[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>

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index a4b9cdbaaa0b99d321a37e2fa1db8bf4063e2c86..dc6131e6a1ba2d40fe32504f1cb0e0f8d8b41def 100644 (file)
--- a/drivers/scsi/scsi_error.c
+++ b/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