[PATCH] lockdep: avoid lockdep warning in md
md_open takes ->reconfig_mutex which causes lockdep to complain. This
(normally) doesn't have deadlock potential as the possible conflict is with a
reconfig_mutex in a different device.
I say "normally" because if a loop were created in the array->member hierarchy
a deadlock could happen. However that causes bigger problems than a deadlock
and should be fixed independently.
So we flag the lock in md_open as a nested lock. This requires defining
mutex_lock_interruptible_nested.
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index d2bcb41..3ce7a5d 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4423,7 +4423,7 @@
mddev_t *mddev = inode->i_bdev->bd_disk->private_data;
int err;
- if ((err = mddev_lock(mddev)))
+ if ((err = mutex_lock_interruptible_nested(&mddev->reconfig_mutex, 1)))
goto out;
err = 0;
