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

[Stefan Bader]

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...

>> Otherwise I guess it should ensure more regular task updates and the fencing of
>> consumers...
> 
> rtg