From: Oliver Hartkopp <socketcan@hartkopp.net>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>,
linux-can@vger.kernel.org, netdev@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC] Questionable RCU/BH usage in cgw_create_job().
Date: Thu, 21 Dec 2023 13:43:19 +0100 [thread overview]
Message-ID: <0338581d-89f0-4cca-a360-7693a27eba37@hartkopp.net> (raw)
In-Reply-To: <94c27fa1-bf19-48ae-bc20-7530d97bbd5f@hartkopp.net>
Hi Sebastian,
I've sent a RFC patch to be reviewed here:
https://lore.kernel.org/linux-can/20231221123703.8170-1-socketcan@hartkopp.net/T/#u
I hope your suggestion to use rcu_replace_pointer()
in the implemented way fits the requirements.
Best regards,
Oliver
On 2023-11-30 20:56, Oliver Hartkopp wrote:
> Hi Sebastian,
>
> On 30.11.23 17:43, Sebastian Andrzej Siewior wrote:
>> On 2023-10-31 17:52:47 [+0100], To Oliver Hartkopp wrote:
>
>>> The point is to replace/ update cf_mod at runtime while following RCU
>>> rules so always either new or the old object is observed. Never an
>>> intermediate step.
>>
>> Do you want me to take care of it?
>
> Yes, sorry.
>
> In fact I've searched some time what would fit best without getting a
> clear picture.
>
> As the changes triggered by the netlink update should come into action
> with the next processed CAN frame I have thought about adding a shadow
> 'mod' structure which is written instantly.
> And then a flag could be set, that is switched by the next incoming CAN
> frame.
>
> I just would have a problem with performing some memory allocation for
> the 'mod' updates which might take some unpredictable time.
>
> If you have some cool ideas please let me know. I'm unsure what is the
> most effective and performant approach for this use case.
>
> Many thanks,
> Oliver
>
prev parent reply other threads:[~2023-12-21 12:49 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-31 11:23 [RFC] Questionable RCU/BH usage in cgw_create_job() Sebastian Andrzej Siewior
2023-10-31 16:14 ` Oliver Hartkopp
2023-10-31 16:52 ` Sebastian Andrzej Siewior
2023-11-30 16:43 ` Sebastian Andrzej Siewior
2023-11-30 19:56 ` Oliver Hartkopp
2023-12-21 12:43 ` Oliver Hartkopp [this message]
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