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authorIlpo Järvinen <ilpo.jarvinen@helsinki.fi>2007-08-21 21:18:07 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2007-08-30 23:01:51 -0700
commit8385cffd22359ad561a173accefeb354bd606ce4 (patch)
tree88c4bc0dddbd8b41e0d6a90a3030767d5a4aae23
parent783366ad4b212cde069c50903494eb6a6b83958c (diff)
TCP: Fix TCP handling of SACK in bidirectional flows.
It's possible that new SACK blocks that should trigger new LOST markings arrive with new data (which previously made is_dupack false). In addition, I think this fixes a case where we get a cumulative ACK with enough SACK blocks to trigger the fast recovery (is_dupack would be false there too). I'm not completely pleased with this solution because readability of the code is somewhat questionable as 'is_dupack' in SACK case is no longer about dupacks only but would mean something like 'lost_marker_work_todo' too... But because of Eifel stuff done in CA_Recovery, the FLAG_DATA_SACKED check cannot be placed to the if statement which seems attractive solution. Nevertheless, I didn't like adding another variable just for that either... :-) Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--net/ipv4/tcp_input.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index aea4b55bac2b..13abf4eaa051 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2112,7 +2112,10 @@ tcp_fastretrans_alert(struct sock *sk, u32 prior_snd_una,
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
- int is_dupack = (tp->snd_una == prior_snd_una && !(flag&FLAG_NOT_DUP));
+ int is_dupack = (tp->snd_una == prior_snd_una &&
+ (!(flag&FLAG_NOT_DUP) ||
+ ((flag&FLAG_DATA_SACKED) &&
+ (tp->fackets_out > tp->reordering))));
/* Some technical things:
* 1. Reno does not count dupacks (sacked_out) automatically. */