diff options
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/mutex.h | 24 |
1 files changed, 1 insertions, 23 deletions
diff --git a/include/linux/mutex.h b/include/linux/mutex.h index 93054fc3635c..878cab4f5fcc 100644 --- a/include/linux/mutex.h +++ b/include/linux/mutex.h | |||
@@ -150,28 +150,6 @@ extern int __must_check mutex_lock_killable(struct mutex *lock); | |||
150 | */ | 150 | */ |
151 | extern int mutex_trylock(struct mutex *lock); | 151 | extern int mutex_trylock(struct mutex *lock); |
152 | extern void mutex_unlock(struct mutex *lock); | 152 | extern void mutex_unlock(struct mutex *lock); |
153 | 153 | extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock); | |
154 | /** | ||
155 | * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0 | ||
156 | * @cnt: the atomic which we are to dec | ||
157 | * @lock: the mutex to return holding if we dec to 0 | ||
158 | * | ||
159 | * return true and hold lock if we dec to 0, return false otherwise | ||
160 | */ | ||
161 | static inline int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock) | ||
162 | { | ||
163 | /* dec if we can't possibly hit 0 */ | ||
164 | if (atomic_add_unless(cnt, -1, 1)) | ||
165 | return 0; | ||
166 | /* we might hit 0, so take the lock */ | ||
167 | mutex_lock(lock); | ||
168 | if (!atomic_dec_and_test(cnt)) { | ||
169 | /* when we actually did the dec, we didn't hit 0 */ | ||
170 | mutex_unlock(lock); | ||
171 | return 0; | ||
172 | } | ||
173 | /* we hit 0, and we hold the lock */ | ||
174 | return 1; | ||
175 | } | ||
176 | 154 | ||
177 | #endif | 155 | #endif |