linux-kernel - Re: [PATCH v2] drm: writeback: Fix drm_writeback_connector

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Message-ID: <ce2f3c96-38e4-4a75-9b6c-838e070a274d@bootlin.com>
Date: Fri, 20 Jun 2025 11:32:16 +0200
From: Louis Chauvet <louis.chauvet@...tlin.com>
To: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: thomas.petazzoni@...tlin.com, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, Mark Yacoub <markyacoub@...gle.com>
Subject: Re: [PATCH v2] drm: writeback: Fix drm_writeback_connector_cleanup
 signature

Hi all,

This patch is pending for 6 weeks, as this is a bug affecting all build 
with CFI and VKMS (the only user of this API), can someone take a look 
and apply it?

Thanks a lot,
Louis Chauvet

Le 29/04/2025 à 10:36, Louis Chauvet a écrit :
> The drm_writeback_connector_cleanup have the signature:
> 
>       static void drm_writeback_connector_cleanup(
> 		struct drm_device *dev,
> 		struct drm_writeback_connector *wb_connector)
> 
> But it is stored and used as a drmres_release_t
> 
>      typedef void (*drmres_release_t)(struct drm_device *dev, void *res);
> 
> While the current code is valid and does not produce any warning, the
> CFI runtime check (CONFIG_CFI_CLANG) can fail because the function
> signature is not the same as drmres_release_t.
> 
> In order to fix this, change the function signature to match what is
> expected by drmres_release_t.
> 
> Fixes: 1914ba2b91ea ("drm: writeback: Create drmm variants for drm_writeback_connector initialization")
> 
> Suggested-by: Mark Yacoub <markyacoub@...gle.com>
> Signed-off-by: Louis Chauvet <louis.chauvet@...tlin.com>
> ---
> Changes in v2:
> - Forgot to update the documentation
> - Link to v1: https://lore.kernel.org/r/20250428-drm-fix-writeback-cleanup-v1-1-e4c723868b73@bootlin.com
> ---
>   drivers/gpu/drm/drm_writeback.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_writeback.c b/drivers/gpu/drm/drm_writeback.c
> index edbeab88ff2b..d983ee85cf13 100644
> --- a/drivers/gpu/drm/drm_writeback.c
> +++ b/drivers/gpu/drm/drm_writeback.c
> @@ -343,17 +343,18 @@ EXPORT_SYMBOL(drm_writeback_connector_init_with_encoder);
>   /**
>    * drm_writeback_connector_cleanup - Cleanup the writeback connector
>    * @dev: DRM device
> - * @wb_connector: Pointer to the writeback connector to clean up
> + * @data: Pointer to the writeback connector to clean up
>    *
>    * This will decrement the reference counter of blobs and destroy properties. It
>    * will also clean the remaining jobs in this writeback connector. Caution: This helper will not
>    * clean up the attached encoder and the drm_connector.
>    */
>   static void drm_writeback_connector_cleanup(struct drm_device *dev,
> -					    struct drm_writeback_connector *wb_connector)
> +					    void *data)
>   {
>   	unsigned long flags;
>   	struct drm_writeback_job *pos, *n;
> +	struct drm_writeback_connector *wb_connector = data;
>   
>   	delete_writeback_properties(dev);
>   	drm_property_blob_put(wb_connector->pixel_formats_blob_ptr);
> @@ -405,7 +406,7 @@ int drmm_writeback_connector_init(struct drm_device *dev,
>   	if (ret)
>   		return ret;
>   
> -	ret = drmm_add_action_or_reset(dev, (void *)drm_writeback_connector_cleanup,
> +	ret = drmm_add_action_or_reset(dev, drm_writeback_connector_cleanup,
>   				       wb_connector);
>   	if (ret)
>   		return ret;
> 
> ---
> base-commit: a22e0051f9eb2281b181218d97f77cebc299310d
> change-id: 20250428-drm-fix-writeback-cleanup-a1179f3b9691
> 
> Best regards,

-- 
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com