Index: head/sys/kern/kern_sx.c =================================================================== --- head/sys/kern/kern_sx.c (revision 313271) +++ head/sys/kern/kern_sx.c (revision 313272) @@ -1,1309 +1,1260 @@ /*- * Copyright (c) 2007 Attilio Rao * Copyright (c) 2001 Jason Evans * 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(s), this list of conditions and the following disclaimer as * the first lines of this file unmodified other than the possible * addition of one or more copyright notices. * 2. Redistributions in binary form must reproduce the above copyright * notice(s), 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 COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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. */ /* * Shared/exclusive locks. This implementation attempts to ensure * deterministic lock granting behavior, so that slocks and xlocks are * interleaved. * * Priority propagation will not generally raise the priority of lock holders, * so should not be relied upon in combination with sx locks. */ #include "opt_ddb.h" #include "opt_hwpmc_hooks.h" #include "opt_no_adaptive_sx.h" #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(SMP) && !defined(NO_ADAPTIVE_SX) #include #endif #ifdef DDB #include #endif #if defined(SMP) && !defined(NO_ADAPTIVE_SX) #define ADAPTIVE_SX #endif CTASSERT((SX_NOADAPTIVE & LO_CLASSFLAGS) == SX_NOADAPTIVE); #ifdef HWPMC_HOOKS #include PMC_SOFT_DECLARE( , , lock, failed); #endif /* Handy macros for sleep queues. */ #define SQ_EXCLUSIVE_QUEUE 0 #define SQ_SHARED_QUEUE 1 /* * Variations on DROP_GIANT()/PICKUP_GIANT() for use in this file. We * drop Giant anytime we have to sleep or if we adaptively spin. */ #define GIANT_DECLARE \ int _giantcnt = 0; \ WITNESS_SAVE_DECL(Giant) \ #define GIANT_SAVE() do { \ if (mtx_owned(&Giant)) { \ WITNESS_SAVE(&Giant.lock_object, Giant); \ while (mtx_owned(&Giant)) { \ _giantcnt++; \ mtx_unlock(&Giant); \ } \ } \ } while (0) #define GIANT_RESTORE() do { \ if (_giantcnt > 0) { \ mtx_assert(&Giant, MA_NOTOWNED); \ while (_giantcnt--) \ mtx_lock(&Giant); \ WITNESS_RESTORE(&Giant.lock_object, Giant); \ } \ } while (0) /* * Returns true if an exclusive lock is recursed. It assumes * curthread currently has an exclusive lock. */ #define sx_recursed(sx) ((sx)->sx_recurse != 0) static void assert_sx(const struct lock_object *lock, int what); #ifdef DDB static void db_show_sx(const struct lock_object *lock); #endif static void lock_sx(struct lock_object *lock, uintptr_t how); #ifdef KDTRACE_HOOKS static int owner_sx(const struct lock_object *lock, struct thread **owner); #endif static uintptr_t unlock_sx(struct lock_object *lock); struct lock_class lock_class_sx = { .lc_name = "sx", .lc_flags = LC_SLEEPLOCK | LC_SLEEPABLE | LC_RECURSABLE | LC_UPGRADABLE, .lc_assert = assert_sx, #ifdef DDB .lc_ddb_show = db_show_sx, #endif .lc_lock = lock_sx, .lc_unlock = unlock_sx, #ifdef KDTRACE_HOOKS .lc_owner = owner_sx, #endif }; #ifndef INVARIANTS #define _sx_assert(sx, what, file, line) #endif #ifdef ADAPTIVE_SX static u_int asx_retries = 10; static u_int asx_loops = 10000; static SYSCTL_NODE(_debug, OID_AUTO, sx, CTLFLAG_RD, NULL, "sxlock debugging"); SYSCTL_UINT(_debug_sx, OID_AUTO, retries, CTLFLAG_RW, &asx_retries, 0, ""); SYSCTL_UINT(_debug_sx, OID_AUTO, loops, CTLFLAG_RW, &asx_loops, 0, ""); static struct lock_delay_config __read_mostly sx_delay = { .initial = 1000, .step = 500, .min = 100, .max = 5000, }; SYSCTL_INT(_debug_sx, OID_AUTO, delay_initial, CTLFLAG_RW, &sx_delay.initial, 0, ""); SYSCTL_INT(_debug_sx, OID_AUTO, delay_step, CTLFLAG_RW, &sx_delay.step, 0, ""); SYSCTL_INT(_debug_sx, OID_AUTO, delay_min, CTLFLAG_RW, &sx_delay.min, 0, ""); SYSCTL_INT(_debug_sx, OID_AUTO, delay_max, CTLFLAG_RW, &sx_delay.max, 0, ""); static void sx_delay_sysinit(void *dummy) { sx_delay.initial = mp_ncpus * 25; sx_delay.step = (mp_ncpus * 25) / 2; sx_delay.min = mp_ncpus * 5; sx_delay.max = mp_ncpus * 25 * 10; } LOCK_DELAY_SYSINIT(sx_delay_sysinit); #endif void assert_sx(const struct lock_object *lock, int what) { sx_assert((const struct sx *)lock, what); } void lock_sx(struct lock_object *lock, uintptr_t how) { struct sx *sx; sx = (struct sx *)lock; if (how) sx_slock(sx); else sx_xlock(sx); } uintptr_t unlock_sx(struct lock_object *lock) { struct sx *sx; sx = (struct sx *)lock; sx_assert(sx, SA_LOCKED | SA_NOTRECURSED); if (sx_xlocked(sx)) { sx_xunlock(sx); return (0); } else { sx_sunlock(sx); return (1); } } #ifdef KDTRACE_HOOKS int owner_sx(const struct lock_object *lock, struct thread **owner) { const struct sx *sx; uintptr_t x; sx = (const struct sx *)lock; x = sx->sx_lock; *owner = NULL; return ((x & SX_LOCK_SHARED) != 0 ? (SX_SHARERS(x) != 0) : ((*owner = (struct thread *)SX_OWNER(x)) != NULL)); } #endif void sx_sysinit(void *arg) { struct sx_args *sargs = arg; sx_init_flags(sargs->sa_sx, sargs->sa_desc, sargs->sa_flags); } void sx_init_flags(struct sx *sx, const char *description, int opts) { int flags; MPASS((opts & ~(SX_QUIET | SX_RECURSE | SX_NOWITNESS | SX_DUPOK | SX_NOPROFILE | SX_NOADAPTIVE | SX_NEW)) == 0); ASSERT_ATOMIC_LOAD_PTR(sx->sx_lock, ("%s: sx_lock not aligned for %s: %p", __func__, description, &sx->sx_lock)); flags = LO_SLEEPABLE | LO_UPGRADABLE; if (opts & SX_DUPOK) flags |= LO_DUPOK; if (opts & SX_NOPROFILE) flags |= LO_NOPROFILE; if (!