From 0ae80ba91f57726f31b5b5890cb7c5173e624ca4 Mon Sep 17 00:00:00 2001
From: Hannes Reinecke <hare@suse.de>
Date: Fri, 12 Jun 2015 16:12:48 +0200
Subject: scsi: retry MODE SENSE on unit attention

The 'sd' driver is calling scsi_mode_sense() to figure out
internal details. But scsi_mode_sense() never checks for
any pending unit attentions, so we're getting annoying error
messages like:

MODE SENSE: unimplemented page/subpage: 0x00/0x00

and a possible wrong decision for device cache handling.

Reviewed-by: Ewan Milne <emilne@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 448ebda..dffa91c 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -2423,7 +2423,7 @@ scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
 	unsigned char cmd[12];
 	int use_10_for_ms;
 	int header_length;
-	int result;
+	int result, retry_count = retries;
 	struct scsi_sense_hdr my_sshdr;
 
 	memset(data, 0, sizeof(*data));
@@ -2502,6 +2502,11 @@ scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
 			data->block_descriptor_length = buffer[3];
 		}
 		data->header_length = header_length;
+	} else if ((status_byte(result) == CHECK_CONDITION) &&
+		   scsi_sense_valid(sshdr) &&
+		   sshdr->sense_key == UNIT_ATTENTION && retry_count) {
+		retry_count--;
+		goto retry;
 	}
 
 	return result;
-- 
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