linux-kernel - Re: [PATCH] soc: samsung: exynos-pmu: fix device leak on regmap lookup

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Message-ID: <d94f40f7-9daf-46a0-bf60-c59e935ece1e@kernel.org>
Date: Thu, 27 Nov 2025 16:55:23 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Johan Hovold <johan@...nel.org>
Cc: Alim Akhtar <alim.akhtar@...sung.com>,
 Peter Griffin <peter.griffin@...aro.org>, linux-samsung-soc@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] soc: samsung: exynos-pmu: fix device leak on regmap
 lookup

On 21/11/2025 16:03, Johan Hovold wrote:
> On Fri, Nov 21, 2025 at 01:59:59PM +0100, Krzysztof Kozlowski wrote:
>> On 21/11/2025 13:18, Johan Hovold wrote:
>>> Make sure to drop the reference taken when looking up the PMU device and
>>> its regmap.
>>>
>>> Note that holding a reference to a device does not prevent its regmap
>>> from going away so there is no point in keeping the reference.
> 
>>> Fixes: 0b7c6075022c ("soc: samsung: exynos-pmu: Add regmap support for SoCs that protect PMU regs")
>>> Cc: stable@...r.kernel.org	# 6.9
>>
>> Fix is fine, but unfortunately the code in v6.9 was different and I
>> believe keeping dev reference made sense there - driver was relying on
>> drvdata. While the leak was there as well, it was intentional. I think
>> the leak can be fixed only since commit
>> 35d6b98c625867209bc47df99cf03edf4280799f .
> 
> It makes no difference actually as holding a reference to a device does
> not prevent its driver data from going away either.

True, fair enough.

Best regards,
Krzysztof