linux-kernel - Re: [PATCH] watchdog: diag288_wdt: Implement module autoload

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Message-ID: <bd9de770-7e51-4ed9-bbef-2a11ad7eb1b3@roeck-us.net>
Date: Tue, 15 Apr 2025 09:51:35 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Heiko Carstens <hca@...ux.ibm.com>
Cc: Wim Van Sebroeck <wim@...ux-watchdog.org>,
 Alexander Gordeev <agordeev@...ux.ibm.com>, Vasily Gorbik
 <gor@...ux.ibm.com>, Christian Borntraeger <borntraeger@...ux.ibm.com>,
 Sven Schnelle <svens@...ux.ibm.com>, linux-watchdog@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org
Subject: Re: [PATCH] watchdog: diag288_wdt: Implement module autoload

On 4/15/25 09:24, Heiko Carstens wrote:
> On Thu, Apr 10, 2025 at 05:10:50AM -0700, Guenter Roeck wrote:
>> On 4/10/25 02:50, Heiko Carstens wrote:
>>> The s390 specific diag288_wdt watchdog driver makes use of the virtual
>>> watchdog timer, which is available in most machine configurations.
>>> If executing the diagnose instruction with subcode 0x288 results in an
>>> exception the watchdog timer is not available, otherwise it is available.
>>>
>>> In order to allow module autoload of the diag288_wdt module, move the
>>> detection of the virtual watchdog timer to early boot code, and provide
>>> its availability as a cpu feature.
>>>
>>> This allows to make use of module_cpu_feature_match() to automatically load
>>> the module iff the virtual watchdog timer is available.
>>>
>>> Suggested-by: Marc Hartmayer <mhartmay@...ux.ibm.com>
>>> Tested-by: Mete Durlu <meted@...ux.ibm.com>
>>> Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
>>
>> Acked-by: Guenter Roeck <linux@...ck-us.net>
>>
>>> ---
>>>    arch/s390/boot/startup.c           | 17 ++++++++++
>>>    arch/s390/include/asm/cpufeature.h |  1 +
>>>    arch/s390/include/asm/diag288.h    | 41 +++++++++++++++++++++++
>>>    arch/s390/include/asm/machine.h    |  1 +
>>>    arch/s390/kernel/cpufeature.c      |  5 +++
>>>    drivers/watchdog/diag288_wdt.c     | 53 ++----------------------------
>>>    6 files changed, 68 insertions(+), 50 deletions(-)
>>>    create mode 100644 arch/s390/include/asm/diag288.h
> 
> Guenter, Wim, I assume this can/should go upstream via the s390 tree?

It touches s390 core code, and you did not suggest otherwise when submitting
the patch, so that was my assumption.

Guenter