Re: [PATCH net-next 05/11] tcp: allow mptcp to drop TS for some packets

[Matthieu Baerts <matttbe@kernel.org>]

On 01/06/2026 17:26, Eric Dumazet wrote:
> On Sun, May 31, 2026 at 11:52 PM Matthieu Baerts <matttbe@kernel.org> wrote:

(...)

>> The modifications in net/ipv4/tcp_output.c would then be limited to:
>>
>>
>> diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
>> index ef0c10cd31c7..f4edc9c4f3fc 100644
>> --- a/net/ipv4/tcp_output.c
>> +++ b/net/ipv4/tcp_output.c
>> @@ -1181,12 +1181,18 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
>>          */
>>         if (sk_is_mptcp(sk)) {
>>                 unsigned int remaining = MAX_TCP_OPTION_SPACE - size;
>> +               bool has_ts = opts->options & OPTION_TS;
>>                 unsigned int opt_size = 0;
>>
>>                 if (mptcp_established_options(sk, skb, &opt_size, remaining,
>> -                                             &opts->mptcp)) {
>> +                                             has_ts, &opts->mptcp)) {
>>                         opts->options |= OPTION_MPTCP;
>>                         size += opt_size;
>> +
>> +#if IS_ENABLED(CONFIG_MPTCP)
>> +                       if (opts->mptcp.drop_ts)
>> +                               opts->options &= ~OPTION_TS;
>> +#endif
> 
> SGTM, but maybe the IS_ENABLED() is not needed in this block,
> guarded by  if (sk_is_mptcp(sk))  ?

It looks like it is still needed, same if I use:

  if (IS_ENABLED(CONFIG_MPTCP) && sk_is_mptcp(sk)) {

Or maybe I missed another technique to avoid an extra #if.

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