linux-kernel - Re: [PATCH v1 1/2] lib/test_bitmap: Correct test data offsets for 32-bit

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Message-ID: <20200108192437.GA13872@yury-thinkpad>
Date:   Wed, 8 Jan 2020 11:24:37 -0800
From:   Yury Norov <yury.norov@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Rasmus Villemoes <linux@...musvillemoes.dk>,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Guenter Roeck <linux@...ck-us.net>
Subject: Re: [PATCH v1 1/2] lib/test_bitmap: Correct test data offsets for
 32-bit

On Wed, Jan 08, 2020 at 08:46:10PM +0200, Andy Shevchenko wrote:
> On 32-bit platform the size of long is only 32 bits which makes wrong offset
> in the array of 64 bit size.
> 
> Calculate offset based on BITS_PER_LONG.
> 
> Fixes: 30544ed5de43 ("lib/bitmap: introduce bitmap_replace() helper")
> Reported-by: Guenter Roeck <linux@...ck-us.net>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  lib/test_bitmap.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
> index 5cb35a734462..af522577a76e 100644
> --- a/lib/test_bitmap.c
> +++ b/lib/test_bitmap.c
> @@ -275,22 +275,23 @@ static void __init test_copy(void)
>  static void __init test_replace(void)
>  {
>  	unsigned int nbits = 64;
> +	unsigned int step = DIV_ROUND_UP(nbits, BITS_PER_LONG);

Step is already defined in this file:
        #define step (sizeof(u64) / sizeof(unsigned long))
to avoid the same problem in other test cases. Introducing another variant of 
it looks messy.

>  	DECLARE_BITMAP(bmap, 1024);
>  
>  	bitmap_zero(bmap, 1024);
> -	bitmap_replace(bmap, &exp2[0], &exp2[1], exp2_to_exp3_mask, nbits);
> +	bitmap_replace(bmap, &exp2[0 * step], &exp2[1 * step], exp2_to_exp3_mask, nbits);
>  	expect_eq_bitmap(bmap, exp3_0_1, nbits);

If nbits is always 64, why don't you pass 64 directly?

Yury

>  	bitmap_zero(bmap, 1024);
> -	bitmap_replace(bmap, &exp2[1], &exp2[0], exp2_to_exp3_mask, nbits);
> +	bitmap_replace(bmap, &exp2[1 * step], &exp2[0 * step], exp2_to_exp3_mask, nbits);
>  	expect_eq_bitmap(bmap, exp3_1_0, nbits);
>  
>  	bitmap_fill(bmap, 1024);
> -	bitmap_replace(bmap, &exp2[0], &exp2[1], exp2_to_exp3_mask, nbits);
> +	bitmap_replace(bmap, &exp2[0 * step], &exp2[1 * step], exp2_to_exp3_mask, nbits);
>  	expect_eq_bitmap(bmap, exp3_0_1, nbits);
>  
>  	bitmap_fill(bmap, 1024);
> -	bitmap_replace(bmap, &exp2[1], &exp2[0], exp2_to_exp3_mask, nbits);
> +	bitmap_replace(bmap, &exp2[1 * step], &exp2[0 * step], exp2_to_exp3_mask, nbits);
>  	expect_eq_bitmap(bmap, exp3_1_0, nbits);
>  }
>  
> -- 
> 2.24.1