Commit-ID: e42f678a0237f84f0004fbaf0fad0b844751eadd Gitweb: http://git.kernel.org/tip/e42f678a0237f84f0004fbaf0fad0b844751eadd Author: Davidlohr Bueso <d...@stgolabs.net> AuthorDate: Tue, 6 Jan 2015 11:45:05 -0800 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Wed, 14 Jan 2015 15:07:22 +0100
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: Davidlohr Bueso <dbu...@suse.de> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Linus Torvalds <torva...@linux-foundation.org> Link: http://lkml.kernel.org/r/1420573509-24774-3-git-send-email-d...@stgolabs.net Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/locking/mutex.c | 16 +++++----------- 1 file changed, 5 insertions(+), 11 deletions(-) diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index b042ea5..6db3d0d 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
