Re: [PATCH v4 04/11] drm/xe/configfs: Use mutex from xe_configfs subsystem

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Sun, Jul 27, 2025 at 07:20:01PM +0200, Michal Wajdeczko wrote:
> It should be sufficient to protect all configuration parameters
> using single mutex already defined inside xe_configfs subsystem.
> 
> While around, also convert code to use guard/scoped_guard classes.

agree on the guard/scope change, but I believe we should keep
the local lock for the local variables only instead of re-using
a global one...

> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_configfs.c | 29 +++++++++++------------------
>  1 file changed, 11 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
> index 6aa0531bcf76..e32517afae58 100644
> --- a/drivers/gpu/drm/xe/xe_configfs.c
> +++ b/drivers/gpu/drm/xe/xe_configfs.c
> @@ -85,14 +85,15 @@
>   *	rmdir /sys/kernel/config/xe/0000:03:00.0/
>   */
>  
> +/*
> + * Use xe_configfs.su_mutex (also accessible from group.cg_subsys->su_mutex)
> + * to protect configuration data.
> + */
>  struct xe_config_device {
>  	struct config_group group;
>  
>  	bool survivability_mode;
>  	u64 engines_allowed;
> -
> -	/* protects attributes */
> -	struct mutex lock;
>  };
>  
>  struct engine_info {
> @@ -135,9 +136,8 @@ static ssize_t survivability_mode_store(struct config_item *item, const char *pa
>  	if (ret)
>  		return ret;
>  
> -	mutex_lock(&dev->lock);
> -	dev->survivability_mode = survivability_mode;
> -	mutex_unlock(&dev->lock);
> +	scoped_guard(mutex, &item->ci_group->cg_subsys->su_mutex)
> +		dev->survivability_mode = survivability_mode;
>  
>  	return len;
>  }
> @@ -219,9 +219,8 @@ static ssize_t engines_allowed_store(struct config_item *item, const char *page,
>  		val |= mask;
>  	}
>  
> -	mutex_lock(&dev->lock);
> -	dev->engines_allowed = val;
> -	mutex_unlock(&dev->lock);
> +	scoped_guard(mutex, &item->ci_group->cg_subsys->su_mutex)
> +		dev->engines_allowed = val;
>  
>  	return len;
>  }
> @@ -239,7 +238,6 @@ static void xe_config_device_release(struct config_item *item)
>  {
>  	struct xe_config_device *dev = to_xe_config_device(item);
>  
> -	mutex_destroy(&dev->lock);
>  	kfree(dev);
>  }
>  
> @@ -286,8 +284,6 @@ static struct config_group *xe_config_make_device_group(struct config_group *gro
>  
>  	config_group_init_type_name(&dev->group, name, &xe_config_device_type);
>  
> -	mutex_init(&dev->lock);
> -
>  	return &dev->group;
>  }
>  
> @@ -311,12 +307,10 @@ static struct configfs_subsystem xe_configfs = {
>  
>  static struct xe_config_device *configfs_find_group(struct pci_dev *pdev)
>  {
> +	guard(mutex)(&xe_configfs.su_mutex);
>  	struct config_item *item;
>  
> -	mutex_lock(&xe_configfs.su_mutex);
>  	item = config_group_find_item(&xe_configfs.su_group, pci_name(pdev));
> -	mutex_unlock(&xe_configfs.su_mutex);
> -
>  	if (!item)
>  		return NULL;
>  
> @@ -360,9 +354,8 @@ void xe_configfs_clear_survivability_mode(struct pci_dev *pdev)
>  	if (!dev)
>  		return;
>  
> -	mutex_lock(&dev->lock);
> -	dev->survivability_mode = 0;
> -	mutex_unlock(&dev->lock);
> +	scoped_guard(mutex, &xe_configfs.su_mutex)
> +		dev->survivability_mode = 0;
>  
>  	config_item_put(&dev->group.cg_item);
>  }
> -- 
> 2.47.1
>