Index: head/sys/kern/kern_rwlock.c =================================================================== --- head/sys/kern/kern_rwlock.c (revision 314473) +++ head/sys/kern/kern_rwlock.c (revision 314474) @@ -1,1396 +1,1396 @@ /*- * Copyright (c) 2006 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. */ /* * Machine independent bits of reader/writer lock implementation. */ #include __FBSDID("$FreeBSD$"); #include "opt_ddb.h" #include "opt_hwpmc_hooks.h" #include "opt_no_adaptive_rwlocks.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(SMP) && !defined(NO_ADAPTIVE_RWLOCKS) #define ADAPTIVE_RWLOCKS #endif #ifdef HWPMC_HOOKS #include PMC_SOFT_DECLARE( , , lock, failed); #endif /* * Return the rwlock address when the lock cookie address is provided. * This functionality assumes that struct rwlock* have a member named rw_lock. */ #define rwlock2rw(c) (__containerof(c, struct rwlock, rw_lock)) #ifdef DDB #include static void db_show_rwlock(const struct lock_object *lock); #endif static void assert_rw(const struct lock_object *lock, int what); static void lock_rw(struct lock_object *lock, uintptr_t how); #ifdef KDTRACE_HOOKS static int owner_rw(const struct lock_object *lock, struct thread **owner); #endif static uintptr_t unlock_rw(struct lock_object *lock); struct lock_class lock_class_rw = { .lc_name = "rw", .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE | LC_UPGRADABLE, .lc_assert = assert_rw, #ifdef DDB .lc_ddb_show = db_show_rwlock, #endif .lc_lock = lock_rw, .lc_unlock = unlock_rw, #ifdef KDTRACE_HOOKS .lc_owner = owner_rw, #endif }; #ifdef ADAPTIVE_RWLOCKS static int rowner_retries = 10; static int rowner_loops = 10000; static SYSCTL_NODE(_debug, OID_AUTO, rwlock, CTLFLAG_RD, NULL, "rwlock debugging"); SYSCTL_INT(_debug_rwlock, OID_AUTO, retry, CTLFLAG_RW, &rowner_retries, 0, ""); SYSCTL_INT(_debug_rwlock, OID_AUTO, loops, CTLFLAG_RW, &rowner_loops, 0, ""); static struct lock_delay_config __read_mostly rw_delay; SYSCTL_INT(_debug_rwlock, OID_AUTO, delay_base, CTLFLAG_RW, &rw_delay.base, 0, ""); SYSCTL_INT(_debug_rwlock, OID_AUTO, delay_max, CTLFLAG_RW, &rw_delay.max, 0, ""); LOCK_DELAY_SYSINIT_DEFAULT(rw_delay); #endif /* * Return a pointer to the owning thread if the lock is write-locked or * NULL if the lock is unlocked or read-locked. */ #define lv_rw_wowner(v) \ ((v) & RW_LOCK_READ ? NULL : \ (struct thread *)RW_OWNER((v))) #define rw_wowner(rw) lv_rw_wowner(RW_READ_VALUE(rw)) /* * Returns if a write owner is recursed. Write ownership is not assured * here and should be previously checked. */ #define rw_recursed(rw) ((rw)->rw_recurse != 0) /* * Return true if curthread helds the lock. */ #define rw_wlocked(rw) (rw_wowner((rw)) == curthread) /* * Return a pointer to the owning thread for this lock who should receive * any priority lent by threads that block on this lock. Currently this * is identical to rw_wowner(). */ #define rw_owner(rw) rw_wowner(rw) #ifndef INVARIANTS #define __rw_assert(c, what, file, line) #endif void assert_rw(const struct lock_object *lock, int what) { rw_assert((const struct rwlock *)lock, what); } void lock_rw(struct lock_object *lock, uintptr_t how) { struct rwlock *rw; rw = (struct rwlock *)lock; if (how) rw_rlock(rw); else rw_wlock(rw); } uintptr_t unlock_rw(struct lock_object *lock) { struct rwlock *rw; rw = (struct rwlock *)lock; rw_assert(rw, RA_LOCKED | LA_NOTRECURSED); if (rw->rw_lock & RW_LOCK_READ) { rw_runlock(rw); return (1); } else { rw_wunlock(rw); return (0); } } #ifdef KDTRACE_HOOKS int owner_rw(const struct lock_object *lock, struct thread **owner) { const struct rwlock *rw = (const struct rwlock *)lock; uintptr_t x = rw->rw_lock; *owner = rw_wowner(rw); return ((x & RW_LOCK_READ) != 0 ? (RW_READERS(x) != 0) : (*owner != NULL)); } #endif void _rw_init_flags(volatile uintptr_t *c, const char *name, int opts) { struct rwlock *rw; int flags; rw = rwlock2rw(c); MPASS((opts & ~(RW_DUPOK | RW_NOPROFILE | RW_NOWITNESS | RW_QUIET | RW_RECURSE | RW_NEW)) == 0); ASSERT_ATOMIC_LOAD_PTR(rw->rw_lock, ("%s: rw_lock not aligned for %s: %p", __func__, name, &rw->rw_lock)); flags = LO_UPGRADABLE; if (opts & RW_DUPOK) flags |= LO_DUPOK; if (opts & RW_NOPROFILE) flags |= LO_NOPROFILE; if (!(opts & RW_NOWITNESS)) flags |= LO_WITNESS; if (opts & RW_RECURSE) flags |= LO_RECURSABLE; if (opts & RW_QUIET) flags |= LO_QUIET; if (opts & RW_NEW) flags |= LO_NEW; lock_init(&rw->lock_object, &lock_class_rw, name, NULL, flags); rw->rw_lock = RW_UNLOCKED; rw->rw_recurse = 0; } void _rw_destroy(volatile uintptr_t *c) { struct rwlock *rw; rw = rwlock2rw(c); KASSERT(rw->rw_lock == RW_UNLOCKED, ("rw lock %p not unlocked", rw)); KASSERT(rw->rw_recurse == 0, ("rw lock %p still recursed", rw)); rw->rw_lock = RW_DESTROYED; lock_destroy(&rw->lock_object); } void rw_sysinit(void *arg) { struct rw_args *args = arg; rw_init((struct rwlock *)args->ra_rw, args->ra_desc); } void rw_sysinit_flags(void *arg) { struct rw_args_flags *args = arg; rw_init_flags((struct rwlock *)args->ra_rw, args->ra_desc, args->ra_flags); } int _rw_wowned(const volatile uintptr_t *c) { return (rw_wowner(rwlock2rw(c)) == curthread); } void _rw_wlock_cookie(volatile uintptr_t *c, const char *file, int line) { struct rwlock *rw; uintptr_t tid, v; rw = rwlock2rw(c); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), ("rw_wlock() by idle thread %p on rwlock %s @ %s:%d", curthread, rw->lock_object.lo_name, file, line)); KASSERT(rw->rw_lock != RW_DESTROYED, ("rw_wlock() of destroyed rwlock @ %s:%d", file, line)); WITNESS_CHECKORDER(&rw->lock_object, LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); tid = (uintptr_t)curthread; v = RW_UNLOCKED; if (!_rw_write_lock_fetch(rw, &v, tid)) _rw_wlock_hard(rw, v, tid, file, line); else LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(rw__acquire, rw, 0, 0, file, line, LOCKSTAT_WRITER); LOCK_LOG_LOCK("WLOCK", &rw->lock_object, 0, rw->rw_recurse, file, line); WITNESS_LOCK(&rw->lock_object, LOP_EXCLUSIVE, file, line); TD_LOCKS_INC(curthread); } int __rw_try_wlock(volatile uintptr_t *c, const char *file, int line) { struct rwlock *rw; struct thread *td; uintptr_t tid, v; int rval; bool recursed; td = curthread; tid = (uintptr_t)td; if (SCHEDULER_STOPPED_TD(td)) return (1); rw = rwlock2rw(c); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), ("rw_try_wlock() by idle thread %p on rwlock %s @ %s:%d", curthread, rw->lock_object.lo_name, file, line)); KASSERT(rw->rw_lock != RW_DESTROYED, ("rw_try_wlock() of destroyed rwlock @ %s:%d", file, line)); rval = 1; recursed = false; v = RW_UNLOCKED; for (;;) { if (atomic_fcmpset_acq_ptr(&rw->rw_lock, &v, tid)) break; if (v == RW_UNLOCKED) continue; if (v == tid && (rw->lock_object.lo_flags & LO_RECURSABLE)) { rw->rw_recurse++; atomic_set_ptr(&rw->rw_lock, RW_LOCK_WRITER_RECURSED); break; } rval = 0; break; } LOCK_LOG_TRY("WLOCK", &rw->lock_object, 0, rval, file, line); if (rval) { WITNESS_LOCK(&rw->lock_object, LOP_EXCLUSIVE | LOP_TRYLOCK, file, line); if (!recursed) LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(rw__acquire, rw, 0, 0, file, line, LOCKSTAT_WRITER); TD_LOCKS_INC(curthread); } return (rval); } void _rw_wunlock_cookie(volatile uintptr_t *c, const char *file, int line) { struct rwlock *rw; rw = rwlock2rw(c); KASSERT(rw->rw_lock != RW_DESTROYED, ("rw_wunlock() of destroyed rwlock @ %s:%d", file, line)); __rw_assert(c, RA_WLOCKED, file, line); WITNESS_UNLOCK(&rw->lock_object, LOP_EXCLUSIVE, file, line); LOCK_LOG_LOCK("WUNLOCK", &rw->lock_object, 0, rw->rw_recurse, file, line); #ifdef LOCK_PROFILING _rw_wunlock_hard(rw, (uintptr_t)curthread, file, line); #else __rw_wunlock(rw, curthread, file, line); #endif TD_LOCKS_DEC(curthread); } /* * Determines whether a new reader can acquire a lock. Succeeds if the * reader already owns a read lock and the lock is locked for read to * prevent deadlock from reader recursion. Also succeeds if the lock * is unlocked and has no writer waiters or spinners. Failing otherwise * prioritizes writers before readers. */ #define RW_CAN_READ(td, _rw) \ (((td)->td_rw_rlocks && (_rw) & RW_LOCK_READ) || ((_rw) & \ (RW_LOCK_READ | RW_LOCK_WRITE_WAITERS | RW_LOCK_WRITE_SPINNER)) == \ RW_LOCK_READ) static bool __always_inline __rw_rlock_try(struct rwlock *rw, struct thread *td, uintptr_t *vp, const char *file, int line) { /* * Handle the easy case. If no other thread has a write * lock, then try to bump up the count of read locks. Note * that we have to preserve the current state of the * RW_LOCK_WRITE_WAITERS flag. If we fail to acquire a * read lock, then rw_lock must have changed, so restart * the loop. Note that this handles the case of a * completely unlocked rwlock since such a lock is encoded * as a read lock with no waiters. */ while (RW_CAN_READ(td, *vp)) { if (atomic_fcmpset_acq_ptr(&rw->rw_lock, vp, *vp + RW_ONE_READER)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR4(KTR_LOCK, "%s: %p succeed %p -> %p", __func__, rw, (void *)*vp, (void *)(*vp + RW_ONE_READER)); td->td_rw_rlocks++; return (true); } } return (false); } static void __noinline __rw_rlock_hard(volatile uintptr_t *c, struct thread *td, uintptr_t v, const char *file, int line) { struct rwlock *rw; struct turnstile *ts; #ifdef ADAPTIVE_RWLOCKS volatile struct thread *owner; int spintries = 0; int i; #endif #ifdef LOCK_PROFILING uint64_t waittime = 0; int contested = 0; #endif #if defined(ADAPTIVE_RWLOCKS) || 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; #if defined(ADAPTIVE_RWLOCKS) lock_delay_arg_init(&lda, &rw_delay); #elif defined(KDTRACE_HOOKS) lock_delay_arg_init(&lda, NULL); #endif rw = rwlock2rw(c); #ifdef KDTRACE_HOOKS all_time -= lockstat_nsecs(&rw->lock_object); #endif #ifdef KDTRACE_HOOKS state = v; #endif for (;;) { if (__rw_rlock_try(rw, td, &v, file, line)) break; #ifdef KDTRACE_HOOKS lda.spin_cnt++; #endif #ifdef HWPMC_HOOKS PMC_SOFT_CALL( , , lock, failed); #endif lock_profile_obtain_lock_failed(&rw->lock_object, &contested, &waittime); #ifdef ADAPTIVE_RWLOCKS /* * If the owner is running on another CPU, spin until * the owner stops running or the state of the lock * changes. */ if ((v & RW_LOCK_READ) == 0) { owner = (struct thread *)RW_OWNER(v); if (TD_IS_RUNNING(owner)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR3(KTR_LOCK, "%s: spinning on %p held by %p", __func__, rw, owner); KTR_STATE1(KTR_SCHED, "thread", sched_tdname(curthread), "spinning", "lockname:\"%s\"", rw->lock_object.lo_name); do { lock_delay(&lda); v = RW_READ_VALUE(rw); owner = lv_rw_wowner(v); } while (owner != NULL && TD_IS_RUNNING(owner)); KTR_STATE0(KTR_SCHED, "thread", sched_tdname(curthread), "running"); continue; } } else if (spintries < rowner_retries) { spintries++; KTR_STATE1(KTR_SCHED, "thread", sched_tdname(curthread), "spinning", "lockname:\"%s\"", rw->lock_object.lo_name); for (i = 0; i < rowner_loops; i++) { v = RW_READ_VALUE(rw); if ((v & RW_LOCK_READ) == 0 || RW_CAN_READ(td, v)) break; cpu_spinwait(); } v = RW_READ_VALUE(rw); #ifdef KDTRACE_HOOKS lda.spin_cnt += rowner_loops - i; #endif KTR_STATE0(KTR_SCHED, "thread", sched_tdname(curthread), "running"); if (i != rowner_loops) continue; } #endif /* * Okay, now it's the hard case. Some other thread already * has a write lock or there are write waiters present, * acquire the turnstile lock so we can begin the process * of blocking. */ ts = turnstile_trywait(&rw->lock_object); /* * The lock might have been released while we spun, so * recheck its state and restart the loop if needed. */ v = RW_READ_VALUE(rw); if (RW_CAN_READ(td, v)) { turnstile_cancel(ts); continue; } #ifdef ADAPTIVE_RWLOCKS /* * The current lock owner might have started executing * on another CPU (or the lock could have changed * owners) while we were waiting on the turnstile * chain lock. If so, drop the turnstile lock and try * again. */ if ((v & RW_LOCK_READ) == 0) { owner = (struct thread *)RW_OWNER(v); if (TD_IS_RUNNING(owner)) { turnstile_cancel(ts); continue; } } #endif /* * The lock is held in write mode or it already has waiters. */ MPASS(!RW_CAN_READ(td, v)); /* * If the RW_LOCK_READ_WAITERS flag is already set, then * we can go ahead and block. If it is not set then try * to set it. If we fail to set it drop the turnstile * lock and restart the loop. */ if (!(v & RW_LOCK_READ_WAITERS)) { if (!atomic_cmpset_ptr(&rw->rw_lock, v, v | RW_LOCK_READ_WAITERS)) { turnstile_cancel(ts); v = RW_READ_VALUE(rw); continue; } if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p set read waiters flag", __func__, rw); } /* * We were unable to acquire the lock and the read waiters * flag is set, so we must block on the turnstile. */ if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p blocking on turnstile", __func__, rw); #ifdef KDTRACE_HOOKS sleep_time -= lockstat_nsecs(&rw->lock_object); #endif turnstile_wait(ts, rw_owner(rw), TS_SHARED_QUEUE); #ifdef KDTRACE_HOOKS sleep_time += lockstat_nsecs(&rw->lock_object); sleep_cnt++; #endif if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p resuming from turnstile", __func__, rw); v = RW_READ_VALUE(rw); } #ifdef KDTRACE_HOOKS all_time += lockstat_nsecs(&rw->lock_object); if (sleep_time) LOCKSTAT_RECORD4(rw__block, rw, sleep_time, LOCKSTAT_READER, (state & RW_LOCK_READ) == 0, (state & RW_LOCK_READ) == 0 ? 0 : RW_READERS(state)); /* Record only the loops spinning and not sleeping. */ if (lda.spin_cnt > sleep_cnt) LOCKSTAT_RECORD4(rw__spin, rw, all_time - sleep_time, LOCKSTAT_READER, (state & RW_LOCK_READ) == 0, (state & RW_LOCK_READ) == 0 ? 0 : RW_READERS(state)); #endif /* * TODO: acquire "owner of record" here. Here be turnstile dragons * however. turnstiles don't like owners changing between calls to * turnstile_wait() currently. */ LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(rw__acquire, rw, contested, waittime, file, line, LOCKSTAT_READER); } void __rw_rlock(volatile uintptr_t *c, const char *file, int line) { struct rwlock *rw; struct thread *td; uintptr_t v; td = curthread; rw = rwlock2rw(c); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(td), ("rw_rlock() by idle thread %p on rwlock %s @ %s:%d", td, rw->lock_object.lo_name, file, line)); KASSERT(rw->rw_lock != RW_DESTROYED, ("rw_rlock() of destroyed rwlock @ %s:%d", file, line)); KASSERT(rw_wowner(rw) != td, ("rw_rlock: wlock already held for %s @ %s:%d", rw->lock_object.lo_name, file, line)); WITNESS_CHECKORDER(&rw->lock_object, LOP_NEWORDER, file, line, NULL); v = RW_READ_VALUE(rw); if (__predict_false(LOCKSTAT_OOL_PROFILE_ENABLED(rw__acquire) || !