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authorIlpo Järvinen <ilpo.jarvinen@helsinki.fi>2007-02-21 23:08:34 -0800
committerDavid S. Miller <davem@sunset.davemloft.net>2007-04-25 22:23:11 -0700
commit7c9a4a5b67926dd186d427bc5b9fce6ccbde154c (patch)
tree8fe8dd5ab09fda204689dfc98fb03dbf99d58cf3
parent[TCP] FRTO: frto_counter modulo-op converted to two assignments (diff)
downloadlinux-dev-7c9a4a5b67926dd186d427bc5b9fce6ccbde154c.tar.xz
linux-dev-7c9a4a5b67926dd186d427bc5b9fce6ccbde154c.zip
[TCP]: Prevent unrelated cwnd adjustment while using FRTO
FRTO controls cwnd when it still processes the ACK input or it has just reverted back to conventional RTO recovery; the normal rules apply when FRTO has reverted to standard congestion control. 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.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 9dc5754141e9..723cee63791f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2522,7 +2522,7 @@ static void tcp_conservative_spur_to_response(struct tcp_sock *tp)
* to prove that the RTO is indeed spurious. It transfers the control
* from F-RTO to the conventional RTO recovery
*/
-static void tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
+static int tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -2534,7 +2534,7 @@ static void tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
if (!before(tp->snd_una, tp->frto_highmark)) {
tcp_enter_frto_loss(sk, tp->frto_counter + 1);
- return;
+ return 1;
}
/* RFC4138 shortcoming in step 2; should also have case c): ACK isn't
@@ -2542,20 +2542,22 @@ static void tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
*/
if ((tp->snd_una == prior_snd_una) && (flag&FLAG_NOT_DUP) &&
!(flag&FLAG_FORWARD_PROGRESS))
- return;
+ return 1;
if (!(flag&FLAG_DATA_ACKED)) {
tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 0 : 3));
- return;
+ return 1;
}
if (tp->frto_counter == 1) {
tp->snd_cwnd = tcp_packets_in_flight(tp) + 2;
tp->frto_counter = 2;
+ return 1;
} else /* frto_counter == 2 */ {
tcp_conservative_spur_to_response(tp);
tp->frto_counter = 0;
}
+ return 0;
}
/* This routine deals with incoming acks, but not outgoing ones. */
@@ -2569,6 +2571,7 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
u32 prior_in_flight;
s32 seq_rtt;
int prior_packets;
+ int frto_cwnd = 0;
/* If the ack is newer than sent or older than previous acks
* then we can probably ignore it.
@@ -2631,15 +2634,16 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
flag |= tcp_clean_rtx_queue(sk, &seq_rtt);
if (tp->frto_counter)
- tcp_process_frto(sk, prior_snd_una, flag);
+ frto_cwnd = tcp_process_frto(sk, prior_snd_una, flag);
if (tcp_ack_is_dubious(sk, flag)) {
/* Advance CWND, if state allows this. */
- if ((flag & FLAG_DATA_ACKED) && tcp_may_raise_cwnd(sk, flag))
+ if ((flag & FLAG_DATA_ACKED) && !frto_cwnd &&
+ tcp_may_raise_cwnd(sk, flag))
tcp_cong_avoid(sk, ack, seq_rtt, prior_in_flight, 0);
tcp_fastretrans_alert(sk, prior_snd_una, prior_packets, flag);
} else {
- if ((flag & FLAG_DATA_ACKED))
+ if ((flag & FLAG_DATA_ACKED) && !frto_cwnd)
tcp_cong_avoid(sk, ack, seq_rtt, prior_in_flight, 1);
}