(opts & SX_NOWITNESS)) flags |= LO_WITNESS; if (opts & SX_RECURSE) flags |= LO_RECURSABLE; if (opts & SX_QUIET) flags |= LO_QUIET; if (opts & SX_NEW) flags |= LO_NEW; flags |= opts & SX_NOADAPTIVE; lock_init(&sx->lock_object, &lock_class_sx, description, NULL, flags); sx->sx_lock = SX_LOCK_UNLOCKED; sx->sx_recurse = 0; } void sx_destroy(struct sx *sx) { KASSERT(sx->sx_lock == SX_LOCK_UNLOCKED, ("sx lock still held")); KASSERT(sx->sx_recurse == 0, ("sx lock still recursed")); sx->sx_lock = SX_LOCK_DESTROYED; lock_destroy(&sx->lock_object); } int -_sx_slock(struct sx *sx, int opts, const char *file, int line) -{ - int error = 0; - - if (SCHEDULER_STOPPED()) - return (0); - KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), - ("sx_slock() by idle thread %p on sx %s @ %s:%d", - curthread, sx->lock_object.lo_name, file, line)); - KASSERT(sx->sx_lock != SX_LOCK_DESTROYED, - ("sx_slock() of destroyed sx @ %s:%d", file, line)); - WITNESS_CHECKORDER(&sx->lock_object, LOP_NEWORDER, file, line, NULL); - error = __sx_slock(sx, opts, file, line); - if (!error) { - LOCK_LOG_LOCK("SLOCK", &sx->lock_object, 0, 0, file, line); - WITNESS_LOCK(&sx->lock_object, 0, file, line); - TD_LOCKS_INC(curthread); - } - - return (error); -} - -int sx_try_slock_(struct sx *sx, const char *file, int line) { uintptr_t x; if (SCHEDULER_STOPPED()) return (1); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), ("sx_try_slock() by idle thread %p on sx %s @ %s:%d", curthread, sx->lock_object.lo_name, file, line)); for (;;) { x = sx->sx_lock; KASSERT(x != SX_LOCK_DESTROYED, ("sx_try_slock() of destroyed sx @ %s:%d", file, line)); if (!(x & SX_LOCK_SHARED)) break; if (atomic_cmpset_acq_ptr(&sx->sx_lock, x, x + SX_ONE_SHARER)) { LOCK_LOG_TRY("SLOCK", &sx->lock_object, 0, 1, file, line); WITNESS_LOCK(&sx->lock_object, LOP_TRYLOCK, file, line); LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(sx__acquire, sx, 0, 0, file, line, LOCKSTAT_READER); TD_LOCKS_INC(curthread); return (1); } } LOCK_LOG_TRY("SLOCK", &sx->lock_object, 0, 0, file, line); return (0); } int _sx_xlock(struct sx *sx, int opts, const char *file, int line) { int error = 0; if (SCHEDULER_STOPPED()) return (0); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), ("sx_xlock() by idle thread %p on sx %s @ %s:%d", curthread, sx->lock_object.lo_name, file, line)); KASSERT(sx->sx_lock != SX_LOCK_DESTROYED, ("sx_xlock() of destroyed sx @ %s:%d", file, line)); WITNESS_CHECKORDER(&sx->lock_object, LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); error = __sx_xlock(sx, curthread, opts, file, line); if (!error) { LOCK_LOG_LOCK("XLOCK", &sx->lock_object, 0, sx->sx_recurse, file, line); WITNESS_LOCK(&sx->lock_object, LOP_EXCLUSIVE, file, line); TD_LOCKS_INC(curthread); } return (error); } int sx_try_xlock_(struct sx *sx, const char *file, int line) { int rval; if (SCHEDULER_STOPPED()) return (1); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), ("sx_try_xlock() by idle thread %p on sx %s @ %s:%d", curthread, sx->lock_object.lo_name, file, line)); KASSERT(sx->sx_lock != SX_LOCK_DESTROYED, ("sx_try_xlock() of destroyed sx @ %s:%d", file, line)); if (sx_xlocked(sx) && (sx->lock_object.lo_flags & LO_RECURSABLE) != 0) { sx->sx_recurse++; atomic_set_ptr(&sx->sx_lock, SX_LOCK_RECURSED); rval = 1; } else rval = atomic_cmpset_acq_ptr(&sx->sx_lock, SX_LOCK_UNLOCKED, (uintptr_t)curthread); LOCK_LOG_TRY("XLOCK", &sx->lock_object, 0, rval, file, line); if (rval) { WITNESS_LOCK(&sx->lock_object, LOP_EXCLUSIVE | LOP_TRYLOCK, file, line); if (!sx_recursed(sx)) LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(sx__acquire, sx, 0, 0, file, line, LOCKSTAT_WRITER); TD_LOCKS_INC(curthread); } return (rval); } void -_sx_sunlock(struct sx *sx, const char *file, int line) -{ - - if (SCHEDULER_STOPPED()) - return; - KASSERT(sx->sx_lock != SX_LOCK_DESTROYED, - ("sx_sunlock() of destroyed sx @ %s:%d", file, line)); - _sx_assert(sx, SA_SLOCKED, file, line); - WITNESS_UNLOCK(&sx->lock_object, 0, file, line); - LOCK_LOG_LOCK("SUNLOCK", &sx->lock_object, 0, 0, file, line); - __sx_sunlock(sx, file, line); - TD_LOCKS_DEC(curthread); -} - -void _sx_xunlock(struct sx *sx, const char *file, int line) { if (SCHEDULER_STOPPED()) return; KASSERT(sx->sx_lock != SX_LOCK_DESTROYED, ("sx_xunlock() of destroyed sx @ %s:%d", file, line)); _sx_assert(sx, SA_XLOCKED, file, line); WITNESS_UNLOCK(&sx->lock_object, LOP_EXCLUSIVE, file, line); LOCK_LOG_LOCK("XUNLOCK", &sx->lock_object, 0, sx->sx_recurse, file, line); __sx_xunlock(sx, curthread, file, line); TD_LOCKS_DEC(curthread); } /* * Try to do a non-blocking upgrade from a shared lock to an exclusive lock. * This will only succeed if this thread holds a single shared lock. * Return 1 if if the upgrade succeed, 0 otherwise. */ int sx_try_upgrade_(struct sx *sx, const char *file, int line) { uintptr_t x; int success; if (SCHEDULER_STOPPED()) return (1); KASSERT(sx->sx_lock != SX_LOCK_DESTROYED, ("sx_try_upgrade() of destroyed sx @ %s:%d", file, line)); _sx_assert(sx, SA_SLOCKED, file, line); /* * Try to switch from one shared lock to an exclusive lock. We need * to maintain the SX_LOCK_EXCLUSIVE_WAITERS flag if set so that * we will wake up the exclusive waiters when we drop the lock. */ x = sx->sx_lock & SX_LOCK_EXCLUSIVE_WAITERS; success = atomic_cmpset_ptr(&sx->sx_lock, SX_SHARERS_LOCK(1) | x, (uintptr_t)curthread | x); LOCK_LOG_TRY("XUPGRADE", &sx->lock_object, 0, success, file, line); if (success) { WITNESS_UPGRADE(&sx->lock_object, LOP_EXCLUSIVE | LOP_TRYLOCK, file, line); LOCKSTAT_RECORD0(sx__upgrade, sx); } return (success); } /* * Downgrade an unrecursed exclusive lock into a single shared lock. */ void sx_downgrade_(struct sx *sx, const char *file, int line) { uintptr_t x; int wakeup_swapper; if (SCHEDULER_STOPPED()) return; KASSERT(sx->sx_lock != SX_LOCK_DESTROYED, ("sx_downgrade() of destroyed sx @ %s:%d", file, line)); _sx_assert(sx, SA_XLOCKED | SA_NOTRECURSED, file, line); #ifndef INVARIANTS if (sx_recursed(sx)) panic("downgrade of a recursed lock"); #endif WITNESS_DOWNGRADE(&sx->lock_object, 0, file, line); /* * Try to switch from an exclusive lock with no shared waiters * to one sharer with no shared waiters. If there are * exclusive waiters, we don't need to lock the sleep queue so * long as we preserve the flag. We do one quick try and if * that fails we grab the sleepq lock to keep the flags from * changing and do it the slow way. * * We have to lock the sleep queue if there are shared waiters * so we can wake them up. */ x = sx->sx_lock; if (!(x & SX_LOCK_SHARED_WAITERS) && atomic_cmpset_rel_ptr(&sx->sx_lock, x, SX_SHARERS_LOCK(1) | (x & SX_LOCK_EXCLUSIVE_WAITERS))) { LOCK_LOG_LOCK("XDOWNGRADE", &sx->lock_object, 0, 0, file, line); return; } /* * Lock the sleep queue so we can read the waiters bits * without any races and wakeup any shared waiters. */ sleepq_lock(&sx->lock_object); /* * Preserve SX_LOCK_EXCLUSIVE_WAITERS while downgraded to a single * shared lock. If there are any shared waiters, wake them up. */ wakeup_swapper = 0; x = sx->sx_lock; atomic_store_rel_ptr(&sx->sx_lock, SX_SHARERS_LOCK(1) | (x & SX_LOCK_EXCLUSIVE_WAITERS)); if (x & SX_LOCK_SHARED_WAITERS) wakeup_swapper = sleepq_broadcast(&sx->lock_object, SLEEPQ_SX, 0, SQ_SHARED_QUEUE); sleepq_release(&sx->lock_object); LOCK_LOG_LOCK("XDOWNGRADE", &sx->lock_object, 0, 0, file, line); LOCKSTAT_RECORD0(sx__downgrade, sx); if (wakeup_swapper) kick_proc0(); } /* * This function represents the so-called 'hard case' for sx_xlock * operation. All 'easy case' failures are redirected to this. Note * that ideally this would be a static function, but it needs to be * accessible from at least sx.h. */ int _sx_xlock_hard(struct sx *sx, uintptr_t x, uintptr_t tid, int opts, const char *file, int line) { GIANT_DECLARE; #ifdef ADAPTIVE_SX volatile struct thread *owner; u_int i, spintries = 0; #endif #ifdef LOCK_PROFILING uint64_t waittime = 0; int contested = 0; #endif int error = 0; #if defined(ADAPTIVE_SX) || defined(KDTRACE_HOOKS) struct lock_delay_arg lda; #endif #ifdef KDTRACE_HOOKS uintptr_t state; u_int sleep_cnt = 0; int64_t sleep_time = 0; int64_t all_time = 0; #endif if (SCHEDULER_STOPPED()) return (0); #if defined(ADAPTIVE_SX) lock_delay_arg_init(&lda, &sx_delay); #elif defined(KDTRACE_HOOKS) lock_delay_arg_init(&lda, NULL); #endif /* If we already hold an exclusive lock, then recurse. */ if (__predict_false(lv_sx_owner(x) == (struct thread *)tid)) { KASSERT((sx->lock_object.lo_flags & LO_RECURSABLE) != 0, ("_sx_xlock_hard: recursed on non-recursive sx %s @ %s:%d\n", sx->lock_object.lo_name, file, line)); sx->sx_recurse++; atomic_set_ptr(&sx->sx_lock, SX_LOCK_RECURSED); if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p recursing", __func__, sx); return (0); } if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR5(KTR_LOCK, "%s: %s contested (lock=%p) at %s:%d", __func__, sx->lock_object.lo_name, (void *)sx->sx_lock, file, line); #ifdef KDTRACE_HOOKS all_time -= lockstat_nsecs(&sx->lock_object); state = x; #endif for (;;) { if (x == SX_LOCK_UNLOCKED) { if (atomic_fcmpset_acq_ptr(&sx->sx_lock, &x, tid)) break; continue; } #ifdef KDTRACE_HOOKS lda.spin_cnt++; #endif #ifdef HWPMC_HOOKS PMC_SOFT_CALL( , , lock, failed); #endif lock_profile_obtain_lock_failed(&sx->lock_object, &contested, &waittime); #ifdef ADAPTIVE_SX /* * If the lock is write locked and the owner is * running on another CPU, spin until the owner stops * running or the state of the lock changes. */ if ((sx->lock_object.lo_flags & SX_NOADAPTIVE) == 0) { if ((x & SX_LOCK_SHARED) == 0) { owner = lv_sx_owner(x); if (TD_IS_RUNNING(owner)) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR3(KTR_LOCK, "%s: spinning on %p held by %p", __func__, sx, owner); KTR_STATE1(KTR_SCHED, "thread", sched_tdname(curthread), "spinning", "lockname:\"%s\"", sx->lock_object.lo_name); GIANT_SAVE(); do { lock_delay(&lda); x = SX_READ_VALUE(sx); owner = lv_sx_owner(x); } while (owner != NULL && TD_IS_RUNNING(owner)); KTR_STATE0(KTR_SCHED, "thread", sched_tdname(curthread), "running"); continue; } } else if (SX_SHARERS(x) && spintries < asx_retries) { KTR_STATE1(KTR_SCHED, "thread", sched_tdname(curthread), "spinning", "lockname:\"%s\"", sx->lock_object.lo_name); GIANT_SAVE(); spintries++; for (i = 0; i < asx_loops; i++) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR4(KTR_LOCK, "%s: shared spinning on %p with %u and %u", __func__, sx, spintries, i); x = sx->sx_lock; if ((x & SX_LOCK_SHARED) == 0 || SX_SHARERS(x) == 0) break; cpu_spinwait(); #ifdef KDTRACE_HOOKS lda.spin_cnt++; #endif } KTR_STATE0(KTR_SCHED, "thread", sched_tdname(curthread), "running"); x = SX_READ_VALUE(sx); if (i != asx_loops) continue; } } #endif sleepq_lock(&sx->lock_object); x = SX_READ_VALUE(sx); /* * If the lock was released while spinning on the * sleep queue chain lock, try again. */ if (x == SX_LOCK_UNLOCKED) { sleepq_release(&sx->lock_object); continue; } #ifdef ADAPTIVE_SX /* * The current lock owner might have started executing * on another CPU (or the lock could have changed * owners) while we were waiting on the sleep queue * chain lock. If so, drop the sleep queue lock and try * again. */ if (!