__rw_rlock_try(rw, td, &v, file, line))) __rw_rlock_hard(c, td, v, file, line); LOCK_LOG_LOCK("RLOCK", &rw->lock_object, 0, 0, file, line); WITNESS_LOCK(&rw->lock_object, 0, file, line); TD_LOCKS_INC(curthread); } int __rw_try_rlock(volatile uintptr_t *c, const char *file, int line) { struct rwlock *rw; uintptr_t x; if (SCHEDULER_STOPPED()) return (1); rw = rwlock2rw(c); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), ("rw_try_rlock() by idle thread %p on rwlock %s @ %s:%d", curthread, rw->lock_object.lo_name, file, line)); x = rw->rw_lock; for (;;) { KASSERT(rw->rw_lock != RW_DESTROYED, ("rw_try_rlock() of destroyed rwlock @ %s:%d", file, line)); if (!(x & RW_LOCK_READ)) break; if (atomic_fcmpset_acq_ptr(&rw->rw_lock, &x, x + RW_ONE_READER)) { LOCK_LOG_TRY("RLOCK", &rw->lock_object, 0, 1, file, line); WITNESS_LOCK(&rw->lock_object, LOP_TRYLOCK, file, line); LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(rw__acquire, rw, 0, 0, file, line, LOCKSTAT_READER); TD_LOCKS_INC(curthread); curthread->td_rw_rlocks++; return (1); } } LOCK_LOG_TRY("RLOCK", &rw->lock_object, 0, 0, file, line); return (0); } static bool __always_inline __rw_runlock_try(struct rwlock *rw, struct thread *td, uintptr_t *vp) { for (;;) { /* * See if there is more than one read lock held. If so, * just drop one and return. */ if (RW_READERS(*vp) > 1) { if (atomic_fcmpset_rel_ptr(&rw->rw_lock, vp, *vp - RW_ONE_READER)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR4(KTR_LOCK, "%s: %p succeeded %p -> %p", __func__, rw, (void *)*vp, (void *)(*vp - RW_ONE_READER)); td->td_rw_rlocks--; return (true); } continue; } /* * If there aren't any waiters for a write lock, then try * to drop it quickly. */ if (!(*vp & RW_LOCK_WAITERS)) { MPASS((*vp & ~RW_LOCK_WRITE_SPINNER) == RW_READERS_LOCK(1)); if (atomic_fcmpset_rel_ptr(&rw->rw_lock, vp, RW_UNLOCKED)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p last succeeded", __func__, rw); td->td_rw_rlocks--; return (true); } continue; } break; } return (false); } static void __noinline __rw_runlock_hard(volatile uintptr_t *c, struct thread *td, uintptr_t v, const char *file, int line) { struct rwlock *rw; struct turnstile *ts; uintptr_t x, queue; if (SCHEDULER_STOPPED()) return; rw = rwlock2rw(c); for (;;) { if (__rw_runlock_try(rw, td, &v)) break; /* * Ok, we know we have waiters and we think we are the * last reader, so grab the turnstile lock. */ turnstile_chain_lock(&rw->lock_object); v = rw->rw_lock & (RW_LOCK_WAITERS | RW_LOCK_WRITE_SPINNER); MPASS(v & RW_LOCK_WAITERS); /* * Try to drop our lock leaving the lock in a unlocked * state. * * If you wanted to do explicit lock handoff you'd have to * do it here. You'd also want to use turnstile_signal() * and you'd have to handle the race where a higher * priority thread blocks on the write lock before the * thread you wakeup actually runs and have the new thread * "steal" the lock. For now it's a lot simpler to just * wakeup all of the waiters. * * As above, if we fail, then another thread might have * acquired a read lock, so drop the turnstile lock and * restart. */ x = RW_UNLOCKED; if (v & RW_LOCK_WRITE_WAITERS) { queue = TS_EXCLUSIVE_QUEUE; x |= (v & RW_LOCK_READ_WAITERS); } else queue = TS_SHARED_QUEUE; if (!atomic_cmpset_rel_ptr(&rw->rw_lock, RW_READERS_LOCK(1) | v, x)) { turnstile_chain_unlock(&rw->lock_object); v = RW_READ_VALUE(rw); continue; } if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p last succeeded with waiters", __func__, rw); /* * Ok. The lock is released and all that's left is to * wake up the waiters. Note that the lock might not be * free anymore, but in that case the writers will just * block again if they run before the new lock holder(s) * release the lock. */ ts = turnstile_lookup(&rw->lock_object); MPASS(ts != NULL); turnstile_broadcast(ts, queue); turnstile_unpend(ts, TS_SHARED_LOCK); turnstile_chain_unlock(&rw->lock_object); td->td_rw_rlocks--; break; } LOCKSTAT_PROFILE_RELEASE_RWLOCK(rw__release, rw, LOCKSTAT_READER); } void _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line) { struct rwlock *rw; struct thread *td; uintptr_t v; rw = rwlock2rw(c); KASSERT(rw->rw_lock != RW_DESTROYED, ("rw_runlock() of destroyed rwlock @ %s:%d", file, line)); __rw_assert(c, RA_RLOCKED, file, line); WITNESS_UNLOCK(&rw->lock_object, 0, file, line); LOCK_LOG_LOCK("RUNLOCK", &rw->lock_object, 0, 0, file, line); td = curthread; v = RW_READ_VALUE(rw); if (__predict_false(LOCKSTAT_OOL_PROFILE_ENABLED(rw__release) || !__rw_runlock_try(rw, td, &v))) __rw_runlock_hard(c, td, v, file, line); TD_LOCKS_DEC(curthread); } /* * This function is called when we are unable to obtain a write lock on the * first try. This means that at least one other thread holds either a * read or write lock. */ void __rw_wlock_hard(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, const char *file, int line) { struct rwlock *rw; struct turnstile *ts; #ifdef ADAPTIVE_RWLOCKS volatile struct thread *owner; int spintries = 0; int i; #endif uintptr_t x; #ifdef LOCK_PROFILING uint64_t waittime = 0; int contested = 0; #endif #if defined(ADAPTIVE_RWLOCKS) || 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; #if defined(ADAPTIVE_RWLOCKS) lock_delay_arg_init(&lda, &rw_delay); #elif defined(KDTRACE_HOOKS) lock_delay_arg_init(&lda, NULL); #endif rw = rwlock2rw(c); if (__predict_false(v == RW_UNLOCKED)) v = RW_READ_VALUE(rw); if (__predict_false(lv_rw_wowner(v) == (struct thread *)tid)) { KASSERT(rw->lock_object.lo_flags & LO_RECURSABLE, ("%s: recursing but non-recursive rw %s @ %s:%d\n", __func__, rw->lock_object.lo_name, file, line)); rw->rw_recurse++; atomic_set_ptr(&rw->rw_lock, RW_LOCK_WRITER_RECURSED); if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p recursing", __func__, rw); return; } if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR5(KTR_LOCK, "%s: %s contested (lock=%p) at %s:%d", __func__, rw->lock_object.lo_name, (void *)rw->rw_lock, file, line); #ifdef KDTRACE_HOOKS all_time -= lockstat_nsecs(&rw->lock_object); state = v; #endif for (;;) { if (v == RW_UNLOCKED) { if (_rw_write_lock_fetch(rw, &v, tid)) break; continue; } #ifdef KDTRACE_HOOKS lda.spin_cnt++; #endif #ifdef HWPMC_HOOKS PMC_SOFT_CALL( , , lock, failed); #endif lock_profile_obtain_lock_failed(&rw->lock_object, &contested, &waittime); #ifdef ADAPTIVE_RWLOCKS /* * 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. */ owner = lv_rw_wowner(v); if (!