locking/mutex: Move MCS related comments to proper location (e42f678a) · Commits · 戴 / test

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

Peter 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:

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;