Index: head/sys/kern/kern_lockstat.c =================================================================== --- head/sys/kern/kern_lockstat.c (revision 312889) +++ head/sys/kern/kern_lockstat.c (revision 312890) @@ -1,81 +1,82 @@ /*- * Copyright 2008-2009 Stacey Son * * 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 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 AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include __FBSDID("$FreeBSD$"); #include +#include #include #include #include #include SDT_PROVIDER_DEFINE(lockstat); SDT_PROBE_DEFINE1(lockstat, , , adaptive__acquire, "struct mtx *"); SDT_PROBE_DEFINE1(lockstat, , , adaptive__release, "struct mtx *"); SDT_PROBE_DEFINE2(lockstat, , , adaptive__spin, "struct mtx *", "uint64_t"); SDT_PROBE_DEFINE2(lockstat, , , adaptive__block, "struct mtx *", "uint64_t"); SDT_PROBE_DEFINE1(lockstat, , , spin__acquire, "struct mtx *"); SDT_PROBE_DEFINE1(lockstat, , , spin__release, "struct mtx *"); SDT_PROBE_DEFINE2(lockstat, , , spin__spin, "struct mtx *", "uint64_t"); SDT_PROBE_DEFINE2(lockstat, , , rw__acquire, "struct rwlock *", "int"); SDT_PROBE_DEFINE2(lockstat, , , rw__release, "struct rwlock *", "int"); SDT_PROBE_DEFINE5(lockstat, , , rw__block, "struct rwlock *", "uint64_t", "int", "int", "int"); SDT_PROBE_DEFINE2(lockstat, , , rw__spin, "struct rwlock *", "uint64_t"); SDT_PROBE_DEFINE1(lockstat, , , rw__upgrade, "struct rwlock *"); SDT_PROBE_DEFINE1(lockstat, , , rw__downgrade, "struct rwlock *"); SDT_PROBE_DEFINE2(lockstat, , , sx__acquire, "struct sx *", "int"); SDT_PROBE_DEFINE2(lockstat, , , sx__release, "struct sx *", "int"); SDT_PROBE_DEFINE5(lockstat, , , sx__block, "struct sx *", "uint64_t", "int", "int", "int"); SDT_PROBE_DEFINE2(lockstat, , , sx__spin, "struct sx *", "uint64_t"); SDT_PROBE_DEFINE1(lockstat, , , sx__upgrade, "struct sx *"); SDT_PROBE_DEFINE1(lockstat, , , sx__downgrade, "struct sx *"); SDT_PROBE_DEFINE2(lockstat, , , thread__spin, "struct mtx *", "uint64_t"); -int lockstat_enabled = 0; +int __read_mostly lockstat_enabled; uint64_t lockstat_nsecs(struct lock_object *lo) { struct bintime bt; uint64_t ns; if (!lockstat_enabled) return (0); if ((lo->lo_flags & LO_NOPROFILE) != 0) return (0); binuptime(&bt); ns = bt.sec * (uint64_t)1000000000; ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32; return (ns); } Index: head/sys/kern/kern_mutex.c =================================================================== --- head/sys/kern/kern_mutex.c (revision 312889) +++ head/sys/kern/kern_mutex.c (revision 312890) @@ -1,1139 +1,1139 @@ /*- * Copyright (c) 1998 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_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ */ /* * Machine independent bits of mutex implementation. */ #include __FBSDID("$FreeBSD$"); #include "opt_adaptive_mutexes.h" #include "opt_ddb.h" #include "opt_hwpmc_hooks.h" #include "opt_sched.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) #define ADAPTIVE_MUTEXES #endif #ifdef HWPMC_HOOKS #include PMC_SOFT_DEFINE( , , lock, failed); #endif /* * Return the mutex address when the lock cookie address is provided. * This functionality assumes that struct mtx* have a member named mtx_lock. */ #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock)) /* * Internal utility macros. */ #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) static void assert_mtx(const struct lock_object *lock, int what); #ifdef DDB static void db_show_mtx(const struct lock_object *lock); #endif static void lock_mtx(struct lock_object *lock, uintptr_t how); static void lock_spin(struct lock_object *lock, uintptr_t how); #ifdef KDTRACE_HOOKS static int owner_mtx(const struct lock_object *lock, struct thread **owner); #endif static uintptr_t unlock_mtx(struct lock_object *lock); static uintptr_t unlock_spin(struct lock_object *lock); /* * Lock classes for sleep and spin mutexes. */ struct lock_class lock_class_mtx_sleep = { .lc_name = "sleep mutex", .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, .lc_assert = assert_mtx, #ifdef DDB .lc_ddb_show = db_show_mtx, #endif .lc_lock = lock_mtx, .lc_unlock = unlock_mtx, #ifdef KDTRACE_HOOKS .lc_owner = owner_mtx, #endif }; struct lock_class lock_class_mtx_spin = { .lc_name = "spin mutex", .lc_flags = LC_SPINLOCK | LC_RECURSABLE, .lc_assert = assert_mtx, #ifdef DDB .lc_ddb_show = db_show_mtx, #endif .lc_lock = lock_spin, .lc_unlock = unlock_spin, #ifdef KDTRACE_HOOKS .lc_owner = owner_mtx, #endif }; #ifdef ADAPTIVE_MUTEXES static SYSCTL_NODE(_debug, OID_AUTO, mtx, CTLFLAG_RD, NULL, "mtx debugging"); -static struct lock_delay_config mtx_delay = { +static struct lock_delay_config __read_mostly mtx_delay = { .initial = 1000, .step = 500, .min = 100, .max = 5000, }; SYSCTL_INT(_debug_mtx, OID_AUTO, delay_initial, CTLFLAG_RW, &mtx_delay.initial, 0, ""); SYSCTL_INT(_debug_mtx, OID_AUTO, delay_step, CTLFLAG_RW, &mtx_delay.step, 0, ""); SYSCTL_INT(_debug_mtx, OID_AUTO, delay_min, CTLFLAG_RW, &mtx_delay.min, 0, ""); SYSCTL_INT(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max, 0, ""); static void mtx_delay_sysinit(void *dummy) { mtx_delay.initial = mp_ncpus * 25; mtx_delay.step = (mp_ncpus * 25) / 2; mtx_delay.min = mp_ncpus * 5; mtx_delay.max = mp_ncpus * 25 * 10; } LOCK_DELAY_SYSINIT(mtx_delay_sysinit); #endif static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin, CTLFLAG_RD, NULL, "mtx spin debugging"); -static struct lock_delay_config mtx_spin_delay = { +static struct lock_delay_config __read_mostly mtx_spin_delay = { .initial = 1000, .step = 500, .min = 100, .max = 5000, }; SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_initial, CTLFLAG_RW, &mtx_spin_delay.initial, 0, ""); SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_step, CTLFLAG_RW, &mtx_spin_delay.step, 0, ""); SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_min, CTLFLAG_RW, &mtx_spin_delay.min, 0, ""); SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_spin_delay.max, 0, ""); static void mtx_spin_delay_sysinit(void *dummy) { mtx_spin_delay.initial = mp_ncpus * 25; mtx_spin_delay.step = (mp_ncpus * 25) / 2; mtx_spin_delay.min = mp_ncpus * 5; mtx_spin_delay.max = mp_ncpus * 25 * 10; } LOCK_DELAY_SYSINIT(mtx_spin_delay_sysinit); /* * System-wide mutexes */ struct mtx blocked_lock; struct mtx Giant; void assert_mtx(const struct lock_object *lock, int what) { mtx_assert((const struct mtx *)lock, what); } void lock_mtx(struct lock_object *lock, uintptr_t how) { mtx_lock((struct mtx *)lock); } void lock_spin(struct lock_object *lock, uintptr_t how) { panic("spin locks can only use msleep_spin"); } uintptr_t unlock_mtx(struct lock_object *lock) { struct mtx *m; m = (struct mtx *)lock; mtx_assert(m, MA_OWNED | MA_NOTRECURSED); mtx_unlock(m); return (0); } uintptr_t unlock_spin(struct lock_object *lock) { panic("spin locks can only use msleep_spin"); } #ifdef KDTRACE_HOOKS int owner_mtx(const struct lock_object *lock, struct thread **owner) { const struct mtx *m; uintptr_t x; m = (const struct mtx *)lock; x = m->mtx_lock; *owner = (struct thread *)(x & ~MTX_FLAGMASK); return (x != MTX_UNOWNED); } #endif /* * Function versions of the inlined __mtx_* macros. These are used by * modules and can also be called from assembly language if needed. */ void __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line) { struct mtx *m; if (SCHEDULER_STOPPED()) return; m = mtxlock2mtx(c); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d", curthread, m->lock_object.lo_name, file, line)); KASSERT(m->mtx_lock != MTX_DESTROYED, ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, file, line)); WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); __mtx_lock(m, curthread, opts, file, line); LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, line); WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE, file, line); TD_LOCKS_INC(curthread); } void __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line) { struct mtx *m; if (SCHEDULER_STOPPED()) return; m = mtxlock2mtx(c); KASSERT(m->mtx_lock != MTX_DESTROYED, ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, file, line)); WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, line); mtx_assert(m, MA_OWNED); __mtx_unlock(m, curthread, opts, file, line); TD_LOCKS_DEC(curthread); } void __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file, int line) { struct mtx *m; if (SCHEDULER_STOPPED()) return; m = mtxlock2mtx(c); KASSERT(m->mtx_lock != MTX_DESTROYED, ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, ("mtx_lock_spin() of sleep mutex %s @ %s:%d", m->lock_object.lo_name, file, line)); if (mtx_owned(m)) KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || (opts & MTX_RECURSE) != 0, ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", m->lock_object.lo_name, file, line)); opts &= ~MTX_RECURSE; WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); __mtx_lock_spin(m, curthread, opts, file, line); LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, line); WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); } int __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file, int line) { struct mtx *m; if (SCHEDULER_STOPPED()) return (1); m = mtxlock2mtx(c); KASSERT(m->mtx_lock != MTX_DESTROYED, ("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line)); KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, ("mtx_trylock_spin() of sleep mutex %s @ %s:%d", m->lock_object.lo_name, file, line)); KASSERT((opts & MTX_RECURSE) == 0, ("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n", m->lock_object.lo_name, file, line)); if (__mtx_trylock_spin(m, curthread, opts, file, line)) { LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line); WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); return (1); } LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line); return (0); } void __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file, int line) { struct mtx *m; if (SCHEDULER_STOPPED()) return; m = mtxlock2mtx(c); KASSERT(m->mtx_lock != MTX_DESTROYED, ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", m->lock_object.lo_name, file, line)); WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, line); mtx_assert(m, MA_OWNED); __mtx_unlock_spin(m); } /* * The important part of mtx_trylock{,_flags}() * Tries to acquire lock `m.' If this function is called on a mutex that * is already owned, it will recursively acquire the lock. */ int _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line) { struct mtx *m; #ifdef LOCK_PROFILING uint64_t waittime = 0; int contested = 0; #endif int rval; if (SCHEDULER_STOPPED()) return (1); m = mtxlock2mtx(c); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", curthread, m->lock_object.lo_name, file, line)); KASSERT(m->mtx_lock != MTX_DESTROYED, ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, file, line)); if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || (opts & MTX_RECURSE) != 0)) { m->mtx_recurse++; atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); rval = 1; } else rval = _mtx_obtain_lock(m, (uintptr_t)curthread); opts &= ~MTX_RECURSE; LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); if (rval) { WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, file, line); TD_LOCKS_INC(curthread); if (m->mtx_recurse == 0) LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested, waittime, file, line); } return (rval); } /* * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. * * We call this if the lock is either contested (i.e. we need to go to * sleep waiting for it), or if we need to recurse on it. */ void __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts, const char *file, int line) { struct mtx *m; struct turnstile *ts; uintptr_t v; #ifdef ADAPTIVE_MUTEXES volatile struct thread *owner; #endif #ifdef KTR int cont_logged = 0; #endif #ifdef LOCK_PROFILING int contested = 0; uint64_t waittime = 0; #endif #if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS) struct lock_delay_arg lda; #endif #ifdef KDTRACE_HOOKS u_int sleep_cnt = 0; int64_t sleep_time = 0; int64_t all_time = 0; #endif if (SCHEDULER_STOPPED()) return; #if defined(ADAPTIVE_MUTEXES) lock_delay_arg_init(&lda, &mtx_delay); #elif