netdev - Re: [PATCH v6 net-next 3/9] net: ethtool: record custom RSS contexts in the XArray

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Date: Fri, 28 Jun 2024 14:15:07 +0200
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Edward Cree <ecree.xilinx@...il.com>, <edward.cree@....com>
CC: <linux-net-drivers@....com>, <netdev@...r.kernel.org>,
	<habetsm.xilinx@...il.com>, <sudheer.mogilappagari@...el.com>,
	<jdamato@...tly.com>, <mw@...ihalf.com>, <linux@...linux.org.uk>,
	<sgoutham@...vell.com>, <gakula@...vell.com>, <sbhatta@...vell.com>,
	<hkelam@...vell.com>, <saeedm@...dia.com>, <leon@...nel.org>,
	<jacob.e.keller@...el.com>, <andrew@...n.ch>, <ahmed.zaki@...el.com>,
	<davem@...emloft.net>, <kuba@...nel.org>, <edumazet@...gle.com>,
	<pabeni@...hat.com>
Subject: Re: [PATCH v6 net-next 3/9] net: ethtool: record custom RSS contexts
 in the XArray

On 6/27/24 16:24, Edward Cree wrote:
> On 26/06/2024 10:05, Przemek Kitszel wrote:
>> On 6/25/24 15:39, Edward Cree wrote:
>>> On 20/06/2024 07:32, Przemek Kitszel wrote:
>>>> why no error code set?
>>>
>>> Because at this point the driver *has* created the context, it's
>>>    in the hardware.  If we wanted to return failure we'd have to
>>>    call the driver again to delete it, and that would still leave
>>>    an ugly case where that call fails.
>>
>> driver is creating both HW context and ID at the same time, after
>> you call it from ethtool, eh :(
>>
>> then my only concern is why do we want to keep old context instead of
>> update? (my only and last concern for this series by now)
>> say dumb driver always says "ctx=1" because it does not now better,
>> but wants to update the context
> 
> Tbh I'm not sure there's a clear case either way, if driver is
>   screwing up we don't know why or how.  The old context could
>   still be present too for all we know.  So my preference is to
>   say "we don't know what happened, let's just not touch the
>   xarray at all".
> In any case the WARN_ON should hopefully quickly catch any
>   drivers that are hitting this, and going forward new drivers
>   using this API shouldn't get added.
> 
> If you still feel strongly this should be changed, please
>   elaborate further on the reasoning.

Thanks, it makes sense as currently in the code, works for me!
I'll review v8