Re: [PATCH 01/10] drm/xe: Guard configfs attribute reads in getters

On Thu, Aug 20, 2026 at 09:06:40PM +0000, Stuart Summers wrote:
> The configfs getters read dev->config members without holding dev->lock,
> so a concurrent store can tear the value being returned. The store paths
> and a few of the getters already take the lock; make it consistent by
> wrapping every read of dev->config in the getters with a scoped_guard(),
> covering the surrounding checks that consume those values as well.
> 
> Signed-off-by: Stuart Summers <[email protected]>
> Assisted-by: Copilot:claude-opus-5

I don't think the locking is terribly important for most of these
configfs interfaces, but it certainly doesn't hurt anything and is good
for consistency.

Reviewed-by: Matt Roper <[email protected]>

> ---
>  drivers/gpu/drm/xe/xe_configfs.c | 29 +++++++++++++++++++----------
>  1 file changed, 19 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
> index 052cce962161..0a85043a9dd0 100644
> --- a/drivers/gpu/drm/xe/xe_configfs.c
> +++ b/drivers/gpu/drm/xe/xe_configfs.c
> @@ -1185,7 +1185,8 @@ bool xe_configfs_get_survivability_mode(struct pci_dev *pdev)
>  	if (!dev)
>  		return device_defaults.survivability_mode;
>  
> -	mode = dev->config.survivability_mode;
> +	scoped_guard(mutex, &dev->lock)
> +		mode = dev->config.survivability_mode;
>  	config_group_put(&dev->group);
>  
>  	return mode;
> @@ -1199,7 +1200,8 @@ static u64 get_gt_types_allowed(struct pci_dev *pdev)
>  	if (!dev)
>  		return device_defaults.gt_types_allowed;
>  
> -	mask = dev->config.gt_types_allowed;
> +	scoped_guard(mutex, &dev->lock)
> +		mask = dev->config.gt_types_allowed;
>  	config_group_put(&dev->group);
>  
>  	return mask;
> @@ -1243,7 +1245,8 @@ u64 xe_configfs_get_engines_allowed(struct pci_dev *pdev)
>  	if (!dev)
>  		return device_defaults.engines_allowed;
>  
> -	engines_allowed = dev->config.engines_allowed;
> +	scoped_guard(mutex, &dev->lock)
> +		engines_allowed = dev->config.engines_allowed;
>  	config_group_put(&dev->group);
>  
>  	return engines_allowed;
> @@ -1263,7 +1266,8 @@ bool xe_configfs_get_psmi_enabled(struct pci_dev *pdev)
>  	if (!dev)
>  		return false;
>  
> -	ret = dev->config.enable_psmi;
> +	scoped_guard(mutex, &dev->lock)
> +		ret = dev->config.enable_psmi;
>  	config_group_put(&dev->group);
>  
>  	return ret;
> @@ -1284,7 +1288,8 @@ bool xe_configfs_get_enable_multi_queue(struct pci_dev *pdev)
>  	if (!dev)
>  		return true;
>  
> -	ret = dev->config.enable_multi_queue;
> +	scoped_guard(mutex, &dev->lock)
> +		ret = dev->config.enable_multi_queue;
>  	config_group_put(&dev->group);
>  
>  	return ret;
> @@ -1308,10 +1313,12 @@ u32 xe_configfs_get_ctx_restore_mid_bb(struct pci_dev *pdev,
>  	if (!dev)
>  		return 0;
>  
> -	if (cs)
> -		*cs = dev->config.ctx_restore_mid_bb[class].cs;
> +	scoped_guard(mutex, &dev->lock) {
> +		if (cs)
> +			*cs = dev->config.ctx_restore_mid_bb[class].cs;
>  
> -	len = dev->config.ctx_restore_mid_bb[class].len;
> +		len = dev->config.ctx_restore_mid_bb[class].len;
> +	}
>  	config_group_put(&dev->group);
>  
>  	return len;
> @@ -1335,8 +1342,10 @@ u32 xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev,
>  	if (!dev)
>  		return 0;
>  
> -	*cs = dev->config.ctx_restore_post_bb[class].cs;
> -	len = dev->config.ctx_restore_post_bb[class].len;
> +	scoped_guard(mutex, &dev->lock) {
> +		*cs = dev->config.ctx_restore_post_bb[class].cs;
> +		len = dev->config.ctx_restore_post_bb[class].len;
> +	}
>  	config_group_put(&dev->group);
>  
>  	return len;
> -- 
> 2.43.0
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation