tcp_nv: fix division by zero in tcpnv_acked()

BugLink: http://bugs.launchpad.net/bugs/1744213
[ Upstream commit 4eebff27ca4182bbf5f039dd60d79e2d7c0a707e ]

Average RTT could become zero. This happened in real life at least twice.
This patch treats zero as 1us.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Lawrence Brakmo <Brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/net/ipv4/tcp_nv.c b/net/ipv4/tcp_nv.c
index 6d650ed3cb598c0027b1c25e75f115b01402da31..5c871666c5612757ae290566cb29ae45f3e9668a 100644 (file)
--- a/net/ipv4/tcp_nv.c
+++ b/net/ipv4/tcp_nv.c
@@ -263,7 +263,7 @@ static void tcpnv_acked(struct sock *sk, const struct ack_sample *sample)
 
        /* rate in 100's bits per second */
        rate64 = ((u64)sample->in_flight) * 8000000;
-       rate = (u32)div64_u64(rate64, (u64)(avg_rtt * 100));
+       rate = (u32)div64_u64(rate64, (u64)(avg_rtt ?: 1) * 100);
 
        /* Remember the maximum rate seen during this RTT
         * Note: It may be more than one RTT. This function should be