4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ka-Cheong Poon <ka-cheong.poon@xxxxxxxxxx>
[ Upstream commit a43cced9a348901f9015f4730b70b69e7c41a9c9 ]
rds_sendmsg() calls rds_send_mprds_hash() to find a c_path to use to
send a message. Suppose the RDS connection is not yet up. In
rds_send_mprds_hash(), it does
if (conn->c_npaths == 0)
wait_event_interruptible(conn->c_hs_waitq,
(conn->c_npaths != 0));
If it is interrupted before the connection is set up,
rds_send_mprds_hash() will return a non-zero hash value. Hence
rds_sendmsg() will use a non-zero c_path to send the message. But if
the RDS connection ends up to be non-MP capable, the message will be
lost as only the zero c_path can be used.
Signed-off-by: Ka-Cheong Poon <ka-cheong.poon@xxxxxxxxxx>
Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/rds/send.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2006 Oracle. All rights reserved.
+ * Copyright (c) 2006, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This software is available to you under a choice of one of two
* licenses. You may choose to be licensed under the terms of the GNU
@@ -983,10 +983,15 @@ static int rds_send_mprds_hash(struct rd
if (conn->c_npaths == 0 && hash != 0) {
rds_send_ping(conn);
- if (conn->c_npaths == 0) {
- wait_event_interruptible(conn->c_hs_waitq,
- (conn->c_npaths != 0));
- }
+ /* The underlying connection is not up yet. Need to wait
+ * until it is up to be sure that the non-zero c_path can be
+ * 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 (wait_event_interruptible(conn->c_hs_waitq,
+ conn->c_npaths != 0))
+ hash = 0;
if (conn->c_npaths == 1)
hash = 0;
}