(x & SX_LOCK_SHARED) && (sx->lock_object.lo_flags & SX_NOADAPTIVE) == 0) { owner = (struct thread *)SX_OWNER(x); if (TD_IS_RUNNING(owner)) { sleepq_release(&sx->lock_object); continue; } } #endif /* * If an exclusive lock was released with both shared * and exclusive waiters and a shared waiter hasn't * woken up and acquired the lock yet, sx_lock will be * set to SX_LOCK_UNLOCKED | SX_LOCK_EXCLUSIVE_WAITERS. * If we see that value, try to acquire it once. Note * that we have to preserve SX_LOCK_EXCLUSIVE_WAITERS * as there are other exclusive waiters still. If we * fail, restart the loop. */ if (x == (SX_LOCK_UNLOCKED | SX_LOCK_EXCLUSIVE_WAITERS)) { if (atomic_cmpset_acq_ptr(&sx->sx_lock, SX_LOCK_UNLOCKED | SX_LOCK_EXCLUSIVE_WAITERS, tid | SX_LOCK_EXCLUSIVE_WAITERS)) { sleepq_release(&sx->lock_object); CTR2(KTR_LOCK, "%s: %p claimed by new writer", __func__, sx); break; } sleepq_release(&sx->lock_object); x = SX_READ_VALUE(sx); continue; } /* * Try to set the SX_LOCK_EXCLUSIVE_WAITERS. If we fail, * than loop back and retry. */ if (!(x & SX_LOCK_EXCLUSIVE_WAITERS)) { if (!atomic_cmpset_ptr(&sx->sx_lock, x, x | SX_LOCK_EXCLUSIVE_WAITERS)) { sleepq_release(&sx->lock_object); x = SX_READ_VALUE(sx); continue; } if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p set excl waiters flag", __func__, sx); } /* * Since we have been unable to acquire the exclusive * lock and the exclusive waiters flag is set, we have * to sleep. */ if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p blocking on sleep queue", __func__, sx); #ifdef KDTRACE_HOOKS sleep_time -= lockstat_nsecs(&sx->lock_object); #endif GIANT_SAVE(); sleepq_add(&sx->lock_object, NULL, sx->lock_object.lo_name, SLEEPQ_SX | ((opts & SX_INTERRUPTIBLE) ? SLEEPQ_INTERRUPTIBLE : 0), SQ_EXCLUSIVE_QUEUE); if (!(opts & SX_INTERRUPTIBLE)) sleepq_wait(&sx->lock_object, 0); else error = sleepq_wait_sig(&sx->lock_object, 0); #ifdef KDTRACE_HOOKS sleep_time += lockstat_nsecs(&sx->lock_object); sleep_cnt++; #endif if (error) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: interruptible sleep by %p suspended by signal", __func__, sx); break; } if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p resuming from sleep queue", __func__, sx); x = SX_READ_VALUE(sx); } #ifdef KDTRACE_HOOKS all_time += lockstat_nsecs(&sx->lock_object); if (sleep_time) LOCKSTAT_RECORD4(sx__block, sx, sleep_time, LOCKSTAT_WRITER, (state & SX_LOCK_SHARED) == 0, (state & SX_LOCK_SHARED) == 0 ? 0 : SX_SHARERS(state)); if (lda.spin_cnt > sleep_cnt) LOCKSTAT_RECORD4(sx__spin, sx, all_time - sleep_time, LOCKSTAT_WRITER, (state & SX_LOCK_SHARED) == 0, (state & SX_LOCK_SHARED) == 0 ? 0 : SX_SHARERS(state)); #endif if (!error) LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(sx__acquire, sx, contested, waittime, file, line, LOCKSTAT_WRITER); GIANT_RESTORE(); return (error); } /* * This function represents the so-called 'hard case' for sx_xunlock * operation. All 'easy case' failures are redirected to this. Note * that ideally this would be a static function, but it needs to be * accessible from at least sx.h. */ void _sx_xunlock_hard(struct sx *sx, uintptr_t tid, const char *file, int line) { uintptr_t x; int queue, wakeup_swapper; if (SCHEDULER_STOPPED()) return; MPASS(!(sx->sx_lock & SX_LOCK_SHARED)); /* If the lock is recursed, then unrecurse one level. */ if (sx_xlocked(sx) && sx_recursed(sx)) { if ((--sx->sx_recurse) == 0) atomic_clear_ptr(&sx->sx_lock, SX_LOCK_RECURSED); if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p unrecursing", __func__, sx); return; } MPASS(sx->sx_lock & (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS)); if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p contested", __func__, sx); sleepq_lock(&sx->lock_object); x = SX_LOCK_UNLOCKED; /* * The wake up algorithm here is quite simple and probably not * ideal. It gives precedence to shared waiters if they are * present. For this condition, we have to preserve the * state of the exclusive waiters flag. * If interruptible sleeps left the shared queue empty avoid a * starvation for the threads sleeping on the exclusive queue by giving * them precedence and cleaning up the shared waiters bit anyway. */ if ((sx->sx_lock & SX_LOCK_SHARED_WAITERS) != 0 && sleepq_sleepcnt(&sx->lock_object, SQ_SHARED_QUEUE) != 0) { queue = SQ_SHARED_QUEUE; x |= (sx->sx_lock & SX_LOCK_EXCLUSIVE_WAITERS); } else queue = SQ_EXCLUSIVE_QUEUE; /* Wake up all the waiters for the specific queue. */ if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR3(KTR_LOCK, "%s: %p waking up all threads on %s queue", __func__, sx, queue == SQ_SHARED_QUEUE ? "shared" : "exclusive"); atomic_store_rel_ptr(&sx->sx_lock, x); wakeup_swapper = sleepq_broadcast(&sx->lock_object, SLEEPQ_SX, 0, queue); sleepq_release(&sx->lock_object); if (wakeup_swapper) kick_proc0(); } -/* - * This function represents the so-called 'hard case' for sx_slock - * operation. All 'easy case' failures are redirected to this. Note - * that ideally this would be a static function, but it needs to be - * accessible from at least sx.h. - */ int -_sx_slock_hard(struct