Commit b2f11c6f authored by Kent Overstreet's avatar Kent Overstreet
Browse files

lib/generic-radix-tree.c: Fix rare race in __genradix_ptr_alloc() 



If we need to increase the tree depth, allocate a new node, and then
race with another thread that increased the tree depth before us, we'll
still have a preallocated node that might be used later.

If we then use that node for a new non-root node, it'll still have a
pointer to the old root instead of being zeroed - fix this by zeroing it
in the cmpxchg failure path.

Signed-off-by: default avatarKent Overstreet <kent.overstreet@linux.dev>
parent 968feb85

lib/generic-radix-tree.c

+2 −0
Original line number Diff line number Diff line
@@ -121,6 +121,8 @@ void *__genradix_ptr_alloc(struct __genradix *radix, size_t offset, 
		if ((v = cmpxchg_release(&radix->root, r, new_root)) == r) {

			v = new_root;

			new_node = NULL;

		} else {

			new_node->children[0] = NULL;

		}

	}