From 9975839a123ff5c5891760841b8622fb471fa3d4 Mon Sep 17 00:00:00 2001 From: Sebastian Huber Date: Tue, 24 Mar 2015 10:02:31 +0100 Subject: SLEEPQUEUE(9): Import from FreeBSD --- freebsd/sys/kern/subr_sleepqueue.c | 1236 ++++++++++++++++++++++++++++++++++++ freebsd/sys/sys/sleepqueue.h | 117 ++++ 2 files changed, 1353 insertions(+) create mode 100644 freebsd/sys/kern/subr_sleepqueue.c create mode 100644 freebsd/sys/sys/sleepqueue.h (limited to 'freebsd') diff --git a/freebsd/sys/kern/subr_sleepqueue.c b/freebsd/sys/kern/subr_sleepqueue.c new file mode 100644 index 00000000..3774e66d --- /dev/null +++ b/freebsd/sys/kern/subr_sleepqueue.c @@ -0,0 +1,1236 @@ +#include + +/*- + * Copyright (c) 2004 John Baldwin + * 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 +__FBSDID("$FreeBSD$"); + +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#ifdef DDB +#include +#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 00000000..ddec1478 --- /dev/null +++ b/freebsd/sys/sys/sleepqueue.h @@ -0,0 +1,117 @@ +/*- + * Copyright (c) 2004 John Baldwin + * 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_ */ -- cgit v1.2.3