[SCSI] Fix out of spec CD-ROM problem with media change

Some CD-ROMs fail to report a media change correctly.  The specific
one for this patch simply fails to respond to commands, then gives a
UNIT ATTENTION after being reset which returns ASC/ASCQ 28/00.  This
is out of spec behaviour, but add a check in the eat CC/UA on reset
path to catch this case so the CD-ROM will function somewhat properly.

[jejb: fixed up white space and accepted without signoff]
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/scsi_error.c

@@ -293,8 +293,16 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
 		 * so that we can deal with it there.
 		 */
 		if (scmd->device->expecting_cc_ua) {
-			scmd->device->expecting_cc_ua = 0;
-			return NEEDS_RETRY;
+			/*
+			 * Because some device does not queue unit
+			 * attentions correctly, we carefully check
+			 * additional sense code and qualifier so as
+			 * not to squash media change unit attention.
+			 */
+			if (sshdr.asc != 0x28 || sshdr.ascq != 0x00) {
+				scmd->device->expecting_cc_ua = 0;
+				return NEEDS_RETRY;
+			}
 		}
 		/*
 		 * if the device is in the process of becoming ready, we