iscsi-target: add int (*iscsit_validate_params)()

Add int (*iscsit_validate_params)() to
struct iscsit_transport, iscsi-target
uses this callback for validating
conn operational parameters.

cxgbit.ko needs this callback to check
and update the value of
MAXXMITDATASEGMENTLENGTH.

Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/iscsi/iscsi_target_login.c

@@ -1387,6 +1387,16 @@ static int __iscsi_target_login_thread(struct iscsi_np *np)
 			goto old_sess_out;
 	}
 
+	if (conn->conn_transport->iscsit_validate_params) {
+		ret = conn->conn_transport->iscsit_validate_params(conn);
+		if (ret < 0) {
+			if (zero_tsih)
+				goto new_sess_out;
+			else
+				goto old_sess_out;
+		}
+	}
+
 	ret = iscsi_target_start_negotiation(login, conn);
 	if (ret < 0)
 		goto new_sess_out;

include/target/iscsi/iscsi_transport.h

@@ -26,6 +26,7 @@ struct iscsit_transport {
 			       struct iscsi_datain_req *, const void *, u32);
 	void (*iscsit_release_cmd)(struct iscsi_conn *, struct iscsi_cmd *);
 	void (*iscsit_get_rx_pdu)(struct iscsi_conn *);
+	int (*iscsit_validate_params)(struct iscsi_conn *);
 	enum target_prot_op (*iscsit_get_sup_prot_ops)(struct iscsi_conn *);
 };