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

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Message-ID: <c64c8a6c-2e24-43ca-8ee7-7e15547ed2d1@kernel.org>
Date: Tue, 16 Apr 2024 22:22:55 +0200 (GMT+02:00)
From: Matthieu Baerts <matttbe@...nel.org>
To: Jason Xing <kerneljasonxing@...il.com>
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

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/

Cheers,
Matt