;
+
+ /*
+ * Look up the sleep queue for this wait channel, then re-check
+ * that the thread is asleep on that channel, if it is not, then
+ * bail.
+ */
+ MPASS(wchan != NULL);
+ sleepq_lock(wchan);
+ sq = sleepq_lookup(wchan);
+ /*
+ * We can not lock the thread here as it may be sleeping on a
+ * different sleepq. However, holding the sleepq lock for this
+ * wchan can guarantee that we do not miss a wakeup for this
+ * channel. The asserts below will catch any false positives.
+ */
+ if (!TD_ON_SLEEPQ(td) || td->td_wchan != wchan) {
+ sleepq_release(wchan);
+ return;
+ }
+ /* Thread is asleep on sleep queue sq, so wake it up. */
+ thread_lock(td);
+ MPASS(sq != NULL);
+ MPASS(td->td_wchan == wchan);
+ wakeup_swapper = sleepq_resume_thread(sq, td, 0);
+ thread_unlock(td);
+ sleepq_release(wchan);
+ if (wakeup_swapper)
+ kick_proc0();
+}
+
+/*
+ * Abort a thread as if an interrupt had occurred. Only abort
+ * interruptible waits (unfortunately it isn't safe to abort others).
+ */
+int
+sleepq_abort(struct thread *td, int intrval)
+{
+ struct sleepqueue *sq;
+ void *wchan;
+
+ THREAD_LOCK_ASSERT(td, MA_OWNED);
+ MPASS(TD_ON_SLEEPQ(td));
+ MPASS(td->td_flags & TDF_SINTR);
+ MPASS(intrval == EINTR || intrval == ERESTART);
+
+ /*
+ * If the TDF_TIMEOUT flag is set, just leave. A
+ * timeout is scheduled anyhow.
+ */
+ if (td->td_flags & TDF_TIMEOUT)
+ return (0);
+
+ CTR3(KTR_PROC, "sleepq_abort: thread %p (pid %ld, %s)",
+ (void *)td, (long)td->td_proc->p_pid, (void *)td->td_name);
+ td->td_intrval = intrval;
+ td->td_flags |= TDF_SLEEPABORT;
+ /*
+ * If the thread has not slept yet it will find the signal in
+ * sleepq_catch_signals() and call sleepq_resume_thread. Otherwise
+ * we have to do it here.
+ */
+ if (!TD_IS_SLEEPING(td))
+ return (0);
+ wchan = td->td_wchan;
+ MPASS(wchan != NULL);
+ sq = sleepq_lookup(wchan);
+ MPASS(sq != NULL);
+
+ /* Thread is asleep on sleep queue sq, so wake it up. */
+ return (sleepq_resume_thread(sq, td, 0));
+}
+
+#ifdef SLEEPQUEUE_PROFILING
+#define SLEEPQ_PROF_LOCATIONS 1024
+#define SLEEPQ_SBUFSIZE 512
+struct sleepq_prof {
+ LIST_ENTRY(sleepq_prof) sp_link;
+ const char *sp_wmesg;
+ long sp_count;
+};
+
+LIST_HEAD(sqphead, sleepq_prof);
+
+struct sqphead sleepq_prof_free;
+struct sqphead sleepq_hash[SC_TABLESIZE];
+static struct sleepq_prof sleepq_profent[SLEEPQ_PROF_LOCATIONS];
+static struct mtx sleepq_prof_lock;
+MTX_SYSINIT(sleepq_prof_lock, &sleepq_prof_lock, "sleepq_prof", MTX_SPIN);
+
+static void
+sleepq_profile(const char *wmesg)
+{
+ struct sleepq_prof *sp;
+
+ mtx_lock_spin(&sleepq_prof_lock);
+ if (prof_enabled == 0)
+ goto unlock;
+ LIST_FOREACH(sp, &sleepq_hash[SC_HASH(wmesg)], sp_link)
+ if (sp->sp_wmesg == wmesg)
+ goto done;
+ sp = LIST_FIRST(&sleepq_prof_free);
+ if (sp == NULL)
+ goto unlock;
+ sp->sp_wmesg = wmesg;
+ LIST_REMOVE(sp, sp_link);
+ LIST_INSERT_HEAD(&sleepq_hash[SC_HASH(wmesg)], sp, sp_link);
