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

Mike Christie
2021-02-11T12:33:50Z

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