netdev - Re: [RESEND PATCH 1/2] TCP: note received valid-cookie Fast Open option

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Message-ID: <f5d244d2-acd4-4dfc-8221-93d2a714b97f@redhat.com>
Date: Tue, 22 Apr 2025 12:36:51 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Jeremy Harris <jgh@...m.org>, netdev@...r.kernel.org
Cc: edumazet@...gle.com, ncardwell@...gle.com
Subject: Re: [RESEND PATCH 1/2] TCP: note received valid-cookie Fast Open
 option

On 4/16/25 11:15 AM, Jeremy Harris wrote:
> Signed-off-by: Jeremy Harris <jgh@...m.org>

The commit description is missing.

> ---
>  include/linux/tcp.h     | 3 ++-
>  net/ipv4/tcp_fastopen.c | 1 +
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/tcp.h b/include/linux/tcp.h
> index 1669d95bb0f9..a96c38574bce 100644
> --- a/include/linux/tcp.h
> +++ b/include/linux/tcp.h
> @@ -385,7 +385,8 @@ struct tcp_sock {
>  		syn_fastopen:1,	/* SYN includes Fast Open option */
>  		syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
>  		syn_fastopen_ch:1, /* Active TFO re-enabling probe */
> -		syn_data_acked:1;/* data in SYN is acked by SYN-ACK */
> +		syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
> +		syn_fastopen_in:1; /* Received SYN includes Fast Open option */

Worth mentioning in the commit message that this will fill a bit hole.
>  
>  	u8	keepalive_probes; /* num of allowed keep alive probes	*/
>  	u32	tcp_tx_delay;	/* delay (in usec) added to TX packets */
> diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
> index 1a6b1bc54245..004d0024cd98 100644
> --- a/net/ipv4/tcp_fastopen.c
> +++ b/net/ipv4/tcp_fastopen.c
> @@ -401,6 +401,7 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
>  				}
>  				NET_INC_STATS(sock_net(sk),
>  					      LINUX_MIB_TCPFASTOPENPASSIVE);
> +				tcp_sk(child)->syn_fastopen_in = 1;

Likely you need to reset the bit on disconnect().

/P