[patch] Declare explicit, hardware based lock ranking in serio

[Arjan van de Ven]

> Thanks.
> 
> So we're taking ps2->cmd_mutex and then we're recurring back into
> ps2_command() and then taking ps2->serio->cmd_mutex.
> 
> I suspect that's all correct/natural/expected and needs another
> make-lockdep-shut-up patch.


The PS/2 code has a natural device order and there is a one level
recursion in this device order in terms of the cmd_mutex; annotate 
this explicit recursion as ok

Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
---
 drivers/input/serio/libps2.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.17-rc5-mm2/drivers/input/serio/libps2.c
===================================================================
--- linux-2.6.17-rc5-mm2.orig/drivers/input/serio/libps2.c
+++ linux-2.6.17-rc5-mm2/drivers/input/serio/libps2.c
@@ -177,7 +177,7 @@ int ps2_command(struct ps2dev *ps2dev, u
 		return -1;
 	}
 
-	mutex_lock(&ps2dev->cmd_mutex);
+	mutex_lock_nested(&ps2dev->cmd_mutex, SINGLE_DEPTH_NESTING);
 
 	serio_pause_rx(ps2dev->serio);
 	ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;

-
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