Re: [PATCH] mutex: set owner only once on acquisition
From: Johannes Weiner <hannes@cmpxchg.org>
Date: 2009-01-15 08:56:25
Also in:
linux-fsdevel, lkml
From: Johannes Weiner <hannes@cmpxchg.org>
Date: 2009-01-15 08:56:25
Also in:
linux-fsdevel, lkml
On Thu, Jan 15, 2009 at 09:41:01AM +0100, Johannes Weiner wrote:
mutex_lock() sets the lock owner, no need to set it upfront in __mutex_lock_common(). Inside __mutex_lock_common() we can cope with the case where the successful acquirer got preempted by us before setting the owner field: there is an explicit check in the spinning code and the sleeping part doesn't rely on it. The debug code does owner checks only on unlock where the field is garuanteed to be set. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> --- kernel/mutex.c | 2 -- 1 file changed, 2 deletions(-) Just a small observation. Peter said it wouldn't matter much as the write is to a hot cache line. But otoh, why keep it if it's not necessary. :)
Damn, I'm really async here, sorry Peter. Just noticed you already picked it up. Hannes