[PATCH] firmware: meson_sm: fix device leak at probe

[PATCH] firmware: meson_sm: fix device leak at probe

[Johan Hovold]

Make sure to drop the reference to the secure monitor device taken by
of_find_device_by_node() when looking up its driver data on behalf of
other drivers (e.g. during probe).

Note that holding a reference to the platform device does not prevent
its driver data from going away so there is no point in keeping the
reference after the helper returns.

Fixes: 8cde3c2153e8 ("firmware: meson_sm: Rework driver as a proper platform driver")
Cc: stable@vger.kernel.org	# 5.5
Cc: Carlo Caione <ccaione@baylibre.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/firmware/meson/meson_sm.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/meson/meson_sm.c b/drivers/firmware/meson/meson_sm.c
index f25a9746249b..3ab67aaa9e5d 100644
--- a/drivers/firmware/meson/meson_sm.c
+++ b/drivers/firmware/meson/meson_sm.c
@@ -232,11 +232,16 @@ EXPORT_SYMBOL(meson_sm_call_write);
 struct meson_sm_firmware *meson_sm_get(struct device_node *sm_node)
 {
 	struct platform_device *pdev = of_find_device_by_node(sm_node);
+	struct meson_sm_firmware *fw;
 
 	if (!pdev)
 		return NULL;
 
-	return platform_get_drvdata(pdev);
+	fw = platform_get_drvdata(pdev);
+
+	put_device(&pdev->dev);
+
+	return fw;
 }
 EXPORT_SYMBOL_GPL(meson_sm_get);
 
-- 
2.49.1

Re: [PATCH] firmware: meson_sm: fix device leak at probe

[Martin Blumenstingl]

On Fri, Jul 25, 2025 at 9:41 AM Johan Hovold <johan@kernel.org> wrote:
>
> Make sure to drop the reference to the secure monitor device taken by
> of_find_device_by_node() when looking up its driver data on behalf of
> other drivers (e.g. during probe).
>
> Note that holding a reference to the platform device does not prevent
> its driver data from going away so there is no point in keeping the
> reference after the helper returns.
>
> Fixes: 8cde3c2153e8 ("firmware: meson_sm: Rework driver as a proper platform driver")
> Cc: stable@vger.kernel.org      # 5.5
> Cc: Carlo Caione <ccaione@baylibre.com>
> Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Re: [PATCH] firmware: meson_sm: fix device leak at probe

[Markus Elfring]

> Make sure to drop the reference to the secure monitor device taken by
> of_find_device_by_node() when looking up its driver data on behalf of
> other drivers (e.g. during probe).
…

How do you think about to use the attribute “put_device” for this purpose?
https://elixir.bootlin.com/linux/v6.16/source/include/linux/device.h#L1140

Regards,
Markus

Re: [PATCH] firmware: meson_sm: fix device leak at probe

[Johan Hovold]

On Fri, Jul 25, 2025 at 09:40:19AM +0200, Johan Hovold wrote:
> Make sure to drop the reference to the secure monitor device taken by
> of_find_device_by_node() when looking up its driver data on behalf of
> other drivers (e.g. during probe).
> 
> Note that holding a reference to the platform device does not prevent
> its driver data from going away so there is no point in keeping the
> reference after the helper returns.
> 
> Fixes: 8cde3c2153e8 ("firmware: meson_sm: Rework driver as a proper platform driver")
> Cc: stable@vger.kernel.org	# 5.5
> Cc: Carlo Caione <ccaione@baylibre.com>
> Signed-off-by: Johan Hovold <johan@kernel.org>

Can someone pick this one up (along with the compile-test patch)?

Johan

Re: [PATCH] firmware: meson_sm: fix device leak at probe

[Neil Armstrong]

On 27/08/2025 11:50, Johan Hovold wrote:
> On Fri, Jul 25, 2025 at 09:40:19AM +0200, Johan Hovold wrote:
>> Make sure to drop the reference to the secure monitor device taken by
>> of_find_device_by_node() when looking up its driver data on behalf of
>> other drivers (e.g. during probe).
>>
>> Note that holding a reference to the platform device does not prevent
>> its driver data from going away so there is no point in keeping the
>> reference after the helper returns.
>>
>> Fixes: 8cde3c2153e8 ("firmware: meson_sm: Rework driver as a proper platform driver")
>> Cc: stable@vger.kernel.org	# 5.5
>> Cc: Carlo Caione <ccaione@baylibre.com>
>> Signed-off-by: Johan Hovold <johan@kernel.org>
> 
> Can someone pick this one up (along with the compile-test patch)?

I'll pick it.

Neil

> 
> Johan