linux-kernel - Re: [PATCH 0/4] wifi: wilc1000: fix RCU usage

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Message-ID: <87cyssmmzd.fsf@kernel.org>
Date: Mon, 19 Feb 2024 18:34:46 +0200
From: Kalle Valo <kvalo@...nel.org>
To: Alexis Lothoré <alexis.lothore@...tlin.com>
Cc: linux-wireless@...r.kernel.org,  Ajay Singh <ajay.kathat@...rochip.com>,
  Claudiu Beznea <claudiu.beznea@...on.dev>,  Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>,  linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] wifi: wilc1000: fix RCU usage

Alexis Lothoré <alexis.lothore@...tlin.com> writes:

> On 2/19/24 17:19, Kalle Valo wrote:
>
>> Alexis Lothoré <alexis.lothore@...tlin.com> writes:
>> 
>>> This small series aims to fix multiple warnings observed when enabling
>>> CONFIG_PROVE_RCU_LIST:
>>> - add missing locks to create corresponding critical read sections
>>> - fix mix between RCU and SRCU API usage
>>>
>>> While at it, since SRCU API is already in use in the driver, any fix done
>>> on RCU usage was also done with the SRCU variant of RCU API. I do not
>>> really get why we are using SRCU in this driver instead of classic RCU, as
>>> it seems to be done in any other wireless driver.
>> 
>> And even more so, no other driver in drivers/net use SRCU.
>> 
>>> My understanding is that primary SRCU use case is for compatibility
>>> with realtime kernel, which needs to be preemptible everywhere. Has
>>> the driver been really developped with this constraint in mind ? If
>>> you have more details about this, feel free to educate me.
>> 
>> Alexis, if you have the time I recommend submitting a patchset
>> converting wilc1000 to use classic RCU. At least I have a hard time
>> understanding why SRCU is needed, especially after seeing the warning
>> you found.
>
> If nobody else comes in with a strong argument in favor of keeping
> SRCU

And emphasis on the word "strong"...

> yes I can certainly add that to my backlog :)

Thanks! Your wilc1000 backlog is getting long, I hope your todo software
won't overload ;)

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches