netdev - Re: [PATCH net-next] tcp: Remove unnecessary arg from tcp_enter_cwr and tcp_init_cwnd

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Date:	Mon, 14 Jul 2014 12:14:41 -0700
From:	Yuchung Cheng <ycheng@...gle.com>
To:	Christoph Paasch <christoph.paasch@...ouvain.be>
Cc:	David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] tcp: Remove unnecessary arg from tcp_enter_cwr
 and tcp_init_cwnd_reduction

On Jul 14, 2014 7:59 AM, "Christoph Paasch"
<christoph.paasch@...ouvain.be> wrote:
>
> Since Yuchung's 9b44190dc11 (tcp: refactor F-RTO), tcp_enter_cwr is always
> called with set_ssthresh = 1. Thus, we can remove this argument from
> tcp_enter_cwr. Further, as we remove this one, tcp_init_cwnd_reduction
> is then always called with set_ssthresh = true, and so we can get rid of
> this argument as well.
>
> Cc: Yuchung Cheng <ycheng@...gle.com>
> Signed-off-by: Christoph Paasch <christoph.paasch@...ouvain.be>

Acked-by: Yuchung Cheng <ycheng@...gle.com>

> ---
>  include/net/tcp.h     |  2 +-
>  net/ipv4/tcp_input.c  | 15 +++++++--------
>  net/ipv4/tcp_output.c |  2 +-
>  3 files changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index c9a75dbba0c7..0aeb2eb749dc 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -928,7 +928,7 @@ static inline __u32 tcp_current_ssthresh(const struct sock *sk)
>  /* Use define here intentionally to get WARN_ON location shown at the caller */
>  #define tcp_verify_left_out(tp)        WARN_ON(tcp_left_out(tp) > tp->packets_out)
>
> -void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
> +void tcp_enter_cwr(struct sock *sk);
>  __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
>
>  /* The maximum number of MSS of available cwnd for which TSO defers
> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index bb684967f7a7..2e16afba182c 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -2475,7 +2475,7 @@ static bool tcp_try_undo_loss(struct sock *sk, bool frto_undo)
>   *     losses and/or application stalls), do not perform any further cwnd
>   *     reductions, but instead slow start up to ssthresh.
>   */
> -static void tcp_init_cwnd_reduction(struct sock *sk, const bool set_ssthresh)
> +static void tcp_init_cwnd_reduction(struct sock *sk)
>  {
>         struct tcp_sock *tp = tcp_sk(sk);
>
> @@ -2485,8 +2485,7 @@ static void tcp_init_cwnd_reduction(struct sock *sk, const bool set_ssthresh)
>         tp->prior_cwnd = tp->snd_cwnd;
>         tp->prr_delivered = 0;
>         tp->prr_out = 0;
> -       if (set_ssthresh)
> -               tp->snd_ssthresh = inet_csk(sk)->icsk_ca_ops->ssthresh(sk);
> +       tp->snd_ssthresh = inet_csk(sk)->icsk_ca_ops->ssthresh(sk);
>         TCP_ECN_queue_cwr(tp);
>  }
>
> @@ -2528,14 +2527,14 @@ static inline void tcp_end_cwnd_reduction(struct sock *sk)
>  }
>
>  /* Enter CWR state. Disable cwnd undo since congestion is proven with ECN */
> -void tcp_enter_cwr(struct sock *sk, const int set_ssthresh)
> +void tcp_enter_cwr(struct sock *sk)
>  {
>         struct tcp_sock *tp = tcp_sk(sk);
>
>         tp->prior_ssthresh = 0;
>         if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
>                 tp->undo_marker = 0;
> -               tcp_init_cwnd_reduction(sk, set_ssthresh);
> +               tcp_init_cwnd_reduction(sk);
>                 tcp_set_ca_state(sk, TCP_CA_CWR);
>         }
>  }
> @@ -2564,7 +2563,7 @@ static void tcp_try_to_open(struct sock *sk, int flag, const int prior_unsacked)
>                 tp->retrans_stamp = 0;
>
>         if (flag & FLAG_ECE)
> -               tcp_enter_cwr(sk, 1);
> +               tcp_enter_cwr(sk);
>
>         if (inet_csk(sk)->icsk_ca_state != TCP_CA_CWR) {
>                 tcp_try_keep_open(sk);
> @@ -2670,7 +2669,7 @@ static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
>         if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
>                 if (!ece_ack)
>                         tp->prior_ssthresh = tcp_current_ssthresh(sk);
> -               tcp_init_cwnd_reduction(sk, true);
> +               tcp_init_cwnd_reduction(sk);
>         }
>         tcp_set_ca_state(sk, TCP_CA_Recovery);
>  }
> @@ -3346,7 +3345,7 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
>                 tp->tlp_high_seq = 0;
>                 /* Don't reduce cwnd if DSACK arrives for TLP retrans. */
>                 if (!(flag & FLAG_DSACKING_ACK)) {
> -                       tcp_init_cwnd_reduction(sk, true);
> +                       tcp_init_cwnd_reduction(sk);
>                         tcp_set_ca_state(sk, TCP_CA_CWR);
>                         tcp_end_cwnd_reduction(sk);
>                         tcp_try_keep_open(sk);
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index bcee13c4627c..306dd5dead7d 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -979,7 +979,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
>         if (likely(err <= 0))
>                 return err;
>
> -       tcp_enter_cwr(sk, 1);
> +       tcp_enter_cwr(sk);
>
>         return net_xmit_eval(err);
>  }
> --
> 1.9.3
>
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