[PATCH 26/30] radix-tree: Fix radix_tree_create for sibling entries

Matthew Wilcox
2016-04-06T21:22:49Z

If the radix tree user attempted to insert a colliding entry with an
existing multiorder entry, then radix_tree_create() could encounter
a sibling entry when walking down the tree to look for a slot.
Use radix_tree_descend() to fix the problem, and add a test-case to make
sure the problem doesn't come back in future.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
---
lib/radix-tree.c | 4 ++--
tools/testing/radix-tree/multiorder.c | 5 +++++
2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index d894654b5ecc..4291f344cb95 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -548,9 +548,9 @@ int __radix_tree_create(struct radix_tree_root *root, unsigned long index,
/* Go a level down */
height--;
shift -= RADIX_TREE_MAP_SHIFT;
- offset = (index >> shift) & RADIX_TREE_MAP_MASK;
node = indirect_to_ptr(slot);
- slot = node->slots[offset];
+ offset = (index >> shift) & RADIX_TREE_MAP_MASK;
+ offset = radix_tree_descend(node, &slot, offset);
}

#ifdef CONFIG_RADIX_TREE_MULTIORDER
diff --git a/tools/testing/radix-tree/multiorder.c b/tools/testing/radix-tree/multiorder.c
index de3d0e96f987..0229e6fb590f 100644
--- a/tools/testing/radix-tree/multiorder.c
+++ b/tools/testing/radix-tree/multiorder.c
@@ -135,6 +135,11 @@ static void multiorder_check(unsigned long index, int order)
item_check_absent(&tree, i);
for (i = max; i < 2*max; i++)
item_check_absent(&tree, i);
+ for (i = min; i < max; i++) {
+ static void *entry = (void *)
+ (0xA0 | RADIX_TREE_EXCEPTIONAL_ENTRY);
+ assert(radix_tree_insert(&tree, i, entry) == -EEXIST);
+ }

assert(item_delete(&tree, index) != 0);

--
2.8.0.rc3