Allow rwlocks to re-enable interrupts

Pass the original flags to rwlock arch-code, so that it can re-enable
interrupts if implemented for that architecture.

Initially, make __raw_read_lock_flags and __raw_write_lock_flags stubs
which just do the same thing as non-flags variants.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Signed-off-by: Robin Holt <holt@sgi.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <linux-arch@vger.kernel.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/spinlock.c b/kernel/spinlock.c
index 7283c6d..7932653 100644
--- a/kernel/spinlock.c
+++ b/kernel/spinlock.c
@@ -121,7 +121,8 @@
 	local_irq_save(flags);
 	preempt_disable();
 	rwlock_acquire_read(&lock->dep_map, 0, 0, _RET_IP_);
-	LOCK_CONTENDED(lock, _raw_read_trylock, _raw_read_lock);
+	LOCK_CONTENDED_FLAGS(lock, _raw_read_trylock, _raw_read_lock,
+			     _raw_read_lock_flags, &flags);
 	return flags;
 }
 EXPORT_SYMBOL(_read_lock_irqsave);
@@ -151,7 +152,8 @@
 	local_irq_save(flags);
 	preempt_disable();
 	rwlock_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-	LOCK_CONTENDED(lock, _raw_write_trylock, _raw_write_lock);
+	LOCK_CONTENDED_FLAGS(lock, _raw_write_trylock, _raw_write_lock,
+			     _raw_write_lock_flags, &flags);
 	return flags;
 }
 EXPORT_SYMBOL(_write_lock_irqsave);