From ff743345bf7685a207868048a70e23164c4785e5 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 13 Mar 2009 12:21:26 +0100 Subject: sched: remove extra call overhead for schedule() Lai Jiangshan's patch reminded me that I promised Nick to remove that extra call overhead in schedule(). Signed-off-by: Peter Zijlstra LKML-Reference: <20090313112300.927414207@chello.nl> Signed-off-by: Ingo Molnar --- kernel/mutex.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/mutex.c') diff --git a/kernel/mutex.c b/kernel/mutex.c index 5d79781394a3..e1fb73510409 100644 --- a/kernel/mutex.c +++ b/kernel/mutex.c @@ -248,7 +248,9 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, /* didnt get the lock, go to sleep: */ spin_unlock_mutex(&lock->wait_lock, flags); - __schedule(); + preempt_enable_no_resched(); + schedule(); + preempt_disable(); spin_lock_mutex(&lock->wait_lock, flags); } -- cgit v1.2.2 From a511e3f968c462a55ef58697257f5347c73d306e Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Wed, 29 Apr 2009 15:59:58 -0700 Subject: mutex: add atomic_dec_and_mutex_lock(), fix include/linux/mutex.h:136: warning: 'mutex_lock' declared inline after being called include/linux/mutex.h:136: warning: previous declaration of 'mutex_lock' was here uninline it. [ Impact: clean up and uninline, address compiler warning ] Signed-off-by: Andrew Morton Cc: Al Viro Cc: Christoph Hellwig Cc: Eric Paris Cc: Paul Mackerras Cc: Peter Zijlstra LKML-Reference: <200904292318.n3TNIsi6028340@imap1.linux-foundation.org> Signed-off-by: Ingo Molnar --- kernel/mutex.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) (limited to 'kernel/mutex.c') diff --git a/kernel/mutex.c b/kernel/mutex.c index 507cf2b5e9f1..e2d25e9e62ae 100644 --- a/kernel/mutex.c +++ b/kernel/mutex.c @@ -471,5 +471,28 @@ int __sched mutex_trylock(struct mutex *lock) return ret; } - EXPORT_SYMBOL(mutex_trylock); + +/** + * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0 + * @cnt: the atomic which we are to dec + * @lock: the mutex to return holding if we dec to 0 + * + * return true and hold lock if we dec to 0, return false otherwise + */ +int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock) +{ + /* dec if we can't possibly hit 0 */ + if (atomic_add_unless(cnt, -1, 1)) + return 0; + /* we might hit 0, so take the lock */ + mutex_lock(lock); + if (!atomic_dec_and_test(cnt)) { + /* when we actually did the dec, we didn't hit 0 */ + mutex_unlock(lock); + return 0; + } + /* we hit 0, and we hold the lock */ + return 1; +} +EXPORT_SYMBOL(atomic_dec_and_mutex_lock); -- cgit v1.2.2