netdev - Re: [PATCH net-next 4/6] mptcp: implement .splice

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Message-ID: <0f074dd6-6a37-4f7e-bdd3-528f201fc8f1@kernel.org>
Date: Fri, 30 Jan 2026 08:24:40 +0100
From: Matthieu Baerts <matttbe@...nel.org>
To: Mat Martineau <martineau@...nel.org>, Geliang Tang <geliang@...nel.org>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Simon Horman <horms@...nel.org>, Neal Cardwell <ncardwell@...gle.com>,
 Kuniyuki Iwashima <kuniyu@...gle.com>, David Ahern <dsahern@...nel.org>,
 Shuah Khan <shuah@...nel.org>
Cc: netdev@...r.kernel.org, mptcp@...ts.linux.dev,
 linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next 4/6] mptcp: implement .splice_read

Hello,

On 29/01/2026 20:23, Matthieu Baerts (NGI0) wrote:
> From: Geliang Tang <tanggeliang@...inos.cn>
> 
> This patch implements .splice_read interface of mptcp struct proto_ops
> as mptcp_splice_read() with reference to tcp_splice_read().
> 
> Corresponding to __tcp_splice_read(), __mptcp_splice_read() is defined,
> invoking mptcp_read_sock() instead of tcp_read_sock().
> 
> mptcp_splice_read() is almost the same as tcp_splice_read(), except for
> sock_rps_record_flow().
> 
> Signed-off-by: Geliang Tang <tanggeliang@...inos.cn>
> Reviewed-by: Mat Martineau <martineau@...nel.org>
> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@...nel.org>
> ---
>  net/mptcp/protocol.c | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 114 insertions(+)
> 
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index c58e306ec3ef..3aee29f70954 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
> @@ -4396,6 +4396,118 @@ static int mptcp_read_sock(struct sock *sk, read_descriptor_t *desc,
>  	return __mptcp_read_sock(sk, desc, recv_actor, false);
>  }
>  
> +static int __mptcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
> +{
> +	/* Store TCP splice context information in read_descriptor_t. */
> +	read_descriptor_t rd_desc = {
> +		.arg.data = tss,
> +		.count	  = tss->len,
> +	};
> +
> +	return mptcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
> +}
> +
> +/**
> + *  mptcp_splice_read - splice data from MPTCP socket to a pipe
> + * @sock:	socket to splice from
> + * @ppos:	position (not valid)
> + * @pipe:	pipe to splice to
> + * @len:	number of bytes to splice
> + * @flags:	splice modifier flags
> + *
> + * Description:
> + *    Will read pages from given socket and fill them into a pipe.

This comment is a copy of tcp_splice_read() where only the first line
has been adapted, but this seems to cause a new kdoc warning:

  net/mptcp/protocol.c:4424 No description found for return value of
'mptcp_splice_read'

I guess something like that should be added in a v2:

  Return:
     Amount of bytes that have been spliced.

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