diff options
| author | Gunnar Beutner <[email protected]> | 2011-10-18 02:32:50 +0200 |
|---|---|---|
| committer | Brian Behlendorf <[email protected]> | 2011-10-19 09:58:41 -0700 |
| commit | 3160d4f56bf35492e9c400094f8c1ff2066d4459 (patch) | |
| tree | 2b8e0fdfe1842f1671244e12d9c79a42efbb9bae /include/sys/mutex.h | |
| parent | f3989ed3223363330af014062caeeb1afbd0503f (diff) | |
Fix race condition in mutex_exit()
On kernels with CONFIG_DEBUG_MUTEXES mutex_exit() clears the mutex
owner after releasing the mutex. This would cause mutex_owner()
to return an incorrect owner if another thread managed to lock the
mutex before mutex_exit() had a chance to clear the owner.
Signed-off-by: Brian Behlendorf <[email protected]>
Closes ZFS issue #167
Diffstat (limited to 'include/sys/mutex.h')
| -rw-r--r-- | include/sys/mutex.h | 14 |
1 files changed, 2 insertions, 12 deletions
diff --git a/include/sys/mutex.h b/include/sys/mutex.h index 659214f50..c55104a41 100644 --- a/include/sys/mutex.h +++ b/include/sys/mutex.h @@ -35,7 +35,7 @@ typedef enum { MUTEX_ADAPTIVE = 2 } kmutex_type_t; -#if defined(HAVE_MUTEX_OWNER) && defined(CONFIG_SMP) +#if defined(HAVE_MUTEX_OWNER) && defined(CONFIG_SMP) && !defined(CONFIG_DEBUG_MUTEXES) /* * We define a 1-field struct rather than a straight typedef to enforce type @@ -79,17 +79,7 @@ mutex_owner(kmutex_t *mp) #define mutex_tryenter(mp) mutex_trylock(&(mp)->m) #define mutex_enter(mp) mutex_lock(&(mp)->m) - -/* mutex->owner is not cleared when CONFIG_DEBUG_MUTEXES is set */ -#ifdef CONFIG_DEBUG_MUTEXES -# define mutex_exit(mp) \ -({ \ - mutex_unlock(&(mp)->m); \ - (mp)->m.owner = NULL; \ -}) -#else -# define mutex_exit(mp) mutex_unlock(&(mp)->m) -#endif /* CONFIG_DEBUG_MUTEXES */ +#define mutex_exit(mp) mutex_unlock(&(mp)->m) #ifdef HAVE_GPL_ONLY_SYMBOLS # define mutex_enter_nested(mp, sc) mutex_lock_nested(&(mp)->m, sc) |