sx *sx, int opts, const char *file, int line) +_sx_slock(struct sx *sx, int opts, const char *file, int line) { GIANT_DECLARE; #ifdef ADAPTIVE_SX volatile struct thread *owner; #endif #ifdef LOCK_PROFILING uint64_t waittime = 0; int contested = 0; #endif uintptr_t x; int error = 0; #if defined(ADAPTIVE_SX) || defined(KDTRACE_HOOKS) struct lock_delay_arg lda; #endif #ifdef KDTRACE_HOOKS uintptr_t state; u_int sleep_cnt = 0; int64_t sleep_time = 0; int64_t all_time = 0; #endif if (SCHEDULER_STOPPED()) return (0); #if defined(ADAPTIVE_SX) lock_delay_arg_init(&lda, &sx_delay); #elif defined(KDTRACE_HOOKS) lock_delay_arg_init(&lda, NULL); #endif #ifdef KDTRACE_HOOKS all_time -= lockstat_nsecs(&sx->lock_object); #endif x = SX_READ_VALUE(sx); #ifdef KDTRACE_HOOKS state = x; #endif /* * As with rwlocks, we don't make any attempt to try to block * shared locks once there is an exclusive waiter. */ for (;;) { /* * If no other thread has an exclusive lock then try to bump up * the count of sharers. Since we have to preserve the state * of SX_LOCK_EXCLUSIVE_WAITERS, if we fail to acquire the * shared lock loop back and retry. */ if (x & SX_LOCK_SHARED) { MPASS(!(x & SX_LOCK_SHARED_WAITERS)); if (atomic_fcmpset_acq_ptr(&sx->sx_lock, &x, x + SX_ONE_SHARER)) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR4(KTR_LOCK, "%s: %p succeed %p -> %p", __func__, sx, (void *)x, (void *)(x + SX_ONE_SHARER)); break; } continue; } #ifdef KDTRACE_HOOKS lda.spin_cnt++; #endif #ifdef HWPMC_HOOKS PMC_SOFT_CALL( , , lock, failed); #endif lock_profile_obtain_lock_failed(&sx->lock_object, &contested, &waittime); #ifdef ADAPTIVE_SX /* * If the owner is running on another CPU, spin until * the owner stops running or the state of the lock * changes. */ if ((sx->lock_object.lo_flags & SX_NOADAPTIVE) == 0) { owner = lv_sx_owner(x); if (TD_IS_RUNNING(owner)) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR3(KTR_LOCK, "%s: spinning on %p held by %p", __func__, sx, owner); KTR_STATE1(KTR_SCHED, "thread", sched_tdname(curthread), "spinning", "lockname:\"%s\"", sx->lock_object.lo_name); GIANT_SAVE(); do { lock_delay(&lda); x = SX_READ_VALUE(sx); owner = lv_sx_owner(x); } while (owner != NULL && TD_IS_RUNNING(owner)); KTR_STATE0(KTR_SCHED, "thread", sched_tdname(curthread), "running"); continue; } } #endif /* * Some other thread already has an exclusive lock, so * start the process of blocking. */ sleepq_lock(&sx->lock_object); x = SX_READ_VALUE(sx); /* * The lock could have been released while we spun. * In this case loop back and retry. */ if (x & SX_LOCK_SHARED) { sleepq_release(&sx->lock_object); continue; } #ifdef ADAPTIVE_SX /* * If the owner is running on another CPU, spin until * the owner stops running or the state of the lock * changes. */ if (!(x & SX_LOCK_SHARED) && (sx->lock_object.lo_flags & SX_NOADAPTIVE) == 0) { owner = (struct thread *)SX_OWNER(x); if (TD_IS_RUNNING(owner)) { sleepq_release(&sx->lock_object); x = SX_READ_VALUE(sx); continue; } } #endif /* * Try to set the SX_LOCK_SHARED_WAITERS flag. If we * fail to set it drop the sleep queue lock and loop * back. */ if (!(x & SX_LOCK_SHARED_WAITERS)) { if (!atomic_cmpset_ptr(&sx->sx_lock, x, x | SX_LOCK_SHARED_WAITERS)) { sleepq_release(&sx->lock_object); x = SX_READ_VALUE(sx); continue; } if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p set shared waiters flag", __func__, sx); } /* * Since we have been unable to acquire the shared lock, * we have to sleep. */ if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p blocking on sleep queue", __func__, sx); #ifdef KDTRACE_HOOKS sleep_time -= lockstat_nsecs(&sx->lock_object); #endif GIANT_SAVE(); sleepq_add(&sx->lock_object, NULL, sx->lock_object.lo_name, SLEEPQ_SX | ((opts & SX_INTERRUPTIBLE) ? SLEEPQ_INTERRUPTIBLE : 0), SQ_SHARED_QUEUE); if (!(opts & SX_INTERRUPTIBLE)) sleepq_wait(&sx->lock_object, 0); else error = sleepq_wait_sig(&sx->lock_object, 0); #ifdef KDTRACE_HOOKS sleep_time += lockstat_nsecs(&sx->lock_object); sleep_cnt++; #endif if (error) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: interruptible sleep by %p suspended by signal", __func__, sx); break; } if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p resuming from sleep queue", __func__, sx); x = SX_READ_VALUE(sx); } #ifdef KDTRACE_HOOKS all_time += lockstat_nsecs(&sx->lock_object); if (sleep_time) LOCKSTAT_RECORD4(sx__block, sx, sleep_time, LOCKSTAT_READER, (state & SX_LOCK_SHARED) == 0, (state & SX_LOCK_SHARED) == 0 ? 0 : SX_SHARERS(state)); if (lda.spin_cnt > sleep_cnt) LOCKSTAT_RECORD4(sx__spin, sx, all_time - sleep_time, LOCKSTAT_READER, (state & SX_LOCK_SHARED) == 0, (state & SX_LOCK_SHARED) == 0 ? 0 : SX_SHARERS(state)); #endif if (error == 0) LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(sx__acquire, sx, contested, waittime, file, line, LOCKSTAT_READER); GIANT_RESTORE(); return (error); } -/* - * This function represents the so-called 'hard case' for sx_sunlock - * operation. All 'easy case' failures are redirected to this. Note - * that ideally this would be a static function, but it needs to be - * accessible from at least sx.h. - */ void -_sx_sunlock_hard(struct sx *sx, const char *file, int line) +_sx_sunlock(struct sx *sx, const char *file, int line) { uintptr_t x; int wakeup_swapper; if (SCHEDULER_STOPPED()) return; + LOCKSTAT_PROFILE_RELEASE_RWLOCK(sx__release, sx, LOCKSTAT_READER); x = SX_READ_VALUE(sx); for (;;) { /* * We should never have sharers while at least one thread * holds a shared lock. */ KASSERT(!