[PATCH 2/2] scsi: scan: retry INQUIRY after timeout

[mwilck@suse.com]

From: Martin Wilck <mwilck@suse.com>

The SCSI mid layer doesn't retry commands after DID_TIME_OUT (see
scsi_noretry_cmd()). Packet loss in the fabric can cause spurious timeouts
during SCSI device probing, causing device probing to fail. This has been
observed in FCoE uplink failover tests, for example.

This patch fixes the issue by retrying the INQUIRY up to 3 times (in practice,
we never observed more than a single retry),

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 drivers/scsi/scsi_scan.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index b9b851ce1b72..f0a248bd1cd3 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -700,6 +700,11 @@ static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result,
 						"scsi scan: retry inquiry after REPORT LUNs\n"));
 				continue;
 			}
+			if (host_byte(result) == DID_TIME_OUT) {
+				SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
+						"scsi scan: retry inquiry after timeout\n"));
+				continue;
+			}
 		} else if (result == 0) {
 			/*
 			 * if nothing was transferred, we try
-- 
2.36.1