| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <CADVnQykjK=7cL9pu1EqU+HyiVX_ujSbJ-T1Ohb+M41w4rm1wuA@mail.gmail.com>
Date: Thu, 23 Aug 2012 13:25:50 -0400
From: Neal Cardwell <ncardwell@...gle.com>
To: Nandita Dukkipati <nanditad@...gle.com>
Cc: Yuchung Cheng <ycheng@...gle.com>, davem@...emloft.net,
mattmathis@...gle.com, netdev@...r.kernel.org
Subject: Re: [PATCH] net-tcp: fix cwnd reduction for non-sack recovery
On Thu, Aug 23, 2012 at 1:21 PM, Nandita Dukkipati <nanditad@...gle.com> wrote:
> On Thu, Aug 23, 2012 at 10:05 AM, Yuchung Cheng <ycheng@...gle.com> wrote:
>> The cwnd reduction in fast recovery is based on the number of packets
>> newly delivered per ACK. For non-sack connections every DUPACK
>> signifies a packet has been delivered, but the sender mistakenly
>> skips counting them for cwnd reduction.
>>
>> The fix is to compute newly_acked_sacked after DUPACKs are accounted
>> in sacked_out for non-sack connections.
>>
>> Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
>> ---
>> net/ipv4/tcp_input.c | 15 +++++++--------
>> 1 files changed, 7 insertions(+), 8 deletions(-)
>>
>> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
>> index bcfccc5..ce4ffe9 100644
>> --- a/net/ipv4/tcp_input.c
>> +++ b/net/ipv4/tcp_input.c
>> @@ -2930,13 +2930,14 @@ static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
>> * tcp_xmit_retransmit_queue().
>> */
>> static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
>> - int newly_acked_sacked, bool is_dupack,
>> + int prior_sacked, bool is_dupack,
>> int flag)
>> {
>> struct inet_connection_sock *icsk = inet_csk(sk);
>> struct tcp_sock *tp = tcp_sk(sk);
>> int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
>> (tcp_fackets_out(tp) > tp->reordering));
>> + int newly_acked_sacked = 0;
>> int fast_rexmit = 0;
>>
>> if (WARN_ON(!tp->packets_out && tp->sacked_out))
>> @@ -2996,6 +2997,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
>> tcp_add_reno_sack(sk);
>> } else
>> do_lost = tcp_try_undo_partial(sk, pkts_acked);
>> + newly_acked_sacked = pkts_acked + tp->sacked_out - prior_sacked;
>> break;
>> case TCP_CA_Loss:
>> if (flag & FLAG_DATA_ACKED)
>> @@ -3017,6 +3019,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
>> if (is_dupack)
>> tcp_add_reno_sack(sk);
>> }
>> + newly_acked_sacked = pkts_acked + tp->sacked_out - prior_sacked;
>>
>> if (icsk->icsk_ca_state <= TCP_CA_Disorder)
>> tcp_try_undo_dsack(sk);
>> @@ -3594,7 +3597,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
>> int prior_packets;
>> int prior_sacked = tp->sacked_out;
>> int pkts_acked = 0;
>> - int newly_acked_sacked = 0;
>> bool frto_cwnd = false;
>>
>> /* If the ack is older than previous acks
>> @@ -3670,8 +3672,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
>> flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una);
>>
>> pkts_acked = prior_packets - tp->packets_out;
>> - newly_acked_sacked = (prior_packets - prior_sacked) -
>> - (tp->packets_out - tp->sacked_out);
>>
>> if (tp->frto_counter)
>> frto_cwnd = tcp_process_frto(sk, flag);
>> @@ -3685,7 +3685,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
>> tcp_may_raise_cwnd(sk, flag))
>> tcp_cong_avoid(sk, ack, prior_in_flight);
>> is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
>> - tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked,
>> + tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
>> is_dupack, flag);
>> } else {
>> if ((flag & FLAG_DATA_ACKED) && !frto_cwnd)
>> @@ -3702,7 +3702,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
>> no_queue:
>> /* If data was DSACKed, see if we can undo a cwnd reduction. */
>> if (flag & FLAG_DSACKING_ACK)
>> - tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked,
>> + tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
>> is_dupack, flag);
>> /* If this ack opens up a zero window, clear backoff. It was
>> * being used to time the probes, and is probably far higher than
>> @@ -3722,8 +3722,7 @@ old_ack:
>> */
>> if (TCP_SKB_CB(skb)->sacked) {
>> flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una);
>> - newly_acked_sacked = tp->sacked_out - prior_sacked;
>> - tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked,
>> + tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
>> is_dupack, flag);
>> }
>>
>> --
>> 1.7.7.3
>>
> Acked-by: Nandita Dukkipati <nanditad@...gle.com>
Acked-by: Neal Cardwell <ncardwell@...gle.com>
neal
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists