linux-kernel - Re: [PATCH v2] drivers: watchdog: Add support for panic notifier callback

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Message-ID:
 <PH8PR18MB5381AE88C48A9960478D5C13C5C32@PH8PR18MB5381.namprd18.prod.outlook.com>
Date: Tue, 25 Feb 2025 13:58:12 +0000
From: George Cherian <gcherian@...vell.com>
To: Guenter Roeck <linux@...ck-us.net>,
        "wim@...ux-watchdog.org"
	<wim@...ux-watchdog.org>,
        "corbet@....net" <corbet@....net>
CC: "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drivers: watchdog: Add support for panic notifier
 callback

> From: Guenter Roeck <groeck7@...il.com> on behalf of Guenter Roeck <linux@...ck-us.net>
> Sent: Tuesday, February 25, 2025 18:44
> To: George Cherian; wim@...ux-watchdog.org; corbet@....net
> Cc: linux-watchdog@...r.kernel.org; linux-doc@...r.kernel.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH v2] drivers: watchdog: Add support for panic notifier callback
>> On 2/25/25 01:52, George Cherian wrote:
>> Watchdog is not turned off in kernel panic situation.
>> In certain systems this might prevent the successful loading
>> of kdump kernel. The kdump kernel might hit a watchdog reset
>> while it is booting.
>>
>> To avoid such scenarios add a panic notifier call back function
>> which can stop the watchdog. This provision can be enabled by
>> passing watchdog.stop_on_panic=1 via kernel command-line parameter.
>>
>> Signed-off-by: George Cherian <george.cherian@...vell.com>
>> ---
>> Changelog:
>> v1 -> v2
>> - Remove the per driver flag setting option
>
>You didn't actually remove it.
My bad .... I didn't really remove the helper function in watchdog.h.
>
>
>> diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
>> index d46d8c8c01f2..8cbebe38b7dd 100644
>> --- a/drivers/watchdog/watchdog_core.c
>> +++ b/drivers/watchdog/watchdog_core.c
...>
>> +/* Use the following function to stop the watchdog on panic */
>> +static inline void watchdog_stop_on_panic(struct watchdog_device *wdd)
>> +{
>> +     set_bit(WDOG_STOP_ON_PANIC, &wdd->status);
>> +}
>
>Under what circumstance could or would a _driver_ request this ?
>I do not see the use case, sorry.

Fixing it up right away and sending v3.
Thanks for the review.

>Guenter

-George