[PATCH 03/34] drm: Convert object_name_idr to XArray

[Daniel Vetter]

On Thu, Feb 21, 2019 at 10:41:25AM -0800, Matthew Wilcox wrote:
> Leave the object_name_lock in place for now as I'm not certain it can be
> removed safely.

It protects all object names, not just the gem flink one, also dma-buf
exports. See struct drm_gem_object.dma_buf kerneldoc. We could completely
replace object_name_lock with xa_lock, but that feels a bit silly (or
would at least need some drm_gem_object_name_lock/unlock helpers to give
it some meaning). But spin_lock is probably not the right one, we run
quite some code under object_name_lock.

Maybe add that to the commit message for the next round and leave as-is.
-Daniel

> Signed-off-by: Matthew Wilcox <willy at infradead.org>
> ---
>  drivers/gpu/drm/drm_debugfs.c | 19 ++++++-------------
>  drivers/gpu/drm/drm_gem.c     | 11 +++++------
>  include/drm/drm_device.h      |  2 +-
>  3 files changed, 12 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
> index f8468eae0503..2bf08f293331 100644
> --- a/drivers/gpu/drm/drm_debugfs.c
> +++ b/drivers/gpu/drm/drm_debugfs.c
> @@ -106,27 +106,20 @@ static int drm_clients_info(struct seq_file *m, void *data)
>  	return 0;
>  }
>  
> -static int drm_gem_one_name_info(int id, void *ptr, void *data)
> -{
> -	struct drm_gem_object *obj = ptr;
> -	struct seq_file *m = data;
> -
> -	seq_printf(m, "%6d %8zd %7d %8d\n",
> -		   obj->name, obj->size,
> -		   obj->handle_count,
> -		   kref_read(&obj->refcount));
> -	return 0;
> -}
> -
>  static int drm_gem_name_info(struct seq_file *m, void *data)
>  {
>  	struct drm_info_node *node = (struct drm_info_node *) m->private;
>  	struct drm_device *dev = node->minor->dev;
> +	struct drm_gem_object *obj;
> +	unsigned long index;
>  
>  	seq_printf(m, "  name     size handles refcount\n");
>  
>  	mutex_lock(&dev->object_name_lock);
> -	idr_for_each(&dev->object_name_idr, drm_gem_one_name_info, m);
> +	xa_for_each(&dev->object_names, index, obj) {
> +		seq_printf(m, "%6d %8zd %7d %8d\n", obj->name, obj->size,
> +				obj->handle_count, kref_read(&obj->refcount));
> +	}
>  	mutex_unlock(&dev->object_name_lock);
>  
>  	return 0;
> diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> index 8b55ece97967..0a52a958cffe 100644
> --- a/drivers/gpu/drm/drm_gem.c
> +++ b/drivers/gpu/drm/drm_gem.c
> @@ -98,7 +98,7 @@ drm_gem_init(struct drm_device *dev)
>  	struct drm_vma_offset_manager *vma_offset_manager;
>  
>  	mutex_init(&dev->object_name_lock);
> -	idr_init_base(&dev->object_name_idr, 1);
> +	xa_init_flags(&dev->object_names, XA_FLAGS_ALLOC1);
>  
>  	vma_offset_manager = kzalloc(sizeof(*vma_offset_manager), GFP_KERNEL);
>  	if (!vma_offset_manager) {
> @@ -205,7 +205,7 @@ static void drm_gem_object_handle_free(struct drm_gem_object *obj)
>  
>  	/* Remove any name for this object */
>  	if (obj->name) {
> -		idr_remove(&dev->object_name_idr, obj->name);
> +		xa_erase(&dev->object_names, obj->name);
>  		obj->name = 0;
>  	}
>  }
> @@ -714,11 +714,10 @@ drm_gem_flink_ioctl(struct drm_device *dev, void *data,
>  	}
>  
>  	if (!obj->name) {
> -		ret = idr_alloc(&dev->object_name_idr, obj, 1, 0, GFP_KERNEL);
> +		ret = xa_alloc(&dev->object_names, &obj->name, obj,
> +				xa_limit_32b, GFP_KERNEL);
>  		if (ret < 0)
>  			goto err;
> -
> -		obj->name = ret;
>  	}
>  
>  	args->name = (uint64_t) obj->name;
> @@ -754,7 +753,7 @@ drm_gem_open_ioctl(struct drm_device *dev, void *data,
>  		return -EOPNOTSUPP;
>  
>  	mutex_lock(&dev->object_name_lock);
> -	obj = idr_find(&dev->object_name_idr, (int) args->name);
> +	obj = xa_load(&dev->object_names, (int) args->name);
>  	if (obj) {
>  		drm_gem_object_get(obj);
>  	} else {
> diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
> index 42411b3ea0c8..52e271b97de8 100644
> --- a/include/drm/drm_device.h
> +++ b/include/drm/drm_device.h
> @@ -219,7 +219,7 @@ struct drm_device {
>  	/** \name GEM information */
>  	/*@{ */
>  	struct mutex object_name_lock;
> -	struct idr object_name_idr;
> +	struct xarray object_names;
>  	struct drm_vma_offset_manager *vma_offset_manager;
>  	/*@} */
>  	int switch_power_state;
> -- 
> 2.20.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch