diff options
author | kib <kib@FreeBSD.org> | 2016-07-30 09:28:13 +0000 |
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committer | kib <kib@FreeBSD.org> | 2016-07-30 09:28:13 +0000 |
commit | fece0ae41ca3913ce8d420b76b9de9a6f268ce95 (patch) | |
tree | 2d494dabfe4fa71fc6a564faceb87fa784689c19 | |
parent | 2d82febc8bf7306533053b596c4c1b3703a6314d (diff) | |
download | FreeBSD-src-fece0ae41ca3913ce8d420b76b9de9a6f268ce95.zip FreeBSD-src-fece0ae41ca3913ce8d420b76b9de9a6f268ce95.tar.gz |
MFC r303211:
Implement mtx_trylock_spin(9).
Approved by: re (gjb)
-rw-r--r-- | share/man/man9/Makefile | 2 | ||||
-rw-r--r-- | share/man/man9/mutex.9 | 46 | ||||
-rw-r--r-- | sys/kern/kern_mutex.c | 28 | ||||
-rw-r--r-- | sys/sys/mutex.h | 44 |
4 files changed, 109 insertions, 11 deletions
diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile index 8617cba..f519e0f 100644 --- a/share/man/man9/Makefile +++ b/share/man/man9/Makefile @@ -1181,6 +1181,8 @@ MLINKS+=mutex.9 mtx_assert.9 \ mutex.9 MTX_SYSINIT.9 \ mutex.9 mtx_trylock.9 \ mutex.9 mtx_trylock_flags.9 \ + mutex.9 mtx_trylock_spin.9 \ + mutex.9 mtx_trylock_spin_flags.9 \ mutex.9 mtx_unlock.9 \ mutex.9 mtx_unlock_flags.9 \ mutex.9 mtx_unlock_spin.9 \ diff --git a/share/man/man9/mutex.9 b/share/man/man9/mutex.9 index 64ec426..f7d242c 100644 --- a/share/man/man9/mutex.9 +++ b/share/man/man9/mutex.9 @@ -28,7 +28,7 @@ .\" from BSDI $Id: mutex.4,v 1.1.2.3 1998/04/27 22:53:13 ewv Exp $ .\" $FreeBSD$ .\" -.Dd December 13, 2014 +.Dd July 18, 2016 .Dt MUTEX 9 .Os .Sh NAME @@ -41,6 +41,8 @@ .Nm mtx_lock_spin_flags , .Nm mtx_trylock , .Nm mtx_trylock_flags , +.Nm mtx_trylock_spin , +.Nm mtx_trylock_spin_flags , .Nm mtx_unlock , .Nm mtx_unlock_spin , .Nm mtx_unlock_flags , @@ -73,6 +75,10 @@ .Ft int .Fn mtx_trylock_flags "struct mtx *mutex" "int flags" .Ft void +.Fn mtx_trylock_spin "struct mtx *mutex" +.Ft int +.Fn mtx_trylock_spin_flags "struct mtx *mutex" "int flags" +.Ft void .Fn mtx_unlock "struct mtx *mutex" .Ft void .Fn mtx_unlock_spin "struct mtx *mutex" @@ -249,26 +255,33 @@ argument, then the mutex can be acquired recursively. .Pp The .Fn mtx_trylock -attempts to acquire the +and +.Fn mtx_trylock_spin +functions attempt to acquire a .Dv MTX_DEF -mutex pointed to by +or +.Dv MTX_SPIN +mutex, respectively, pointed to by .Fa mutex . -If the mutex cannot be immediately acquired -.Fn mtx_trylock -will return 0, -otherwise the mutex will be acquired -and a non-zero value will be returned. +If the mutex cannot be immediately acquired, the functions will return 0, +otherwise the mutex will be acquired and a non-zero value will be returned. .Pp The .Fn mtx_trylock_flags -function has the same behavior as +and +.Fn mtx_trylock_spin_flags +functions have the same behavior as .Fn mtx_trylock -but should be used when the caller desires to pass in a +and +.Fn mtx_trylock_spin +respectively, but should be used when the caller desires to pass in a .Fa flags value. Presently, the only valid value in the .Fn mtx_trylock -case is +and +.Fn mtx_trylock_spin +cases is .Dv MTX_QUIET , and its effects are identical to those described for .Fn mtx_lock @@ -447,6 +460,13 @@ while any spin lock is held. .It Dv MTX_RECURSE Specifies that the initialized mutex is allowed to recurse. This bit must be present if the mutex is permitted to recurse. +.Pp +Note that neither +.Fn mtx_trylock +nor +.Fn mtx_trylock_spin +support recursion; +that is, attempting to acquire an already-owned mutex fails. .It Dv MTX_QUIET Do not log any mutex operations for this lock. .It Dv MTX_NOWITNESS @@ -534,3 +554,7 @@ functions appeared in .Bsx 4.1 and .Fx 5.0 . +The +.Fn mtx_trylock_spin +function was added in +.Fx 12.0 . diff --git a/sys/kern/kern_mutex.c b/sys/kern/kern_mutex.c index 012cf7c..453add4 100644 --- a/sys/kern/kern_mutex.c +++ b/sys/kern/kern_mutex.c @@ -281,6 +281,34 @@ __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file, 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) diff --git a/sys/sys/mutex.h b/sys/sys/mutex.h index 0443922..374aaab 100644 --- a/sys/sys/mutex.h +++ b/sys/sys/mutex.h @@ -112,6 +112,8 @@ void __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line); void __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file, int line); +int __mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, + const char *file, int line); void __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file, int line); #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) @@ -152,6 +154,8 @@ void thread_lock_flags_(struct thread *, int, const char *, int); __mtx_unlock_flags(&(m)->mtx_lock, o, f, l) #define _mtx_lock_spin_flags(m, o, f, l) \ __mtx_lock_spin_flags(&(m)->mtx_lock, o, f, l) +#define _mtx_trylock_spin_flags(m, o, f, l) \ + __mtx_trylock_spin_flags(&(m)->mtx_lock, o, f, l) #define _mtx_unlock_spin_flags(m, o, f, l) \ __mtx_unlock_spin_flags(&(m)->mtx_lock, o, f, l) #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) @@ -212,6 +216,21 @@ void thread_lock_flags_(struct thread *, int, const char *, int); LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, \ mp, 0, 0, file, line); \ } while (0) +#define __mtx_trylock_spin(mp, tid, opts, file, line) __extension__ ({ \ + uintptr_t _tid = (uintptr_t)(tid); \ + int _ret; \ + \ + spinlock_enter(); \ + if (((mp)->mtx_lock != MTX_UNOWNED || !_mtx_obtain_lock((mp), _tid))) {\ + spinlock_exit(); \ + _ret = 0; \ + } else { \ + LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, \ + mp, 0, 0, file, line); \ + _ret = 1; \ + } \ + _ret; \ +}) #else /* SMP */ #define __mtx_lock_spin(mp, tid, opts, file, line) do { \ uintptr_t _tid = (uintptr_t)(tid); \ @@ -224,6 +243,20 @@ void thread_lock_flags_(struct thread *, int, const char *, int); (mp)->mtx_lock = _tid; \ } \ } while (0) +#define __mtx_trylock_spin(mp, tid, opts, file, line) __extension__ ({ \ + uintptr_t _tid = (uintptr_t)(tid); \ + int _ret; \ + \ + spinlock_enter(); \ + if ((mp)->mtx_lock != MTX_UNOWNED) { \ + spinlock_exit(); \ + _ret = 0; \ + } else { \ + (mp)->mtx_lock = _tid; \ + _ret = 1; \ + } \ + _ret; \ +}) #endif /* SMP */ /* Unlock a normal mutex. */ @@ -293,6 +326,10 @@ void thread_lock_flags_(struct thread *, int, const char *, int); * mtx_trylock_flags(m, opts) is used the same way as mtx_trylock() but accepts * relevant option flags `opts.' * + * mtx_trylock_spin(m) attempts to acquire MTX_SPIN mutex `m' but doesn't + * spin if it cannot. Rather, it returns 0 on failure and non-zero on + * success. It always returns failure for recursed lock attempts. + * * mtx_initialized(m) returns non-zero if the lock `m' has been initialized. * * mtx_owned(m) returns non-zero if the current thread owns the lock `m' @@ -302,6 +339,7 @@ void thread_lock_flags_(struct thread *, int, const char *, int); #define mtx_lock(m) mtx_lock_flags((m), 0) #define mtx_lock_spin(m) mtx_lock_spin_flags((m), 0) #define mtx_trylock(m) mtx_trylock_flags((m), 0) +#define mtx_trylock_spin(m) mtx_trylock_spin_flags((m), 0) #define mtx_unlock(m) mtx_unlock_flags((m), 0) #define mtx_unlock_spin(m) mtx_unlock_spin_flags((m), 0) @@ -335,6 +373,8 @@ extern struct mtx_pool *mtxpool_sleep; _mtx_unlock_flags((m), (opts), (file), (line)) #define mtx_lock_spin_flags_(m, opts, file, line) \ _mtx_lock_spin_flags((m), (opts), (file), (line)) +#define mtx_trylock_spin_flags_(m, opts, file, line) \ + _mtx_trylock_spin_flags((m), (opts), (file), (line)) #define mtx_unlock_spin_flags_(m, opts, file, line) \ _mtx_unlock_spin_flags((m), (opts), (file), (line)) #else /* LOCK_DEBUG == 0 && !MUTEX_NOINLINE */ @@ -344,6 +384,8 @@ extern struct mtx_pool *mtxpool_sleep; __mtx_unlock((m), curthread, (opts), (file), (line)) #define mtx_lock_spin_flags_(m, opts, file, line) \ __mtx_lock_spin((m), curthread, (opts), (file), (line)) +#define mtx_trylock_spin_flags_(m, opts, file, line) \ + __mtx_trylock_spin((m), curthread, (opts), (file), (line)) #define mtx_unlock_spin_flags_(m, opts, file, line) \ __mtx_unlock_spin((m)) #endif /* LOCK_DEBUG > 0 || MUTEX_NOINLINE */ @@ -369,6 +411,8 @@ extern struct mtx_pool *mtxpool_sleep; mtx_unlock_spin_flags_((m), (opts), LOCK_FILE, LOCK_LINE) #define mtx_trylock_flags(m, opts) \ mtx_trylock_flags_((m), (opts), LOCK_FILE, LOCK_LINE) +#define mtx_trylock_spin_flags(m, opts) \ + mtx_trylock_spin_flags_((m), (opts), LOCK_FILE, LOCK_LINE) #define mtx_assert(m, what) \ mtx_assert_((m), (what), __FILE__, __LINE__) |