From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Tue, 12 Mar 2019 18:52:18 +0000 (-0400)
Subject: maple_tree: Rework internal walk.
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=77ac5a345fd4527877085271bf27ef3baf1bc1ab;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Rework internal walk.

Reduce possible calls to get an rcu entry.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index cd3b099b5058d..8a53c362b5617 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1278,6 +1278,9 @@ done:
 	return ret;
 }
 
+/*
+ * Private: Returns true if mas->node is a leaf
+ */
 static inline bool _mas_walk(struct ma_state *mas)
 {
 	enum maple_type type;
@@ -1399,13 +1402,14 @@ void *mas_walk(struct ma_state *mas)
 	void *entry = NULL;
 	unsigned char slot = MAPLE_NODE_SLOTS;
 	bool leaf = false;
+	void *root = rcu_dereference(mas->tree->ma_root);
 
-	if (rcu_dereference(mas->tree->ma_root) == NULL)
+	if (root == NULL)
 		return NULL;
 
-	if (!xa_is_node(mas->tree->ma_root)) {
+	if (!xa_is_node(root)) {
 		if (mas->last == 0)
-			return rcu_dereference(mas->tree->ma_root);
+			return root;
 		return NULL;
 	}