+done:
+ sp->sp_count++;
+unlock:
+ mtx_unlock_spin(&sleepq_prof_lock);
+ return;
+}
+
+static void
+sleepq_prof_reset(void)
+{
+ struct sleepq_prof *sp;
+ int enabled;
+ int i;
+
+ mtx_lock_spin(&sleepq_prof_lock);
+ enabled = prof_enabled;
+ prof_enabled = 0;
+ for (i = 0; i < SC_TABLESIZE; i++)
+ LIST_INIT(&sleepq_hash[i]);
+ LIST_INIT(&sleepq_prof_free);
+ for (i = 0; i < SLEEPQ_PROF_LOCATIONS; i++) {
+ sp = &sleepq_profent[i];
+ sp->sp_wmesg = NULL;
+ sp->sp_count = 0;
+ LIST_INSERT_HEAD(&sleepq_prof_free, sp, sp_link);
+ }
+ prof_enabled = enabled;
+ mtx_unlock_spin(&sleepq_prof_lock);
+}
+
+static int
+enable_sleepq_prof(SYSCTL_HANDLER_ARGS)
+{
+ int error, v;
+
+ v = prof_enabled;
+ error = sysctl_handle_int(oidp, &v, v, req);
+ if (error)
+ return (error);
+ if (req->newptr == NULL)
+ return (error);
+ if (v == prof_enabled)
+ return (0);
+ if (v == 1)
+ sleepq_prof_reset();
+ mtx_lock_spin(&sleepq_prof_lock);
+ prof_enabled = !!v;
+ mtx_unlock_spin(&sleepq_prof_lock);
+
+ return (0);
+}
+
+static int
+reset_sleepq_prof_stats(SYSCTL_HANDLER_ARGS)
+{
+ int error, v;
+
+ v = 0;
+ error = sysctl_handle_int(oidp, &v, 0, req);
+ if (error)
+ return (error);
+ if (req->newptr == NULL)
+ return (error);
+ if (v == 0)
+ return (0);
+ sleepq_prof_reset();
+
+ return (0);
+}
+
+static int
+dump_sleepq_prof_stats(SYSCTL_HANDLER_ARGS)
+{
+ struct sleepq_prof *sp;
+ struct sbuf *sb;
+ int enabled;
+ int error;
+ int i;
+
+ error = sysctl_wire_old_buffer(req, 0);
+ if (error != 0)
+ return (error);
+ sb = sbuf_new_for_sysctl(NULL, NULL, SLEEPQ_SBUFSIZE, req);
+ sbuf_printf(sb, "\nwmesg\tcount\n");
+ enabled = prof_enabled;
+ mtx_lock_spin(&sleepq_prof_lock);
+ prof_enabled = 0;
+ mtx_unlock_spin(&sleepq_prof_lock);
+ for (i = 0; i < SC_TABLESIZE; i++) {
+ LIST_FOREACH(sp, &sleepq_hash[i], sp_link) {
+ sbuf_printf(sb, "%s\t%ld\n",
+ sp->sp_wmesg, sp->sp_count);
+ }
+ }
+ mtx_lock_spin(&sleepq_prof_lock);
+ prof_enabled = enabled;
+ mtx_unlock_spin(&sleepq_prof_lock);
+
+ error = sbuf_finish(sb);
+ sbuf_delete(sb);
+ return (error);
+}
+
+SYSCTL_PROC(_debug_sleepq, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
+ NULL, 0, dump_sleepq_prof_stats, "A", "Sleepqueue profiling statistics");
+SYSCTL_PROC(_debug_sleepq, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
+ NULL, 0, reset_sleepq_prof_stats, "I",
+ "Reset sleepqueue profiling statistics");
+SYSCTL_PROC(_debug_sleepq, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
+ NULL, 0, enable_sleepq_prof, "I", "Enable sleepqueue profiling");
+#endif
+
+#ifdef DDB
+DB_SHOW_COMMAND(sleepq, db_show_sleepqueue)
+{
+ struct sleepqueue_chain *sc;
+ struct sleepqueue *sq;
+#ifdef INVARIANTS
+ struct lock_object *lock;
+#endif
+ struct thread *td;
+ void *wchan;
+ int i;
+
+ if (!have_addr)
+ return;
+
+ /*
+ * First, see if there is an active sleep queue for the wait channel
+ * indicated by the address.
