linux-kernel - Re: [PATCH v2 16/16] maple_tree: remove unneeded mas_wr_walk() in mas_store

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Date: Thu, 13 Jun 2024 11:02:46 -0400
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Sidhartha Kumar <sidhartha.kumar@...cle.com>
Cc: linux-kernel@...r.kernel.org, maple-tree@...ts.infradead.org,
        linux-mm@...ck.org, akpm@...ux-foundation.org, willy@...radead.org
Subject: Re: [PATCH v2 16/16] maple_tree: remove unneeded mas_wr_walk() in
 mas_store_prealloc()

* Sidhartha Kumar <sidhartha.kumar@...cle.com> [240607 14:53]:
> Users of mas_store_prealloc() enter this function with nodes already
> preallocated. This means the store type must be already set. We can then
> remove the call to mas_wr_store_type() and initialize the write state to
> continue the partial walk that was done when determining the store type.
> 
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
> ---
>  lib/maple_tree.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 3d334e7c19a5..5854f25a4ae5 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -4027,9 +4027,6 @@ static inline void mas_wr_end_piv(struct ma_wr_state *wr_mas)
>  		wr_mas->end_piv = wr_mas->pivots[wr_mas->offset_end];
>  	else
>  		wr_mas->end_piv = wr_mas->mas->max;
> -
> -	if (!wr_mas->entry)
> -		mas_wr_extend_null(wr_mas);
>  }
>  
>  static inline unsigned char mas_wr_new_end(struct ma_wr_state *wr_mas)
> @@ -5598,12 +5595,23 @@ void mas_store_prealloc(struct ma_state *mas, void *entry)
>  {
>  	MA_WR_STATE(wr_mas, mas, entry);
>  
> -	mas_wr_prealloc_setup(&wr_mas);
> -	mas_wr_store_type(&wr_mas);
> +	if (mas->store_type == wr_store_root) {
> +		mas_wr_prealloc_setup(&wr_mas);
> +		goto store;
> +	}
> +
> +	mas_wr_walk_descend(&wr_mas);
> +	if (mas->store_type != wr_spanning_store) {
> +		/* set wr_mas->content to current slot */
> +		wr_mas.content = mas_slot_locked(mas, wr_mas.slots, mas->offset);
> +		mas_wr_end_piv(&wr_mas);
> +	}
> +store:
>  	trace_ma_write(__func__, mas, 0, entry);
>  	mas_wr_store_entry(&wr_mas);
>  	MAS_WR_BUG_ON(&wr_mas, mas_is_err(mas));
>  	mas_destroy(mas);
> +

nit, this new line should probably be before the "store" label?

>  }
>  EXPORT_SYMBOL_GPL(mas_store_prealloc);
>  
> -- 
> 2.45.2
>