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

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Date: Mon, 19 Feb 2024 18:19:40 +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:

> 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.

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

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