From: Christoph Paasch <christoph.paasch@xxxxxxxxxxxx> This patch has been added to the 3.12 stable tree. If you have any objections, please let us know. =============== [ Upstream commit 1f74e613ded11517db90b2bd57e9464d9e0fb161 ] In vegas we do a multiplication of the cwnd and the rtt. This may overflow and thus their result is stored in a u64. However, we first need to cast the cwnd so that actually 64-bit arithmetic is done. Then, we need to do do_div to allow this to be used on 32-bit arches. Cc: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> Cc: Neal Cardwell <ncardwell@xxxxxxxxxx> Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx> Cc: David Laight <David.Laight@xxxxxxxxxx> Cc: Doug Leith <doug.leith@xxxxxxx> Fixes: 8d3a564da34e (tcp: tcp_vegas cong avoid fix) Signed-off-by: Christoph Paasch <christoph.paasch@xxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> --- net/ipv4/tcp_vegas.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_vegas.c b/net/ipv4/tcp_vegas.c index 80fa2bfd7ede..c042e529a11e 100644 --- a/net/ipv4/tcp_vegas.c +++ b/net/ipv4/tcp_vegas.c @@ -218,7 +218,8 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) * This is: * (actual rate in segments) * baseRTT */ - target_cwnd = tp->snd_cwnd * vegas->baseRTT / rtt; + target_cwnd = (u64)tp->snd_cwnd * vegas->baseRTT; + do_div(target_cwnd, rtt); /* Calculate the difference between the window we had, * and the window we would like to have. This quantity -- 2.0.4 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html