scsi: iscsi_tcp: Fix shost can_queue initialization

We are setting the shost's can_queue after we add the host which is too
late, because the SCSI midlayer will have allocated the tag set based on
the can_queue value at that time. This patch has us use the
iscsi_host_get_max_scsi_cmds() helper to figure out the number of SCSI
cmds.

It also fixes up the template can_queue so it reflects the max SCSI cmds we
can support like how other drivers work.

Link: https://lore.kernel.org/r/20210207044608.27585-7-michael.christie@oracle.comReviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/iscsi_tcp.c

@@ -847,6 +847,7 @@ iscsi_sw_tcp_session_create(struct iscsi_endpoint *ep, uint16_t cmds_max,
 	struct iscsi_session *session;
 	struct iscsi_sw_tcp_host *tcp_sw_host;
 	struct Scsi_Host *shost;
+	int rc;
 
 	if (ep) {
 		printk(KERN_ERR "iscsi_tcp: invalid ep %p.\n", ep);
@@ -864,6 +865,11 @@ iscsi_sw_tcp_session_create(struct iscsi_endpoint *ep, uint16_t cmds_max,
 	shost->max_channel = 0;
 	shost->max_cmd_len = SCSI_MAX_VARLEN_CDB_SIZE;
 
+	rc = iscsi_host_get_max_scsi_cmds(shost, cmds_max);
+	if (rc < 0)
+		goto free_host;
+	shost->can_queue = rc;
+
 	if (iscsi_host_add(shost, NULL))
 		goto free_host;
 
@@ -878,7 +884,6 @@ iscsi_sw_tcp_session_create(struct iscsi_endpoint *ep, uint16_t cmds_max,
 	tcp_sw_host = iscsi_host_priv(shost);
 	tcp_sw_host->session = session;
 
-	shost->can_queue = session->scsi_cmds_max;
 	if (iscsi_tcp_r2tpool_alloc(session))
 		goto remove_session;
 	return cls_session;
@@ -981,7 +986,7 @@ static struct scsi_host_template iscsi_sw_tcp_sht = {
 	.name			= "iSCSI Initiator over TCP/IP",
 	.queuecommand           = iscsi_queuecommand,
 	.change_queue_depth	= scsi_change_queue_depth,
-	.can_queue		= ISCSI_DEF_XMIT_CMDS_MAX - 1,
+	.can_queue		= ISCSI_TOTAL_CMDS_MAX,
 	.sg_tablesize		= 4096,
 	.max_sectors		= 0xFFFF,
 	.cmd_per_lun		= ISCSI_DEF_CMD_PER_LUN,