lib/rbtree: set successor's parent unconditionally
diff mbox series

Message ID 20190825011010.31072-1-richardw.yang@linux.intel.com
State New
Headers show
Series
  • lib/rbtree: set successor's parent unconditionally
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Commit Message

Wei Yang Aug. 25, 2019, 1:10 a.m. UTC
Both in Case 2 and 3, we exchange n and s. This mean no matter whether
child2 is NULL or not, successor's parent should be assigned to node's.

This patch takes this step out to make it explicit and reduce the
ambiguity.

Besides, this step reduces some symbol size like rb_erase().

   KERN_CONFIG       upstream       patched
   OPT_FOR_PERF      877            870
   OPT_FOR_SIZE      635            621

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
---
 include/linux/rbtree_augmented.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Patch
diff mbox series

diff --git a/include/linux/rbtree_augmented.h b/include/linux/rbtree_augmented.h
index 179faab29f52..8fcddfef7876 100644
--- a/include/linux/rbtree_augmented.h
+++ b/include/linux/rbtree_augmented.h
@@ -237,14 +237,13 @@  __rb_erase_augmented(struct rb_node *node, struct rb_root *root,
 		__rb_change_child(node, successor, tmp, root);
 
 		if (child2) {
-			successor->__rb_parent_color = pc;
 			rb_set_parent_color(child2, parent, RB_BLACK);
 			rebalance = NULL;
 		} else {
 			unsigned long pc2 = successor->__rb_parent_color;
-			successor->__rb_parent_color = pc;
 			rebalance = __rb_is_black(pc2) ? parent : NULL;
 		}
+		successor->__rb_parent_color = pc;
 		tmp = successor;
 	}