Re: [PATCH] maple_tree: Remove redundant mte_to_node() in mte_dead_node()

[Liam R. Howlett]

* I Hsin Cheng <richard120310@xxxxxxxxx> [250210 03:35]:

> In mte_dead_node(), it already assign "node" as "mte_to_node(enode)" in
> the first place, calling "mte_parent(enode)" will result in the same
> "mte_to_node(enode)" again which is redundant.

This is a very confusing way of saying "avoid calling mte_to_node() in
the mte_parent() call by using the ma_dead_node() instead."

In fact, the subject is wrong as well, since the mte_to_node() was
removed from the call path of mte_dead_node(), and not the function
itself.

> 
> Refactor mte_dead_node() and utilize ma_dead_node() to perform the
> parent check without the redundant "mte_to_node()".
> 
> Signed-off-by: I Hsin Cheng <richard120310@xxxxxxxxx>

The code looks right, but the subject and change log are not.  Please
respin the patch, something like this:

maple_tree: Use ma_dead_node() in mte_dead_node()

Using ma_dead_node() in mte_dead_node() avoids decoding the maple enode
for a second time to find the parent.

Feel free to change it as you'd like, but I couldn't follow what you
meant.

> ---
>  lib/maple_tree.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index f7153ade1be5..362f85c62678 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -584,13 +584,10 @@ static __always_inline bool ma_dead_node(const struct maple_node *node)
>   */
>  static __always_inline bool mte_dead_node(const struct maple_enode *enode)
>  {
> -	struct maple_node *parent, *node;
> +	struct maple_node *node;
>  
>  	node = mte_to_node(enode);
> -	/* Do not reorder reads from the node prior to the parent check */
> -	smp_rmb();
> -	parent = mte_parent(enode);
> -	return (parent == node);
> +	return ma_dead_node(node);
>  }
>  
>  /*
> -- 
> 2.43.0
>