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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-06-12 16:53:38 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-06-12 16:53:38 +1000
commitbc47ab0241c7c86da4f5e5f82fbca7d45387c18d (patch)
treeb9c33ae8b6de43e44cc5fcbaa3e4a15f18a5ed42 /kernel/mutex.c
parent37f9ef553bed630957e025504cdcbc76f5de49d5 (diff)
parent8ebf975608aaebd7feb33d77f07ba21a6380e086 (diff)
Merge commit 'origin/master' into next
Manual merge of: arch/powerpc/kernel/asm-offsets.c
Diffstat (limited to 'kernel/mutex.c')
-rw-r--r--kernel/mutex.c31
1 files changed, 28 insertions, 3 deletions
diff --git a/kernel/mutex.c b/kernel/mutex.c
index 507cf2b5e9f..947b3ad551f 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -89,7 +89,7 @@ __mutex_lock_slowpath(atomic_t *lock_count);
*
* This function is similar to (but not equivalent to) down().
*/
-void inline __sched mutex_lock(struct mutex *lock)
+void __sched mutex_lock(struct mutex *lock)
{
might_sleep();
/*
@@ -249,7 +249,9 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
/* didnt get the lock, go to sleep: */
spin_unlock_mutex(&lock->wait_lock, flags);
- __schedule();
+ preempt_enable_no_resched();
+ schedule();
+ preempt_disable();
spin_lock_mutex(&lock->wait_lock, flags);
}
@@ -471,5 +473,28 @@ int __sched mutex_trylock(struct mutex *lock)
return ret;
}
-
EXPORT_SYMBOL(mutex_trylock);
+
+/**
+ * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0
+ * @cnt: the atomic which we are to dec
+ * @lock: the mutex to return holding if we dec to 0
+ *
+ * return true and hold lock if we dec to 0, return false otherwise
+ */
+int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock)
+{
+ /* dec if we can't possibly hit 0 */
+ if (atomic_add_unless(cnt, -1, 1))
+ return 0;
+ /* we might hit 0, so take the lock */
+ mutex_lock(lock);
+ if (!atomic_dec_and_test(cnt)) {
+ /* when we actually did the dec, we didn't hit 0 */
+ mutex_unlock(lock);
+ return 0;
+ }
+ /* we hit 0, and we hold the lock */
+ return 1;
+}
+EXPORT_SYMBOL(atomic_dec_and_mutex_lock);