+ */
+ wchan = (void *)addr;
+ sc = SC_LOOKUP(wchan);
+ LIST_FOREACH(sq, &sc->sc_queues, sq_hash)
+ if (sq->sq_wchan == wchan)
+ goto found;
+
+ /*
+ * Second, see if there is an active sleep queue at the address
+ * indicated.
+ */
+ for (i = 0; i < SC_TABLESIZE; i++)
+ LIST_FOREACH(sq, &sleepq_chains[i].sc_queues, sq_hash) {
+ if (sq == (struct sleepqueue *)addr)
+ goto found;
+ }
+
+ db_printf("Unable to locate a sleep queue via %p\n", (void *)addr);
+ return;
+found:
+ db_printf("Wait channel: %p\n", sq->sq_wchan);
+ db_printf("Queue type: %d\n", sq->sq_type);
+#ifdef INVARIANTS
+ if (sq->sq_lock) {
+ lock = sq->sq_lock;
+ db_printf("Associated Interlock: %p - (%s) %s\n", lock,
+ LOCK_CLASS(lock)->lc_name, lock->lo_name);
+ }
+#endif
+ db_printf("Blocked threads:\n");
+ for (i = 0; i < NR_SLEEPQS; i++) {
+ db_printf("\nQueue[%d]:\n", i);
+ if (TAILQ_EMPTY(&sq->sq_blocked[i]))
+ db_printf("\tempty\n");
+ else
+ TAILQ_FOREACH(td, &sq->sq_blocked[0],
+ td_slpq) {
+ db_printf("\t%p (tid %d, pid %d, \"%s\")\n", td,
+ td->td_tid, td->td_proc->p_pid,
+ td->td_name);
+ }
+ db_printf("(expected: %u)\n", sq->sq_blockedcnt[i]);
+ }
+}
+
+/* Alias 'show sleepqueue' to 'show sleepq'. */
+DB_SHOW_ALIAS(sleepqueue, db_show_sleepqueue);
+#endif
diff --git a/freebsd/sys/sys/sleepqueue.h b/freebsd/sys/sys/sleepqueue.h
new file mode 100644
index 0000000..ddec147
--- /dev/null
+++ b/freebsd/sys/sys/sleepqueue.h
@@ -0,0 +1,117 @@
+/*-
+ * Copyright (c) 2004 John Baldwin <jhb at 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _SYS_SLEEPQUEUE_H_
+#define _SYS_SLEEPQUEUE_H_
+
+/*
+ * Sleep queue interface. Sleep/wakeup, condition variables, and sx
+ * locks use a sleep queue for the queue of threads blocked on a sleep
+ * channel.
+ *
+ * A thread calls sleepq_lock() to lock the sleep queue chain associated
+ * with a given wait channel. A thread can then call call sleepq_add() to
+ * add themself onto a sleep queue and call one of the sleepq_wait()
+ * functions to actually go to sleep. If a thread needs to abort a sleep
+ * operation it should call sleepq_release() to unlock the associated sleep
+ * queue chain lock. If the thread also needs to remove itself from a queue
+ * it just enqueued itself on, it can use sleepq_remove() instead.
