Re: [RFC mptcp-next v5 7/8] mptcp: fix the mptcp_check_readable

[Matthieu Baerts <matttbe@kernel.org>]

Hi Geliang, Gang,

On 22/12/2025 04:15, Geliang Tang wrote:
> From: Gang Yan <yangang@kylinos.cn>
> 
> 'mptcp_check_readble' is corresponding to the 'tcp_stream_is_readable',
> but the later one will call the 'sk_is_readble' ->
> 'prot->sock_is_readable(sk)' -> 'tls_sw_sock_is_readable'.
> 
> If not apply this patch, it will cause an error in 'poll_wait_split'
> test when running tls_test in mptcp mode.

Which error?

It might be better to move this before patch 2 and mention that this is
to aligned with TCP, and will be used in the case of KTLS, because
'prot' will be modified, tls_sw_sock_is_readable is expected to be
called from prot->sock_is_readable(), etc.

> 
> Signed-off-by: Gang Yan <yangang@kylinos.cn>
> ---
>  net/mptcp/protocol.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index bdf53e4b3f7e..8363d89d3a13 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
> @@ -3260,7 +3260,9 @@ void __mptcp_unaccepted_force_close(struct sock *sk)
>  
>  static __poll_t mptcp_check_readable(struct sock *sk)

Might be good to add a comment to say that it is similar to
tcp_stream_is_readable()

While at it, maybe rename it to mptcp_stream_is_readable() so it is
aligned with TCP?

>  {
> -	return mptcp_epollin_ready(sk) ? EPOLLIN | EPOLLRDNORM : 0;
> +	if (mptcp_epollin_ready(sk))
> +		return true;
> +	return sk_is_readable(sk);
>  }
>  
>  static void mptcp_check_listen_stop(struct sock *sk)
> @@ -4322,7 +4324,8 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
>  		mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
>  
>  	if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) {
> -		mask |= mptcp_check_readable(sk);
> +		if (mptcp_check_readable(sk))
> +			mask |= EPOLLIN | EPOLLRDNORM;
>  		if (shutdown & SEND_SHUTDOWN)
>  			mask |= EPOLLOUT | EPOLLWRNORM;
>  		else

Cheers,
Matt
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