linux-kernel - Re: [PATCH] drm/i915: Free the returned object of acpi_evaluate

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Message-ID: <YV7HmF3J6RI9L40u@intel.com>
Date:   Thu, 7 Oct 2021 13:10:32 +0300
From:   Ville Syrjälä <ville.syrjala@...ux.intel.com>
To:     Zenghui Yu <yuzenghui@...wei.com>
Cc:     intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, jani.nikula@...ux.intel.com,
        joonas.lahtinen@...ux.intel.com, rodrigo.vivi@...el.com,
        airlied@...ux.ie, daniel@...ll.ch, tiwai@...e.de,
        wanghaibin.wang@...wei.com,
        Kai-Heng Feng <kai.heng.feng@...onical.com>
Subject: Re: [PATCH] drm/i915: Free the returned object of acpi_evaluate_dsm()

On Mon, Sep 06, 2021 at 11:35:41AM +0800, Zenghui Yu wrote:
> As per the comment on top of acpi_evaluate_dsm():
> 
> | * Evaluate device's _DSM method with specified GUID, revision id and
> | * function number. Caller needs to free the returned object.
> 
> We should free the returned object of acpi_evaluate_dsm() to avoid memory
> leakage. Otherwise the kmemleak splat will be triggered at boot time (if we
> compile kernel with CONFIG_DEBUG_TEST_DRIVER_REMOVE=y).
> 
> Fixes: 8e55f99c510f ("drm/i915: Invoke another _DSM to enable MUX on HP Workstation laptops")
> Cc: Kai-Heng Feng <kai.heng.feng@...onical.com>
> Signed-off-by: Zenghui Yu <yuzenghui@...wei.com>

Applied to drm-intel-next. Thanks, and sorry for the lag.

> ---
>  drivers/gpu/drm/i915/display/intel_acpi.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_acpi.c b/drivers/gpu/drm/i915/display/intel_acpi.c
> index 7cfe91fc05f2..68abeaf2d7d4 100644
> --- a/drivers/gpu/drm/i915/display/intel_acpi.c
> +++ b/drivers/gpu/drm/i915/display/intel_acpi.c
> @@ -186,13 +186,16 @@ void intel_dsm_get_bios_data_funcs_supported(struct drm_i915_private *i915)
>  {
>  	struct pci_dev *pdev = to_pci_dev(i915->drm.dev);
>  	acpi_handle dhandle;
> +	union acpi_object *obj;
>  
>  	dhandle = ACPI_HANDLE(&pdev->dev);
>  	if (!dhandle)
>  		return;
>  
> -	acpi_evaluate_dsm(dhandle, &intel_dsm_guid2, INTEL_DSM_REVISION_ID,
> -			  INTEL_DSM_FN_GET_BIOS_DATA_FUNCS_SUPPORTED, NULL);
> +	obj = acpi_evaluate_dsm(dhandle, &intel_dsm_guid2, INTEL_DSM_REVISION_ID,
> +				INTEL_DSM_FN_GET_BIOS_DATA_FUNCS_SUPPORTED, NULL);
> +	if (obj)
> +		ACPI_FREE(obj);
>  }
>  
>  /*
> -- 
> 2.19.1

-- 
Ville Syrjälä
Intel