From f29051f12f33078b81ac710bee9ebd7a85ee1849 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 22 Dec 2016 08:36:35 +0000 Subject: [PATCH] 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: Chris Wilson Reviewed-by: Joonas Lahtinen Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20161222083641.2691-33-chris@chris-wilson.co.uk --- drivers/gpu/drm/drm_mm.c | 35 ++++++++++++++++++----------------- include/drm/drm_mm.h | 7 +------ 2 files changed, 19 insertions(+), 23 deletions(-) diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index 0441d84fba74..ccca8dafb7fc 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -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; diff --git a/include/drm/drm_mm.h b/include/drm/drm_mm.h index d6701d56ea74..ff120b7d0f85 100644 --- a/include/drm/drm_mm.h +++ b/include/drm/drm_mm.h @@ -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; }; -- 2.20.1