Re: [PATCH v4 6/9] rbtree: Implement generic latch_tree

[Lai Jiangshan <laijs@cn.fujitsu.com>]

On 04/09/2015 12:48 AM, Peter Zijlstra wrote:

> +
> +struct latch_tree_node {
> +	/*
> +	 * Because we have an array of two entries in struct latch_tree_nodes
> +	 * it's not possible to use container_of() to get back to the
> +	 * encapsulating structure; therefore we have to put in a back pointer.
> +	 */
> +	void		*priv;
> +	struct rb_node	node;
> +};

I don't think @priv is strictly needed. It is possible to use container_of()
to go back. @priv is even not used in this file (except the initialization).

First, we can use container_of() to find encapsulating structure from the
struct latch_tree_nodeS.

Second, we can add a @idx to __lt_insert() and __lt_find(), thus we can
find the encapsulating latch_tree_nodes from rb_node or latch_tree_node.
and struct latch_tree_ops uses latch_tree_nodes instead.

Did I miss anything? If the @priv is possible to be removed, removing it will
simplify this file but it may add a little more code in the module.c where
the ltn_core&ltn_init can't share the same ->less() and ->comp() after.

If you do remove @priv, please also use rb_node instead of old latch_tree_node
and rename old latch_tree_nodes to latch_tree_node.