[PATCH 02/55] drm/i915: Prefer list_first_entry_or_null

Chris Wilson
2016-07-25T17:33:11Z

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 <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-3-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
---
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 &&
--
2.8.1