Re: [PATCH] scsi: Avoid crashing if device uses DIX but adapter does not support it

["Martin K. Petersen" <martin.petersen@oracle.com>]

>>>>> "Ewan" == Ewan D Milne <emilne@redhat.com> writes:

Ewan> This can happen if a multipathed device uses DIX and another path
Ewan> is added via an adapter that does not support it.  Multipath
Ewan> should not allow this path to be added,

No it shouldn't :)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 6d5c0b8..4f14f4a 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1143,7 +1143,17 @@ int scsi_init_io(struct scsi_cmnd *cmd)
 		struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
 		int ivecs, count;
 
-		BUG_ON(prot_sdb == NULL);
+		if (prot_sdb == NULL) {
+			/*
+			 * This can happen if someone (e.g. multipath)
+			 * queues a command to a device on an adapter
+			 * that does not support T10 PI.

s/T10 PI/DIX/

+			 */
+			WARN_ON_ONCE(1);
+			error = BLKPREP_KILL;
+			goto err_exit;
+		}
+
 		ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
 
 		if (scsi_alloc_sgtable(prot_sdb, ivecs, is_mq)) {

Failing more gracefully is OK with me.

Acked-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen	Oracle Linux Engineering