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 dfcc2edfb3a91d7350f3ee534146afc76937c889..ee083601dabe98f30de7df15a457dc706d6337fc 100644 (file)
--- 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;