[PATCH 3.18 34/64] libata: drop WARN from protocol error in ata_sff_qc_issue()

[Greg Kroah-Hartman]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tejun Heo <tj@xxxxxxxxxx>


[ Upstream commit 0580b762a4d6b70817476b90042813f8573283fa ]

ata_sff_qc_issue() expects upper layers to never issue commands on a
command protocol that it doesn't implement.  While the assumption
holds fine with the usual IO path, nothing filters based on the
command protocol in the passthrough path (which was added later),
allowing the warning to be tripped with a passthrough command with the
right (well, wrong) protocol.

Failing with AC_ERR_SYSTEM is the right thing to do anyway.  Remove
the unnecessary WARN.

Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/CACT4Y+bXkvevNZU8uP6X0QVqsj6wNoUA_1exfTSOzc+SmUtMOA@xxxxxxxxxxxxxx
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/ata/libata-sff.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -1480,7 +1480,6 @@ unsigned int ata_sff_qc_issue(struct ata
 		break;
 
 	default:
-		WARN_ON_ONCE(1);
 		return AC_ERR_SYSTEM;
 	}