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

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Message-ID: <d7c25433-d133-4897-30c5-ec2c3bf8437e@amd.com>
Date:   Wed, 15 Mar 2017 18:11:09 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     David Miller <davem@...emloft.net>
CC:     <netdev@...r.kernel.org>
Subject: Re: [PATCH net] amd-xgbe: Fix jumbo MTU processing on newer hardware

On 3/15/2017 5:52 PM, Tom Lendacky wrote:
> On 3/15/2017 5:41 PM, David Miller wrote:
>> From: Tom Lendacky <thomas.lendacky@....com>
>> Date: Wed, 15 Mar 2017 17:40:51 -0500
>>
>>> On 3/15/2017 5:37 PM, David Miller wrote:
>>>> 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.
>>>
>>> Thanks David.  This is another patch for 4.10 stable. Can you please
>>> queue it up?
>>
>> Can you properly state this in your patch postings, instead of always
>> mentioning it later?
>>
>
> Sorry, yes, I can do that.  I didn't realize you preferred it that way.
> Do you want the "Cc" tag to stable included in the patch or just
> mention the stable targets in the patch description?  I know you
> coordinate the stable submissions and I don't want to mess anything up.
>

Never mind, just found the section in the netdev-FAQ.txt file that talks
about it.  Sorry to bother you.

Thanks,
Tom

> Thanks,
> Tom
>
>
>> Thank you.
>>