From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Blunck Subject: [patch 1/3] Make rt_down_read_trylock() behave like down_read_trylock() Date: Wed, 08 Apr 2009 01:58:54 +0200 Message-ID: <20090407235902.196040156@suse.de> References: <20090407235853.309888494@suse.de> Cc: kvm@vger.kernel.org To: rt-users Return-path: Content-Disposition: inline; filename=patches.rt/rt_down_read_trylock-fix.diff Sender: linux-rt-users-owner@vger.kernel.org List-Id: kvm.vger.kernel.org This patch removes the stupid "Read locks within the self-held write lock succeed" behaviour. This is breaking in mm_take_all_locks() since it is quite common to ensure that a lock is taken with BUG_ON(down_read_trylock(&mm->mmap_sem)). Signed-off-by: Jan Blunck --- kernel/rt.c | 12 ------------ 1 file changed, 12 deletions(-) Index: b/kernel/rt.c =================================================================== --- a/kernel/rt.c +++ b/kernel/rt.c @@ -381,18 +381,6 @@ int rt_down_read_trylock(struct rw_sema unsigned long flags; int ret; - /* - * Read locks within the self-held write lock succeed. - */ - spin_lock_irqsave(&rwsem->lock.wait_lock, flags); - if (rt_mutex_real_owner(&rwsem->lock) == current) { - spin_unlock_irqrestore(&rwsem->lock.wait_lock, flags); - rwsem_acquire_read(&rwsem->dep_map, 0, 1, _RET_IP_); - rwsem->read_depth++; - return 1; - } - spin_unlock_irqrestore(&rwsem->lock.wait_lock, flags);