From 41719b03091911028116155deddc5eedf8c45e37 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 14 Jan 2009 15:36:26 +0100 Subject: mutex: preemption fixes The problem is that dropping the spinlock right before schedule is a voluntary preemption point and can cause a schedule, right after which we schedule again. Fix this inefficiency by keeping preemption disabled until we schedule, do this by explicity disabling preemption and providing a schedule() variant that assumes preemption is already disabled. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- kernel/mutex.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel/mutex.c') diff --git a/kernel/mutex.c b/kernel/mutex.c index 357c6d2..524ffc3 100644 --- a/kernel/mutex.c +++ b/kernel/mutex.c @@ -131,6 +131,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, struct mutex_waiter waiter; unsigned long flags; + preempt_disable(); spin_lock_mutex(&lock->wait_lock, flags); debug_mutex_lock_common(lock, &waiter); @@ -170,13 +171,14 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, spin_unlock_mutex(&lock->wait_lock, flags); debug_mutex_free_waiter(&waiter); + preempt_enable(); return -EINTR; } __set_task_state(task, state); /* didnt get the lock, go to sleep: */ spin_unlock_mutex(&lock->wait_lock, flags); - schedule(); + __schedule(); spin_lock_mutex(&lock->wait_lock, flags); } @@ -193,6 +195,7 @@ done: spin_unlock_mutex(&lock->wait_lock, flags); debug_mutex_free_waiter(&waiter); + preempt_enable(); return 0; } -- cgit v1.1