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authorYuchung Cheng <ycheng@google.com>2015-07-13 12:10:20 -0700
committerDavid S. Miller <davem@davemloft.net>2015-07-15 17:17:21 -0700
commitf82b681a511f4d61069e9586a9cf97bdef371ef3 (patch)
treef609823a121510cd1de4697305b916f674ea0db1 /net
parent5ebc784625ea68a9570d1f70557e7932988cd1b4 (diff)
downloadlinux-f82b681a511f4d61069e9586a9cf97bdef371ef3.tar.gz
tcp: don't use F-RTO on non-recurring timeouts
Currently F-RTO may repeatedly send new data packets on non-recurring
timeouts in CA_Loss mode. This is a bug because F-RTO (RFC5682)
should only be used on either new recovery or recurring timeouts.

This exacerbates the recovery progress during frequent timeout &
repair, because we prioritize sending new data packets instead of
repairing the holes when the bandwidth is already scarce.

Fix it by correcting the test of a new recovery episode.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_input.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 684f095d196e..728f5b3d3c64 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1917,14 +1917,13 @@ void tcp_enter_loss(struct sock *sk)
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct sk_buff *skb;
-	bool new_recovery = false;
+	bool new_recovery = icsk->icsk_ca_state < TCP_CA_Recovery;
 	bool is_reneg;			/* is receiver reneging on SACKs? */
 
 	/* Reduce ssthresh if it has not yet been made inside this window. */
 	if (icsk->icsk_ca_state <= TCP_CA_Disorder ||
 	    !after(tp->high_seq, tp->snd_una) ||
 	    (icsk->icsk_ca_state == TCP_CA_Loss && !icsk->icsk_retransmits)) {
-		new_recovery = true;
 		tp->prior_ssthresh = tcp_current_ssthresh(sk);
 		tp->snd_ssthresh = icsk->icsk_ca_ops->ssthresh(sk);
 		tcp_ca_event(sk, CA_EVENT_LOSS);