svcrdma: Refactor the creation of listener CMA ID

In a moment, I will add a second consumer of CMA ID creation in
svcrdma. Refactor so this code can be reused.
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/xprtrdma/svc_rdma_transport.c

@@ -65,6 +65,8 @@
 
 static struct svcxprt_rdma *svc_rdma_create_xprt(struct svc_serv *serv,
 						 struct net *net, int node);
+static int svc_rdma_listen_handler(struct rdma_cm_id *cma_id,
+				   struct rdma_cm_event *event);
 static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
 					struct net *net,
 					struct sockaddr *sa, int salen,
@@ -122,6 +124,41 @@ static void qp_event_handler(struct ib_event *event, void *context)
 	}
 }
 
+static struct rdma_cm_id *
+svc_rdma_create_listen_id(struct net *net, struct sockaddr *sap,
+			  void *context)
+{
+	struct rdma_cm_id *listen_id;
+	int ret;
+
+	listen_id = rdma_create_id(net, svc_rdma_listen_handler, context,
+				   RDMA_PS_TCP, IB_QPT_RC);
+	if (IS_ERR(listen_id))
+		return listen_id;
+
+	/* Allow both IPv4 and IPv6 sockets to bind a single port
+	 * at the same time.
+	 */
+#if IS_ENABLED(CONFIG_IPV6)
+	ret = rdma_set_afonly(listen_id, 1);
+	if (ret)
+		goto out_destroy;
+#endif
+	ret = rdma_bind_addr(listen_id, sap);
+	if (ret)
+		goto out_destroy;
+
+	ret = rdma_listen(listen_id, RPCRDMA_LISTEN_BACKLOG);
+	if (ret)
+		goto out_destroy;
+
+	return listen_id;
+
+out_destroy:
+	rdma_destroy_id(listen_id);
+	return ERR_PTR(ret);
+}
+
 static struct svcxprt_rdma *svc_rdma_create_xprt(struct svc_serv *serv,
 						 struct net *net, int node)
 {
@@ -307,7 +344,6 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
 {
 	struct rdma_cm_id *listen_id;
 	struct svcxprt_rdma *cma_xprt;
-	int ret;
 
 	if (sa->sa_family != AF_INET && sa->sa_family != AF_INET6)
 		return ERR_PTR(-EAFNOSUPPORT);
@@ -317,30 +353,13 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
 	set_bit(XPT_LISTENER, &cma_xprt->sc_xprt.xpt_flags);
 	strcpy(cma_xprt->sc_xprt.xpt_remotebuf, "listener");
 
-	listen_id = rdma_create_id(net, svc_rdma_listen_handler, cma_xprt,
-				   RDMA_PS_TCP, IB_QPT_RC);
+	listen_id = svc_rdma_create_listen_id(net, sa, cma_xprt);
 	if (IS_ERR(listen_id)) {
-		ret = PTR_ERR(listen_id);
-		goto err0;
+		kfree(cma_xprt);
+		return (struct svc_xprt *)listen_id;
 	}
-
-	/* Allow both IPv4 and IPv6 sockets to bind a single port
-	 * at the same time.
-	 */
-#if IS_ENABLED(CONFIG_IPV6)
-	ret = rdma_set_afonly(listen_id, 1);
-	if (ret)
-		goto err1;
-#endif
-	ret = rdma_bind_addr(listen_id, sa);
-	if (ret)
-		goto err1;
 	cma_xprt->sc_cm_id = listen_id;
 
-	ret = rdma_listen(listen_id, RPCRDMA_LISTEN_BACKLOG);
-	if (ret)
-		goto err1;
-
 	/*
 	 * We need to use the address from the cm_id in case the
 	 * caller specified 0 for the port number.
@@ -349,12 +368,6 @@ static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
 	svc_xprt_set_local(&cma_xprt->sc_xprt, sa, salen);
 
 	return &cma_xprt->sc_xprt;
-
- err1:
-	rdma_destroy_id(listen_id);
- err0:
-	kfree(cma_xprt);
-	return ERR_PTR(ret);
 }
 
 /*