defined(KDTRACE_HOOKS) lock_delay_arg_init(&lda, NULL); #endif m = mtxlock2mtx(c); v = MTX_READ_VALUE(m); if (__predict_false(lv_mtx_owner(v) == (struct thread *)tid)) { KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || (opts & MTX_RECURSE) != 0, ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", m->lock_object.lo_name, file, line)); opts &= ~MTX_RECURSE; m->mtx_recurse++; atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); if (LOCK_LOG_TEST(&m->lock_object, opts)) CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); return; } opts &= ~MTX_RECURSE; #ifdef HWPMC_HOOKS PMC_SOFT_CALL( , , lock, failed); #endif lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); if (LOCK_LOG_TEST(&m->lock_object, opts)) CTR4(KTR_LOCK, "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", m->lock_object.lo_name, (void *)m->mtx_lock, file, line); #ifdef KDTRACE_HOOKS all_time -= lockstat_nsecs(&m->lock_object); #endif for (;;) { if (v == MTX_UNOWNED) { if (_mtx_obtain_lock(m, tid)) break; v = MTX_READ_VALUE(m); continue; } #ifdef KDTRACE_HOOKS lda.spin_cnt++; #endif #ifdef ADAPTIVE_MUTEXES /* * If the owner is running on another CPU, spin until the * owner stops running or the state of the lock changes. */ owner = lv_mtx_owner(v); if (TD_IS_RUNNING(owner)) { if (LOCK_LOG_TEST(&m->lock_object, 0)) CTR3(KTR_LOCK, "%s: spinning on %p held by %p", __func__, m, owner); KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), "spinning", "lockname:\"%s\"", m->lock_object.lo_name); do { lock_delay(&lda); v = MTX_READ_VALUE(m); owner = lv_mtx_owner(v); } while (v != MTX_UNOWNED && TD_IS_RUNNING(owner)); KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), "running"); continue; } #endif ts = turnstile_trywait(&m->lock_object); v = MTX_READ_VALUE(m); /* * Check if the lock has been released while spinning for * the turnstile chain lock. */ if (v == MTX_UNOWNED) { turnstile_cancel(ts); continue; } #ifdef ADAPTIVE_MUTEXES /* * 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. */ owner = lv_mtx_owner(v); if (TD_IS_RUNNING(owner)) { turnstile_cancel(ts); continue; } #endif /* * If the mutex isn't already contested and a failure occurs * setting the contested bit, the mutex was either released * or the state of the MTX_RECURSED bit changed. */ if ((v & MTX_CONTESTED) == 0 && !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) { turnstile_cancel(ts); v = MTX_READ_VALUE(m); continue; } /* * We definitely must sleep for this lock. */ mtx_assert(m, MA_NOTOWNED); #ifdef KTR if (!cont_logged) { CTR6(KTR_CONTENTION, "contention: %p at %s:%d wants %s, taken by %s:%d", (void *)tid, file, line, m->lock_object.lo_name, WITNESS_FILE(&m->lock_object), WITNESS_LINE(&m->lock_object)); cont_logged = 1; } #endif /* * Block on the turnstile. */ #ifdef KDTRACE_HOOKS sleep_time -= lockstat_nsecs(&m->lock_object); #endif turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); #ifdef KDTRACE_HOOKS sleep_time += lockstat_nsecs(&m->lock_object); sleep_cnt++; #endif v = MTX_READ_VALUE(m); } #ifdef KDTRACE_HOOKS all_time += lockstat_nsecs(&m->lock_object); #endif #ifdef KTR if (cont_logged) { CTR4(KTR_CONTENTION, "contention end: %s acquired by %p at %s:%d", m->lock_object.lo_name, (void *)tid, file, line); } #endif LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested, waittime, file, line); #ifdef KDTRACE_HOOKS if (sleep_time) LOCKSTAT_RECORD1(adaptive__block, m, sleep_time); /* * Only record the loops spinning and not sleeping. */ if (lda.spin_cnt > sleep_cnt) LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time); #endif } static void _mtx_lock_spin_failed(struct mtx *m) { struct thread *td; td = mtx_owner(m); /* If the mutex is unlocked, try again. */ if (td == NULL) return; printf( "spin lock %p (%s) held by %p (tid %d) too long\n", m, m->lock_object.lo_name, td, td->td_tid); #ifdef WITNESS witness_display_spinlock(&m->lock_object, td, printf); #endif panic("spin lock held too long"); } #ifdef SMP /* * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock. * * This is only called if we need to actually spin for the lock. Recursion * is handled inline. */ void _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts, const char *file, int line) { struct mtx *m; struct lock_delay_arg lda; uintptr_t v; #ifdef LOCK_PROFILING int contested = 0; uint64_t waittime = 0; #endif #ifdef KDTRACE_HOOKS int64_t spin_time = 0; #endif if (SCHEDULER_STOPPED()) return; lock_delay_arg_init(&lda, &mtx_spin_delay); m = mtxlock2mtx(c); if (LOCK_LOG_TEST(&m->lock_object, opts)) CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), "spinning", "lockname:\"%s\"", m->lock_object.lo_name); #ifdef HWPMC_HOOKS PMC_SOFT_CALL( , , lock, failed); #endif lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); #ifdef KDTRACE_HOOKS spin_time -= lockstat_nsecs(&m->lock_object); #endif v = MTX_READ_VALUE(m); for (;;) { if (v == MTX_UNOWNED) { if (_mtx_obtain_lock(m, tid)) break; v = MTX_READ_VALUE(m); continue; } /* Give interrupts a chance while we spin. */ spinlock_exit(); do { if (lda.spin_cnt < 10000000) { lock_delay(&lda); } else { lda.spin_cnt++; if (lda.spin_cnt < 60000000 || kdb_active || panicstr != NULL) DELAY(1); else _mtx_lock_spin_failed(m); cpu_spinwait(); } v = MTX_READ_VALUE(m); } while (v != MTX_UNOWNED); spinlock_enter(); } #ifdef KDTRACE_HOOKS spin_time += lockstat_nsecs(&m->lock_object); #endif if (LOCK_LOG_TEST(&m->lock_object, opts)) CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid), "running"); #ifdef KDTRACE_HOOKS LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, contested, waittime, file, line); if (spin_time != 0) LOCKSTAT_RECORD1(spin__spin, m, spin_time); #endif } #endif /* SMP */ void thread_lock_flags_(struct thread *td, int opts, const char *file, int line) { struct mtx *m; uintptr_t tid, v; struct lock_delay_arg lda; #ifdef LOCK_PROFILING int contested = 0; uint64_t waittime = 0; #endif #ifdef KDTRACE_HOOKS int64_t spin_time = 0; #endif tid = (uintptr_t)curthread; if (SCHEDULER_STOPPED()) { /* * Ensure that spinlock sections are balanced even when the * scheduler is stopped, since we may otherwise inadvertently * re-enable interrupts while dumping core. */ spinlock_enter(); return; } lock_delay_arg_init(&lda, &mtx_spin_delay); #ifdef KDTRACE_HOOKS spin_time -= lockstat_nsecs(&td->td_lock->lock_object); #endif for (;;) { retry: spinlock_enter(); m = td->td_lock; KASSERT(m->mtx_lock != MTX_DESTROYED, ("thread_lock() of destroyed mutex @ %s:%d", file, line)); KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, ("thread_lock() of sleep mutex %s @ %s:%d", m->lock_object.lo_name, file, line)); if (mtx_owned(m)) KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", m->lock_object.lo_name, file, line)); WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); v = MTX_READ_VALUE(m); for (;;) { if (v == MTX_UNOWNED) { if (_mtx_obtain_lock(m, tid)) break; v = MTX_READ_VALUE(m); continue; } if (v == tid) { m->mtx_recurse++; break; } #ifdef HWPMC_HOOKS PMC_SOFT_CALL( , , lock, failed); #endif lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); /* Give interrupts a chance while we spin. */ spinlock_exit(); do { if (lda.spin_cnt < 10000000) { lock_delay(&lda); } else { lda.spin_cnt++; if (lda.spin_cnt < 60000000 || kdb_active || panicstr != NULL) DELAY(1); else _mtx_lock_spin_failed(m); cpu_spinwait(); } if (m != td->td_lock) goto retry; v = MTX_READ_VALUE(m); } while (v != MTX_UNOWNED); spinlock_enter(); } if (m == td->td_lock) break; __mtx_unlock_spin(m); /* does spinlock_exit() */ } #ifdef KDTRACE_HOOKS spin_time += lockstat_nsecs(&m->lock_object); #endif if (m->mtx_recurse == 0) LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m, contested, waittime, file, line); LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, line); WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); #ifdef KDTRACE_HOOKS if (spin_time != 0) LOCKSTAT_RECORD1(thread__spin, m, spin_time); #endif } struct mtx * thread_lock_block(struct thread *td) { struct mtx *lock; THREAD_LOCK_ASSERT(td, MA_OWNED); lock = td->td_lock; td->td_lock = &blocked_lock; mtx_unlock_spin(lock); return (lock); } void thread_lock_unblock(struct thread *td, struct mtx *new) { mtx_assert(new, MA_OWNED); MPASS(td->td_lock == &blocked_lock); atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); } void thread_lock_set(struct thread *td, struct mtx *new) { struct mtx *lock; mtx_assert(new, MA_OWNED); THREAD_LOCK_ASSERT(td, MA_OWNED); lock = td->td_lock; td->td_lock = new; mtx_unlock_spin(lock); } /* * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. * * We are only called here if the lock is recursed or contested (i.e. we * need to wake up a blocked thread). */ void __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line) { struct mtx *m; struct turnstile *ts; if (SCHEDULER_STOPPED()) return; m = mtxlock2mtx(c); if (mtx_recursed(m)) { if (--(m->mtx_recurse) == 0) atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); if (LOCK_LOG_TEST(&m->lock_object, opts)) CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); return; } /* * We have to lock the chain before the turnstile so this turnstile * can be removed from the hash list if it is empty. */ turnstile_chain_lock(&m->lock_object); ts = turnstile_lookup(&m->lock_object); if (LOCK_LOG_TEST(&m->lock_object, opts)) CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); MPASS(ts != NULL); turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); _mtx_release_lock_quick(m); /* * This turnstile is now no longer associated with the mutex. We can * unlock the chain lock so a new turnstile may take it's place. */ turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); turnstile_chain_unlock(&m->lock_object); } /* * All the unlocking of MTX_SPIN locks is done inline. * See the __mtx_unlock_spin() macro for the details. */ /* * The backing function for the INVARIANTS-enabled mtx_assert() */ #ifdef INVARIANT_SUPPORT void __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line) { const struct mtx *m; if (panicstr != NULL || dumping || SCHEDULER_STOPPED()) return; m = mtxlock2mtx(c); switch (what) { case MA_OWNED: case MA_OWNED | MA_RECURSED: case MA_OWNED | MA_NOTRECURSED: if (!mtx_owned(m)) panic("mutex %s not owned at %s:%d", m->lock_object.lo_name, file, line); if (mtx_recursed(m)) { if ((what & MA_NOTRECURSED) != 0) panic("mutex %s recursed at %s:%d", m->lock_object.lo_name, file, line); } else if ((what & MA_RECURSED) != 0) { panic("mutex %s unrecursed at %s:%d", m->lock_object.lo_name, file, line); } break; case MA_NOTOWNED: if (mtx_owned(m)) panic("mutex %s owned at %s:%d", m->lock_object.lo_name, file, line); break; default: panic("unknown mtx_assert at %s:%d", file, line); } } #endif /* * General init routine used by the MTX_SYSINIT() macro. */ void mtx_sysinit(void *arg) { struct mtx_args *margs = arg; mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); } /* * Mutex initialization routine; initialize lock `m' of type contained in * `opts' with options contained in `opts' and name `name.' The optional * lock type `type' is used as a general lock category name for use with * witness. */ void _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts) { struct mtx *m; struct lock_class *class; int flags; m = mtxlock2mtx(c); MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0); ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, ("%s: mtx_lock not aligned for %s: %p", __func__, name, &m->mtx_lock)); /* Determine lock class and lock flags. */ if (opts & MTX_SPIN) class = &lock_class_mtx_spin; else class = &lock_class_mtx_sleep; flags = 0; if (opts & MTX_QUIET) flags |= LO_QUIET; if (opts & MTX_RECURSE) flags |= LO_RECURSABLE; if ((opts & MTX_NOWITNESS) == 0) flags |= LO_WITNESS; if (opts & MTX_DUPOK) flags |= LO_DUPOK; if (opts & MTX_NOPROFILE) flags |= LO_NOPROFILE; if (opts & MTX_NEW) flags |= LO_NEW; /* Initialize mutex. */ lock_init(&m->lock_object, class, name, type, flags); m->mtx_lock = MTX_UNOWNED; m->mtx_recurse = 0; } /* * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be * passed in as a flag here because if the corresponding mtx_init() was * called with MTX_QUIET set, then it will already be set in the mutex's * flags. */ void _mtx_destroy(volatile uintptr_t *c) { struct mtx *m; m = mtxlock2mtx(c); if (!mtx_owned(m)) MPASS(mtx_unowned(m)); else { MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); /* Perform the non-mtx related part of mtx_unlock_spin(). */ if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) spinlock_exit(); else TD_LOCKS_DEC(curthread); lock_profile_release_lock(&m->lock_object); /* Tell witness this isn't locked to make it happy. */ WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, __LINE__); } m->mtx_lock = MTX_DESTROYED; lock_destroy(&m->lock_object); } /* * Intialize the mutex code and system mutexes. This is called from the MD * startup code prior to mi_startup(). The per-CPU data space needs to be * setup before this is called. */ void mutex_init(void) { /* Setup turnstiles so that sleep mutexes work. */ init_turnstiles(); /* * Initialize mutexes. */ mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN); mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN); mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN); mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN); mtx_init(&devmtx, "cdev", NULL, MTX_DEF); mtx_lock(&Giant); } #ifdef DDB void db_show_mtx(const struct lock_object *lock) { struct thread *td; const struct mtx *m; m = (const struct mtx *)lock; db_printf(" flags: {"); if (LOCK_CLASS(lock) == &lock_class_mtx_spin) db_printf("SPIN"); else db_printf("DEF"); if (m->lock_object.lo_flags & LO_RECURSABLE) db_printf(", RECURSE"); if (m->lock_object.lo_flags & LO_DUPOK) db_printf(", DUPOK"); db_printf("}\n"); db_printf(" state: {"); if (mtx_unowned(m)) db_printf("UNOWNED"); else if (mtx_destroyed(m)) db_printf("DESTROYED"); else { db_printf("OWNED"); if (m->mtx_lock & MTX_CONTESTED) db_printf(", CONTESTED"); if (m->mtx_lock & MTX_RECURSED) db_printf(", RECURSED"); } db_printf("}\n"); if (!mtx_unowned(m) && !mtx_destroyed(m)) { td = mtx_owner(m); db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, td->td_tid, td->td_proc->p_pid, td->td_name); if (mtx_recursed(m)) db_printf(" recursed: %d\n", m->mtx_recurse); } } #endif Index: head/sys/kern/kern_rwlock.c =================================================================== --- head/sys/kern/kern_rwlock.c (revision 312889) +++ head/sys/kern/kern_rwlock.c (revision 312890) @@ -1,1335 +1,1335 @@ /*- * 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 rw_delay = { +static struct lock_delay_config __read_mostly rw_delay = { .initial = 1000, .step = 500, .min = 100, .max = 5000, }; SYSCTL_INT(_debug_rwlock, OID_AUTO, delay_initial, CTLFLAG_RW, &rw_delay.initial, 0, ""); SYSCTL_INT(_debug_rwlock, OID_AUTO, delay_step, CTLFLAG_RW, &rw_delay.step, 0, ""); SYSCTL_INT(_debug_rwlock, OID_AUTO, delay_min, CTLFLAG_RW, &rw_delay.min, 0, ""); SYSCTL_INT(_debug_rwlock, OID_AUTO, delay_max, CTLFLAG_RW, &rw_delay.max, 0, ""); static void rw_delay_sysinit(void *dummy) { rw_delay.initial = mp_ncpus * 25; rw_delay.step = (mp_ncpus * 25) / 2; rw_delay.min = mp_ncpus * 5; rw_delay.max = mp_ncpus * 25 * 10; } LOCK_DELAY_SYSINIT(rw_delay_sysinit); #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; if (SCHEDULER_STOPPED()) return; 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); __rw_wlock(rw, curthread, file, line); 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; int rval; if (SCHEDULER_STOPPED()) 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)); if (rw_wlocked(rw) && (rw->lock_object.lo_flags & LO_RECURSABLE) != 0) { rw->rw_recurse++; rval = 1; } else rval = atomic_cmpset_acq_ptr(&rw->rw_lock, RW_UNLOCKED, (uintptr_t)curthread); 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 (!rw_recursed(rw)) 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; if (SCHEDULER_STOPPED()) return; 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); __rw_wunlock(rw, curthread, file, line); 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(_rw) \ ((curthread->td_rw_rlocks && (_rw) & RW_LOCK_READ) || ((_rw) & \ (RW_LOCK_READ | RW_LOCK_WRITE_WAITERS | RW_LOCK_WRITE_SPINNER)) == \ RW_LOCK_READ) void __rw_rlock(volatile uintptr_t *c, 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 uintptr_t v; #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); KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), ("rw_rlock() by idle thread %p on rwlock %s @ %s:%d", curthread, 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) != curthread, ("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); #ifdef KDTRACE_HOOKS all_time -= lockstat_nsecs(&rw->lock_object); #endif v = RW_READ_VALUE(rw); #ifdef KDTRACE_HOOKS state = v; #endif for (;;) { /* * 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. */ if (RW_CAN_READ(v)) { /* * The RW_LOCK_READ_WAITERS flag should only be set * if the lock has been unlocked and write waiters * were present. */ if (atomic_cmpset_acq_ptr(&rw->rw_lock, v, v + RW_ONE_READER)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR4(KTR_LOCK, "%s: %p succeed %p -> %p", __func__, rw, (void *)v, (void *)(v + RW_ONE_READER)); break; } v = RW_READ_VALUE(rw); 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 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(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(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(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); LOCK_LOG_LOCK("RLOCK", &rw->lock_object, 0, 0, file, line); WITNESS_LOCK(&rw->lock_object, 0, file, line); TD_LOCKS_INC(curthread); curthread->td_rw_rlocks++; } 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)); for (;;) { x = rw->rw_lock; KASSERT(rw->rw_lock != RW_DESTROYED, ("rw_try_rlock() of destroyed rwlock @ %s:%d", file, line)); if (!