(x & SX_LOCK_SHARED_WAITERS), ("%s: waiting sharers", __func__)); /* * See if there is more than one shared lock held. If * so, just drop one and return. */ if (SX_SHARERS(x) > 1) { if (atomic_fcmpset_rel_ptr(&sx->sx_lock, &x, x - SX_ONE_SHARER)) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR4(KTR_LOCK, "%s: %p succeeded %p -> %p", __func__, sx, (void *)x, (void *)(x - SX_ONE_SHARER)); break; } continue; } /* * If there aren't any waiters for an exclusive lock, * then try to drop it quickly. */ if (!(x & SX_LOCK_EXCLUSIVE_WAITERS)) { MPASS(x == SX_SHARERS_LOCK(1)); x = SX_SHARERS_LOCK(1); if (atomic_fcmpset_rel_ptr(&sx->sx_lock, &x, SX_LOCK_UNLOCKED)) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p last succeeded", __func__, sx); break; } continue; } /* * At this point, there should just be one sharer with * exclusive waiters. */ MPASS(x == (SX_SHARERS_LOCK(1) | SX_LOCK_EXCLUSIVE_WAITERS)); sleepq_lock(&sx->lock_object); /* * Wake up semantic here is quite simple: * Just wake up all the exclusive waiters. * Note that the state of the lock could have changed, * so if it fails loop back and retry. */ if (!atomic_cmpset_rel_ptr(&sx->sx_lock, SX_SHARERS_LOCK(1) | SX_LOCK_EXCLUSIVE_WAITERS, SX_LOCK_UNLOCKED)) { sleepq_release(&sx->lock_object); x = SX_READ_VALUE(sx); continue; } if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p waking up all thread on" "exclusive queue", __func__, sx); wakeup_swapper = sleepq_broadcast(&sx->lock_object, SLEEPQ_SX, 0, SQ_EXCLUSIVE_QUEUE); sleepq_release(&sx->lock_object); if (wakeup_swapper) kick_proc0(); break; } } #ifdef INVARIANT_SUPPORT #ifndef INVARIANTS #undef _sx_assert #endif /* * In the non-WITNESS case, sx_assert() can only detect that at least * *some* thread owns an slock, but it cannot guarantee that *this* * thread owns an slock. */ void _sx_assert(const struct sx *sx, int what, const char *file, int line) { #ifndef WITNESS int slocked = 0; #endif if (panicstr != NULL) return; switch (what) { case SA_SLOCKED: case SA_SLOCKED | SA_NOTRECURSED: case SA_SLOCKED | SA_RECURSED: #ifndef WITNESS slocked = 1; /* FALLTHROUGH */ #endif case SA_LOCKED: case SA_LOCKED | SA_NOTRECURSED: case SA_LOCKED | SA_RECURSED: #ifdef WITNESS witness_assert(&sx->lock_object, what, file, line); #else /* * If some other thread has an exclusive lock or we * have one and are asserting a shared lock, fail. * Also, if no one has a lock at all, fail. */ if (sx->sx_lock == SX_LOCK_UNLOCKED || (!(sx->sx_lock & SX_LOCK_SHARED) && (slocked || sx_xholder(sx) != curthread))) panic("Lock %s not %slocked @ %s:%d\n", sx->lock_object.lo_name, slocked ? "share " : "", file, line); if (!(sx->sx_lock & SX_LOCK_SHARED)) { if (sx_recursed(sx)) { if (what & SA_NOTRECURSED) panic("Lock %s recursed @ %s:%d\n", sx->lock_object.lo_name, file, line); } else if (what & SA_RECURSED) panic("Lock %s not recursed @ %s:%d\n", sx->lock_object.lo_name, file, line); } #endif break; case SA_XLOCKED: case SA_XLOCKED | SA_NOTRECURSED: case SA_XLOCKED | SA_RECURSED: if (sx_xholder(sx) != curthread) panic("Lock %s not exclusively locked @ %s:%d\n", sx->lock_object.lo_name, file, line); if (sx_recursed(sx)) { if (what & SA_NOTRECURSED) panic("Lock %s recursed @ %s:%d\n", sx->lock_object.lo_name, file, line); } else if (what & SA_RECURSED) panic("Lock %s not recursed @ %s:%d\n", sx->lock_object.lo_name, file, line); break; case SA_UNLOCKED: #ifdef WITNESS witness_assert(&sx->lock_object, what, file, line); #else /* * If we hold an exclusve lock fail. We can't * reliably check to see if we hold a shared lock or * not. */ if (sx_xholder(sx) == curthread) panic("Lock %s exclusively locked @ %s:%d\n", sx->lock_object.lo_name, file, line); #endif break; default: panic("Unknown sx lock assertion: %d @ %s:%d", what, file, line); } } #endif /* INVARIANT_SUPPORT */ #ifdef DDB static void db_show_sx(const struct lock_object *lock) { struct thread *td; const struct sx *sx; sx = (const struct sx *)lock; db_printf(" state: "); if (sx->sx_lock == SX_LOCK_UNLOCKED) db_printf("UNLOCKED\n"); else if (sx->sx_lock == SX_LOCK_DESTROYED) { db_printf("DESTROYED\n"); return; } else if (sx->sx_lock & SX_LOCK_SHARED) db_printf("SLOCK: %ju\n", (uintmax_t)SX_SHARERS(sx->sx_lock)); else { td = sx_xholder(sx); db_printf("XLOCK: %p (tid %d, pid %d, \"%s\")\n", td, td->td_tid, td->td_proc->p_pid, td->td_name); if (sx_recursed(sx)) db_printf(" recursed: %d\n", sx->sx_recurse); } db_printf(" waiters: "); switch(sx->sx_lock & (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS)) { case SX_LOCK_SHARED_WAITERS: db_printf("shared\n"); break; case SX_LOCK_EXCLUSIVE_WAITERS: db_printf("exclusive\n"); break; case SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS: db_printf("exclusive and shared\n"); break; default: db_printf("none\n"); } } /* * Check to see if a thread that is blocked on a sleep queue is actually * blocked on an sx lock. If so, output some details and return true. * If the lock has an exclusive owner, return that in *ownerp. */ int sx_chain(struct thread *td, struct thread **ownerp) { struct sx *sx; /* * Check to see if this thread is blocked on an sx lock. * First, we check the lock class. If that is ok, then we * compare the lock name against the wait message. */ sx = td->td_wchan; if (LOCK_CLASS(&sx->lock_object) != &lock_class_sx || sx->lock_object.lo_name != td->td_wmesg) return (0); /* We think we have an sx lock, so output some details. */ db_printf("blocked on sx \"%s\" ", td->td_wmesg); *ownerp = sx_xholder(sx); if (sx->sx_lock & SX_LOCK_SHARED) db_printf("SLOCK (count %ju)\n", (uintmax_t)SX_SHARERS(sx->sx_lock)); else db_printf("XLOCK\n"); return (1); } #endif Index: head/sys/sys/sx.h =================================================================== --- head/sys/sys/sx.h (revision 313271) +++ head/sys/sys/sx.h (revision 313272) @@ -1,329 +1,286 @@ /*- * Copyright (c) 2007 Attilio Rao * Copyright (c) 2001 Jason Evans * 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(s), this list of conditions and the following disclaimer as * the first lines of this file unmodified other than the possible * addition of one or more copyright notices. * 2. Redistributions in binary form must reproduce the above copyright * notice(s), 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 COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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_SX_H_ #define _SYS_SX_H_ #include #include #ifdef _KERNEL #include #include #include #include #endif /* * In general, the sx locks and rwlocks use very similar algorithms. * The main difference in the implementations is how threads are * blocked when a lock is unavailable. For this, sx locks use sleep * queues which do not support priority propagation, and rwlocks use * turnstiles which do. * * The sx_lock field consists of several fields. The low bit * indicates if the lock is locked with a shared or exclusive lock. A * value of 0 indicates an exclusive lock, and a value of 1 indicates * a shared lock. Bit 1 is a boolean indicating if there are any * threads waiting for a shared lock. Bit 2 is a boolean indicating * if there are any threads waiting for an exclusive lock. Bit 3 is a * boolean indicating if an exclusive lock is recursively held. The * rest of the variable's definition is dependent on the value of the * first bit. For an exclusive lock, it is a pointer to the thread * holding the lock, similar to the mtx_lock field of mutexes. For * shared locks, it is a count of read locks that are held. * * When the lock is not locked by any thread, it is encoded as a * shared lock with zero waiters. */ #define SX_LOCK_SHARED 0x01 #define SX_LOCK_SHARED_WAITERS 0x02 #define SX_LOCK_EXCLUSIVE_WAITERS 0x04 #define SX_LOCK_RECURSED 0x08 #define SX_LOCK_FLAGMASK \ (SX_LOCK_SHARED | SX_LOCK_SHARED_WAITERS | \ SX_LOCK_EXCLUSIVE_WAITERS | SX_LOCK_RECURSED) #define SX_OWNER(x) ((x) & ~SX_LOCK_FLAGMASK) #define SX_SHARERS_SHIFT 4 #define SX_SHARERS(x) (SX_OWNER(x) >> SX_SHARERS_SHIFT) #define SX_SHARERS_LOCK(x) \ ((x) << SX_SHARERS_SHIFT | SX_LOCK_SHARED) #define SX_ONE_SHARER (1 << SX_SHARERS_SHIFT) #define SX_LOCK_UNLOCKED SX_SHARERS_LOCK(0) #define SX_LOCK_DESTROYED \ (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS) #ifdef _KERNEL #define sx_recurse lock_object.lo_data #define SX_READ_VALUE(sx) ((sx)->sx_lock) #define lv_sx_owner(v) \ ((v & SX_LOCK_SHARED) ? NULL : (struct thread *)SX_OWNER(v)) /* * Function prototipes. Routines that start with an underscore are not part * of the public interface and are wrappered with a macro. */ void sx_sysinit(void *arg); #define sx_init(sx, desc) sx_init_flags((sx), (desc), 0) void sx_init_flags(struct sx *sx, const char *description, int opts); void sx_destroy(struct sx *sx); int sx_try_slock_(struct sx *sx, const char *file, int line); int sx_try_xlock_(struct sx *sx, const char *file, int line); int sx_try_upgrade_(struct sx *sx, const char *file, int line); void sx_downgrade_(struct sx *sx, const char *file, int line); int _sx_slock(struct sx *sx, int opts, const char *file, int line); int _sx_xlock(struct sx *sx, int opts, const char *file, int line); void _sx_sunlock(struct sx *sx, const char *file, int line); void _sx_xunlock(struct sx *sx, const char *file, int line); int _sx_xlock_hard(struct sx *sx, uintptr_t v, uintptr_t tid, int opts, const char *file, int line); -int _sx_slock_hard(struct sx *sx, int opts, const char *file, int line); void _sx_xunlock_hard(struct sx *sx, uintptr_t tid, const char *file, int line); -void _sx_sunlock_hard(struct sx *sx, const char *file, int line); #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) void _sx_assert(const struct sx *sx, int what, const char *file, int line); #endif #ifdef DDB int sx_chain(struct thread *td, struct thread **ownerp); #endif struct sx_args { struct sx *sa_sx; const char *sa_desc; int sa_flags; }; #define SX_SYSINIT_FLAGS(name, sxa, desc, flags) \ static struct sx_args name##_args = { \ (sxa), \ (desc), \ (flags) \ }; \ SYSINIT(name##_sx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ sx_sysinit, &name##_args); \ SYSUNINIT(name##_sx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ sx_destroy, (sxa)) #define SX_SYSINIT(name, sxa, desc) SX_SYSINIT_FLAGS(name, sxa, desc, 0) /* * Full lock operations that are suitable to be inlined in non-debug kernels. * If the lock can't be acquired or released trivially then the work is * deferred to 'tougher' functions. */ /* Acquire an exclusive lock. */ static __inline int __sx_xlock(struct sx *sx, struct thread *td, int opts, const char *file, int line) { uintptr_t tid = (uintptr_t)td; uintptr_t v; int error = 0; v = SX_LOCK_UNLOCKED; if (!atomic_fcmpset_acq_ptr(&sx->sx_lock, &v, tid)) error = _sx_xlock_hard(sx, v, tid, opts, file, line); else LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(sx__acquire, sx, 0, 0, file, line, LOCKSTAT_WRITER); return (error); } /* Release an exclusive lock. */ static __inline void __sx_xunlock(struct sx *sx, struct thread *td, const char *file, int line) { uintptr_t tid = (uintptr_t)td; if (sx->sx_recurse == 0) LOCKSTAT_PROFILE_RELEASE_RWLOCK(sx__release, sx, LOCKSTAT_WRITER); if (!atomic_cmpset_rel_ptr(&sx->sx_lock, tid, SX_LOCK_UNLOCKED)) _sx_xunlock_hard(sx, tid, file, line); } -/* Acquire a shared lock. */ -static __inline int -__sx_slock(struct sx *sx, int opts, const char *file, int line) -{ - uintptr_t x = sx->sx_lock; - int error = 0; - - if (!