Re: [PATCH 5/6] zsmalloc: remove unnecessary type casting

[Nitin Gupta <ngupta@vflare.org>]

On 04/25/2012 02:23 AM, Minchan Kim wrote:

> Let's remove unnecessary type casting of (void *).
> 
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
>  drivers/staging/zsmalloc/zsmalloc-main.c |    3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/drivers/staging/zsmalloc/zsmalloc-main.c
> index b7d31cc..ff089f8 100644
> --- a/drivers/staging/zsmalloc/zsmalloc-main.c
> +++ b/drivers/staging/zsmalloc/zsmalloc-main.c
> @@ -644,8 +644,7 @@ void zs_free(struct zs_pool *pool, void *obj)
>  	spin_lock(&class->lock);
>  
>  	/* Insert this object in containing zspage's freelist */
> -	link = (struct link_free *)((unsigned char *)kmap_atomic(f_page)
> -							+ f_offset);
> +	link = (struct link_free *)(kmap_atomic(f_page)	+ f_offset);
>  	link->next = first_page->freelist;
>  	kunmap_atomic(link);
>  	first_page->freelist = obj;



Incrementing a void pointer looks weired and should not be allowed by C
compilers though gcc and clang seem to allow this without any warnings.
(fortunately C++ forbids incrementing void pointers)

So, we should keep this cast to unsigned char pointer to avoid relying
on a non-standard, compiler specific behavior.

Thanks,
Nitin

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