rds: RDS (tcp) hangs on sendto() to unresponding address

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.poon@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 3 deletions

diff --git a/net/rds/send.c b/net/rds/send.c
index 57b3d5a8b2db..fe785ee819dd 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];