[PATCH 11/14] vhost-scsi: Convert to new submission API

From: Mike Christie <michael.christie@oracle.com>
To: hch@lst.de, loberman@redhat.com, martin.petersen@oracle.com,
	linux-scsi@vger.kernel.org, target-devel@vger.kernel.org,
	mst@redhat.com, stefanha@redhat.com
Cc: Mike Christie <michael.christie@oracle.com>
Subject: [PATCH 11/14] vhost-scsi: Convert to new submission API
Date: Thu, 11 Feb 2021 06:27:25 -0600	[thread overview]
Message-ID: <20210211122728.31721-12-michael.christie@oracle.com> (raw)
In-Reply-To: <20210211122728.31721-1-michael.christie@oracle.com>

target_submit_cmd_map_sgls is being removed, so convert vhost-scsi
to the new submission API. This has it use
target_init_cmd/target_submit_prep/target_submit because we need to
have lio core map sgls which is now done in target_submit_prep,
and in the last patches we will do the target_submit step from
the lio workqueue.

Note: vhost-scsi never calls target_stop_session so
target_submit_cmd_map_sgls never failed (in the new API
target_init_cmd handles target_stop_session being called when cmds
are being submitted). If it were to have used target_stop_session
and got an error, we would have hit a refcount bug like xen and usb,
because it does:

if (rc < 0) {
	transport_send_check_condition_and_sense(se_cmd,
			TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
	transport_generic_free_cmd(se_cmd, 0);
}

transport_send_check_condition_and_sense calls queue_status which
does transport_generic_free_cmd, and then we do an extra
transport_generic_free_cmd call above which would have dropped
the refcount to -1 and the refcount code would spit out errors.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
---
 drivers/vhost/scsi.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 4ce9f00ae10e..76508d408bb3 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -789,7 +789,6 @@ static void vhost_scsi_submission_work(struct work_struct *work)
 	struct vhost_scsi_nexus *tv_nexus;
 	struct se_cmd *se_cmd = &cmd->tvc_se_cmd;
 	struct scatterlist *sg_ptr, *sg_prot_ptr = NULL;
-	int rc;
 
 	/* FIXME: BIDI operation */
 	if (cmd->tvc_sgl_count) {
@@ -805,18 +804,17 @@ static void vhost_scsi_submission_work(struct work_struct *work)
 	tv_nexus = cmd->tvc_nexus;
 
 	se_cmd->tag = 0;
-	rc = target_submit_cmd_map_sgls(se_cmd, tv_nexus->tvn_se_sess,
-			cmd->tvc_cdb, &cmd->tvc_sense_buf[0],
+	target_init_cmd(se_cmd, tv_nexus->tvn_se_sess, &cmd->tvc_sense_buf[0],
 			cmd->tvc_lun, cmd->tvc_exp_data_len,
 			vhost_scsi_to_tcm_attr(cmd->tvc_task_attr),
-			cmd->tvc_data_direction, TARGET_SCF_ACK_KREF,
-			sg_ptr, cmd->tvc_sgl_count, NULL, 0, sg_prot_ptr,
-			cmd->tvc_prot_sgl_count);
-	if (rc < 0) {
-		transport_send_check_condition_and_sense(se_cmd,
-				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
-		transport_generic_free_cmd(se_cmd, 0);
-	}
+			cmd->tvc_data_direction, TARGET_SCF_ACK_KREF);
+
+	if (target_submit_prep(se_cmd, cmd->tvc_cdb, sg_ptr,
+			       cmd->tvc_sgl_count, NULL, 0, sg_prot_ptr,
+			       cmd->tvc_prot_sgl_count))
+		return;
+
+	target_submit(se_cmd);
 }
 
 static void
-- 
2.25.1