(x & RW_LOCK_READ)) break; if (atomic_cmpset_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); } void _rw_runlock_cookie(volatile uintptr_t *c, const char *file, int line) { struct rwlock *rw; struct turnstile *ts; uintptr_t x, v, queue; if (SCHEDULER_STOPPED()) return; 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); /* TODO: drop "owner of record" here. */ x = RW_READ_VALUE(rw); for (;;) { /* * See if there is more than one read lock held. If so, * just drop one and return. */ if (RW_READERS(x) > 1) { if (atomic_cmpset_rel_ptr(&rw->rw_lock, x, x - RW_ONE_READER)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR4(KTR_LOCK, "%s: %p succeeded %p -> %p", __func__, rw, (void *)x, (void *)(x - RW_ONE_READER)); break; } x = RW_READ_VALUE(rw); continue; } /* * If there aren't any waiters for a write lock, then try * to drop it quickly. */ if (!(x & RW_LOCK_WAITERS)) { MPASS((x & ~RW_LOCK_WRITE_SPINNER) == RW_READERS_LOCK(1)); if (atomic_cmpset_rel_ptr(&rw->rw_lock, x, RW_UNLOCKED)) { if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p last succeeded", __func__, rw); break; } x = RW_READ_VALUE(rw); continue; } /* * 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); x = 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); break; } LOCKSTAT_PROFILE_RELEASE_RWLOCK(rw__release, rw, LOCKSTAT_READER); TD_LOCKS_DEC(curthread); curthread->td_rw_rlocks--; } /* * 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 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 v, 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); 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++; 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(rw, tid)) break; v = RW_READ_VALUE(rw); 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 the first try at releasing a write lock failed. * This means that 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); if (rw_wlocked(rw) && rw_recursed(rw)) { rw->rw_recurse--; if (LOCK_LOG_TEST(&rw->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p unrecursing", __func__, rw); 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); 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 312889) +++ head/sys/kern/kern_sx.c (revision 312890) @@ -1,1316 +1,1316 @@ /*- * 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 sx_delay = { +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 tid, int opts, const char *file, int line) { GIANT_DECLARE; #ifdef ADAPTIVE_SX volatile struct thread *owner; u_int i, spintries = 0; #endif uintptr_t x; #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 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_cmpset_acq_ptr(&sx->sx_lock, x, tid)) break; x = SX_READ_VALUE(sx); 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) { 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_cmpset_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; } x = SX_READ_VALUE(sx); 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) { uintptr_t x; int wakeup_swapper; if (SCHEDULER_STOPPED()) return; 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_cmpset_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; } x = SX_READ_VALUE(sx); 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)); if (atomic_cmpset_rel_ptr(&sx->sx_lock, SX_SHARERS_LOCK(1), SX_LOCK_UNLOCKED)) { if (LOCK_LOG_TEST(&sx->lock_object, 0)) CTR2(KTR_LOCK, "%s: %p last succeeded", __func__, sx); break; } x = SX_READ_VALUE(sx); 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/kern/subr_lock.c =================================================================== --- head/sys/kern/subr_lock.c (revision 312889) +++ head/sys/kern/subr_lock.c (revision 312890) @@ -1,674 +1,674 @@ /*- * 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. */ /* * This module holds the global variables and functions used to maintain * lock_object structures. */ #include __FBSDID("$FreeBSD$"); #include "opt_ddb.h" #include "opt_mprof.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DDB #include #endif #include CTASSERT(LOCK_CLASS_MAX == 15); struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = { &lock_class_mtx_spin, &lock_class_mtx_sleep, &lock_class_sx, &lock_class_rm, &lock_class_rm_sleepable, &lock_class_rw, &lock_class_lockmgr, }; void lock_init(struct lock_object *lock, struct lock_class *class, const char *name, const char *type, int flags) { int i; /* Check for double-init and zero object. */ KASSERT(flags & LO_NEW || !lock_initialized(lock), ("lock \"%s\" %p already initialized", name, lock)); /* Look up lock class to find its index. */ for (i = 0; i < LOCK_CLASS_MAX; i++) if (lock_classes[i] == class) { lock->lo_flags = i << LO_CLASSSHIFT; break; } KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class)); /* Initialize the lock object. */ lock->lo_name = name; lock->lo_flags |= flags | LO_INITIALIZED; LOCK_LOG_INIT(lock, 0); WITNESS_INIT(lock, (type != NULL) ? type : name); } void lock_destroy(struct lock_object *lock) { KASSERT(lock_initialized(lock), ("lock %p is not initialized", lock)); WITNESS_DESTROY(lock); LOCK_LOG_DESTROY(lock, 0); lock->lo_flags &= ~LO_INITIALIZED; } void lock_delay(struct lock_delay_arg *la) { u_int i, delay, backoff, min, max; struct lock_delay_config *lc = la->config; delay = la->delay; if (delay == 0) delay = lc->initial; else { delay += lc->step; max = lc->max; if (delay > max) delay = max; } backoff = cpu_ticks() % delay; min = lc->min; if (backoff < min) backoff = min; for (i = 0; i < backoff; i++) cpu_spinwait(); la->delay = delay; la->spin_cnt += backoff; } #ifdef DDB DB_SHOW_COMMAND(lock, db_show_lock) { struct lock_object *lock; struct lock_class *class; if (!have_addr) return; lock = (struct lock_object *)addr; if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) { db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock)); return; } class = LOCK_CLASS(lock); db_printf(" class: %s\n", class->lc_name); db_printf(" name: %s\n", lock->lo_name); class->lc_ddb_show(lock); } #endif #ifdef LOCK_PROFILING /* * One object per-thread for each lock the thread owns. Tracks individual * lock instances. */ struct lock_profile_object { LIST_ENTRY(lock_profile_object) lpo_link; struct lock_object *lpo_obj; const char *lpo_file; int lpo_line; uint16_t lpo_ref; uint16_t lpo_cnt; uint64_t lpo_acqtime; uint64_t lpo_waittime; u_int lpo_contest_locking; }; /* * One lock_prof for each (file, line, lock object) triple. */ struct lock_prof { SLIST_ENTRY(lock_prof) link; struct lock_class *class; const char *file; const char *name; int line; int ticks; uintmax_t cnt_wait_max; uintmax_t cnt_max; uintmax_t cnt_tot; uintmax_t cnt_wait; uintmax_t cnt_cur; uintmax_t cnt_contest_locking; }; SLIST_HEAD(lphead, lock_prof); #define LPROF_HASH_SIZE 4096 #define LPROF_HASH_MASK (LPROF_HASH_SIZE - 1) #define LPROF_CACHE_SIZE 4096 /* * Array of objects and profs for each type of object for each cpu. Spinlocks * are handled separately because a thread may be preempted and acquire a * spinlock while in the lock profiling code of a non-spinlock. In this way * we only need a critical section to protect the per-cpu lists. */ struct lock_prof_type { struct lphead lpt_lpalloc; struct lpohead lpt_lpoalloc; struct lphead lpt_hash[LPROF_HASH_SIZE]; struct lock_prof lpt_prof[LPROF_CACHE_SIZE]; struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE]; }; struct lock_prof_cpu { struct lock_prof_type lpc_types[2]; /* One for spin one for other. */ }; struct lock_prof_cpu *lp_cpu[MAXCPU]; -volatile int lock_prof_enable = 0; +volatile int __read_mostly lock_prof_enable; static volatile int lock_prof_resetting; #define LPROF_SBUF_SIZE 256 static int lock_prof_rejected; static int lock_prof_skipspin; static int lock_prof_skipcount; #ifndef USE_CPU_NANOSECONDS uint64_t nanoseconds(void) { struct bintime bt; uint64_t ns; binuptime(&bt); /* From bintime2timespec */ ns = bt.sec * (uint64_t)1000000000; ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32; return (ns); } #endif static void lock_prof_init_type(struct lock_prof_type *type) { int i; SLIST_INIT(&type->lpt_lpalloc); LIST_INIT(&type->lpt_lpoalloc); for (i = 0; i < LPROF_CACHE_SIZE; i++) { SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i], link); LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i], lpo_link); } } static void lock_prof_init(void *arg) { int cpu; for (cpu = 0; cpu <= mp_maxid; cpu++) { lp_cpu[cpu] = malloc(sizeof(*lp_cpu[cpu]), M_DEVBUF, M_WAITOK | M_ZERO); lock_prof_init_type(&lp_cpu[cpu]->lpc_types[0]); lock_prof_init_type(&lp_cpu[cpu]->lpc_types[1]); } } SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL); static void lock_prof_reset_wait(void) { /* * Spin relinquishing our cpu so that quiesce_all_cpus may * complete. */ while (lock_prof_resetting) sched_relinquish(curthread); } static void lock_prof_reset(void) { struct lock_prof_cpu *lpc; int enabled, i, cpu; /* * We not only race with acquiring and releasing locks but also * thread exit. To be certain that threads exit without valid head * pointers they must see resetting set before enabled is cleared. * Otherwise a lock may not be removed from a per-thread list due * to disabled being set but not wait for reset() to remove it below. */ atomic_store_rel_int(&lock_prof_resetting, 1); enabled = lock_prof_enable; lock_prof_enable = 0; quiesce_all_cpus("profreset", 0); /* * Some objects may have migrated between CPUs. Clear all links * before we zero the structures. Some items may still be linked * into per-thread lists as well. */ for (cpu = 0; cpu <= mp_maxid; cpu++) { lpc = lp_cpu[cpu]; for (i = 0; i < LPROF_CACHE_SIZE; i++) { LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link); LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link); } } for (cpu = 0; cpu <= mp_maxid; cpu++) { lpc = lp_cpu[cpu]; bzero(lpc, sizeof(*lpc)); lock_prof_init_type(&lpc->lpc_types[0]); lock_prof_init_type(&lpc->lpc_types[1]); } atomic_store_rel_int(&lock_prof_resetting, 0); lock_prof_enable = enabled; } static void lock_prof_output(struct lock_prof *lp, struct sbuf *sb) { const char *p; for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3); sbuf_printf(sb, "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n", lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000, lp->cnt_wait / 1000, lp->cnt_cur, lp->cnt_cur == 0 ? (uintmax_t)0 : lp->cnt_tot / (lp->cnt_cur * 1000), lp->cnt_cur == 0 ? (uintmax_t)0 : lp->cnt_wait / (lp->cnt_cur * 1000), (uintmax_t)0, lp->cnt_contest_locking, p, lp->line, lp->class->lc_name, lp->name); } static void lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash, int spin, int t) { struct lock_prof_type *type; struct lock_prof *l; int cpu; dst->file = match->file; dst->line = match->line; dst->class = match->class; dst->name = match->name; for (cpu = 0; cpu <= mp_maxid; cpu++) { if (lp_cpu[cpu] == NULL) continue; type = &lp_cpu[cpu]->lpc_types[spin]; SLIST_FOREACH(l, &type->lpt_hash[hash], link) { if (l->ticks == t) continue; if (l->file != match->file || l->line != match->line || l->name != match->name) continue; l->ticks = t; if (l->cnt_max > dst->cnt_max) dst->cnt_max = l->cnt_max; if (l->cnt_wait_max > dst->cnt_wait_max) dst->cnt_wait_max = l->cnt_wait_max; dst->cnt_tot += l->cnt_tot; dst->cnt_wait += l->cnt_wait; dst->cnt_cur += l->cnt_cur; dst->cnt_contest_locking += l->cnt_contest_locking; } } } static void lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin, int t) { struct lock_prof *l; int i; for (i = 0; i < LPROF_HASH_SIZE; ++i) { SLIST_FOREACH(l, &type->lpt_hash[i], link) { struct lock_prof lp = {}; if (l->ticks == t) continue; lock_prof_sum(l, &lp, i, spin, t); lock_prof_output(&lp, sb); } } } static int dump_lock_prof_stats(SYSCTL_HANDLER_ARGS) { struct sbuf *sb; int error, cpu, t; int enabled; error = sysctl_wire_old_buffer(req, 0); if (error != 0) return (error); sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req); sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n", "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name"); enabled = lock_prof_enable; lock_prof_enable = 0; quiesce_all_cpus("profstat", 0); t = ticks; for (cpu = 0; cpu <= mp_maxid; cpu++) { if (lp_cpu[cpu] == NULL) continue; lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t); lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t); } lock_prof_enable = enabled; error = sbuf_finish(sb); /* Output a trailing NUL. */ if (error == 0) error = SYSCTL_OUT(req, "", 1); sbuf_delete(sb); return (error); } static