linux-kernel - Re: [PATCH] mm/slub: remove unneeded return value of slab_pad

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Message-ID: <Yl/y7GWdKCbVPeYS@hyeyoo>
Date:   Wed, 20 Apr 2022 20:47:56 +0900
From:   Hyeonggon Yoo <42.hyeyoo@...il.com>
To:     Miaohe Lin <linmiaohe@...wei.com>
Cc:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo.kim@....com, akpm@...ux-foundation.org, vbabka@...e.cz,
        roman.gushchin@...ux.dev, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/slub: remove unneeded return value of slab_pad_check

On Tue, Apr 19, 2022 at 08:03:52PM +0800, Miaohe Lin wrote:
> The return value of slab_pad_check is never used. So we can make it return
> void now.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> ---
>  mm/slub.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 6dc703488d30..1f699ddfff7f 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1017,7 +1017,7 @@ static int check_pad_bytes(struct kmem_cache *s, struct slab *slab, u8 *p)
>  }
>  
>  /* Check the pad bytes at the end of a slab page */
> -static int slab_pad_check(struct kmem_cache *s, struct slab *slab)
> +static void slab_pad_check(struct kmem_cache *s, struct slab *slab)
>  {
>  	u8 *start;
>  	u8 *fault;
> @@ -1027,21 +1027,21 @@ static int slab_pad_check(struct kmem_cache *s, struct slab *slab)
>  	int remainder;
>  
>  	if (!(s->flags & SLAB_POISON))
> -		return 1;
> +		return;
>  
>  	start = slab_address(slab);
>  	length = slab_size(slab);
>  	end = start + length;
>  	remainder = length % s->size;
>  	if (!remainder)
> -		return 1;
> +		return;
>  
>  	pad = end - remainder;
>  	metadata_access_enable();
>  	fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder);
>  	metadata_access_disable();
>  	if (!fault)
> -		return 1;
> +		return;
>  	while (end > fault && end[-1] == POISON_INUSE)
>  		end--;
>  
> @@ -1050,7 +1050,6 @@ static int slab_pad_check(struct kmem_cache *s, struct slab *slab)
>  	print_section(KERN_ERR, "Padding ", pad, remainder);
>  
>  	restore_bytes(s, "slab padding", POISON_INUSE, fault, end);
> -	return 0;
>  }
>  
>  static int check_object(struct kmem_cache *s, struct slab *slab,
> @@ -1642,8 +1641,7 @@ static inline int free_debug_processing(
>  	void *head, void *tail, int bulk_cnt,
>  	unsigned long addr) { return 0; }
>  
> -static inline int slab_pad_check(struct kmem_cache *s, struct slab *slab)
> -			{ return 1; }
> +static inline void slab_pad_check(struct kmem_cache *s, struct slab *slab) {}
>  static inline int check_object(struct kmem_cache *s, struct slab *slab,
>  			void *object, u8 val) { return 1; }
>  static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,

Seems the return value was not used even at birth of SLUB.

Looks good to me.

Reviewed-by: Hyeonggon Yoo <42.hyeyoo@...il.com>

Thanks!

> -- 
> 2.23.0
> 
> 

-- 
Thanks,
Hyeonggon