+ *
+ * If the thread only wishes to sleep for a limited amount of time, it can
+ * call sleepq_set_timeout() after sleepq_add() to setup a timeout. It
+ * should then use one of the sleepq_timedwait() functions to block.
+ *
+ * If the thread wants the sleep to be interruptible by signals, it can
+ * call sleepq_catch_signals() after sleepq_add(). It should then use
+ * one of the sleepq_wait_sig() functions to block. After the thread has
+ * been resumed, it should call sleepq_calc_signal_retval() to determine
+ * if it should return EINTR or ERESTART passing in the value returned from
+ * the earlier call to sleepq_catch_signals().
+ *
+ * A thread is normally resumed from a sleep queue by either the
+ * sleepq_signal() or sleepq_broadcast() functions. Sleepq_signal() wakes
+ * the thread with the highest priority that is sleeping on the specified
+ * wait channel. Sleepq_broadcast() wakes all threads that are sleeping
+ * on the specified wait channel. A thread sleeping in an interruptible
+ * sleep can be interrupted by calling sleepq_abort(). A thread can also
+ * be removed from a specified sleep queue using the sleepq_remove()
+ * function. Note that the sleep queue chain must first be locked via
+ * sleepq_lock() before calling sleepq_abort(), sleepq_broadcast(), or
+ * sleepq_signal(). These routines each return a boolean that will be true
+ * if at least one swapped-out thread was resumed. In that case, the caller
+ * is responsible for waking up the swapper by calling kick_proc0() after
+ * releasing the sleep queue chain lock.
+ *
+ * Each thread allocates a sleep queue at thread creation via sleepq_alloc()
+ * and releases it at thread destruction via sleepq_free(). Note that
+ * a sleep queue is not tied to a specific thread and that the sleep queue
+ * released at thread destruction may not be the same sleep queue that the
+ * thread allocated when it was created.
+ *
+ * XXX: Some other parts of the kernel such as ithread sleeping may end up
+ * using this interface as well (death to TDI_IWAIT!)
+ */
+
+struct lock_object;
+struct sleepqueue;
+struct thread;
+
+#ifdef _KERNEL
+
+#define SLEEPQ_TYPE 0x0ff /* Mask of sleep queue types. */
+#define SLEEPQ_SLEEP 0x00 /* Used by sleep/wakeup. */
+#define SLEEPQ_CONDVAR 0x01 /* Used for a cv. */
+#define SLEEPQ_PAUSE 0x02 /* Used by pause. */
+#define SLEEPQ_SX 0x03 /* Used by an sx lock. */
+#define SLEEPQ_LK 0x04 /* Used by a lockmgr. */
+#define SLEEPQ_INTERRUPTIBLE 0x100 /* Sleep is interruptible. */
+#define SLEEPQ_STOP_ON_BDRY 0x200 /* Stop sleeping thread on
+ user mode boundary */
+
+void init_sleepqueues(void);
+int sleepq_abort(struct thread *td, int intrval);
+void sleepq_add(void *wchan, struct lock_object *lock, const char *wmesg,
+ int flags, int queue);
+struct sleepqueue *sleepq_alloc(void);
+int sleepq_broadcast(void *wchan, int flags, int pri, int queue);
+void sleepq_free(struct sleepqueue *sq);
+void sleepq_lock(void *wchan);
+struct sleepqueue *sleepq_lookup(void *wchan);
+void sleepq_release(void *wchan);
+void sleepq_remove(struct thread *td, void *wchan);
+int sleepq_signal(void *wchan, int flags, int pri, int queue);
+void sleepq_set_timeout(void *wchan, int timo);
+u_int sleepq_sleepcnt(void *wchan, int queue);
+int sleepq_timedwait(void *wchan, int pri);
+int sleepq_timedwait_sig(void *wchan, int pri);
+int sleepq_type(void *wchan);
+void sleepq_wait(void *wchan, int pri);
+int sleepq_wait_sig(void *wchan, int pri);
+
+#endif /* _KERNEL */
+#endif /* !_SYS_SLEEPQUEUE_H_ */
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