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From:   Eric Dumazet <edumazet@google.com>
Date:   Thu, 10 Feb 2022 08:29:23 -0800
Message-ID: <CANn89iKhkQ_0TbSJnPtMJrC57nz=0iiRXR-XzeZj5q6OPYZnFA@mail.gmail.com>
Subject: Re: [PATCH v3 net-next 1/7] net: skb_drop_reason: add document for
 drop reasons
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Menglong Dong <menglong8.dong@gmail.com>,
        David Ahern <dsahern@gmail.com>,
        David Ahern <dsahern@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        David Miller <davem@davemloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@netfilter.org>,
        Florian Westphal <fw@strlen.de>,
        Menglong Dong <imagedong@tencent.com>,
        Alexander Lobakin <alobakin@pm.me>, paulb@nvidia.com,
        Kees Cook <keescook@chromium.org>,
        Talal Ahmad <talalahmad@google.com>,
        Kevin Hao <haokexin@gmail.com>,
        Kumar Kartikeya Dwivedi <memxor@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>, netfilter-devel@vger.kernel.org,
        coreteam@netfilter.org, Cong Wang <cong.wang@bytedance.com>
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On Thu, Feb 10, 2022 at 8:13 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Thu, 10 Feb 2022 21:42:14 +0800 Menglong Dong wrote:
> > How about introducing a field to 'struct sock' for drop reasons? As sk is
> > locked during the packet process in tcp_v4_do_rcv(), this seems to work.
>
> I find adding temporary storage to persistent data structures awkward.
> You can put a structure on the stack and pass it thru the call chain,
> that's just my subjective preference, tho, others may have better ideas.

I had a similar TODO item, because stuff like 'waking up task' or free
one skb (or list of skb) could be performed outside of socket lock.