[PATCH AUTOSEL 4.18 21/27] rds: RDS (tcp) hangs on sendto() to unresponding address

Sasha Levin
2018-10-22T10:20:15Z

From: Ka-Cheong Poon <ka-cheong.poon@oracle.com>

[ Upstream commit 9a4890bd6d6325a1c88564a20ab310b2d56f6094 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 59f17a2335f4..0e54ca0f4e9e 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -1006,7 +1006,8 @@ 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;

@@ -1022,10 +1023,16 @@ 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;
}
@@ -1170,7 +1177,7 @@ 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];

--
2.17.1