[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>

1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index a4b9cdbaaa0b..dc6131e6a1ba 100644
--- 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