netdev - Re: [PATCH] bgmac: omit the fcs

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Message-Id: <20130228.142142.242861205295035084.davem@davemloft.net>
Date:	Thu, 28 Feb 2013 14:21:42 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	zajec5@...il.com
Cc:	hauke@...ke-m.de, netdev@...r.kernel.org
Subject: Re: [PATCH] bgmac: omit the fcs

From: Rafa┅ Mi┅ecki <zajec5@...il.com>
Date: Thu, 28 Feb 2013 18:57:03 +0100

> 2013/2/28 Hauke Mehrtens <hauke@...ke-m.de>:
>> Do not include the frame check sequence when adding the skb to
>> netif_receive_skb(). This causes problems when this interface was
>> bridged to a wifi ap and a big package should be forwarded from this
>> Ethernet driver through a bride to the wifi client.
> 
> Is this a real fix?
> 
> Don't get me wrong, but it sounds a little like a workaround for some
> issue in another network layer ;)

FCS should never be included in the SKB unless a specific debugging
configuration knob has enabled it.

Having the FCS there will screw up things like device provided partial
checksums (CHECKSUM_PARTIAL), which operate over the entire contents
of the packet starting at a particular offset, so if the FCS is there
we'll include it.

This change is therefore about as correct as can possibly be.
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