linux-kernel - Re: [PATCH 3/5] thermal/core: Remove unneeded mutex

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Date:   Thu, 19 Jan 2023 13:48:00 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Zhang, Rui" <rui.zhang@...el.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "amitk@...nel.org" <amitk@...nel.org>
Subject: Re: [PATCH 3/5] thermal/core: Remove unneeded mutex_destroy()

On 19/01/2023 13:11, Rafael J. Wysocki wrote:
> On Thu, Jan 19, 2023 at 10:30 AM Daniel Lezcano
> <daniel.lezcano@...aro.org> wrote:
>>
>> On 19/01/2023 08:41, Zhang, Rui wrote:
>>> On Wed, 2023-01-18 at 22:11 +0100, Daniel Lezcano wrote:
>>>> If the thermal framework fails to initialize, the mutex can be used
>>>> by
>>>> the different functions registering a thermal zone anyway.
>>>
>>> Hmm, even with no governors and unregistered thermal sysfs class?
>>>
>>> IMO, thermal APIs for registering a thermal_zone/cooling_device should
>>> yield early if thermal_init fails.
>>> For other APIs that relies on a valid
>>> thermal_zone_device/thermal_cooling_device pointer, nothing needs to
>>> be changed.
>>>
>>> what do you think?
>>
>> I think you are right.
>>
>> It would be nice if we can check if the thermal class is registered and
>> bail out if not. But there is no function to check that AFAICS.
>>
>> Alternatively we can convert the thermal class static structure to a
>> pointer and set it to NULL in case of error in thermal_init() ?
> 
> It doesn't matter if this is a NULL pointer or a static object that's
> clearly marked as unused.

Without introducing another global variable, is it possible to know if 
the class is used or not ?

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