[PATCH net] rds: RDS (tcp) hangs on sendto() to unresponding address

[Ka-Cheong Poon]

In rds_send_mprds_hash(), if the calculated hash value is non-zero and
the MPRDS connections are not yet up, it will wait.  But it should not
wait if the send is non-blocking.  In this case, it should just use the
base c_path for sending the message.

Signed-off-by: Ka-Cheong Poon <ka-cheong.p...@oracle.com>
---
 net/rds/send.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/net/rds/send.c b/net/rds/send.c
index 57b3d5a..fe785ee 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -1007,7 +1007,8 @@ static int rds_cmsg_send(struct rds_sock *rs, struct 
rds_message *rm,
        return ret;
 }
 
-static int rds_send_mprds_hash(struct rds_sock *rs, struct rds_connection 
*conn)
+static int rds_send_mprds_hash(struct rds_sock *rs,
+                              struct rds_connection *conn, int nonblock)
 {
        int hash;
 
@@ -1023,10 +1024,16 @@ static int rds_send_mprds_hash(struct rds_sock *rs, 
struct rds_connection *conn)
                 * used.  But if we are interrupted, we have to use the zero
                 * c_path in case the connection ends up being non-MP capable.
                 */
-               if (conn->c_npaths == 0)
+               if (conn->c_npaths == 0) {
+                       /* Cannot wait for the connection be made, so just use
+                        * the base c_path.
+                        */
+                       if (nonblock)
+                               return 0;
                        if (wait_event_interruptible(conn->c_hs_waitq,
                                                     conn->c_npaths != 0))
                                hash = 0;
+               }
                if (conn->c_npaths == 1)
                        hash = 0;
        }
@@ -1256,7 +1263,7 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, 
size_t payload_len)
        }
 
        if (conn->c_trans->t_mp_capable)
-               cpath = &conn->c_path[rds_send_mprds_hash(rs, conn)];
+               cpath = &conn->c_path[rds_send_mprds_hash(rs, conn, nonblock)];
        else
                cpath = &conn->c_path[0];
 
-- 
1.8.3.1