netdev - Re: [PATCH net v3] net: ethtool: do runtime PM outside RTNL

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Date: Fri, 15 Dec 2023 14:42:01 +0100
From: Heiner Kallweit <hkallweit1@...il.com>
To: Marc MERLIN <marc@...lins.org>, Jakub Kicinski <kuba@...nel.org>
Cc: Przemek Kitszel <przemyslaw.kitszel@...el.com>,
 Johannes Berg <johannes@...solutions.net>, netdev@...r.kernel.org,
 "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>
Subject: Re: [PATCH net v3] net: ethtool: do runtime PM outside RTNL

On 11.12.2023 05:52, Marc MERLIN wrote:
> On Thu, Dec 07, 2023 at 09:40:21AM -0800, Jakub Kicinski wrote:
>> On Thu, 7 Dec 2023 11:16:10 +0100 Przemek Kitszel wrote:
>>> I have let know our igc TL, architect, and anybody that could be
>>> interested via cc: IWL. And I'm happy that this could be done at
>>> relaxed pace thanks to Johannes
>>
>> I think you may be expecting us to take Johannes's patch.
>> It's still on the table, but to make things clear -
>> upstream we prefer to wait for the "real fix", so if we agree
>> that fixing igb/igc is a better way (as Heiner pointed out on previous
>> version PM functions are called by the stack under rtnl elsewhere too,
>> just not while device is open) - we'll wait for that. Especially
>> that I'm 80% I complained about the PM in those drivers in
>> the past and nobody seemed to care. It's a constant source of rtnl
>> deadlocks.
> 
> For whatever it's worth, I want to be clear that all stock kernels
> are 100% unusable on lenovo P17gen2 because of this deadlock and that
> without the temporary patch, my laptop would be usuable.
> It was also a risk of data loss due to repeated deadlocks and unclean
> shutdowns.
> 
Why don't you simply disable runtime pm for the affected device as a
workaround? This can be done via sysfs.

> I cannot say what the correct fix is, but I am definitely hoping you
> will accept some solution for the next stable kernel.
> 
> Thank you
> Marc