linux-kernel - Re: [PATCH v1] bitmap: Drop unnecessary 0 check for u32 array operations

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Date:   Thu, 31 May 2018 17:47:49 +0300
From:   Yury Norov <ynorov@...iumnetworks.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] bitmap: Drop unnecessary 0 check for u32 array
 operations

On Thu, May 31, 2018 at 04:19:14PM +0300, Andy Shevchenko wrote:
> The nbits == 0 is safe to be supplied to the function body, so,
> remove unnecessary checks in bitmap_to_arr32() and bitmap_from_arr32().
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

Indeed. Thanks for the catch.

> ---
>  lib/bitmap.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index 58f9750e49c6..33e95cd359a2 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -1132,14 +1132,10 @@ EXPORT_SYMBOL(bitmap_copy_le);
>   *	@buf: array of u32 (in host byte order), the source bitmap
>   *	@nbits: number of bits in @bitmap
>   */
> -void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
> -						unsigned int nbits)
> +void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf, unsigned int nbits)

This line is 81 characters length, and it will trigger checkpatch warning.
(But I'm OK with it.)

>  {
>  	unsigned int i, halfwords;
>  
> -	if (!nbits)
> -		return;
> -
>  	halfwords = DIV_ROUND_UP(nbits, 32);
>  	for (i = 0; i < halfwords; i++) {
>  		bitmap[i/2] = (unsigned long) buf[i];
> @@ -1163,9 +1159,6 @@ void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
>  {
>  	unsigned int i, halfwords;
>  
> -	if (!nbits)
> -		return;
> -
>  	halfwords = DIV_ROUND_UP(nbits, 32);
>  	for (i = 0; i < halfwords; i++) {
>  		buf[i] = (u32) (bitmap[i/2] & UINT_MAX);
> -- 
> 2.17.0

Acked-by: Yury Norov <ynorov@...iumnetworks.com>