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authorIlpo Järvinen <ilpo.jarvinen@helsinki.fi>2008-04-07 22:33:57 -0700
committerDavid S. Miller <davem@davemloft.net>2008-04-07 22:33:57 -0700
commit6adb4f733e9996b4fd68a6db50dd51bd2463ccac (patch)
tree2ed50e47632902fe93f601d79fbb0ee8cb43c11c
parent882bebaaca4bb1484078d44ef011f918c0e1e14e (diff)
[TCP]: Don't allow FRTO to take place while MTU is being probed
MTU probe can cause some remedies for FRTO because the normal packet ordering may be violated allowing FRTO to make a wrong decision (it might not be that serious threat for anything though). Thus it's safer to not run FRTO while MTU probe is underway. It seems that the basic FRTO variant should also look for an skb at probe_seq.start to check if that's retransmitted one but I didn't implement it now (plain seqno in window check isn't robust against wraparounds). Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_input.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b4812c3cbbc..5119856017a 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1691,11 +1691,16 @@ static inline void tcp_reset_reno_sack(struct tcp_sock *tp)
int tcp_use_frto(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
+ const struct inet_connection_sock *icsk = inet_csk(sk);
struct sk_buff *skb;
if (!sysctl_tcp_frto)
return 0;
+ /* MTU probe and F-RTO won't really play nicely along currently */
+ if (icsk->icsk_mtup.probe_size)
+ return 0;
+
if (IsSackFrto())
return 1;