From bbba96931762bcad8a691dfbf8d1520b71831c3a Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Sat, 4 Feb 2017 11:19:13 +0000 Subject: 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 Cc: Joonas Lahtinen Reviewed-by: Joonas Lahtinen Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20170204111913.12416-1-chris@chris-wilson.co.uk --- include/drm/drm_mm.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/drm/drm_mm.h') 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, -- cgit v1.2.3