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Commit f29051f1 authored by Chris Wilson's avatar Chris Wilson Committed by Daniel Vetter
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drm: Simplify drm_mm scan-list manipulation 



Since we mandate a strict reverse-order of drm_mm_scan_remove_block()
after drm_mm_scan_add_block() we can further simplify the list
manipulations when generating the temporary scan-hole.

v2: Highlight the games being played with the lists to track the scan
holes without allocation.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161222083641.2691-33-chris@chris-wilson.co.uk
parent 9a956b15

drivers/gpu/drm/drm_mm.c

+18 −17
Original line number Diff line number Diff line
@@ -518,9 +518,7 @@ void drm_mm_remove_node(struct drm_mm_node *node) 
	struct drm_mm_node *prev_node;



	DRM_MM_BUG_ON(!node->allocated);

	DRM_MM_BUG_ON(node->scanned_block ||

		      node->scanned_prev_free ||

		      node->scanned_next_free);

	DRM_MM_BUG_ON(node->scanned_block);



	prev_node =

	    list_entry(node->node_list.prev, struct drm_mm_node, node_list);
@@ -757,8 +755,6 @@ void drm_mm_scan_init_with_range(struct drm_mm_scan *scan, 


	scan->hit_start = U64_MAX;

	scan->hit_end = 0;



	scan->prev_scanned_node = NULL;

}

EXPORT_SYMBOL(drm_mm_scan_init_with_range);
@@ -787,14 +783,14 @@ bool drm_mm_scan_add_block(struct drm_mm_scan *scan, 
	node->scanned_block = true;

	mm->scan_active++;



	/* Remove this block from the node_list so that we enlarge the hole

	 * (distance between the end of our previous node and the start of

	 * or next), without poisoning the link so that we can restore it

	 * later in drm_mm_scan_remove_block().

	 */

	hole = list_prev_entry(node, node_list);



	node->scanned_preceeds_hole = hole->hole_follows;

	hole->hole_follows = 1;

	list_del(&node->node_list);

	node->node_list.prev = &hole->node_list;

	node->node_list.next = &scan->prev_scanned_node->node_list;

	scan->prev_scanned_node = node;

	DRM_MM_BUG_ON(list_next_entry(hole, node_list) != node);

	__list_del_entry(&node->node_list);



	hole_start = __drm_mm_hole_node_start(hole);

	hole_end = __drm_mm_hole_node_end(hole);
@@ -888,9 +884,17 @@ bool drm_mm_scan_remove_block(struct drm_mm_scan *scan, 
	DRM_MM_BUG_ON(!node->mm->scan_active);

	node->mm->scan_active--;



	/* During drm_mm_scan_add_block() we decoupled this node leaving

	 * its pointers intact. Now that the caller is walking back along

	 * the eviction list we can restore this block into its rightful

	 * place on the full node_list. To confirm that the caller is walking

	 * backwards correctly we check that prev_node->next == node->next,

	 * i.e. both believe the same node should be on the other side of the

	 * hole.

	 */

	prev_node = list_prev_entry(node, node_list);



	prev_node->hole_follows = node->scanned_preceeds_hole;

	DRM_MM_BUG_ON(list_next_entry(prev_node, node_list) !=

		      list_next_entry(node, node_list));

	list_add(&node->node_list, &prev_node->node_list);



	return (node->start + node->size > scan->hit_start &&
@@ -917,9 +921,6 @@ void drm_mm_init(struct drm_mm *mm, u64 start, u64 size) 
	INIT_LIST_HEAD(&mm->head_node.node_list);

	mm->head_node.allocated = 0;

	mm->head_node.hole_follows = 1;

	mm->head_node.scanned_block = 0;

	mm->head_node.scanned_prev_free = 0;

	mm->head_node.scanned_next_free = 0;

	mm->head_node.mm = mm;

	mm->head_node.start = start + size;

	mm->head_node.size = start - mm->head_node.start;

include/drm/drm_mm.h

+1 −6
Original line number Diff line number Diff line
@@ -74,11 +74,8 @@ struct drm_mm_node { 
	struct list_head hole_stack;

	struct rb_node rb;

	unsigned hole_follows : 1;

	unsigned scanned_block : 1;

	unsigned scanned_prev_free : 1;

	unsigned scanned_next_free : 1;

	unsigned scanned_preceeds_hole : 1;

	unsigned allocated : 1;

	bool scanned_block : 1;

	unsigned long color;

	u64 start;

	u64 size;
@@ -118,8 +115,6 @@ struct drm_mm_scan { 
	u64 hit_start;

	u64 hit_end;



	struct drm_mm_node *prev_scanned_node;



	unsigned long color;

	unsigned int flags;

};