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authorChris Wilson <chris@chris-wilson.co.uk>2017-02-04 14:19:13 +0300
committerDaniel Vetter <daniel.vetter@ffwll.ch>2017-02-06 18:57:37 +0300
commitbbba96931762bcad8a691dfbf8d1520b71831c3a (patch)
treef3e4eaf765b4b1dcb1207a30532e40f6478e5117 /include/drm/drm_mm.h
parentc5a828148f302c72a137af7f5487a4e52f19f4c9 (diff)
downloadlinux-bbba96931762bcad8a691dfbf8d1520b71831c3a.tar.xz
drm: Micro-optimise drm_mm_for_each_node_in_range()
As we require valid start/end parameters, we can replace the initial potential NULL with a pointer to the drm_mm.head_node and so reduce the test on every iteration from a NULL + address comparison to just an address comparison. add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-26 (-26) function old new delta i915_gem_evict_for_node 719 693 -26 (No other users outside of the test harness.) Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/20170204111913.12416-1-chris@chris-wilson.co.uk
Diffstat (limited to 'include/drm/drm_mm.h')
-rw-r--r--include/drm/drm_mm.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h
index d81b0ba9921f..f262da180117 100644
--- a/include/drm/drm_mm.h
+++ b/include/drm/drm_mm.h
@@ -459,10 +459,13 @@ __drm_mm_interval_first(const struct drm_mm *mm, u64 start, u64 last);
* but using the internal interval tree to accelerate the search for the
* starting node, and so not safe against removal of elements. It assumes
* that @end is within (or is the upper limit of) the drm_mm allocator.
+ * If [@start, @end] are beyond the range of the drm_mm, the iterator may walk
+ * over the special _unallocated_ &drm_mm.head_node, and may even continue
+ * indefinitely.
*/
#define drm_mm_for_each_node_in_range(node__, mm__, start__, end__) \
for (node__ = __drm_mm_interval_first((mm__), (start__), (end__)-1); \
- node__ && node__->start < (end__); \
+ node__->start < (end__); \
node__ = list_next_entry(node__, node_list))
void drm_mm_scan_init_with_range(struct drm_mm_scan *scan,