(x & SX_LOCK_SHARED) || - !atomic_cmpset_acq_ptr(&sx->sx_lock, x, x + SX_ONE_SHARER)) - error = _sx_slock_hard(sx, opts, file, line); - else - LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(sx__acquire, sx, - 0, 0, file, line, LOCKSTAT_READER); - - return (error); -} - /* - * Release a shared lock. We can just drop a single shared lock so - * long as we aren't trying to drop the last shared lock when other - * threads are waiting for an exclusive lock. This takes advantage of - * the fact that an unlocked lock is encoded as a shared lock with a - * count of 0. - */ -static __inline void -__sx_sunlock(struct sx *sx, const char *file, int line) -{ - uintptr_t x = sx->sx_lock; - - LOCKSTAT_PROFILE_RELEASE_RWLOCK(sx__release, sx, LOCKSTAT_READER); - if (x == (SX_SHARERS_LOCK(1) | SX_LOCK_EXCLUSIVE_WAITERS) || - !atomic_cmpset_rel_ptr(&sx->sx_lock, x, x - SX_ONE_SHARER)) - _sx_sunlock_hard(sx, file, line); -} - -/* * Public interface for lock operations. */ #ifndef LOCK_DEBUG #error "LOCK_DEBUG not defined, include before " #endif #if (LOCK_DEBUG > 0) || defined(SX_NOINLINE) #define sx_xlock_(sx, file, line) \ (void)_sx_xlock((sx), 0, (file), (line)) #define sx_xlock_sig_(sx, file, line) \ _sx_xlock((sx), SX_INTERRUPTIBLE, (file), (line)) #define sx_xunlock_(sx, file, line) \ _sx_xunlock((sx), (file), (line)) -#define sx_slock_(sx, file, line) \ - (void)_sx_slock((sx), 0, (file), (line)) -#define sx_slock_sig_(sx, file, line) \ - _sx_slock((sx), SX_INTERRUPTIBLE, (file) , (line)) -#define sx_sunlock_(sx, file, line) \ - _sx_sunlock((sx), (file), (line)) #else #define sx_xlock_(sx, file, line) \ (void)__sx_xlock((sx), curthread, 0, (file), (line)) #define sx_xlock_sig_(sx, file, line) \ __sx_xlock((sx), curthread, SX_INTERRUPTIBLE, (file), (line)) #define sx_xunlock_(sx, file, line) \ __sx_xunlock((sx), curthread, (file), (line)) +#endif /* LOCK_DEBUG > 0 || SX_NOINLINE */ #define sx_slock_(sx, file, line) \ - (void)__sx_slock((sx), 0, (file), (line)) + (void)_sx_slock((sx), 0, (file), (line)) #define sx_slock_sig_(sx, file, line) \ - __sx_slock((sx), SX_INTERRUPTIBLE, (file), (line)) + _sx_slock((sx), SX_INTERRUPTIBLE, (file) , (line)) #define sx_sunlock_(sx, file, line) \ - __sx_sunlock((sx), (file), (line)) -#endif /* LOCK_DEBUG > 0 || SX_NOINLINE */ + _sx_sunlock((sx), (file), (line)) #define sx_try_slock(sx) sx_try_slock_((sx), LOCK_FILE, LOCK_LINE) #define sx_try_xlock(sx) sx_try_xlock_((sx), LOCK_FILE, LOCK_LINE) #define sx_try_upgrade(sx) sx_try_upgrade_((sx), LOCK_FILE, LOCK_LINE) #define sx_downgrade(sx) sx_downgrade_((sx), LOCK_FILE, LOCK_LINE) #ifdef INVARIANTS #define sx_assert_(sx, what, file, line) \ _sx_assert((sx), (what), (file), (line)) #else #define sx_assert_(sx, what, file, line) (void)0 #endif #define sx_xlock(sx) sx_xlock_((sx), LOCK_FILE, LOCK_LINE) #define sx_xlock_sig(sx) sx_xlock_sig_((sx), LOCK_FILE, LOCK_LINE) #define sx_xunlock(sx) sx_xunlock_((sx), LOCK_FILE, LOCK_LINE) #define sx_slock(sx) sx_slock_((sx), LOCK_FILE, LOCK_LINE) #define sx_slock_sig(sx) sx_slock_sig_((sx), LOCK_FILE, LOCK_LINE) #define sx_sunlock(sx) sx_sunlock_((sx), LOCK_FILE, LOCK_LINE) #define sx_assert(sx, what) sx_assert_((sx), (what), __FILE__, __LINE__) /* * Return a pointer to the owning thread if the lock is exclusively * locked. */ #define sx_xholder(sx) \ ((sx)->sx_lock & SX_LOCK_SHARED ? NULL : \ (struct thread *)SX_OWNER((sx)->sx_lock)) #define sx_xlocked(sx) \ (((sx)->sx_lock & ~(SX_LOCK_FLAGMASK & ~SX_LOCK_SHARED)) == \ (uintptr_t)curthread) #define sx_unlock_(sx, file, line) do { \ if (sx_xlocked(sx)) \ sx_xunlock_(sx, file, line); \ else \ sx_sunlock_(sx, file, line); \ } while (0) #define sx_unlock(sx) sx_unlock_((sx), LOCK_FILE, LOCK_LINE) #define sx_sleep(chan, sx, pri, wmesg, timo) \ _sleep((chan), &(sx)->lock_object, (pri), (wmesg), \ tick_sbt * (timo), 0, C_HARDCLOCK) /* * Options passed to sx_init_flags(). */ #define SX_DUPOK 0x01 #define SX_NOPROFILE 0x02 #define SX_NOWITNESS 0x04 #define SX_QUIET 0x08 #define SX_NOADAPTIVE 0x10 #define SX_RECURSE 0x20 #define SX_NEW 0x40 /* * Options passed to sx_*lock_hard(). */ #define SX_INTERRUPTIBLE 0x40 #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) #define SA_LOCKED LA_LOCKED #define SA_SLOCKED LA_SLOCKED #define SA_XLOCKED LA_XLOCKED #define SA_UNLOCKED LA_UNLOCKED #define SA_RECURSED LA_RECURSED #define SA_NOTRECURSED LA_NOTRECURSED /* Backwards compatibility. */ #define SX_LOCKED LA_LOCKED #define SX_SLOCKED LA_SLOCKED #define SX_XLOCKED LA_XLOCKED #define SX_UNLOCKED LA_UNLOCKED #define SX_RECURSED LA_RECURSED #define SX_NOTRECURSED LA_NOTRECURSED #endif #endif /* _KERNEL */ #endif /* !_SYS_SX_H_ */