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Commit e42f678a authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Ingo Molnar
Browse files

locking/mutex: Move MCS related comments to proper location 



It serves much better if the comments are right before the osq_lock() call.
Also delete a useless comment.

Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1420573509-24774-3-git-send-email-dave@stgolabs.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 63dc47e9

kernel/locking/mutex.c

+5 −11
Original line number Diff line number Diff line
@@ -193,17 +193,6 @@ ww_mutex_set_context_fastpath(struct ww_mutex *lock, 




#ifdef CONFIG_MUTEX_SPIN_ON_OWNER

/*

 * In order to avoid a stampede of mutex spinners from acquiring the mutex

 * more or less simultaneously, the spinners need to acquire a MCS lock

 * first before spinning on the owner field.

 *

 */



/*

 * Mutex spinning code migrated from kernel/sched/core.c

 */



static inline bool owner_running(struct mutex *lock, struct task_struct *owner)

{

	if (lock->owner != owner)
@@ -307,6 +296,11 @@ static bool mutex_optimistic_spin(struct mutex *lock, 
	if (!mutex_can_spin_on_owner(lock))

		goto done;



	/*

	 * In order to avoid a stampede of mutex spinners trying to

	 * acquire the mutex all at once, the spinners need to take a

	 * MCS (queued) lock first before spinning on the owner field.

	 */

	if (!osq_lock(&lock->osq))

		goto done;