ata: libata-core: improve tag checks in ata_qc_issue()

Make sure to check that the tag of a queued command is valid when
ata_qc_issue() is called, and fail the QC if the tag is not valid, or if
there is an on-going non-NCQ command already on the link.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>

Author: damien-lemoal

drivers/ata/libata-core.c

@@ -5146,8 +5146,13 @@ void ata_qc_issue(struct ata_queued_cmd *qc)
 	struct ata_link *link = qc->dev->link;
 	u8 prot = qc->tf.protocol;
 
-	/* Make sure only one non-NCQ command is outstanding. */
-	WARN_ON_ONCE(ata_tag_valid(link->active_tag));
+	/*
+	 * Make sure we have a valid tag and that only one non-NCQ command is
+	 * outstanding.
+	 */
+	if (WARN_ON_ONCE(!ata_tag_valid(qc->tag)) ||
+	    WARN_ON_ONCE(ata_tag_valid(link->active_tag)))
+		goto sys_err;
 
 	if (ata_is_ncq(prot)) {
 		WARN_ON_ONCE(link->sactive & (1 << qc->hw_tag));