[PATCH 0/2] soc: apple: fix device leak on mbox lookup

[PATCH 0/2] soc: apple: fix device leak on mbox lookup

[Johan Hovold]

This series fixes a device reference leak when looking up mboxes and
simplifies the sart lookup by dropping the corresponding reference
sooner.

Johan


Johan Hovold (2):
  soc: apple: mailbox: fix device leak on lookup
  soc: apple: sart: drop device reference after lookup

 drivers/soc/apple/mailbox.c | 15 +++++++++++----
 drivers/soc/apple/sart.c    | 13 ++-----------
 2 files changed, 13 insertions(+), 15 deletions(-)

-- 
2.49.1

[PATCH 1/2] soc: apple: mailbox: fix device leak on lookup

[Johan Hovold]

Make sure to drop the reference taken to the mbox platform device when
looking up its driver data.

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

Fixes: 6e1457fcad3f ("soc: apple: mailbox: Add ASC/M3 mailbox driver")
Cc: stable@vger.kernel.org	# 6.8
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/soc/apple/mailbox.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/soc/apple/mailbox.c b/drivers/soc/apple/mailbox.c
index 49a0955e82d6..1685da1da23d 100644
--- a/drivers/soc/apple/mailbox.c
+++ b/drivers/soc/apple/mailbox.c
@@ -299,11 +299,18 @@ struct apple_mbox *apple_mbox_get(struct device *dev, int index)
 		return ERR_PTR(-EPROBE_DEFER);
 
 	mbox = platform_get_drvdata(pdev);
-	if (!mbox)
-		return ERR_PTR(-EPROBE_DEFER);
+	if (!mbox) {
+		mbox = ERR_PTR(-EPROBE_DEFER);
+		goto out_put_pdev;
+	}
+
+	if (!device_link_add(dev, &pdev->dev, DL_FLAG_AUTOREMOVE_CONSUMER)) {
+		mbox = ERR_PTR(-ENODEV);
+		goto out_put_pdev;
+	}
 
-	if (!device_link_add(dev, &pdev->dev, DL_FLAG_AUTOREMOVE_CONSUMER))
-		return ERR_PTR(-ENODEV);
+out_put_pdev:
+	put_device(&pdev->dev);
 
 	return mbox;
 }
-- 
2.49.1

Re: [PATCH 1/2] soc: apple: mailbox: fix device leak on lookup

[Markus Elfring]

> Make sure to drop the reference taken to the mbox platform device when
> looking up its driver data.
…

How do you think about to increase the application of scope-based resource management?
https://elixir.bootlin.com/linux/v6.17-rc7/source/include/linux/device.h#L1180
https://elixir.bootlin.com/linux/v6.17-rc7/source/include/linux/of.h#L138

Regards,
Markus

[PATCH 2/2] soc: apple: sart: drop device reference after lookup

[Johan Hovold]

Holding a reference to a device does not prevent its driver data from
going away so there is no point in keeping the reference after looking
up the sart device.

Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/soc/apple/sart.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/soc/apple/sart.c b/drivers/soc/apple/sart.c
index afa111736899..6952afc41308 100644
--- a/drivers/soc/apple/sart.c
+++ b/drivers/soc/apple/sart.c
@@ -164,17 +164,11 @@ static int apple_sart_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static void apple_sart_put_device(void *dev)
-{
-	put_device(dev);
-}
-
 struct apple_sart *devm_apple_sart_get(struct device *dev)
 {
 	struct device_node *sart_node;
 	struct platform_device *sart_pdev;
 	struct apple_sart *sart;
-	int ret;
 
 	sart_node = of_parse_phandle(dev->of_node, "apple,sart", 0);
 	if (!sart_node)
@@ -192,14 +186,11 @@ struct apple_sart *devm_apple_sart_get(struct device *dev)
 		return ERR_PTR(-EPROBE_DEFER);
 	}
 
-	ret = devm_add_action_or_reset(dev, apple_sart_put_device,
-				       &sart_pdev->dev);
-	if (ret)
-		return ERR_PTR(ret);
-
 	device_link_add(dev, &sart_pdev->dev,
 			DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
 
+	put_device(&sart_pdev->dev);
+
 	return sart;
 }
 EXPORT_SYMBOL_GPL(devm_apple_sart_get);
-- 
2.49.1

Re: [PATCH 0/2] soc: apple: fix device leak on mbox lookup

[Neal Gompa]

On Fri, Sep 26, 2025 at 10:31 AM Johan Hovold <johan@kernel.org> wrote:
>
> This series fixes a device reference leak when looking up mboxes and
> simplifies the sart lookup by dropping the corresponding reference
> sooner.
>
> Johan
>
>
> Johan Hovold (2):
>   soc: apple: mailbox: fix device leak on lookup
>   soc: apple: sart: drop device reference after lookup
>
>  drivers/soc/apple/mailbox.c | 15 +++++++++++----
>  drivers/soc/apple/sart.c    | 13 ++-----------
>  2 files changed, 13 insertions(+), 15 deletions(-)
>
> --
> 2.49.1
>

These patches look reasonable to me.

Reviewed-by: Neal Gompa <neal@gompa.dev>


-- 
真実はいつも一つ！/ Always, there's only one truth!

Re: [PATCH 0/2] soc: apple: fix device leak on mbox lookup

[Sven Peter]

On Fri, 26 Sep 2025 16:31:30 +0200, Johan Hovold wrote:
> This series fixes a device reference leak when looking up mboxes and
> simplifies the sart lookup by dropping the corresponding reference
> sooner.
> 
> Johan
> 
> 
> [...]

Applied to local tree (apple-soc/drivers-6.19), thanks!

[1/2] soc: apple: mailbox: fix device leak on lookup
      https://github.com/AsahiLinux/linux/commit/f401671e90cc
[2/2] soc: apple: sart: drop device reference after lookup
      https://github.com/AsahiLinux/linux/commit/f95f3bceade2

Best regards,
-- 
Sven Peter <sven@kernel.org>