[PATCH 4.17 077/101] rds: avoid unenecessary cong_update in loop transport
From: Greg Kroah-Hartman
Date: Fri Jul 20 2018 - 08:44:56 EST
4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx>
commit f1693c63ab133d16994cc50f773982b5905af264 upstream.
Loop transport which is self loopback, remote port congestion
update isn't relevant. Infact the xmit path already ignores it.
Receive path needs to do the same.
Reported-by: syzbot+4c20b3866171ce8441d2@xxxxxxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Sowmini Varadhan <sowmini.varadhan@xxxxxxxxxx>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/rds/loop.c | 1 +
net/rds/rds.h | 5 +++++
net/rds/recv.c | 5 +++++
3 files changed, 11 insertions(+)
--- a/net/rds/loop.c
+++ b/net/rds/loop.c
@@ -193,4 +193,5 @@ struct rds_transport rds_loop_transport
.inc_copy_to_user = rds_message_inc_copy_to_user,
.inc_free = rds_loop_inc_free,
.t_name = "loopback",
+ .t_type = RDS_TRANS_LOOP,
};
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -479,6 +479,11 @@ struct rds_notifier {
int n_status;
};
+/* Available as part of RDS core, so doesn't need to participate
+ * in get_preferred transport etc
+ */
+#define RDS_TRANS_LOOP 3
+
/**
* struct rds_transport - transport specific behavioural hooks
*
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -103,6 +103,11 @@ static void rds_recv_rcvbuf_delta(struct
rds_stats_add(s_recv_bytes_added_to_socket, delta);
else
rds_stats_add(s_recv_bytes_removed_from_socket, -delta);
+
+ /* loop transport doesn't send/recv congestion updates */
+ if (rs->rs_transport->t_type == RDS_TRANS_LOOP)
+ return;
+
now_congested = rs->rs_rcv_bytes > rds_sk_rcvbuf(rs);
rdsdebug("rs %p (%pI4:%u) recv bytes %d buf %d "