(v & RW_LOCK_READ) && TD_IS_RUNNING(owner)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR3(KTR_LOCK, "%s: spinning on %p held by %p", __func__, rw, owner); KTR_STATE1(KTR_SCHED, "thread", sched_tdname(curthread), "spinning", "lockname:\"%s\"", rw->lock_object.lo_name); do { lock_delay(&lda); v = RW_READ_VALUE(rw); owner = lv_rw_wowner(v); } while (owner != NULL && TD_IS_RUNNING(owner)); KTR_STATE0(KTR_SCHED, "thread", sched_tdname(curthread), "running"); continue; } if ((v & RW_LOCK_READ) && RW_READERS(v) && spintries < rowner_retries) { if (!(v & RW_LOCK_WRITE_SPINNER)) { if (!atomic_cmpset_ptr(&rw->rw_lock, v, v | RW_LOCK_WRITE_SPINNER)) { v = RW_READ_VALUE(rw); continue; } } spintries++; KTR_STATE1(KTR_SCHED, "thread", sched_tdname(curthread), "spinning", "lockname:\"%s\"", rw->lock_object.lo_name); for (i = 0; i < rowner_loops; i++) { if ((rw->rw_lock & RW_LOCK_WRITE_SPINNER) == 0) break; cpu_spinwait(); } KTR_STATE0(KTR_SCHED, "thread", sched_tdname(curthread), "running"); v = RW_READ_VALUE(rw); #ifdef KDTRACE_HOOKS lda.spin_cnt += rowner_loops - i; #endif if (i != rowner_loops) continue; } #endif ts = turnstile_trywait(&rw->lock_object); v = RW_READ_VALUE(rw); #ifdef ADAPTIVE_RWLOCKS /* * The current lock owner might have started executing * on another CPU (or the lock could have changed * owners) while we were waiting on the turnstile * chain lock. If so, drop the turnstile lock and try * again. */ if (!(v & RW_LOCK_READ)) { owner = (struct thread *)RW_OWNER(v); if (TD_IS_RUNNING(owner)) { turnstile_cancel(ts); continue; } } #endif /* * Check for the waiters flags about this rwlock. * If the lock was released, without maintain any pending * waiters queue, simply try to acquire it. * If a pending waiters queue is present, claim the lock * ownership and maintain the pending queue. */ x = v & (RW_LOCK_WAITERS | RW_LOCK_WRITE_SPINNER); if ((v & ~x) == RW_UNLOCKED) { x &= ~RW_LOCK_WRITE_SPINNER; if (atomic_cmpset_acq_ptr(&rw->rw_lock, v, tid | x)) { if (x) turnstile_claim(ts); else turnstile_cancel(ts); break; } turnstile_cancel(ts); v = RW_READ_VALUE(rw); continue; } /* * If the RW_LOCK_WRITE_WAITERS flag isn't set, then try to * set it. If we fail to set it, then loop back and try * again. */ if (!(v & RW_LOCK_WRITE_WAITERS)) { if (!atomic_cmpset_ptr(&rw->rw_lock, v, v | RW_LOCK_WRITE_WAITERS)) { turnstile_cancel(ts); v = RW_READ_VALUE(rw); continue; } if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p set write waiters flag", __func__, rw); } /* * We were unable to acquire the lock and the write waiters * flag is set, so we must block on the turnstile. */ if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p blocking on turnstile", __func__, rw); #ifdef KDTRACE_HOOKS sleep_time -= lockstat_nsecs(&rw->lock_object); #endif turnstile_wait(ts, rw_owner(rw), TS_EXCLUSIVE_QUEUE); #ifdef KDTRACE_HOOKS sleep_time += lockstat_nsecs(&rw->lock_object); sleep_cnt++; #endif if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p resuming from turnstile", __func__, rw); #ifdef ADAPTIVE_RWLOCKS spintries = 0; #endif v = RW_READ_VALUE(rw); } #ifdef KDTRACE_HOOKS all_time += lockstat_nsecs(&rw->lock_object); if (sleep_time) LOCKSTAT_RECORD4(rw__block, rw, sleep_time, LOCKSTAT_WRITER, (state & RW_LOCK_READ) == 0, (state & RW_LOCK_READ) == 0 ? 0 : RW_READERS(state)); /* Record only the loops spinning and not sleeping. */ if (lda.spin_cnt > sleep_cnt) LOCKSTAT_RECORD4(rw__spin, rw, all_time - sleep_time, LOCKSTAT_WRITER, (state & RW_LOCK_READ) == 0, (state & RW_LOCK_READ) == 0 ? 0 : RW_READERS(state)); #endif LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(rw__acquire, rw, contested, waittime, file, line, LOCKSTAT_WRITER); } /* * This function is called if lockstat is active or the first try at releasing * a write lock failed. The latter means that the lock is recursed or one of * the 2 waiter bits must be set indicating that at least one thread is waiting * on this lock. */ void __rw_wunlock_hard(volatile uintptr_t *c, uintptr_t tid, const char *file, int line) { struct rwlock *rw; struct turnstile *ts; uintptr_t v; int queue; if (SCHEDULER_STOPPED()) return; rw = rwlock2rw(c); v = RW_READ_VALUE(rw); if (v & RW_LOCK_WRITER_RECURSED) { if (--(rw->rw_recurse) == 0) atomic_clear_ptr(&rw->rw_lock, RW_LOCK_WRITER_RECURSED); if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p unrecursing", __func__, rw); return; } LOCKSTAT_PROFILE_RELEASE_RWLOCK(rw__release, rw, LOCKSTAT_WRITER); if (v == tid && _rw_write_unlock(rw, tid)) return; KASSERT(rw->rw_lock & (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS), ("%s: neither of the waiter flags are set", __func__)); if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p contested", __func__, rw); turnstile_chain_lock(&rw->lock_object); ts = turnstile_lookup(&rw->lock_object); MPASS(ts != NULL); /* * Use the same algo as sx locks for now. Prefer waking up shared * waiters if we have any over writers. This is probably not ideal. * * 'v' is the value we are going to write back to rw_lock. If we * have waiters on both queues, we need to preserve the state of * the waiter flag for the queue we don't wake up. For now this is * hardcoded for the algorithm mentioned above. * * In the case of both readers and writers waiting we wakeup the * readers but leave the RW_LOCK_WRITE_WAITERS flag set. If a * new writer comes in before a reader it will claim the lock up * above. There is probably a potential priority inversion in * there that could be worked around either by waking both queues * of waiters or doing some complicated lock handoff gymnastics. */ v = RW_UNLOCKED; if (rw->rw_lock & RW_LOCK_WRITE_WAITERS) { queue = TS_EXCLUSIVE_QUEUE; v |= (rw->rw_lock & RW_LOCK_READ_WAITERS); } else queue = TS_SHARED_QUEUE; /* Wake up all waiters for the specific queue. */ if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR3(KTR_LOCK, "%s: %p waking up %s waiters", __func__, rw, queue == TS_SHARED_QUEUE ? "read" : "write"); turnstile_broadcast(ts, queue); atomic_store_rel_ptr(&rw->rw_lock, v); turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); turnstile_chain_unlock(&rw->lock_object); } /* * Attempt to do a non-blocking upgrade from a read lock to a write * lock. This will only succeed if this thread holds a single read * lock. Returns true if the upgrade succeeded and false otherwise. */ int __rw_try_upgrade(volatile uintptr_t *c, const char *file, int line) { struct rwlock *rw; uintptr_t v, x, tid; struct turnstile *ts; int success; if (SCHEDULER_STOPPED()) return (1); rw = rwlock2rw(c); KASSERT(rw->rw_lock != RW_DESTROYED, ("rw_try_upgrade() of destroyed rwlock @ %s:%d", file, line)); __rw_assert(c, RA_RLOCKED, file, line); /* * Attempt to switch from one reader to a writer. If there * are any write waiters, then we will have to lock the * turnstile first to prevent races with another writer * calling turnstile_wait() before we have claimed this * turnstile. So, do the simple case of no waiters first. */ tid = (uintptr_t)curthread; success = 0; for (;;) { v = rw->rw_lock; if (RW_READERS(v) > 1) break; if (!