Hi Andy,
On 1/23/23 18:10, Andy Shevchenko wrote:
> acpi_dev_get_first_match_dev() gets ACPI device with the bumped
> refcount. The caller must drop it when it's done.
>
> Fix ACPI device refcounting in apple_gmux_backlight_present().
>
> Fixes: 3cf3b7f012f3 ("ACPI: video: Fix Apple GMUX backlight detection")
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Thank you for your work on this, much appreciated and I like
the new acpi_get_first_match_physical_node().
But I don't think this patch is a good idea. There is a
regression related to apple_gmux_backlight_present()
with a patch-set fixing it pending.
And that patch-set actually removes this function. Adding
a fix for this real, but not really important leak now,
will just make backporting the actual fix harder.
So I would prefer for this patch to not go in and to
go for (a to be submitted v2) of the patch-set fixing
the regression right away instead.
Regards,
Hans
> ---
> drivers/acpi/video_detect.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
> index 65cec7bb6d96..0ccde0d4c527 100644
> --- a/drivers/acpi/video_detect.c
> +++ b/drivers/acpi/video_detect.c
> @@ -114,12 +114,14 @@ static bool apple_gmux_backlight_present(void)
> {
> struct acpi_device *adev;
> struct device *dev;
> + bool ret;
>
> adev = acpi_dev_get_first_match_dev(GMUX_ACPI_HID, NULL, -1);
> if (!adev)
> return false;
>
> - dev = acpi_get_first_physical_node(adev);
> + dev = get_device(acpi_get_first_physical_node(adev));
> + acpi_dev_put(adev);
> if (!dev)
> return false;
>
> @@ -127,7 +129,9 @@ static bool apple_gmux_backlight_present(void)
> * drivers/platform/x86/apple-gmux.c only supports old style
> * Apple GMUX with an IO-resource.
> */
> - return pnp_get_resource(to_pnp_dev(dev), IORESOURCE_IO, 0) != NULL;
> + ret = pnp_get_resource(to_pnp_dev(dev), IORESOURCE_IO, 0) != NULL;
> + put_device(dev);
> + return ret;
> }
>
> /* Force to use vendor driver when the ACPI device is known to be
