Re: [Patch net-next v2] tcp: introduce a per-route knob for quick ack

[Eric Dumazet <eric.dumazet@gmail.com>]

On Thu, 2013-06-13 at 14:24 +0800, Cong Wang wrote:


> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
> index 907311c..51ed9b7 100644
> --- a/net/ipv4/tcp_input.c
> +++ b/net/ipv4/tcp_input.c
> @@ -3726,6 +3726,7 @@ void tcp_reset(struct sock *sk)
>  static void tcp_fin(struct sock *sk)
>  {
>  	struct tcp_sock *tp = tcp_sk(sk);
> +	const struct dst_entry *dst;
>  
>  	inet_csk_schedule_ack(sk);
>  
> @@ -3737,7 +3738,9 @@ static void tcp_fin(struct sock *sk)
>  	case TCP_ESTABLISHED:
>  		/* Move to CLOSE_WAIT */
>  		tcp_set_state(sk, TCP_CLOSE_WAIT);
> -		inet_csk(sk)->icsk_ack.pingpong = 1;
> +		dst = __sk_dst_get(sk);

	What if dst is NULL ?

> +		if (!dst_metric(dst, RTAX_QUICKACK))
> +			inet_csk(sk)->icsk_ack.pingpong = 1;
>  		break;
>  
>  	case TCP_CLOSE_WAIT:
> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
> index ec335fa..f840b92 100644
> --- a/net/ipv4/tcp_output.c
> +++ b/net/ipv4/tcp_output.c
> @@ -160,6 +160,7 @@ static void tcp_event_data_sent(struct tcp_sock *tp,
>  {
>  	struct inet_connection_sock *icsk = inet_csk(sk);
>  	const u32 now = tcp_time_stamp;
> +	const struct dst_entry *dst = __sk_dst_get(sk);
>  


Same here : Are you sure dst cannot be NULL ?