From 89338ffb4e173b2ab787c5f9e985ad2743897b5c Mon Sep 17 00:00:00 2001
From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
Date: Tue, 15 Sep 2020 12:13:12 -0400
Subject: [PATCH] maple_tree: Alias rcu check to mas_slot() and
 mas_slot_protected

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---
 lib/maple_tree.c | 44 ++++++++++++++++++++++++++++----------------
 1 file changed, 28 insertions(+), 16 deletions(-)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 045b47c10bb8..cbb813acdb69 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -540,7 +540,7 @@ static inline unsigned long _mas_safe_pivot(const struct ma_state *mas,
 }
 
 /*
- * mas_safe_pivot() - Return the pivot or the mas->max.
+ * mas_safe_pivot() - Return pivot, implied or otherwise.
  * @mas: The maple state.
  * @piv:  the pivot location.
  *
@@ -555,6 +555,10 @@ static inline unsigned long mas_safe_pivot(const struct ma_state *mas,
 	return _mas_safe_pivot(mas, pivots, piv, type);
 }
 
+/*
+ * mas_safe_min() - Return the minimum for a given offset.
+ *
+ */
 static inline unsigned long mas_safe_min(struct ma_state *mas,
 					 unsigned long *pivots,
 					 unsigned char piv)
@@ -603,19 +607,28 @@ static inline void __rcu **ma_slots(struct maple_node *mn, enum maple_type mt)
 	}
 }
 
-static inline void *ma_slot(struct ma_state *mas, void **slots,
-			    unsigned char offset)
+static inline void *mas_slot_protected(struct ma_state *mas, void **slots,
+				       unsigned char offset)
+{
+	if (mt_in_rcu(mas->tree))
+		return rcu_dereference_protected(slots[offset],
+					lockdep_is_held(&mas->tree->ma_lock));
+	return slots[offset];
+}
+
+static inline void *mas_slot(struct ma_state *mas, void **slots,
+			     unsigned char offset)
 {
 	if (mt_in_rcu(mas->tree))
 		return rcu_dereference(slots[offset]);
-	else
-		return slots[offset];
+
+	return slots[offset];
 }
 
 static inline struct maple_enode *mas_get_slot(struct ma_state *mas,
 		unsigned char offset)
 {
-	return ma_slot(mas, ma_slots(mas_mn(mas), mte_node_type(mas->node)),
+	return mas_slot(mas, ma_slots(mas_mn(mas), mte_node_type(mas->node)),
 		       offset);
 }
 
@@ -1191,7 +1204,7 @@ static inline unsigned long mas_first_entry(struct ma_state *mas,
 
 	while ((pivot < limit) && (offset < mt_slot_count(mas->node))) {
 		pivot = mas_safe_pivot(mas, offset);
-		entry = rcu_dereference(slots[offset]);
+		entry = mas_slot(mas, slots, offset);
 		if (entry) {
 			mas_set_offset(mas, offset);
 			return pivot;
@@ -1429,8 +1442,7 @@ static inline void mas_mab_cp(struct ma_state *mas, unsigned char mas_start,
 		gaps = ma_gaps(node, mt);
 
 	for (i = mas_start, j = mab_start; i <= mas_end; i++, j++) {
-		b_node->slot[j] = rcu_dereference_protected(slots[i],
-					lockdep_is_held(&mas->tree->ma_lock));
+		b_node->slot[j] = mas_slot_protected(mas, slots, i);
 
 		if (gaps)
 			b_node->gap[j] = gaps[i];
@@ -3160,7 +3172,7 @@ restart_prev_node:
 	mas->max = mas_safe_pivot(mas, offset);
 	while (level > 1) {
 		level--;
-		mas->node = rcu_dereference(slots[offset]);
+		mas->node = mas_slot(mas, slots, offset);
 		if (mas_dead_node(mas, start_piv))
 			goto restart_prev_node;
 		mt = mte_node_type(mas->node);
@@ -3174,7 +3186,7 @@ restart_prev_node:
 	mas->min = mas_safe_min(mas, ma_pivots(mas_mn(mas),
 					       mte_node_type(mas->node)),
 				offset);
-	mas->node = rcu_dereference(slots[offset]);
+	mas->node = mas_slot(mas, slots, offset);
 	if (mas_dead_node(mas, start_piv))
 		goto restart_prev_node;
 	return;
@@ -3235,14 +3247,14 @@ restart_next_node:
 	// Descend, if necessary.
 	while (level > 1) {
 		level--;
-		mas->node = rcu_dereference(slots[offset]);
+		mas->node = mas_slot(mas, slots, offset);
 		mt = mte_node_type(mas->node);
 		slots = ma_slots(mas_mn(mas), mt);
 		offset = 0;
 		pivot = mas_safe_pivot(mas, offset);
 	}
 
-	mas->node = rcu_dereference(slots[offset]);
+	mas->node = mas_slot(mas, slots,offset);
 	mas->min = prev_piv + 1;
 	mas->max = pivot;
 	return mas->max;
@@ -3314,7 +3326,7 @@ static inline bool mas_next_nentry(struct ma_state *mas, unsigned long max,
 		if (r_start > mas->max)
 			goto no_entry;
 
-		entry = ma_slot(mas, slots, offset);
+		entry = mas_slot(mas, slots, offset);
 		if (entry)
 			goto found;
 
@@ -3547,7 +3559,7 @@ bool _mas_rev_awalk(struct ma_state *mas, unsigned long size)
 
 		if (!ma_is_leaf(type))
 			gap = gaps[offset];
-		else if (rcu_dereference(slots[offset]))
+		else if (mas_slot(mas, slots, offset))
 			continue; // no gap in leaf.
 		else
 			gap = max - min + 1;
@@ -3573,7 +3585,7 @@ bool _mas_rev_awalk(struct ma_state *mas, unsigned long size)
 	}
 
 	//descend
-	mas->node = rcu_dereference(slots[offset]);
+	mas->node = mas_slot(mas, slots, offset);
 	mas->min = min;
 	mas->max = max;
 	mas_set_offset(mas, mt_pivot_count(mas->node));
-- 
2.50.1