From: Liam R. Howlett <Liam.Howlett@oracle.com>
Date: Thu, 1 Sep 2022 01:03:02 +0000 (-0400)
Subject: maple_tree: Avoid BUG_ON() when setting a leaf node as a parent
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=2398c88a53309860594cdb44754d4720d2b13a42;p=users%2Fjedix%2Flinux-maple.git

maple_tree: Avoid BUG_ON() when setting a leaf node as a parent

Don't crash the kernel in the very unlikely case that the node passed as
the parent is actually a leaf.  Instead, use MT_WARN_ON() to increase
the probability of the debug information being recorded.

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

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index dfcc2edfb3a9..ee083601dabe 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -443,7 +443,7 @@ enum maple_type mas_parent_enum(struct ma_state *mas, struct maple_enode *enode)
 }
 
 /*
- * mte_set_parent() - Set the parent node and encode the slot
+ * mas_set_parent() - Set the parent node and encode the slot
  * @enode: The encoded maple node.
  * @parent: The encoded maple node that is the parent of @enode.
  * @slot: The slot that @enode resides in @parent.
@@ -452,16 +452,19 @@ enum maple_type mas_parent_enum(struct ma_state *mas, struct maple_enode *enode)
  * parent type.
  */
 static inline
-void mte_set_parent(struct maple_enode *enode, const struct maple_enode *parent,
-		    unsigned char slot)
+void mas_set_parent(struct ma_state *mas, struct maple_enode *enode,
+		    const struct maple_enode *parent, unsigned char slot)
 {
 	unsigned long val = (unsigned long) parent;
 	unsigned long shift;
 	unsigned long type;
 	enum maple_type p_type = mte_node_type(parent);
 
-	BUG_ON(p_type == maple_dense);
-	BUG_ON(p_type == maple_leaf_64);
+	if (MT_WARN_ON(mas->tree, p_type == maple_dense))
+		pr_err("Dense node %p cannot be parent\n", parent);
+
+	if (MT_WARN_ON(mas->tree, p_type == maple_leaf_64))
+		pr_err("Leaf node %p cannot be parent\n", parent);
 
 	switch (p_type) {
 	case maple_range_64:
@@ -1729,7 +1732,7 @@ static inline void mas_adopt_children(struct ma_state *mas,
 	offset = ma_data_end(node, type, pivots, mas->max);
 	do {
 		child = mas_slot_locked(mas, slots, offset);
-		mte_set_parent(child, parent, offset);
+		mas_set_parent(mas, child, parent, offset);
 	} while (offset--);
 }
 
@@ -2716,9 +2719,9 @@ static inline void mas_set_split_parent(struct ma_state *mas,
 		return;
 
 	if ((*slot) <= split)
-		mte_set_parent(mas->node, left, *slot);
+		mas_set_parent(mas, mas->node, left, *slot);
 	else if (right)
-		mte_set_parent(mas->node, right, (*slot) - split - 1);
+		mas_set_parent(mas, mas->node, right, (*slot) - split - 1);
 
 	(*slot)++;
 }
@@ -3113,12 +3116,12 @@ static int mas_spanning_rebalance(struct ma_state *mas,
 				mte_node_type(mast->orig_l->node));
 	mast->orig_l->depth++;
 	mab_mas_cp(mast->bn, 0, mt_slots[mast->bn->type] - 1, &l_mas, true);
-	mte_set_parent(left, l_mas.node, slot);
+	mas_set_parent(mas, left, l_mas.node, slot);
 	if (middle)
-		mte_set_parent(middle, l_mas.node, ++slot);
+		mas_set_parent(mas, middle, l_mas.node, ++slot);
 
 	if (right)
-		mte_set_parent(right, l_mas.node, ++slot);
+		mas_set_parent(mas, right, l_mas.node, ++slot);
 
 	if (mas_is_root_limits(mast->l)) {
 new_root:
@@ -3345,8 +3348,8 @@ static inline bool mas_split_final_node(struct maple_subtree_state *mast,
 	 * The Big_node data should just fit in a single node.
 	 */
 	ancestor = mas_new_ma_node(mas, mast->bn);
-	mte_set_parent(mast->l->node, ancestor, mast->l->offset);
-	mte_set_parent(mast->r->node, ancestor, mast->r->offset);
+	mas_set_parent(mas, mast->l->node, ancestor, mast->l->offset);
+	mas_set_parent(mas, mast->r->node, ancestor, mast->r->offset);
 	mte_to_node(ancestor)->parent = mas_mn(mas)->parent;
 
 	mast->l->node = ancestor;