netdev - Re: [PATCH RFC] net/macb: Fix UDPv4 checksum offload

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Message-Id: <20150428.164751.1765242259665119244.davem@davemloft.net>
Date:	Tue, 28 Apr 2015 16:47:51 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	jaeden.amero@...com
Cc:	nicolas.ferre@...el.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, jeff.westfahl@...com,
	mihai.neagu@...com
Subject: Re: [PATCH RFC] net/macb: Fix UDPv4 checksum offload

From: Jaeden Amero <jaeden.amero@...com>
Date: Tue, 28 Apr 2015 15:36:54 -0500

> On 04/27/2015 09:47 PM, David Miller wrote:
>> From: Jaeden Amero <jaeden.amero@...com>
>> Date: Mon, 27 Apr 2015 17:43:30 -0500
>>
>> A UDP checksum of zero, means "checksum not computed".  And your
>> device isn't computing the checksum at all, but rather is leaving it
>> at zero.
> 
> The "zero" checksum is not what gets sent over the wire. Independent of
> the value of the checksum field, hardware generates a correct checksum
> for payloads of 3 or more bytes. The bug is that hardware generates an
> incorrect checksum for payloads of 2 or less bytes, unless the checksum
> field is zeroed.

Ok, then you need to add a comment here, because other people might come
to the same conclusion I did.
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