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Subject[PATCH 4.9 41/66] rds: avoid unenecessary cong_update in loop transport
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Santosh Shilimkar <santosh.shilimkar@oracle.com>

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@syzkaller.appspotmail.com
Reviewed-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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
@@ -440,6 +440,11 @@ 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
@@ -94,6 +94,11 @@ static void rds_recv_rcvbuf_delta(struct
return;

rs->rs_rcv_bytes += 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 "

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