linux-kernel - Re: [PATCH v4 1/2] watchdog: Add a new flag WDIOF_STOP

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Message-ID: <28a711e5-b2cb-4d5f-bb78-259a01cd4bcc@roeck-us.net>
Date: Wed, 5 Mar 2025 15:58:40 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Ahmad Fatoum <a.fatoum@...gutronix.de>,
 George Cherian <gcherian@...vell.com>
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 Marek Behún <kabel@...nel.org>
Subject: Re: [PATCH v4 1/2] watchdog: Add a new flag WDIOF_STOP_MAYSLEEP

On 3/5/25 03:01, Ahmad Fatoum wrote:
> Hi George,
> Hi Guenter,
> 
> On 05.03.25 11:34, George Cherian wrote:
>>> why is armada_37xx_wdt also here?
>>> The stop function in that driver may not sleep.
>> Marek,
>>
>> Thanks for reviewing.
>> Since the stop function has a regmap_write(), I thought it might sleep.
>> Now that you pointed it out, I assume that it is an MMIO based regmap being used for armada.
>> I will update the same in the next version
> 
> Failure to add WDIOF_STOP_MAYSLEEP when it's needed can lead to
> kernel hanging. Failure to add an alternative WDIOF_STOP_ATOMIC
> would lead to the kernel option being a no-op.
> 
> I think a no-op stop_on_panic (or reset_on_panic) is a saner default.
> 

Agreed. Also, I like WDIOF_STOP_ATOMIC more than the WDIOF_STOP_NOSLEEP
I had suggested in my other response.

Thanks,
Guenter