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

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

[Johan Hovold]

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@vger.kernel.org	# 6.9
Cc: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/soc/samsung/exynos-pmu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/soc/samsung/exynos-pmu.c b/drivers/soc/samsung/exynos-pmu.c
index 22c50ca2aa79..ba4de8194a0e 100644
--- a/drivers/soc/samsung/exynos-pmu.c
+++ b/drivers/soc/samsung/exynos-pmu.c
@@ -346,6 +346,8 @@ struct regmap *exynos_get_pmu_regmap_by_phandle(struct device_node *np,
 	if (!dev)
 		return ERR_PTR(-EPROBE_DEFER);
 
+	put_device(dev);
+
 	return syscon_node_to_regmap(pmu_np);
 }
 EXPORT_SYMBOL_GPL(exynos_get_pmu_regmap_by_phandle);
-- 
2.51.2

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

[Krzysztof Kozlowski]

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.

Thanks for the patch, it's 3rd or fourth try from LKML on that, but you
were the only one actually really reading the code instead of sprinking
puts all around.

> 
> Fixes: 0b7c6075022c ("soc: samsung: exynos-pmu: Add regmap support for SoCs that protect PMU regs")
> Cc: stable@vger.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 .


Best regards,
Krzysztof

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

[Johan Hovold]

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@vger.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.

Johan

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

[Krzysztof Kozlowski]

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@vger.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

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

[Krzysztof Kozlowski]

On Fri, 21 Nov 2025 13:18:52 +0100, 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.
> 
> 
> [...]

Applied for late. I might send it during merge window or might miss it and roll
for the next one. In any case I will keep it in my tree.

Applied, thanks!

[1/1] soc: samsung: exynos-pmu: fix device leak on regmap lookup
      https://git.kernel.org/krzk/linux/c/990eb9a8eb4540ab90c7b34bb07b87ff13881cad

Best regards,
-- 
Krzysztof Kozlowski <krzk@kernel.org>