ACK Lucid SRU: UBUNTU: SAUCE: igb: Protect stats update

[Stefan Bader]

On 21.09.2011 16:56, Tim Gardner wrote:
> On 09/21/2011 08:48 AM, Stefan Bader wrote:
>> On 21.09.2011 16:43, Tim Gardner wrote:
>>> On 09/21/2011 08:29 AM, Stefan Bader wrote:
>>>> On 21.09.2011 15:43, Tim Gardner wrote:
>>>>> This patch is a partial backport of upstream
>>>>> 12dcd86b75d571772512676ab301279952efc0b0. Its purpose is twofold; 1) Protect
>>>>> simultaneous readers and writers, 2) refresh statistics when read from
>>>>> ethtool.
>>>>>
>>>>> rtg
>>>>>
>>>> Wondering whether there is any chance of a running user task holding the
>>>> spinlock by that watchdog work...
>>>>
>>>
>>> If by 'running user task' you mean the ethtool interface, then yes the lock
>>> _should_ be held whilst the statistics update is in progress.
>>>
>> Yeah, no (if that makes any sense). I was more wondering whether the lock may be
>> tried to be taken from the watchdog task (scheduled_work) while a user-space
>> process does something like ethtool on the same cpu...
>>
> 
> That could only happen if CONFIG_PREEMPT=y, in which case the spin lock logic
> should do the right thing.
> 
> rtg

With this mornigns discussion I' ack it as well. Just seems already applied