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From:   Menglong Dong <menglong8.dong@gmail.com>
Date:   Thu, 17 Mar 2022 13:57:47 +0800
Message-ID: <CADxym3attjUpVhP6NYO+MyFg8Psko1VhrSo9aNf=atgQgWo_uQ@mail.gmail.com>
Subject: Re: [PATCH net-next v3 3/3] net: icmp: add reasons of the skb drops
 to icmp protocol
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     David Ahern <dsahern@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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On Thu, Mar 17, 2022 at 11:18 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
[......]
> > -bool ping_rcv(struct sk_buff *skb)
> > +enum skb_drop_reason ping_rcv(struct sk_buff *skb)
> >  {
> > +     enum skb_drop_reason reason = SKB_DROP_REASON_NO_SOCKET;
> >       struct sock *sk;
> >       struct net *net = dev_net(skb->dev);
> >       struct icmphdr *icmph = icmp_hdr(skb);
> > -     bool rc = false;
> >
> >       /* We assume the packet has already been checked by icmp_rcv */
> >
> > @@ -980,15 +980,17 @@ bool ping_rcv(struct sk_buff *skb)
> >               struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
> >
> >               pr_debug("rcv on socket %p\n", sk);
> > -             if (skb2 && !ping_queue_rcv_skb(sk, skb2))
> > -                     rc = true;
> > +             if (skb2)
> > +                     reason = __ping_queue_rcv_skb(sk, skb2);
> > +             else
> > +                     reason = SKB_DROP_REASON_NOMEM;
> >               sock_put(sk);
> >       }
> >
> > -     if (!rc)
> > +     if (reason)
> >               pr_debug("no socket, dropping\n");
>
> This is going to be printed on memory allocation failures now as well.

Enn...This logic is not changed. In the previous, skb2==NULL means
rc is false, and this message is printed too.

Seems this can be optimized by the way? Printing the message only for
no socket found.