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Date: Fri, 17 Apr 2020 22:50:32 +0800 From: Alex Shi <alex.shi@...ux.alibaba.com> To: unlisted-recipients:; (no To-header on input) Cc: Alex Shi <alex.shi@...ux.alibaba.com>, Thomas Gleixner <tglx@...utronix.de>, Davidlohr Bueso <dave@...olabs.net>, Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org Subject: [PATCH 2/2] locking/rtmutex: optimize rt_mutex_cmpxchgs Checking l->owner first to skip time cost cmpxchgs. Suggested-by: Davidlohr Bueso <dave@...olabs.net> Signed-off-by: Alex Shi <alex.shi@...ux.alibaba.com> Cc: Thomas Gleixner <tglx@...utronix.de> Cc: Davidlohr Bueso <dave@...olabs.net> Cc: Ingo Molnar <mingo@...hat.com> Cc: Will Deacon <will@...nel.org> Cc: linux-kernel@...r.kernel.org --- kernel/locking/rtmutex.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index cfdd5b93264d..232727a4a220 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -141,8 +141,10 @@ static void fixup_rt_mutex_waiters(struct rt_mutex *lock) * set up. */ #ifndef CONFIG_DEBUG_RT_MUTEXES -# define rt_mutex_cmpxchg_acquire(l,c,n) (cmpxchg_acquire(&l->owner, c, n) == c) -# define rt_mutex_cmpxchg_release(l,c,n) (cmpxchg_release(&l->owner, c, n) == c) +# define rt_mutex_cmpxchg_acquire(l, c, n) \ + (l->owner == c && cmpxchg_acquire(&l->owner, c, n) == c) +# define rt_mutex_cmpxchg_release(l, c, n) \ + (l->owner == c && cmpxchg_release(&l->owner, c, n) == c) /* * Callers must hold the ->wait_lock -- which is the whole purpose as we force -- 1.8.3.1
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