rds: avoid unenecessary cong_update in loop transport

BugLink: http://bugs.launchpad.net/bugs/1811877
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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/net/rds/loop.c b/net/rds/loop.c
index f2bf78de5688a3ee44862fe158bffee4ca94d91a..dac6218a460ed4d4a5b7b03ad4f6056a68784a16 100644 (file)
--- 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,
 };

diff --git a/net/rds/rds.h b/net/rds/rds.h
index d09f6c1facb4a83c5d47340e5ae7134230089388..f685d8b514e553ceaba724918489717cba46bfc2 100644 (file)
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -454,6 +454,11 @@ 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
  *

diff --git a/net/rds/recv.c b/net/rds/recv.c
index 555f07ccf0dc60d480adb0495091a748dca9b3ba..c27cceae52e1f118ef9c5a4b19831d7654327f96 100644 (file)
--- a/net/rds/recv.c
+++ b/net/rds/recv.c
@@ -103,6 +103,11 @@ static void rds_recv_rcvbuf_delta(struct rds_sock *rs, struct sock *sk,
                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 "