(v & RW_LOCK_WAITERS)) { - success = atomic_cmpset_ptr(&rw->rw_lock, v, tid); + success = atomic_cmpset_acq_ptr(&rw->rw_lock, v, tid); if (!success) continue; break; } /* * Ok, we think we have waiters, so lock the turnstile. */ ts = turnstile_trywait(&rw->lock_object); v = rw->rw_lock; if (RW_READERS(v) > 1) { turnstile_cancel(ts); break; } /* * Try to switch from one reader to a writer again. This time * we honor the current state of the waiters flags. * If we obtain the lock with the flags set, then claim * ownership of the turnstile. */ x = rw->rw_lock & RW_LOCK_WAITERS; success = atomic_cmpset_ptr(&rw->rw_lock, v, tid | x); if (success) { if (x) turnstile_claim(ts); else turnstile_cancel(ts); break; } turnstile_cancel(ts); } LOCK_LOG_TRY("WUPGRADE", &rw->lock_object, 0, success, file, line); if (success) { curthread->td_rw_rlocks--; WITNESS_UPGRADE(&rw->lock_object, LOP_EXCLUSIVE | LOP_TRYLOCK, file, line); LOCKSTAT_RECORD0(rw__upgrade, rw); } return (success); } /* * Downgrade a write lock into a single read lock. */ void __rw_downgrade(volatile uintptr_t *c, const char *file, int line) { struct rwlock *rw; struct turnstile *ts; uintptr_t tid, v; int rwait, wwait; if (SCHEDULER_STOPPED()) return; rw = rwlock2rw(c); KASSERT(rw->rw_lock != RW_DESTROYED, ("rw_downgrade() of destroyed rwlock @ %s:%d", file, line)); __rw_assert(c, RA_WLOCKED | RA_NOTRECURSED, file, line); #ifndef INVARIANTS if (rw_recursed(rw)) panic("downgrade of a recursed lock"); #endif WITNESS_DOWNGRADE(&rw->lock_object, 0, file, line); /* * Convert from a writer to a single reader. First we handle * the easy case with no waiters. If there are any waiters, we * lock the turnstile and "disown" the lock. */ tid = (uintptr_t)curthread; if (atomic_cmpset_rel_ptr(&rw->rw_lock, tid, RW_READERS_LOCK(1))) goto out; /* * Ok, we think we have waiters, so lock the turnstile so we can * read the waiter flags without any races. */ turnstile_chain_lock(&rw->lock_object); v = rw->rw_lock & RW_LOCK_WAITERS; rwait = v & RW_LOCK_READ_WAITERS; wwait = v & RW_LOCK_WRITE_WAITERS; MPASS(rwait | wwait); /* * Downgrade from a write lock while preserving waiters flag * and give up ownership of the turnstile. */ ts = turnstile_lookup(&rw->lock_object); MPASS(ts != NULL); if (!wwait) v &= ~RW_LOCK_READ_WAITERS; atomic_store_rel_ptr(&rw->rw_lock, RW_READERS_LOCK(1) | v); /* * Wake other readers if there are no writers pending. Otherwise they * won't be able to acquire the lock anyway. */ if (rwait && !wwait) { turnstile_broadcast(ts, TS_SHARED_QUEUE); turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); } else turnstile_disown(ts); turnstile_chain_unlock(&rw->lock_object); out: curthread->td_rw_rlocks++; LOCK_LOG_LOCK("WDOWNGRADE", &rw->lock_object, 0, 0, file, line); LOCKSTAT_RECORD0(rw__downgrade, rw); } #ifdef INVARIANT_SUPPORT #ifndef INVARIANTS #undef __rw_assert #endif /* * In the non-WITNESS case, rw_assert() can only detect that at least * *some* thread owns an rlock, but it cannot guarantee that *this* * thread owns an rlock. */ void __rw_assert(const volatile uintptr_t *c, int what, const char *file, int line) { const struct rwlock *rw; if (panicstr != NULL) return; rw = rwlock2rw(c); switch (what) { case RA_LOCKED: case RA_LOCKED | RA_RECURSED: case RA_LOCKED | RA_NOTRECURSED: case RA_RLOCKED: case RA_RLOCKED | RA_RECURSED: case RA_RLOCKED | RA_NOTRECURSED: #ifdef WITNESS witness_assert(&rw->lock_object, what, file, line); #else /* * If some other thread has a write lock or we have one * and are asserting a read lock, fail. Also, if no one * has a lock at all, fail. */ if (rw->rw_lock == RW_UNLOCKED || (!(rw->rw_lock & RW_LOCK_READ) && (what & RA_RLOCKED || rw_wowner(rw) != curthread))) panic("Lock %s not %slocked @ %s:%d\n", rw->lock_object.lo_name, (what & RA_RLOCKED) ? "read " : "", file, line); if (!(rw->rw_lock & RW_LOCK_READ) && !(what & RA_RLOCKED)) { if (rw_recursed(rw)) { if (what & RA_NOTRECURSED) panic("Lock %s recursed @ %s:%d\n", rw->lock_object.lo_name, file, line); } else if (what & RA_RECURSED) panic("Lock %s not recursed @ %s:%d\n", rw->lock_object.lo_name, file, line); } #endif break; case RA_WLOCKED: case RA_WLOCKED | RA_RECURSED: case RA_WLOCKED | RA_NOTRECURSED: if (rw_wowner(rw) != curthread) panic("Lock %s not exclusively locked @ %s:%d\n", rw->lock_object.lo_name, file, line); if (rw_recursed(rw)) { if (what & RA_NOTRECURSED) panic("Lock %s recursed @ %s:%d\n", rw->lock_object.lo_name, file, line); } else if (what & RA_RECURSED) panic("Lock %s not recursed @ %s:%d\n", rw->lock_object.lo_name, file, line); break; case RA_UNLOCKED: #ifdef WITNESS witness_assert(&rw->lock_object, what, file, line); #else /* * If we hold a write lock fail. We can't reliably check * to see if we hold a read lock or not. */ if (rw_wowner(rw) == curthread) panic("Lock %s exclusively locked @ %s:%d\n", rw->lock_object.lo_name, file, line); #endif break; default: panic("Unknown rw lock assertion: %d @ %s:%d", what, file, line); } } #endif /* INVARIANT_SUPPORT */ #ifdef DDB void db_show_rwlock(const struct lock_object *lock) { const struct rwlock *rw; struct thread *td; rw = (const struct rwlock *)lock; db_printf(" state: "); if (rw->rw_lock == RW_UNLOCKED) db_printf("UNLOCKED\n"); else if (rw->rw_lock == RW_DESTROYED) { db_printf("DESTROYED\n"); return; } else if (rw->rw_lock & RW_LOCK_READ) db_printf("RLOCK: %ju locks\n", (uintmax_t)(RW_READERS(rw->rw_lock))); else { td = rw_wowner(rw); db_printf("WLOCK: %p (tid %d, pid %d, \"%s\")\n", td, td->td_tid, td->td_proc->p_pid, td->td_name); if (rw_recursed(rw)) db_printf(" recursed: %u\n", rw->rw_recurse); } db_printf(" waiters: "); switch (rw->rw_lock & (RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS)) { case RW_LOCK_READ_WAITERS: db_printf("readers\n"); break; case RW_LOCK_WRITE_WAITERS: db_printf("writers\n"); break; case RW_LOCK_READ_WAITERS | RW_LOCK_WRITE_WAITERS: db_printf("readers and writers\n"); break; default: db_printf("none\n"); break; } } #endif Index: head/sys/kern/kern_sx.c =================================================================== --- head/sys/kern/kern_sx.c (revision 314473) +++ head/sys/kern/kern_sx.c (revision 314474) @@ -1,1333 +1,1333 @@ /*- * 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; SYSCTL_INT(_debug_sx, OID_AUTO, delay_base, CTLFLAG_RW, &sx_delay.base, 0, ""); SYSCTL_INT(_debug_sx, OID_AUTO, delay_max, CTLFLAG_RW, &sx_delay.max, 0, ""); LOCK_DELAY_SYSINIT_DEFAULT(sx_delay); #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_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)); x = sx->sx_lock; for (;;) { KASSERT(x != SX_LOCK_DESTROYED, ("sx_try_slock() of destroyed sx @ %s:%d", file, line)); if (!