Re: [PATCH 07/15] drm/i915: Stop using obj->obj_exec_link outside of execbuf

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> i915_gem_stolen_list_info() sneakily takes advantage of the
> obj->obj_exec_link to save itself from having to allocate. Enough of the
> subterfuge, just allocate an array of pointers and sort them instead of
> the list.
>

Justifiable by itself but I suspect you have plans for mutex.

Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>

> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 52 ++++++++++++++++++++-----------------
>  1 file changed, 28 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index ddae8e442176..75efa1ae234e 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -27,7 +27,7 @@
>   */
>  
>  #include <linux/debugfs.h>
> -#include <linux/list_sort.h>
> +#include <linux/sort.h>
>  #include "intel_drv.h"
>  
>  static inline struct drm_i915_private *node_to_i915(struct drm_info_node *node)
> @@ -230,13 +230,12 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
>  		seq_printf(m, " (frontbuffer: 0x%03x)", frontbuffer_bits);
>  }
>  
> -static int obj_rank_by_stolen(void *priv,
> -			      struct list_head *A, struct list_head *B)
> +static int obj_rank_by_stolen(const void *A, const void *B)
>  {
> -	struct drm_i915_gem_object *a =
> -		container_of(A, struct drm_i915_gem_object, obj_exec_link);
> -	struct drm_i915_gem_object *b =
> -		container_of(B, struct drm_i915_gem_object, obj_exec_link);
> +	const struct drm_i915_gem_object *a =
> +		*(const struct drm_i915_gem_object **)A;
> +	const struct drm_i915_gem_object *b =
> +		*(const struct drm_i915_gem_object **)B;
>  
>  	if (a->stolen->start < b->stolen->start)
>  		return -1;
> @@ -249,49 +248,54 @@ static int i915_gem_stolen_list_info(struct seq_file *m, void *data)
>  {
>  	struct drm_i915_private *dev_priv = node_to_i915(m->private);
>  	struct drm_device *dev = &dev_priv->drm;
> +	struct drm_i915_gem_object **objects;
>  	struct drm_i915_gem_object *obj;
>  	u64 total_obj_size, total_gtt_size;
> -	LIST_HEAD(stolen);
> -	int count, ret;
> +	unsigned long count, n;
> +	int ret;
>  
>  	ret = mutex_lock_interruptible(&dev->struct_mutex);
>  	if (ret)
>  		return ret;
>  
> +	objects = drm_malloc_ab(dev_priv->mm.object_count, sizeof(*objects));
> +	if (!objects) {
> +		ret = -ENOMEM;
> +		goto out_unlock;
> +	}
> +
>  	total_obj_size = total_gtt_size = count = 0;
>  	list_for_each_entry(obj, &dev_priv->mm.bound_list, global_link) {
>  		if (obj->stolen == NULL)
>  			continue;
>  
> -		list_add(&obj->obj_exec_link, &stolen);
> -
> +		objects[count++] = obj;
>  		total_obj_size += obj->base.size;
>  		total_gtt_size += i915_gem_obj_total_ggtt_size(obj);
> -		count++;
>  	}
>  	list_for_each_entry(obj, &dev_priv->mm.unbound_list, global_link) {
>  		if (obj->stolen == NULL)
>  			continue;
>  
> -		list_add(&obj->obj_exec_link, &stolen);
> -
> +		objects[count++] = obj;
>  		total_obj_size += obj->base.size;
> -		count++;
>  	}
> -	list_sort(NULL, &stolen, obj_rank_by_stolen);
> +
> +	sort(objects, count, sizeof(*objects), obj_rank_by_stolen, NULL);
> +
>  	seq_puts(m, "Stolen:\n");
> -	while (!list_empty(&stolen)) {
> -		obj = list_first_entry(&stolen, typeof(*obj), obj_exec_link);
> +	for (n = 0; n < count; n++) {
>  		seq_puts(m, "   ");
> -		describe_obj(m, obj);
> +		describe_obj(m, objects[n]);
>  		seq_putc(m, '\n');
> -		list_del_init(&obj->obj_exec_link);
>  	}
> -	mutex_unlock(&dev->struct_mutex);
> -
> -	seq_printf(m, "Total %d objects, %llu bytes, %llu GTT size\n",
> +	seq_printf(m, "Total %lu objects, %llu bytes, %llu GTT size\n",
>  		   count, total_obj_size, total_gtt_size);
> -	return 0;
> +
> +	drm_free_large(objects);
> +out_unlock:
> +	mutex_unlock(&dev->struct_mutex);
> +	return ret;
>  }
>  
>  struct file_stats {
> -- 
> 2.11.0
>
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