svcrdma: Copy transport address and arm CQ before calling rdma_accept

This race was found by inspection. Messages can be received from the peer
immediately following the rdma_accept call, however, the CQ have not yet
been armed and the transport address has not yet been set.

Set the transport address in the connect request handler and arm the CQ
prior to calling rdma_accept.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>

net/sunrpc/xprtrdma/svc_rdma_transport.c

@@ -570,6 +570,7 @@ static void handle_connect_req(struct rdma_cm_id *new_cma_id)
 {
 	struct svcxprt_rdma *listen_xprt = new_cma_id->context;
 	struct svcxprt_rdma *newxprt;
+	struct sockaddr *sa;
 
 	/* Create a new transport */
 	newxprt = rdma_create_xprt(listen_xprt->sc_xprt.xpt_server, 0);
@@ -582,6 +583,12 @@ static void handle_connect_req(struct rdma_cm_id *new_cma_id)
 	dprintk("svcrdma: Creating newxprt=%p, cm_id=%p, listenxprt=%p\n",
 		newxprt, newxprt->sc_cm_id, listen_xprt);
 
+	/* Set the local and remote addresses in the transport */
+	sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.dst_addr;
+	svc_xprt_set_remote(&newxprt->sc_xprt, sa, svc_addr_len(sa));
+	sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.src_addr;
+	svc_xprt_set_local(&newxprt->sc_xprt, sa, svc_addr_len(sa));
+
 	/*
 	 * Enqueue the new transport on the accept queue of the listening
 	 * transport
@@ -750,7 +757,6 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 	struct rdma_conn_param conn_param;
 	struct ib_qp_init_attr qp_attr;
 	struct ib_device_attr devattr;
-	struct sockaddr *sa;
 	int ret;
 	int i;
 
@@ -883,6 +889,13 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 	/* Swap out the handler */
 	newxprt->sc_cm_id->event_handler = rdma_cma_handler;
 
+	/*
+	 * Arm the CQs for the SQ and RQ before accepting so we can't
+	 * miss the first message
+	 */
+	ib_req_notify_cq(newxprt->sc_sq_cq, IB_CQ_NEXT_COMP);
+	ib_req_notify_cq(newxprt->sc_rq_cq, IB_CQ_NEXT_COMP);
+
 	/* Accept Connection */
 	set_bit(RDMAXPRT_CONN_PENDING, &newxprt->sc_flags);
 	memset(&conn_param, 0, sizeof conn_param);
@@ -919,14 +932,6 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
 		newxprt->sc_max_requests,
 		newxprt->sc_ord);
 
-	/* Set the local and remote addresses in the transport */
-	sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.dst_addr;
-	svc_xprt_set_remote(&newxprt->sc_xprt, sa, svc_addr_len(sa));
-	sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.src_addr;
-	svc_xprt_set_local(&newxprt->sc_xprt, sa, svc_addr_len(sa));
-
-	ib_req_notify_cq(newxprt->sc_sq_cq, IB_CQ_NEXT_COMP);
-	ib_req_notify_cq(newxprt->sc_rq_cq, IB_CQ_NEXT_COMP);
 	return &newxprt->sc_xprt;
 
  errout: