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authorLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 16:09:13 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 16:09:13 -0700
commit0c46d68d1930c8a58d0f291328b9759da754e599 (patch)
tree5cc551f56a86e204d648488c036fc1092fcd22a0 /include/asm-generic
parent3e42dee676e8cf5adca817b1518b2e99d1c138ff (diff)
parent166989e366ffa66108b2f37b870e66b85b2185ad (diff)
Merge branch 'core-mutexes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull WW mutex support from Ingo Molnar: "This tree adds support for wound/wait style locks, which the graphics guys would like to make use of in the TTM graphics subsystem. Wound/wait mutexes are used when other multiple lock acquisitions of a similar type can be done in an arbitrary order. The deadlock handling used here is called wait/wound in the RDBMS literature: The older tasks waits until it can acquire the contended lock. The younger tasks needs to back off and drop all the locks it is currently holding, ie the younger task is wounded. See this LWN.net description of W/W mutexes: https://lwn.net/Articles/548909/ The comments there outline specific usecases for this facility (which have already been implemented for the DRM tree). Also see Documentation/ww-mutex-design.txt for more details" * 'core-mutexes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking-selftests: Handle unexpected failures more strictly mutex: Add more w/w tests to test EDEADLK path handling mutex: Add more tests to lib/locking-selftest.c mutex: Add w/w tests to lib/locking-selftest.c mutex: Add w/w mutex slowpath debugging mutex: Add support for wound/wait style locks arch: Make __mutex_fastpath_lock_retval return whether fastpath succeeded or not
Diffstat (limited to 'include/asm-generic')
-rw-r--r--include/asm-generic/mutex-dec.h10
-rw-r--r--include/asm-generic/mutex-null.h2
-rw-r--r--include/asm-generic/mutex-xchg.h10
3 files changed, 9 insertions, 13 deletions
diff --git a/include/asm-generic/mutex-dec.h b/include/asm-generic/mutex-dec.h
index f104af7cf437..d4f9fb4e53df 100644
--- a/include/asm-generic/mutex-dec.h
+++ b/include/asm-generic/mutex-dec.h
@@ -28,17 +28,15 @@ __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
* __mutex_fastpath_lock_retval - try to take the lock by moving the count
* from 1 to a 0 value
* @count: pointer of type atomic_t
- * @fail_fn: function to call if the original value was not 1
*
- * Change the count from 1 to a value lower than 1, and call <fail_fn> if
- * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
- * or anything the slow path function returns.
+ * Change the count from 1 to a value lower than 1. This function returns 0
+ * if the fastpath succeeds, or -1 otherwise.
*/
static inline int
-__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
+__mutex_fastpath_lock_retval(atomic_t *count)
{
if (unlikely(atomic_dec_return(count) < 0))
- return fail_fn(count);
+ return -1;
return 0;
}
diff --git a/include/asm-generic/mutex-null.h b/include/asm-generic/mutex-null.h
index e1bbbc72b6a2..61069ed334e2 100644
--- a/include/asm-generic/mutex-null.h
+++ b/include/asm-generic/mutex-null.h
@@ -11,7 +11,7 @@
#define _ASM_GENERIC_MUTEX_NULL_H
#define __mutex_fastpath_lock(count, fail_fn) fail_fn(count)
-#define __mutex_fastpath_lock_retval(count, fail_fn) fail_fn(count)
+#define __mutex_fastpath_lock_retval(count) (-1)
#define __mutex_fastpath_unlock(count, fail_fn) fail_fn(count)
#define __mutex_fastpath_trylock(count, fail_fn) fail_fn(count)
#define __mutex_slowpath_needs_to_unlock() 1
diff --git a/include/asm-generic/mutex-xchg.h b/include/asm-generic/mutex-xchg.h
index c04e0db8a2d6..f169ec064785 100644
--- a/include/asm-generic/mutex-xchg.h
+++ b/include/asm-generic/mutex-xchg.h
@@ -39,18 +39,16 @@ __mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
* __mutex_fastpath_lock_retval - try to take the lock by moving the count
* from 1 to a 0 value
* @count: pointer of type atomic_t
- * @fail_fn: function to call if the original value was not 1
*
- * Change the count from 1 to a value lower than 1, and call <fail_fn> if it
- * wasn't 1 originally. This function returns 0 if the fastpath succeeds,
- * or anything the slow path function returns
+ * Change the count from 1 to a value lower than 1. This function returns 0
+ * if the fastpath succeeds, or -1 otherwise.
*/
static inline int
-__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
+__mutex_fastpath_lock_retval(atomic_t *count)
{
if (unlikely(atomic_xchg(count, 0) != 1))
if (likely(atomic_xchg(count, -1) != 1))
- return fail_fn(count);
+ return -1;
return 0;
}