rds_rdma: rds_sendmsg should return EAGAIN if connection not setup

In rds_sendmsg(), in the case RDS_CMSG_RDMA_MAP is requested and
rds_cmsg_send() is called, a "struct rds_mr" needs to be created.
For creating the "struct rds_mr", the connection needs to be
established(ready) for rds_ib_transport. Otherwise, __rds_rdma_map()
would fail because it can't find the right rds_ib_device (which is
associated with the ip address matching rds_sock's bound ip address).
The ip address is set at the completion of the rdma connection.

But actually in code, the connecting is triggered after the call of call
rds_cmsg_send() so rds_cmsg_send() would fail with -NODEV.

The fix is to move the trigger of connection before calling
rds_cmsg_send() and return -EAGAIN in case connection is not
ready yet when we are calling rds_cmsg_send().

Orabug: 21551474

Signed-off-by: Wengang Wang <[email protected]>
Reviewed-by: Chien-Hua Yen <[email protected]>

Author: Wengang-oracle

net/rds/send.c

@@ -1226,11 +1226,6 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
 
 	rm->m_daddr = daddr;
 
-	/* Parse any control messages the user may have included. */
-	ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
-	if (ret)
-		goto out;
-
 	if (rm->rdma.op_active)
 		total_payload_len += rm->rdma.op_bytes;
 
@@ -1318,6 +1313,16 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
 		goto out;
 	}
 
+	if (!rds_conn_up(conn)) {
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	/* Parse any control messages the user may have included. */
+	ret = rds_cmsg_send(rs, rm, msg, &allocated_mr);
+	if (ret)
+		goto out;
+
 	while (!rds_send_queue_rm(rs, conn, rm, rs->rs_bound_port,
 				  dport, &queued)) {
 		rds_stats_inc(s_send_queue_full);