1 files changed, 19 insertions, 3 deletions

diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h
index 7c88ad156a29..f54be7082207 100644
--- a/include/linux/radix-tree.h
+++ b/include/linux/radix-tree.h
@@ -379,12 +379,28 @@ void **radix_tree_next_chunk(struct radix_tree_root *root,
                              struct radix_tree_iter *iter, unsigned flags);
 
 /**
+ * radix_tree_iter_retry - retry this chunk of the iteration
+ * @iter:       iterator state
+ *
+ * If we iterate over a tree protected only by the RCU lock, a race
+ * against deletion or creation may result in seeing a slot for which
+ * radix_tree_deref_retry() returns true.  If so, call this function
+ * and continue the iteration.
+ */
+static inline __must_check
+void **radix_tree_iter_retry(struct radix_tree_iter *iter)
+{
+        iter->next_index = iter->index;
+        return NULL;
+}
+
+/**
  * radix_tree_chunk_size - get current chunk size
  *
  * @iter:       pointer to radix tree iterator
  * Returns:     current chunk size
  */
-static __always_inline unsigned
+static __always_inline long
 radix_tree_chunk_size(struct radix_tree_iter *iter)
 {
         return iter->next_index - iter->index;
@@ -418,9 +434,9 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags)
                         return slot + offset + 1;
                 }
         } else {
-                unsigned size = radix_tree_chunk_size(iter) - 1;
+                long size = radix_tree_chunk_size(iter);
 
-                while (size--) {
+                while (--size > 0) {
                         slot++;
                         iter->index++;
                         if (likely(*slot))