netdev - Re: [PATCH net-next v4 4/6] tcp: support rstreason for passive reset

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Message-ID: <CAL+tcoArkeBSW=1c=e+JoCr2bRDwUFHcYMAsv84BjKfBsC8pAA@mail.gmail.com>
Date: Wed, 17 Apr 2024 08:23:19 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Matthieu Baerts <matttbe@...nel.org>
Cc: Eric Dumazet <edumazet@...gle.com>, dsahern@...nel.org, martineau@...nel.org, 
	geliang@...nel.org, kuba@...nel.org, pabeni@...hat.com, davem@...emloft.net, 
	rostedt@...dmis.org, mhiramat@...nel.org, mathieu.desnoyers@...icios.com, 
	atenart@...nel.org, mptcp@...ts.linux.dev, netdev@...r.kernel.org, 
	Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next v4 4/6] tcp: support rstreason for passive reset

Hello Matthieu,

On Wed, Apr 17, 2024 at 4:23 AM Matthieu Baerts <matttbe@...nel.org> wrote:
>
> Hi Jason,
>
> 16 Apr 2024 14:25:13 Jason Xing <kerneljasonxing@...il.com>:
>
> > On Tue, Apr 16, 2024 at 3:45 PM Jason Xing <kerneljasonxing@...il.com> wrote:
> >>
> >> On Tue, Apr 16, 2024 at 2:34 PM Eric Dumazet <edumazet@...gle.com> wrote:
> >>>
> >>> On Thu, Apr 11, 2024 at 1:57 PM Jason Xing <kerneljasonxing@...il.com> wrote:
> >>>>
> >>>> From: Jason Xing <kernelxing@...cent.com>
> >>>>
> >>>> Reuse the dropreason logic to show the exact reason of tcp reset,
> >>>> so we don't need to implement those duplicated reset reasons.
> >>>> This patch replaces all the prior NOT_SPECIFIED reasons.
> >>>>
> >>>> Signed-off-by: Jason Xing <kernelxing@...cent.com>
> >>>> ---
> >>>> net/ipv4/tcp_ipv4.c | 8 ++++----
> >>>> net/ipv6/tcp_ipv6.c | 8 ++++----
> >>>> 2 files changed, 8 insertions(+), 8 deletions(-)
> >>>>
> >>>> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> >>>> index 441134aebc51..863397c2a47b 100644
> >>>> --- a/net/ipv4/tcp_ipv4.c
> >>>> +++ b/net/ipv4/tcp_ipv4.c
> >>>> @@ -1935,7 +1935,7 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
> >>>>         return 0;
> >>>>
> >>>> reset:
> >>>> -       tcp_v4_send_reset(rsk, skb, SK_RST_REASON_NOT_SPECIFIED);
> >>>> +       tcp_v4_send_reset(rsk, skb, (u32)reason);
> >>>> discard:
> >>>>         kfree_skb_reason(skb, reason);
> >>>>         /* Be careful here. If this function gets more complicated and
> >>>> @@ -2278,7 +2278,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
> >>>>                 } else {
> >>>>                         drop_reason = tcp_child_process(sk, nsk, skb);
> >>>>                         if (drop_reason) {
> >>>> -                               tcp_v4_send_reset(nsk, skb, SK_RST_REASON_NOT_SPECIFIED);
> >>>> +                               tcp_v4_send_reset(nsk, skb, (u32)drop_reason);
> >>>
> >>> Are all these casts really needed ?
> >>
> >> Not really. If without, the compiler wouldn't complain about it.
> >
> > The truth is mptcp CI treats it as an error (see link[1]) when I
> > submitted the V5 patchset but my machine works well. I wonder whether
> > I should not remove all the casts or ignore the warnings?
>
> Please do not ignore the warnings, they are not specific to the
> MPTCP CI, they are also visible on the Netdev CI, and avoidable:
>
> https://patchwork.kernel.org/project/netdevbpf/patch/20240416114003.62110-5-kerneljasonxing@gmail.com/

Thanks for the information. Will add back the casts in V6 soon :)

Thanks,
Jason