int enable_lock_prof(SYSCTL_HANDLER_ARGS) { int error, v; v = lock_prof_enable; error = sysctl_handle_int(oidp, &v, v, req); if (error) return (error); if (req->newptr == NULL) return (error); if (v == lock_prof_enable) return (0); if (v == 1) lock_prof_reset(); lock_prof_enable = !!v; return (0); } static int reset_lock_prof_stats(SYSCTL_HANDLER_ARGS) { int error, v; v = 0; error = sysctl_handle_int(oidp, &v, 0, req); if (error) return (error); if (req->newptr == NULL) return (error); if (v == 0) return (0); lock_prof_reset(); return (0); } static struct lock_prof * lock_profile_lookup(struct lock_object *lo, int spin, const char *file, int line) { const char *unknown = "(unknown)"; struct lock_prof_type *type; struct lock_prof *lp; struct lphead *head; const char *p; u_int hash; p = file; if (p == NULL || *p == '\0') p = unknown; hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line; hash &= LPROF_HASH_MASK; type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; head = &type->lpt_hash[hash]; SLIST_FOREACH(lp, head, link) { if (lp->line == line && lp->file == p && lp->name == lo->lo_name) return (lp); } lp = SLIST_FIRST(&type->lpt_lpalloc); if (lp == NULL) { lock_prof_rejected++; return (lp); } SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link); lp->file = p; lp->line = line; lp->class = LOCK_CLASS(lo); lp->name = lo->lo_name; SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link); return (lp); } static struct lock_profile_object * lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file, int line) { struct lock_profile_object *l; struct lock_prof_type *type; struct lpohead *head; head = &curthread->td_lprof[spin]; LIST_FOREACH(l, head, lpo_link) if (l->lpo_obj == lo && l->lpo_file == file && l->lpo_line == line) return (l); type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; l = LIST_FIRST(&type->lpt_lpoalloc); if (l == NULL) { lock_prof_rejected++; return (NULL); } LIST_REMOVE(l, lpo_link); l->lpo_obj = lo; l->lpo_file = file; l->lpo_line = line; l->lpo_cnt = 0; LIST_INSERT_HEAD(head, l, lpo_link); return (l); } void lock_profile_obtain_lock_success(struct lock_object *lo, int contested, uint64_t waittime, const char *file, int line) { static int lock_prof_count; struct lock_profile_object *l; int spin; if (SCHEDULER_STOPPED()) return; /* don't reset the timer when/if recursing */ if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE)) return; if (lock_prof_skipcount && (++lock_prof_count % lock_prof_skipcount) != 0) return; spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0; if (spin && lock_prof_skipspin == 1) return; critical_enter(); /* Recheck enabled now that we're in a critical section. */ if (lock_prof_enable == 0) goto out; l = lock_profile_object_lookup(lo, spin, file, line); if (l == NULL) goto out; l->lpo_cnt++; if (++l->lpo_ref > 1) goto out; l->lpo_contest_locking = contested; l->lpo_acqtime = nanoseconds(); if (waittime && (l->lpo_acqtime > waittime)) l->lpo_waittime = l->lpo_acqtime - waittime; else l->lpo_waittime = 0; out: critical_exit(); } void lock_profile_thread_exit(struct thread *td) { #ifdef INVARIANTS struct lock_profile_object *l; MPASS(curthread->td_critnest == 0); #endif /* * If lock profiling was disabled we have to wait for reset to * clear our pointers before we can exit safely. */ lock_prof_reset_wait(); #ifdef INVARIANTS LIST_FOREACH(l, &td->td_lprof[0], lpo_link) printf("thread still holds lock acquired at %s:%d\n", l->lpo_file, l->lpo_line); LIST_FOREACH(l, &td->td_lprof[1], lpo_link) printf("thread still holds lock acquired at %s:%d\n", l->lpo_file, l->lpo_line); #endif MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL); MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL); } void lock_profile_release_lock(struct lock_object *lo) { struct lock_profile_object *l; struct lock_prof_type *type; struct lock_prof *lp; uint64_t curtime, holdtime; struct lpohead *head; int spin; if (SCHEDULER_STOPPED()) return; if (lo->lo_flags & LO_NOPROFILE) return; spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0; head = &curthread->td_lprof[spin]; if (LIST_FIRST(head) == NULL) return; critical_enter(); /* Recheck enabled now that we're in a critical section. */ if (lock_prof_enable == 0 && lock_prof_resetting == 1) goto out; /* * If lock profiling is not enabled we still want to remove the * lpo from our queue. */ LIST_FOREACH(l, head, lpo_link) if (l->lpo_obj == lo) break; if (l == NULL) goto out; if (--l->lpo_ref > 0) goto out; lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line); if (lp == NULL) goto release; curtime = nanoseconds(); if (curtime < l->lpo_acqtime) goto release; holdtime = curtime - l->lpo_acqtime; /* * Record if the lock has been held longer now than ever * before. */ if (holdtime > lp->cnt_max) lp->cnt_max = holdtime; if (l->lpo_waittime > lp->cnt_wait_max) lp->cnt_wait_max = l->lpo_waittime; lp->cnt_tot += holdtime; lp->cnt_wait += l->lpo_waittime; lp->cnt_contest_locking += l->lpo_contest_locking; lp->cnt_cur += l->lpo_cnt; release: LIST_REMOVE(l, lpo_link); type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin]; LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link); out: critical_exit(); } static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging"); static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL, "lock profiling"); SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW, &lock_prof_skipspin, 0, "Skip profiling on spinlocks."); SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW, &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions."); SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD, &lock_prof_rejected, 0, "Number of rejected profiling records"); SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD, NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics"); SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW, NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics"); SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW, NULL, 0, enable_lock_prof, "I", "Enable lock profiling"); #endif