Re: [PATCH v2 net-next 2/2] mptcp: Don't call tcp_update_recv_tstamps() if not needed.

[Matthieu Baerts <matttbe@kernel.org>]

Hi Kuniyuki,

On 05/11/2026 22:51, Kuniyuki Iwashima wrote:
> As with TCP, __mptcp_recvmsg_mskq() also always triggers
> tcp_recv_timestamp() if skb has hwtstamp.
> 
> Accessing sk->sk_tsflags incurs unnecessary costs for sockets
> that do not need RX tstamp.
> 
> Let's check SOCK_RCVTSTAMP and SOCK_TIMESTAMPING_ANY under
> lock_sock().

Thank you for also fixing MPTCP!

> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
> ---
>  net/mptcp/protocol.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
> index 7a22e9388e0e..797797ce4e88 100644
> --- a/net/mptcp/protocol.c
> +++ b/net/mptcp/protocol.c
> @@ -2189,7 +2189,8 @@ static int __mptcp_recvmsg_mskq(struct sock *sk, struct msghdr *msg,
>  			}
>  		}
>  
> -		if (MPTCP_SKB_CB(skb)->has_rxtstamp) {
> +		if (MPTCP_SKB_CB(skb)->has_rxtstamp &&
> +		    tcp_want_rx_tstamp_cmsg(sk)) {

It is "strange" to call a TCP helper on an MPTCP socket (and not on a
TCP subflow), and that's why I preferred the previous name (sk_*). But I
understand you got asked to change that name, so better not to change it
again just for MPTCP I suppose :)

Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>

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