linux-kernel - Re: [PATCH 1/2] thermal/core: Hardening the self-encapsulation

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Date:   Thu, 12 Oct 2023 15:14:23 +0200
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Lukasz Luba <lukasz.luba@....com>
Cc:     Thierry Reding <thierry.reding@...il.com>, rafael@...nel.org,
        Amit Kucheria <amitk@...nel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] thermal/core: Hardening the self-encapsulation


Hi Lukasz,

On 12/10/2023 14:01, Lukasz Luba wrote:
> Hi Daniel,
> 
> On 10/12/23 11:26, Daniel Lezcano wrote:
>> The thermal private header has leaked all around the drivers which
>> interacted with the core internals. The thermal zone structure which
>> was part of the exported header led also to a leakage of the fields
>> into the different drivers, making very difficult to improve the core
>> code without having to change the drivers.
>>
>> Now we mostly fixed how the thermal drivers were interacting with the
>> thermal zones (actually fixed how they should not interact). The
>> thermal zone structure will be moved to the private thermal core
>> header. This header has been removed from the different drivers and
>> must belong to the core code only. In order to prevent this private
>> header to be included again in the drivers, make explicit only the
>> core code can include this header by defining a THERMAL_CORE_SUBSYS
>> macro. The private header will contain a check against this macro.
>>
>> The Tegra SoCtherm driver needs to access thermal_core.h to have the
>> get_thermal_instance() function definition. It is the only one
>> remaining driver which need to access the thermal_core.h header, so
>> the check will emit a warning at compilation time.
>>
>> Thierry Reding is reworking the driver to get rid of this function [1]
>> and thus when the changes will be merged, the compilation warning will
>> be converted to a compilation error, closing definitively the door to
>> the drivers willing to play with the thermal zone device internals.
> 
> That looks like a good idea. Although, shouldn't we avoid the
> compilation warnings and just first merge the fixes for drivers?

Yes, we should but there is the series for nvidia (pointed in the 
changelog) which need a slight refresh for the bindings AFAIR. That 
series is since March 2023 and Thierry seems busy [1]. I'm holding the 
hardening since then.

So I don't know how to make progress on this? I was assuming we can 
merge this series and let the compiler recall what has to be fixed.

[1] https://lore.kernel.org/all/ZK14edZUih1kH_sZ@orome/

and as soon as it is fixed, we convert the WARNING to ERROR :P




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