diff options
| author | Waiman Long <Waiman.Long@hp.com> | 2013-04-17 15:23:14 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-04-19 09:33:36 +0200 |
| commit | cc189d2513d1f45cde87a9043fe3be28559c7490 (patch) | |
| tree | 064796cc597cfae5cc657d8bdc212774ea5251ff | |
| parent | 2bd2c92cf07cc4a373bf316c75b78ac465fefd35 (diff) | |
mutex: Back out architecture specific check for negative mutex count
Linus suggested that probably all the supported architectures can
allow a negative mutex count without incorrect behavior, so we can
then back out the architecture specific change and allow the
mutex count to go to any negative number. That should further
reduce contention for non-x86 architecture.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Chandramouleeswaran Aswin <aswin@hp.com>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Norton Scott J <scott.norton@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Dave Jones <davej@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1366226594-5506-5-git-send-email-Waiman.Long@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/include/asm/mutex.h | 10 | ||||
| -rw-r--r-- | kernel/mutex.c | 9 |
2 files changed, 2 insertions, 17 deletions
diff --git a/arch/x86/include/asm/mutex.h b/arch/x86/include/asm/mutex.h index bc2a0b0dcea6..7d3a48275394 100644 --- a/arch/x86/include/asm/mutex.h +++ b/arch/x86/include/asm/mutex.h @@ -3,13 +3,3 @@ #else # include <asm/mutex_64.h> #endif - -#ifndef __ASM_MUTEX_H -#define __ASM_MUTEX_H -/* - * For the x86 architecture, it allows any negative number (besides -1) in - * the mutex count to indicate that some other threads are waiting on the - * mutex. - */ -#define __ARCH_ALLOW_ANY_NEGATIVE_MUTEX_COUNT 1 -#endif diff --git a/kernel/mutex.c b/kernel/mutex.c index 1dbd4210baef..ad53a664f113 100644 --- a/kernel/mutex.c +++ b/kernel/mutex.c @@ -38,15 +38,10 @@ #endif /* - * A mutex count of -1 indicates that waiters are sleeping waiting for the - * mutex. Some architectures can allow any negative number, not just -1, for - * this purpose. + * A negative mutex count indicates that waiters are sleeping waiting for the + * mutex. */ -#ifdef __ARCH_ALLOW_ANY_NEGATIVE_MUTEX_COUNT #define MUTEX_SHOW_NO_WAITER(mutex) (atomic_read(&(mutex)->count) >= 0) -#else -#define MUTEX_SHOW_NO_WAITER(mutex) (atomic_read(&(mutex)->count) != -1) -#endif void __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key) |