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[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>
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parent
94d0ea7786
commit
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1 changed files with 11 additions and 7 deletions
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@ -2522,7 +2522,7 @@ static void tcp_conservative_spur_to_response(struct tcp_sock *tp)
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* to prove that the RTO is indeed spurious. It transfers the control
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* from F-RTO to the conventional RTO recovery
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*/
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static void tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
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static int tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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@ -2534,7 +2534,7 @@ static void tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
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if (!before(tp->snd_una, tp->frto_highmark)) {
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tcp_enter_frto_loss(sk, tp->frto_counter + 1);
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return;
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return 1;
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}
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/* RFC4138 shortcoming in step 2; should also have case c): ACK isn't
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@ -2542,20 +2542,22 @@ static void tcp_process_frto(struct sock *sk, u32 prior_snd_una, int flag)
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*/
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if ((tp->snd_una == prior_snd_una) && (flag&FLAG_NOT_DUP) &&
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!(flag&FLAG_FORWARD_PROGRESS))
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return;
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return 1;
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if (!(flag&FLAG_DATA_ACKED)) {
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tcp_enter_frto_loss(sk, (tp->frto_counter == 1 ? 0 : 3));
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return;
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return 1;
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}
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if (tp->frto_counter == 1) {
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tp->snd_cwnd = tcp_packets_in_flight(tp) + 2;
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tp->frto_counter = 2;
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return 1;
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} else /* frto_counter == 2 */ {
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tcp_conservative_spur_to_response(tp);
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tp->frto_counter = 0;
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}
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return 0;
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}
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/* This routine deals with incoming acks, but not outgoing ones. */
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@ -2569,6 +2571,7 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
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u32 prior_in_flight;
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s32 seq_rtt;
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int prior_packets;
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int frto_cwnd = 0;
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/* If the ack is newer than sent or older than previous acks
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* then we can probably ignore it.
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@ -2631,15 +2634,16 @@ static int tcp_ack(struct sock *sk, struct sk_buff *skb, int flag)
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flag |= tcp_clean_rtx_queue(sk, &seq_rtt);
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if (tp->frto_counter)
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tcp_process_frto(sk, prior_snd_una, flag);
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frto_cwnd = tcp_process_frto(sk, prior_snd_una, flag);
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if (tcp_ack_is_dubious(sk, flag)) {
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/* Advance CWND, if state allows this. */
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if ((flag & FLAG_DATA_ACKED) && tcp_may_raise_cwnd(sk, flag))
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if ((flag & FLAG_DATA_ACKED) && !frto_cwnd &&
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tcp_may_raise_cwnd(sk, flag))
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tcp_cong_avoid(sk, ack, seq_rtt, prior_in_flight, 0);
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tcp_fastretrans_alert(sk, prior_snd_una, prior_packets, flag);
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} else {
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if ((flag & FLAG_DATA_ACKED))
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if ((flag & FLAG_DATA_ACKED) && !frto_cwnd)
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tcp_cong_avoid(sk, ack, seq_rtt, prior_in_flight, 1);
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}
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