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Date:   Thu, 17 Mar 2022 22:10:28 -0600
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Subject: Re: [PATCH net-next v3 3/3] net: icmp: add reasons of the skb drops
 to icmp protocol
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To:     Menglong Dong <menglong8.dong@gmail.com>
Cc:     Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, xeb@mail.ru,
        David Miller <davem@davemloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Menglong Dong <imagedong@tencent.com>,
        Eric Dumazet <edumazet@google.com>, Martin Lau <kafai@fb.com>,
        Talal Ahmad <talalahmad@google.com>,
        Kees Cook <keescook@chromium.org>,
        Alexander Lobakin <alobakin@pm.me>,
        Hao Peng <flyingpeng@tencent.com>,
        Mengen Sun <mengensun@tencent.com>, dongli.zhang@oracle.com,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Biao Jiang <benbjiang@tencent.com>
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From:   David Ahern <dsahern@kernel.org>
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On 3/17/22 7:37 PM, Menglong Dong wrote:
> On Thu, Mar 17, 2022 at 10:48 PM David Ahern <dsahern@kernel.org> wrote:
>>
>> On 3/16/22 10:05 PM, Jakub Kicinski wrote:
>>> On Wed, 16 Mar 2022 21:35:47 -0600 David Ahern wrote:
>>>> On 3/16/22 9:18 PM, Jakub Kicinski wrote:
>>>>>
>>>>> I guess this set raises the follow up question to Dave if adding
>>>>> drop reasons to places with MIB exception stats means improving
>>>>> the granularity or one MIB stat == one reason?
>>>>
>>>> There are a few examples where multiple MIB stats are bumped on a drop,
>>>> but the reason code should always be set based on first failure. Did you
>>>> mean something else with your question?
>>>
>>> I meant whether we want to differentiate between TYPE, and BROADCAST or
>>> whatever other possible invalid protocol cases we can get here or just
>>> dump them all into a single protocol error code.
>>
>> I think a single one is a good starting point.
> 
> Ok, I'll try my best to make a V4 base this way...Is there any inspiration?
> 
> Such as we make SKB_DROP_REASON_PTYPE_ABSENT to
> SKB_DROP_REASON_L2_PROTO, which means the L2 protocol is not
> supported or invalied.

not following. PTYPE is a Linux name. That means nothing to a user.

I am not sure where you want to use L2_PROTO.

> 
> And use SKB_DROP_REASON_L4_PROTO for the L4 protocol problem,
> such as GRE version not supported, ICMP type not supported, etc.
> 
> Sounds nice, isn't it?