From: Eric Dumazet <eric.dumazet@gmail.com>
To: Felipe Dias <felipediassss@gmail.com>
Cc: netdev@vger.kernel.org
Subject: Re: dev_add_pack() duplicate skb ?
Date: Wed, 13 Feb 2013 07:05:25 -0800 [thread overview]
Message-ID: <1360767925.6884.22.camel@edumazet-glaptop> (raw)
In-Reply-To: <CAJX4=r08yC7PPtO7KA-3rsY5SMsZueJ=tVDdi2HT6MvnuO1ung@mail.gmail.com>
On Wed, 2013-02-13 at 10:11 -0200, Felipe Dias wrote:
> Hi, someone might try to tell me what I'm doing wrong, please?
>
>
> I have a simple module and I registered one packet handler, in init function:
> ---
> pseudo_proto.type = htons(ETH_P_ALL);
> pseudo_proto.dev = NULL;
> pseudo_proto.func = packet_handler;
> dev_add_pack(&pseudo_proto);
> ---
>
> My packet_handler, is a simple function just to print in dmesg info
> about the packet:
>
> ---
> ...
>
> switch (ntohs(eth_hdr(skb)->h_proto))
> {
> case ETH_P_IPV6:
> printk(KERN_INFO "%s: (%s %d %s, %s %d) Packet\n",
> THIS_MODULE->name,
> skb->dev->name,
> skb->dev->type,
> ntohs(eth_hdr(skb)->h_proto,
> ipv6_hdr(skb)->nexthdr,
> skb->len);
> break;
> ...
> ---
>
> When I sent a icmpv6 with a ping6 -c1 ::1 , this in my tcpdump show
> only 2 packets (icmp request and icmp reply), but in my dmesg I see
> 4!:
>
> ---
> 595:[30469.099222] test: (lo 772 0x86dd, 0x3a 118) Packet
> 596:[30469.099226] test: (lo 772 0x86dd, 0x3a 104) Packet
> 597:[30469.099234] test: (lo 772 0x86dd, 0x3a 118) Packet
> 598:[30469.099236] test: (lo 772 0x86dd, 0x3a 104) Packet
> ---
>
> This show 4 packets in ipv4 too. What I'm doing wrong ?
The ICMP request is sent, _and_ received : 2 packets
The ICMP response is sent, _and_ received : 2 packets
Total : 4 packets.
af_packet has special code to avoid seeing packets twice on loopback, as
it would be a bit annoying.
next prev parent reply other threads:[~2013-02-13 15:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-13 12:11 dev_add_pack() duplicate skb ? Felipe Dias
2013-02-13 15:05 ` Eric Dumazet [this message]
2013-02-13 16:09 ` Felipe Dias
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