netdev - Re: [PATCH net] amd-xgbe: Fix jumbo MTU processing on newer hardware

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Message-Id: <20170315.153710.150813448900229829.davem@davemloft.net>
Date:   Wed, 15 Mar 2017 15:37:10 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     thomas.lendacky@....com
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net] amd-xgbe: Fix jumbo MTU processing on newer
 hardware

From: Tom Lendacky <thomas.lendacky@....com>
Date: Wed, 15 Mar 2017 15:11:23 -0500

> Newer hardware does not provide a cumulative payload length when multiple
> descriptors are needed to handle the data. Once the MTU increases beyond
> the size that can be handled by a single descriptor, the SKB does not get
> built properly by the driver.
> 
> The driver will now calculate the size of the data buffers used by the
> hardware.  The first buffer of the first descriptor is for packet headers
> or packet headers and data when the headers can't be split. Subsequent
> descriptors in a multi-descriptor chain will not use the first buffer. The
> second buffer is used by all the descriptors in the chain for payload data.
> Based on whether the driver is processing the first, intermediate, or last
> descriptor it can calculate the buffer usage and build the SKB properly.
> 
> Tested and verified on both old and new hardware.
> 
> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>

Applied, thanks Tom.