On ma, 2016-07-25 at 08:44 +0100, Chris Wilson wrote:
> list_first_entry_or_null() can generate better code than using
> if (!list_empty()) {ptr = list_first_entry()) ..., so put it to use.
>
> Signed-off-by: Chris Wilson <[email protected]>
It looks cleaner, not so sure of the code impact.
Reviewed-by: Joonas Lahtinen <[email protected]>
> ---
> drivers/gpu/drm/i915/i915_gem_gtt.c | 12 +++++-------
> drivers/gpu/drm/i915/i915_gem_request.c | 8 +++-----
> drivers/gpu/drm/i915/i915_gem_shrinker.c | 9 +++++----
> 3 files changed, 13 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c
> b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 30da543e1bdf..38e7d992a20d 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -2736,13 +2736,11 @@ static void i915_gtt_color_adjust(struct drm_mm_node
> *node,
> if (node->color != color)
> *start += 4096;
>
> - if (!list_empty(&node->node_list)) {
> - node = list_entry(node->node_list.next,
> - struct drm_mm_node,
> - node_list);
> - if (node->allocated && node->color != color)
> - *end -= 4096;
> - }
> + node = list_first_entry_or_null(&node->node_list,
> + struct drm_mm_node,
> + node_list);
> + if (node && node->allocated && node->color != color)
> + *end -= 4096;
> }
>
> static int i915_gem_setup_global_gtt(struct drm_device *dev,
> diff --git a/drivers/gpu/drm/i915/i915_gem_request.c
> b/drivers/gpu/drm/i915/i915_gem_request.c
> index 60a3a343b3a8..49396b895a36 100644
> --- a/drivers/gpu/drm/i915/i915_gem_request.c
> +++ b/drivers/gpu/drm/i915/i915_gem_request.c
> @@ -317,12 +317,10 @@ __i915_gem_request_alloc(struct intel_engine_cs *engine,
> return ret;
>
> /* Move the oldest request to the slab-cache (if not in use!) */
> - if (!list_empty(&engine->request_list)) {
> - req = list_first_entry(&engine->request_list,
> + req = list_first_entry_or_null(&engine->request_list,
> typeof(*req), list);
> - if (i915_gem_request_completed(req))
> - i915_gem_request_retire(req);
> - }
> + if (req && i915_gem_request_completed(req))
> + i915_gem_request_retire(req);
>
> req = kmem_cache_zalloc(dev_priv->requests, GFP_KERNEL);
> if (!req)
> diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c
> b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> index afaa2597e35e..5d4772c146b1 100644
> --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
> +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> @@ -163,17 +163,18 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
> */
> for (phase = phases; phase->list; phase++) {
> struct list_head still_in_list;
> + struct drm_i915_gem_object *obj;
>
> if ((flags & phase->bit) == 0)
> continue;
>
> INIT_LIST_HEAD(&still_in_list);
> - while (count < target && !list_empty(phase->list)) {
> - struct drm_i915_gem_object *obj;
> + while (count < target &&
> + (obj = list_first_entry_or_null(phase->list,
> + typeof(*obj),
> + global_list))) {
> struct i915_vma *vma, *v;
>
> - obj = list_first_entry(phase->list,
> - typeof(*obj), global_list);
> list_move_tail(&obj->global_list, &still_in_list);
>
> if (flags & I915_SHRINK_PURGEABLE &&
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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