(x & SX_LOCK_SHARED)) break; if (atomic_fcmpset_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) { uintptr_t tid, x; int error = 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); tid = (uintptr_t)curthread; x = SX_LOCK_UNLOCKED; if (!atomic_fcmpset_acq_ptr(&sx->sx_lock, &x, tid)) error = _sx_xlock_hard(sx, x, tid, opts, file, line); else LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(sx__acquire, sx, 0, 0, file, line, LOCKSTAT_WRITER); 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) { struct thread *td; uintptr_t tid, x; int rval; bool recursed; td = curthread; tid = (uintptr_t)td; if (SCHEDULER_STOPPED_TD(td)) 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)); rval = 1; recursed = false; x = SX_LOCK_UNLOCKED; for (;;) { if (atomic_fcmpset_acq_ptr(&sx->sx_lock, &x, tid)) break; if (x == SX_LOCK_UNLOCKED) continue; if (x == tid && (sx->lock_object.lo_flags & LO_RECURSABLE)) { sx->sx_recurse++; atomic_set_ptr(&sx->sx_lock, SX_LOCK_RECURSED); break; } rval = 0; break; } 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 (!recursed) LOCKSTAT_PROFILE_OBTAIN_RWLOCK_SUCCESS(sx__acquire, sx, 0, 0, file, line, LOCKSTAT_WRITER); TD_LOCKS_INC(curthread); } return (rval); } void _sx_xunlock(struct sx *sx, const char *file, int line) { 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); #if LOCK_DEBUG > 0 _sx_xunlock_hard(sx, (uintptr_t)curthread, file, line); #else __sx_xunlock(sx, curthread, file, line); #endif 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, + success = atomic_cmpset_acq_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 (__predict_false(x == SX_LOCK_UNLOCKED)) x = SX_READ_VALUE(sx); /* 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)); x = SX_READ_VALUE(sx); if (x & SX_LOCK_RECURSED) { /* The lock is recursed, unrecurse one level. */ 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; } LOCKSTAT_PROFILE_RELEASE_RWLOCK(sx__release, sx, LOCKSTAT_WRITER); if (x == tid && atomic_cmpset_rel_ptr(&sx->sx_lock, tid, SX_LOCK_UNLOCKED)) 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(); } static bool __always_inline __sx_slock_try(struct sx *sx, uintptr_t *xp, const char *file, int line) { /* * 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. */ while (*xp & SX_LOCK_SHARED) { MPASS(!(*xp & SX_LOCK_SHARED_WAITERS)); if (atomic_fcmpset_acq_ptr(&sx->sx_lock, xp, *xp + SX_ONE_SHARER)) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR4(KTR_LOCK, "%s: %p succeed %p -> %p", __func__, sx, (void *)*xp, (void *)(*xp + SX_ONE_SHARER)); return (true); } } return (false); } static int __noinline _sx_slock_hard(struct sx *sx, int opts, const char *file, int line, uintptr_t x) { GIANT_DECLARE; #ifdef ADAPTIVE_SX volatile struct thread *owner; #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 #ifdef KDTRACE_HOOKS all_time -= lockstat_nsecs(&sx->lock_object); 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 (__sx_slock_try(sx, &x, file, line)) break; #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); } int _sx_slock(struct sx *sx, int opts, const char *file, int line) { uintptr_t x; int error; 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 = 0; x = SX_READ_VALUE(sx); if (__predict_false(LOCKSTAT_OOL_PROFILE_ENABLED(sx__acquire) || !__sx_slock_try(sx, &x, file, line))) error = _sx_slock_hard(sx, opts, file, line, x); if (error == 0) { 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); } static bool __always_inline _sx_sunlock_try(struct sx *sx, uintptr_t *xp) { for (;;) { /* * We should never have sharers while at least one thread * holds a shared lock. */ KASSERT(!(*xp & 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(*xp) > 1) { if (atomic_fcmpset_rel_ptr(&sx->sx_lock, xp, *xp - SX_ONE_SHARER)) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR4(KTR_LOCK, "%s: %p succeeded %p -> %p", __func__, sx, (void *)*xp, (void *)(*xp - SX_ONE_SHARER)); return (true); } continue; } /* * If there aren't any waiters for an exclusive lock, * then try to drop it quickly. */ if (!(*xp & SX_LOCK_EXCLUSIVE_WAITERS)) { MPASS(*xp == SX_SHARERS_LOCK(1)); *xp = SX_SHARERS_LOCK(1); if (atomic_fcmpset_rel_ptr(&sx->sx_lock, xp, SX_LOCK_UNLOCKED)) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p last succeeded", __func__, sx); return (true); } continue; } break; } return (false); } static void __noinline _sx_sunlock_hard(struct sx *sx, uintptr_t x, const char *file, int line) { int wakeup_swapper; if (SCHEDULER_STOPPED()) return; LOCKSTAT_PROFILE_RELEASE_RWLOCK(sx__release, sx, LOCKSTAT_READER); for (;;) { if (_sx_sunlock_try(sx, &x)) break; /* * 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; } } void _sx_sunlock(struct sx *sx, const char *file, int line) { uintptr_t x; 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); x = SX_READ_VALUE(sx); if (__predict_false(LOCKSTAT_OOL_PROFILE_ENABLED(sx__release) || !_sx_sunlock_try(sx, &x))) _sx_sunlock_hard(sx, x, file, line); TD_LOCKS_DEC(curthread); } #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/mutex.h =================================================================== --- head/sys/sys/mutex.h (revision 314473) +++ head/sys/sys/mutex.h (revision 314474) @@ -1,525 +1,525 @@ /*- * Copyright (c) 1997 Berkeley Software Design, Inc. 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. * 3. Berkeley Software Design Inc's name may not be used to endorse or * promote products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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. * * from BSDI $Id: mutex.h,v 2.7.2.35 2000/04/27 03:10:26 cp Exp $ * $FreeBSD$ */ #ifndef _SYS_MUTEX_H_ #define _SYS_MUTEX_H_ #include #include #include #ifdef _KERNEL #include #include #include #include #include /* * Mutex types and options passed to mtx_init(). MTX_QUIET and MTX_DUPOK * can also be passed in. */ #define MTX_DEF 0x00000000 /* DEFAULT (sleep) lock */ #define MTX_SPIN 0x00000001 /* Spin lock (disables interrupts) */ #define MTX_RECURSE 0x00000004 /* Option: lock allowed to recurse */ #define MTX_NOWITNESS 0x00000008 /* Don't do any witness checking. */ #define MTX_NOPROFILE 0x00000020 /* Don't profile this lock */ #define MTX_NEW 0x00000040 /* Don't check for double-init */ /* * Option flags passed to certain lock/unlock routines, through the use * of corresponding mtx_{lock,unlock}_flags() interface macros. */ #define MTX_QUIET LOP_QUIET /* Don't log a mutex event */ #define MTX_DUPOK LOP_DUPOK /* Don't log a duplicate acquire */ /* * State bits kept in mutex->mtx_lock, for the DEFAULT lock type. None of this, * with the exception of MTX_UNOWNED, applies to spin locks. */ #define MTX_RECURSED 0x00000001 /* lock recursed (for MTX_DEF only) */ #define MTX_CONTESTED 0x00000002 /* lock contested (for MTX_DEF only) */ #define MTX_UNOWNED 0x00000004 /* Cookie for free mutex */ #define MTX_FLAGMASK (MTX_RECURSED | MTX_CONTESTED | MTX_UNOWNED) /* * Value stored in mutex->mtx_lock to denote a destroyed mutex. */ #define MTX_DESTROYED (MTX_CONTESTED | MTX_UNOWNED) /* * Prototypes * * NOTE: Functions prepended with `_' (underscore) are exported to other parts * of the kernel via macros, thus allowing us to use the cpp LOCK_FILE * and LOCK_LINE or for hiding the lock cookie crunching to the * consumers. These functions should not be called directly by any * code using the API. Their macros cover their functionality. * Functions with a `_' suffix are the entrypoint for the common * KPI covering both compat shims and fast path case. These can be * used by consumers willing to pass options, file and line * informations, in an option-independent way. * * [See below for descriptions] * */ void _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts); void _mtx_destroy(volatile uintptr_t *c); void mtx_sysinit(void *arg); int _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line); void mutex_init(void); #if LOCK_DEBUG > 0 void __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, int opts, const char *file, int line); void __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line); #else void __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, uintptr_t tid); void __mtx_unlock_sleep(volatile uintptr_t *c); #endif #ifdef SMP void _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v, uintptr_t tid, int opts, const char *file, int line); #endif void __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line); void __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line); void __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file, int line); int __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file, int line); void __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file, int line); #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) void __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line); #endif void thread_lock_flags_(struct thread *, int, const char *, int); #define thread_lock(tdp) \ thread_lock_flags_((tdp), 0, __FILE__, __LINE__) #define thread_lock_flags(tdp, opt) \ thread_lock_flags_((tdp), (opt), __FILE__, __LINE__) #define thread_unlock(tdp) \ mtx_unlock_spin((tdp)->td_lock) /* * Top-level macros to provide lock cookie once the actual mtx is passed. * They will also prevent passing a malformed object to the mtx KPI by * failing compilation as the mtx_lock reserved member will not be found. */ #define mtx_init(m, n, t, o) \ _mtx_init(&(m)->mtx_lock, n, t, o) #define mtx_destroy(m) \ _mtx_destroy(&(m)->mtx_lock) #define mtx_trylock_flags_(m, o, f, l) \ _mtx_trylock_flags_(&(m)->mtx_lock, o, f, l) #if LOCK_DEBUG > 0 #define _mtx_lock_sleep(m, v, t, o, f, l) \ __mtx_lock_sleep(&(m)->mtx_lock, v, t, o, f, l) #define _mtx_unlock_sleep(m, o, f, l) \ __mtx_unlock_sleep(&(m)->mtx_lock, o, f, l) #else #define _mtx_lock_sleep(m, v, t, o, f, l) \ __mtx_lock_sleep(&(m)->mtx_lock, v, t) #define _mtx_unlock_sleep(m, o, f, l) \ __mtx_unlock_sleep(&(m)->mtx_lock) #endif #ifdef SMP #define _mtx_lock_spin(m, v, t, o, f, l) \ _mtx_lock_spin_cookie(&(m)->mtx_lock, v, t, o, f, l) #endif #define _mtx_lock_flags(m, o, f, l) \ __mtx_lock_flags(&(m)->mtx_lock, o, f, l) #define _mtx_unlock_flags(m, o, f, l) \ __mtx_unlock_flags(&(m)->mtx_lock, o, f, l) #define _mtx_lock_spin_flags(m, o, f, l) \ __mtx_lock_spin_flags(&(m)->mtx_lock, o, f, l) #define _mtx_trylock_spin_flags(m, o, f, l) \ __mtx_trylock_spin_flags(&(m)->mtx_lock, o, f, l) #define _mtx_unlock_spin_flags(m, o, f, l) \ __mtx_unlock_spin_flags(&(m)->mtx_lock, o, f, l) #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) #define _mtx_assert(m, w, f, l) \ __mtx_assert(&(m)->mtx_lock, w, f, l) #endif #define mtx_recurse lock_object.lo_data /* Very simple operations on mtx_lock. */ /* Try to obtain mtx_lock once. */ #define _mtx_obtain_lock(mp, tid) \ atomic_cmpset_acq_ptr(&(mp)->mtx_lock, MTX_UNOWNED, (tid)) #define _mtx_obtain_lock_fetch(mp, vp, tid) \ - atomic_fcmpset_rel_ptr(&(mp)->mtx_lock, vp, (tid)) + atomic_fcmpset_acq_ptr(&(mp)->mtx_lock, vp, (tid)) /* Try to release mtx_lock if it is unrecursed and uncontested. */ #define _mtx_release_lock(mp, tid) \ atomic_cmpset_rel_ptr(&(mp)->mtx_lock, (tid), MTX_UNOWNED) /* Release mtx_lock quickly, assuming we own it. */ #define _mtx_release_lock_quick(mp) \ atomic_store_rel_ptr(&(mp)->mtx_lock, MTX_UNOWNED) /* * Full lock operations that are suitable to be inlined in non-debug * kernels. If the lock cannot be acquired or released trivially then * the work is deferred to another function. */ /* Lock a normal mutex. */ #define __mtx_lock(mp, tid, opts, file, line) do { \ uintptr_t _tid = (uintptr_t)(tid); \ uintptr_t _v = MTX_UNOWNED; \ \ if (__predict_false(LOCKSTAT_PROFILE_ENABLED(adaptive__acquire) ||\ !_mtx_obtain_lock_fetch((mp), &_v, _tid))) \ _mtx_lock_sleep((mp), _v, _tid, (opts), (file), (line));\ } while (0) /* * Lock a spin mutex. For spinlocks, we handle recursion inline (it * turns out that function calls can be significantly expensive on * some architectures). Since spin locks are not _too_ common, * inlining this code is not too big a deal. */ #ifdef SMP #define __mtx_lock_spin(mp, tid, opts, file, line) do { \ uintptr_t _tid = (uintptr_t)(tid); \ uintptr_t _v = MTX_UNOWNED; \ \ spinlock_enter(); \ if (!_mtx_obtain_lock_fetch((mp), &_v, _tid)) \ _mtx_lock_spin((mp), _v, _tid, (opts), (file), (line)); \ else \ LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, \ mp, 0, 0, file, line); \ } while (0) #define __mtx_trylock_spin(mp, tid, opts, file, line) __extension__ ({ \ uintptr_t _tid = (uintptr_t)(tid); \ int _ret; \ \ spinlock_enter(); \ if (((mp)->mtx_lock != MTX_UNOWNED || !_mtx_obtain_lock((mp), _tid))) {\ spinlock_exit(); \ _ret = 0; \ } else { \ LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, \ mp, 0, 0, file, line); \ _ret = 1; \ } \ _ret; \ }) #else /* SMP */ #define __mtx_lock_spin(mp, tid, opts, file, line) do { \ uintptr_t _tid = (uintptr_t)(tid); \ \ spinlock_enter(); \ if ((mp)->mtx_lock == _tid) \ (mp)->mtx_recurse++; \ else { \ KASSERT((mp)->mtx_lock == MTX_UNOWNED, ("corrupt spinlock")); \ (mp)->mtx_lock = _tid; \ } \ } while (0) #define __mtx_trylock_spin(mp, tid, opts, file, line) __extension__ ({ \ uintptr_t _tid = (uintptr_t)(tid); \ int _ret; \ \ spinlock_enter(); \ if ((mp)->mtx_lock != MTX_UNOWNED) { \ spinlock_exit(); \ _ret = 0; \ } else { \ (mp)->mtx_lock = _tid; \ _ret = 1; \ } \ _ret; \ }) #endif /* SMP */ /* Unlock a normal mutex. */ #define __mtx_unlock(mp, tid, opts, file, line) do { \ uintptr_t _tid = (uintptr_t)(tid); \ \ if (__predict_false(LOCKSTAT_PROFILE_ENABLED(adaptive__release) ||\ !