[PATCH 4.9 01/25] tcp_nv: fix division by zero in tcpnv_acked()

Greg Kroah-Hartman
2017-11-22T10:14:02Z

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

[ 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>
---
net/ipv4/tcp_nv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/tcp_nv.c
+++ b/net/ipv4/tcp_nv.c
@@ -263,7 +263,7 @@ static void tcpnv_acked(struct sock *sk,

/* 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