linux-kernel - Re: [PATCH] maple_tree: Use ma_dead_node() in mte_dead

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Message-ID: <6d2e6cecbstwvy7h3beplud3fvzyyje5v6iurhl34pr6nlne6z@dt7gl3omst63>
Date: Tue, 11 Feb 2025 10:34:25 -0500
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: I Hsin Cheng <richard120310@...il.com>
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        jserv@...s.ncku.edu.tw, skhan@...uxfoundation.org
Subject: Re: [PATCH] maple_tree: Use ma_dead_node() in mte_dead_node()

* I Hsin Cheng <richard120310@...il.com> [250211 02:19]:
> Utilize ma_dead_node() in mte_dead_node(). It can prevent decoding the
> maple enode for a second time. Use the "node" to find parent for
> comparison.

This is much better, thanks.

> 
> Signed-off-by: I Hsin Cheng <richard120310@...il.com>


Reviewed-by: Liam R. Howlett <Liam.Howlett@...cle.com>

> ---
>  lib/maple_tree.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)

In the future, please include a link and changes to v1 here.  This is
instead of a cover letter for a single patch.

v1: https://lore.kernel.org/linux-mm/20250210083526.252955-1-richard120310@gmail.com/

Also, the subject should have v2.

> 
> 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
>