_mtx_release_lock((mp), _tid))) \ _mtx_unlock_sleep((mp), (opts), (file), (line)); \ } while (0) /* * Unlock a spin mutex. For spinlocks, we can handle everything * inline, as it's pretty simple and a function call would be too * expensive (at least on some architectures). Since spin locks are * not _too_ common, inlining this code is not too big a deal. * * Since we always perform a spinlock_enter() when attempting to acquire a * spin lock, we need to always perform a matching spinlock_exit() when * releasing a spin lock. This includes the recursion cases. */ #ifdef SMP #define __mtx_unlock_spin(mp) do { \ if (mtx_recursed((mp))) \ (mp)->mtx_recurse--; \ else { \ LOCKSTAT_PROFILE_RELEASE_LOCK(spin__release, mp); \ _mtx_release_lock_quick((mp)); \ } \ spinlock_exit(); \ } while (0) #else /* SMP */ #define __mtx_unlock_spin(mp) do { \ if (mtx_recursed((mp))) \ (mp)->mtx_recurse--; \ else { \ LOCKSTAT_PROFILE_RELEASE_LOCK(spin__release, mp); \ (mp)->mtx_lock = MTX_UNOWNED; \ } \ spinlock_exit(); \ } while (0) #endif /* SMP */ /* * Exported lock manipulation interface. * * mtx_lock(m) locks MTX_DEF mutex `m' * * mtx_lock_spin(m) locks MTX_SPIN mutex `m' * * mtx_unlock(m) unlocks MTX_DEF mutex `m' * * mtx_unlock_spin(m) unlocks MTX_SPIN mutex `m' * * mtx_lock_spin_flags(m, opts) and mtx_lock_flags(m, opts) locks mutex `m' * and passes option flags `opts' to the "hard" function, if required. * With these routines, it is possible to pass flags such as MTX_QUIET * to the appropriate lock manipulation routines. * * mtx_trylock(m) attempts to acquire MTX_DEF mutex `m' but doesn't sleep if * it cannot. Rather, it returns 0 on failure and non-zero on success. * It does NOT handle recursion as we assume that if a caller is properly * using this part of the interface, he will know that the lock in question * is _not_ recursed. * * mtx_trylock_flags(m, opts) is used the same way as mtx_trylock() but accepts * relevant option flags `opts.' * * mtx_trylock_spin(m) attempts to acquire MTX_SPIN mutex `m' but doesn't * spin if it cannot. Rather, it returns 0 on failure and non-zero on * success. It always returns failure for recursed lock attempts. * * mtx_initialized(m) returns non-zero if the lock `m' has been initialized. * * mtx_owned(m) returns non-zero if the current thread owns the lock `m' * * mtx_recursed(m) returns non-zero if the lock `m' is presently recursed. */ #define mtx_lock(m) mtx_lock_flags((m), 0) #define mtx_lock_spin(m) mtx_lock_spin_flags((m), 0) #define mtx_trylock(m) mtx_trylock_flags((m), 0) #define mtx_trylock_spin(m) mtx_trylock_spin_flags((m), 0) #define mtx_unlock(m) mtx_unlock_flags((m), 0) #define mtx_unlock_spin(m) mtx_unlock_spin_flags((m), 0) struct mtx_pool; struct mtx_pool *mtx_pool_create(const char *mtx_name, int pool_size, int opts); void mtx_pool_destroy(struct mtx_pool **poolp); struct mtx *mtx_pool_find(struct mtx_pool *pool, void *ptr); struct mtx *mtx_pool_alloc(struct mtx_pool *pool); #define mtx_pool_lock(pool, ptr) \ mtx_lock(mtx_pool_find((pool), (ptr))) #define mtx_pool_lock_spin(pool, ptr) \ mtx_lock_spin(mtx_pool_find((pool), (ptr))) #define mtx_pool_unlock(pool, ptr) \ mtx_unlock(mtx_pool_find((pool), (ptr))) #define mtx_pool_unlock_spin(pool, ptr) \ mtx_unlock_spin(mtx_pool_find((pool), (ptr))) /* * mtxpool_sleep is a general purpose pool of sleep mutexes. */ extern struct mtx_pool *mtxpool_sleep; #ifndef LOCK_DEBUG #error LOCK_DEBUG not defined, include before #endif #if LOCK_DEBUG > 0 || defined(MUTEX_NOINLINE) #define mtx_lock_flags_(m, opts, file, line) \ _mtx_lock_flags((m), (opts), (file), (line)) #define mtx_unlock_flags_(m, opts, file, line) \ _mtx_unlock_flags((m), (opts), (file), (line)) #define mtx_lock_spin_flags_(m, opts, file, line) \ _mtx_lock_spin_flags((m), (opts), (file), (line)) #define mtx_trylock_spin_flags_(m, opts, file, line) \ _mtx_trylock_spin_flags((m), (opts), (file), (line)) #define mtx_unlock_spin_flags_(m, opts, file, line) \ _mtx_unlock_spin_flags((m), (opts), (file), (line)) #else /* LOCK_DEBUG == 0 && !MUTEX_NOINLINE */ #define mtx_lock_flags_(m, opts, file, line) \ __mtx_lock((m), curthread, (opts), (file), (line)) #define mtx_unlock_flags_(m, opts, file, line) \ __mtx_unlock((m), curthread, (opts), (file), (line)) #define mtx_lock_spin_flags_(m, opts, file, line) \ __mtx_lock_spin((m), curthread, (opts), (file), (line)) #define mtx_trylock_spin_flags_(m, opts, file, line) \ __mtx_trylock_spin((m), curthread, (opts), (file), (line)) #define mtx_unlock_spin_flags_(m, opts, file, line) \ __mtx_unlock_spin((m)) #endif /* LOCK_DEBUG > 0 || MUTEX_NOINLINE */ #ifdef INVARIANTS #define mtx_assert_(m, what, file, line) \ _mtx_assert((m), (what), (file), (line)) #define GIANT_REQUIRED mtx_assert_(&Giant, MA_OWNED, __FILE__, __LINE__) #else /* INVARIANTS */ #define mtx_assert_(m, what, file, line) (void)0 #define GIANT_REQUIRED #endif /* INVARIANTS */ #define mtx_lock_flags(m, opts) \ mtx_lock_flags_((m), (opts), LOCK_FILE, LOCK_LINE) #define mtx_unlock_flags(m, opts) \ mtx_unlock_flags_((m), (opts), LOCK_FILE, LOCK_LINE) #define mtx_lock_spin_flags(m, opts) \ mtx_lock_spin_flags_((m), (opts), LOCK_FILE, LOCK_LINE) #define mtx_unlock_spin_flags(m, opts) \ mtx_unlock_spin_flags_((m), (opts), LOCK_FILE, LOCK_LINE) #define mtx_trylock_flags(m, opts) \ mtx_trylock_flags_((m), (opts), LOCK_FILE, LOCK_LINE) #define mtx_trylock_spin_flags(m, opts) \ mtx_trylock_spin_flags_((m), (opts), LOCK_FILE, LOCK_LINE) #define mtx_assert(m, what) \ mtx_assert_((m), (what), __FILE__, __LINE__) #define mtx_sleep(chan, mtx, pri, wmesg, timo) \ _sleep((chan), &(mtx)->lock_object, (pri), (wmesg), \ tick_sbt * (timo), 0, C_HARDCLOCK) #define MTX_READ_VALUE(m) ((m)->mtx_lock) #define mtx_initialized(m) lock_initialized(&(m)->lock_object) #define lv_mtx_owner(v) ((struct thread *)((v) & ~MTX_FLAGMASK)) #define mtx_owner(m) lv_mtx_owner(MTX_READ_VALUE(m)) #define mtx_owned(m) (mtx_owner(m) == curthread) #define mtx_recursed(m) ((m)->mtx_recurse != 0) #define mtx_name(m) ((m)->lock_object.lo_name) /* * Global locks. */ extern struct mtx Giant; extern struct mtx blocked_lock; /* * Giant lock manipulation and clean exit macros. * Used to replace return with an exit Giant and return. * * Note that DROP_GIANT*() needs to be paired with PICKUP_GIANT() * The #ifndef is to allow lint-like tools to redefine DROP_GIANT. */ #ifndef DROP_GIANT #define DROP_GIANT() \ do { \ int _giantcnt = 0; \ WITNESS_SAVE_DECL(Giant); \ \ if (mtx_owned(&Giant)) { \ WITNESS_SAVE(&Giant.lock_object, Giant); \ for (_giantcnt = 0; mtx_owned(&Giant) && \ !SCHEDULER_STOPPED(); _giantcnt++) \ mtx_unlock(&Giant); \ } #define PICKUP_GIANT() \ PARTIAL_PICKUP_GIANT(); \ } while (0) #define PARTIAL_PICKUP_GIANT() \ mtx_assert(&Giant, MA_NOTOWNED); \ if (_giantcnt > 0) { \ while (_giantcnt--) \ mtx_lock(&Giant); \ WITNESS_RESTORE(&Giant.lock_object, Giant); \ } #endif struct mtx_args { void *ma_mtx; const char *ma_desc; int ma_opts; }; #define MTX_SYSINIT(name, mtx, desc, opts) \ static struct mtx_args name##_args = { \ (mtx), \ (desc), \ (opts) \ }; \ SYSINIT(name##_mtx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ mtx_sysinit, &name##_args); \ SYSUNINIT(name##_mtx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ _mtx_destroy, __DEVOLATILE(void *, &(mtx)->mtx_lock)) /* * The INVARIANTS-enabled mtx_assert() functionality. * * The constants need to be defined for INVARIANT_SUPPORT infrastructure * support as _mtx_assert() itself uses them and the latter implies that * _mtx_assert() must build. */ #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) #define MA_OWNED LA_XLOCKED #define MA_NOTOWNED LA_UNLOCKED #define MA_RECURSED LA_RECURSED #define MA_NOTRECURSED LA_NOTRECURSED #endif /* * Common lock type names. */ #define MTX_NETWORK_LOCK "network driver" #endif /* _KERNEL */ #endif /* _SYS_MUTEX_H_ */