[PATCH] libata: clear sdev->locked on door lock failure
SCSI EH locks door if sdev->locked is set. Sometimes door lock
command fails continuously (e.g. when medium is not present) and as
libata uses EH to acquire sense data, this easily creates a loop where
a failed lock door invokes EH and EH issues lock door on completion.
This patch clears sdev->locked on door lock failure to break this
loop. This problem has been spotted and diagnosed by Unicorn Chang
<uchang@tw.ibm.com>.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 7ced41e..e92c31d 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -2353,6 +2353,19 @@
ata_gen_ata_desc_sense(qc);
}
+ /* SCSI EH automatically locks door if sdev->locked is
+ * set. Sometimes door lock request continues to
+ * fail, for example, when no media is present. This
+ * creates a loop - SCSI EH issues door lock which
+ * fails and gets invoked again to acquire sense data
+ * for the failed command.
+ *
+ * If door lock fails, always clear sdev->locked to
+ * avoid this infinite loop.
+ */
+ if (qc->cdb[0] == ALLOW_MEDIUM_REMOVAL)
+ qc->dev->sdev->locked = 0;
+
qc->scsicmd->result = SAM_STAT_CHECK_CONDITION;
qc->scsidone(cmd);
ata_qc_free(qc);