void debugfs_remove_recursive(struct dentry *dentry)
{
	struct dentry *child, *parent;

	if (IS_ERR_OR_NULL(dentry))
		return;

	parent = dentry;
 down:
	inode_lock(d_inode(parent));
 loop:
	/*
	 * The parent->d_subdirs is protected by the d_lock. Outside that
	 * lock, the child can be unlinked and set to be freed which can
	 * use the d_u.d_child as the rcu head and corrupt this list.
	 */
	spin_lock(&parent->d_lock);
	list_for_each_entry(child, &parent->d_subdirs, d_child) {
		if (!simple_positive(child))
			continue;

		/* perhaps simple_empty(child) makes more sense */
		if (!list_empty(&child->d_subdirs)) {
			spin_unlock(&parent->d_lock);
			inode_unlock(d_inode(parent));
			parent = child;
			goto down;
		}

		spin_unlock(&parent->d_lock);

		if (!__debugfs_remove(child, parent))
			simple_release_fs(&debugfs_mount, &debugfs_mount_count);

		/*
		 * The parent->d_lock protects agaist child from unlinking
		 * from d_subdirs. When releasing the parent->d_lock we can
		 * no longer trust that the next pointer is valid.
		 * Restart the loop. We'll skip this one with the
		 * simple_positive() check.
		 */
		goto loop;
	}
	spin_unlock(&parent->d_lock);

	inode_unlock(d_inode(parent));
	child = parent;
	parent = parent->d_parent;
	inode_lock(d_inode(parent));

	if (child != dentry)
		/* go up */
		goto loop;

	if (!__debugfs_remove(child, parent))
		simple_release_fs(&debugfs_mount, &debugfs_mount_count);
	inode_unlock(d_inode(parent));

	synchronize_srcu(&debugfs_srcu);
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.