Subject: Re: [PATCH net 05/10] mptcp: fix snd_wnd initialization for passive socket: manual merge

From: Matthieu Baerts <[email-masked]>
Date: Fri, 23 Feb 2024 17:35:30 +0100

Hi Jakub, Paolo, Stephen,

On 23/02/2024 5:14 pm, Matthieu Baerts (NGI0) wrote:
> From: Paolo Abeni <[email-masked]>
> 
> Such value should be inherited from the first subflow, but
> passive sockets always used 'rsk_rcv_wnd'.
> 
> Fixes: 6f8a612a33e4 ("mptcp: keep track of advertised windows right edge")
> Cc: [email-masked]
> Signed-off-by: Paolo Abeni <[email-masked]>
> Reviewed-by: Mat Martineau <[email-masked]>
> Signed-off-by: Matthieu Baerts (NGI0) <[email-masked]>
> ---
>  net/mptcp/protocol.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index 442fa7d9b57a..2c8f931c6d5b 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
> @@ -3211,7 +3211,7 @@ struct sock *mptcp_sk_clone_init(const struct sock *sk,
>  	msk->write_seq = subflow_req->idsn + 1;
>  	msk->snd_nxt = msk->write_seq;
>  	msk->snd_una = msk->write_seq;
> -	msk->wnd_end = msk->snd_nxt + req->rsk_rcv_wnd;
> +	msk->wnd_end = msk->snd_nxt + tcp_sk(ssk)->snd_wnd;

Please note that this patch will conflict with the following commit from
net-next:

  3f83d8a77eee ("mptcp: fix more tx path fields initialization")

That's because this commit modifies the same line as the one modified
here. We cannot avoid a conflict here. To fix it, please use
'WRITE_ONCE()' with the new line from -net:

  WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);

A 3-way diff has been attached to this email.

>  	msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
>  	mptcp_init_sched(msk, mptcp_sk(sk)->sched);
>  
> 

Cheers,
Matt
-- 
Sponsored by the NGI0 Core fund.

diff --cc net/mptcp/protocol.c
index 7833a49f6214,9df4eaddfd48..000000000000
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@@ -3242,25 -3204,18 +3247,25 @@@ struct sock *mptcp_sk_clone_init(const 
  
  	__mptcp_init_sock(nsk);
  
 +#if IS_ENABLED(CONFIG_MPTCP_IPV6)
 +	if (nsk->sk_family == AF_INET6)
 +		mptcp_copy_ip6_options(nsk, sk);
 +	else
 +#endif
 +		mptcp_copy_ip_options(nsk, sk);
 +
  	msk = mptcp_sk(nsk);
- 	msk->local_key = subflow_req->local_key;
- 	msk->token = subflow_req->token;
+ 	WRITE_ONCE(msk->local_key, subflow_req->local_key);
+ 	WRITE_ONCE(msk->token, subflow_req->token);
  	msk->in_accept_queue = 1;
  	WRITE_ONCE(msk->fully_established, false);
  	if (mp_opt->suboptions & OPTION_MPTCP_CSUMREQD)
  		WRITE_ONCE(msk->csum_enabled, true);
  
- 	msk->write_seq = subflow_req->idsn + 1;
- 	msk->snd_nxt = msk->write_seq;
- 	msk->snd_una = msk->write_seq;
- 	msk->wnd_end = msk->snd_nxt + tcp_sk(ssk)->snd_wnd;
+ 	WRITE_ONCE(msk->write_seq, subflow_req->idsn + 1);
+ 	WRITE_ONCE(msk->snd_nxt, msk->write_seq);
+ 	WRITE_ONCE(msk->snd_una, msk->write_seq);
 -	WRITE_ONCE(msk->wnd_end, msk->snd_nxt + req->rsk_rcv_wnd);
++	WRITE_ONCE(msk->wnd_end, msk->snd_nxt + tcp_sk(ssk)->snd_wnd);
  	msk->setsockopt_seq = mptcp_sk(sk)->setsockopt_seq;
  	mptcp_init_sched(msk, mptcp_sk(sk)->sched);