From: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Wed, 9 Dec 2020 21:59:32 +0000 (-0500)
Subject: maple_tree: Rework mas_ascend()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=ad4991f51c3e94ebe880103944210c4d0fb6e113;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Rework mas_ascend()

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

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index da299ebde616..9369487497a6 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -772,62 +772,64 @@ static inline void mte_set_gap(const struct maple_enode *mn,
 
 static void mas_ascend(struct ma_state *mas)
 {
-	struct maple_enode *p_enode = mas->node; // parent enode.
-	struct maple_enode *a_enode = mas->node; // ancestor enode.
+	struct maple_enode *p_enode; // parent enode.
+	struct maple_enode *a_enode; // ancestor enode.
 	struct maple_node *a_node = mas_mn(mas); // ancestor node.
-	unsigned char a_slot = 0;
-	enum maple_type a_type = mte_node_type(mas->node);
-	unsigned long max = 0, min = ULONG_MAX;
+	unsigned char a_slot;
+	enum maple_type a_type;
+	unsigned long min, max;
+	unsigned long *pivots;
 	bool set_max = false, set_min = false;
 
 	if (ma_is_root(a_node))
-		goto no_parent;
+		return;
 
 	a_type = mas_parent_enum(mas, mas->node);
 	a_enode = mt_mk_node(mte_parent(mas->node), a_type);
-	p_enode = a_enode;
-	if (mte_is_root(a_enode))
-		goto parent_is_root;
-
-	mas->node = p_enode;
-ascend:
-	a_type = mas_parent_enum(mas, mas->node);
-	a_node = mte_parent(mas->node);
-	a_slot = mte_parent_slot(mas->node);
-	a_enode = mt_mk_node(a_node, a_type);
-	if (!set_min && a_slot) {
-		set_min = true;
-		min = mte_pivot(a_enode, a_slot - 1) + 1;
-	}
-
-	if (!set_max && a_slot < mt_pivots[a_type]) {
-		set_max = true;
-		max = mte_pivot(a_enode, a_slot);
-	}
-
-no_parent:
-	if (unlikely(ma_is_root(a_node))) {
-parent_is_root:
-		if (!set_min)
-			min = 0;
-		if (!set_max)
-			max = mt_max[a_type];
+	mas->node = a_enode;
+	if (mte_is_root(a_enode)) {
+		mas->max = ULONG_MAX;
+		mas->min = 0;
+		return;
 	}
 
-	if (!max || min == ULONG_MAX) {
-		if (mas->node == a_enode) {
+	min = 0;
+	max = ULONG_MAX;
+	p_enode = a_enode;
+	do {
+		a_type = mas_parent_enum(mas, p_enode);
+		a_node = mte_parent(p_enode);
+		a_slot = mte_parent_slot(p_enode);
+		pivots = ma_pivots(a_node, a_type);
+		a_enode = mt_mk_node(a_node, a_type);
+
+		if (unlikely(p_enode == a_enode)) {
+			// Dead node.
 			pr_err("Failed on node %p (%p)\n", mas_mn(mas),
 			       a_enode);
 			//FIXME: Restart and retry if the lock is held.
-			MT_BUG_ON(mas->tree, mas->node == a_enode);
+			MT_BUG_ON(mas->tree, p_enode == a_enode);
 		}
-		mas->node = a_enode;
-		goto ascend;
-	}
+
+		if (!set_min && a_slot) {
+			set_min = true;
+			min = pivots[a_slot - 1] + 1;
+		}
+
+		if (!set_max && a_slot < mt_pivots[a_type]) {
+			set_max = true;
+			max = pivots[a_slot];
+		}
+
+		if (unlikely(ma_is_root(a_node))) {
+			break;
+		}
+
+		p_enode = a_enode;
+	} while (!set_min || !set_max);
 
 	mas->max = max;
 	mas->min = min;
-	mas->node = p_enode;
 }
 
 static inline struct maple_node *mas_pop_node(struct ma_state *mas)