Re: [PATCH v4 2/2] lib/bitmap: add tests for bitmap_find_next_zero_area_off()

[Yury Norov]

On Mon, Jun 01, 2026 at 05:42:34PM +0800, Yi Sun wrote:
> Add functional and performance tests
> for bitmap_find_next_zero_area_off().
> 
> Signed-off-by: Yi Sun <yi.sun@xxxxxxxxxx>
> ---
>  lib/find_bit_benchmark.c | 17 +++++++++++++++++
>  lib/test_bitmap.c        | 28 ++++++++++++++++++++++++++++
>  2 files changed, 45 insertions(+)
> 
> diff --git a/lib/find_bit_benchmark.c b/lib/find_bit_benchmark.c
> index 00d9dc61cd46..37fe76ad322e 100644
> --- a/lib/find_bit_benchmark.c
> +++ b/lib/find_bit_benchmark.c
> @@ -149,6 +149,21 @@ static int __init test_find_next_and_bit(const void *bitmap,
>  	return 0;
>  }
>  
> +static int __init
> +test_bitmap_find_next_zero_area_off(unsigned long *bitmap, unsigned long len)
> +{
> +	unsigned long i, cnt;
> +	ktime_t time;
> +
> +	time = ktime_get();
> +	for (cnt = i = 0; i < BITMAP_LEN; cnt++)
> +		i = bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN, i, 8, 0, 0) + 1;
> +	time = ktime_get() - time;
> +	pr_err("bitmap_find_next_zero_area_off:  %18llu ns, %6ld iterations\n", time, cnt);
> +
> +	return 0;
> +}
> +
>  static int __init find_bit_test(void)
>  {
>  	unsigned long nbits = BITMAP_LEN / SPARSE;
> @@ -158,6 +173,7 @@ static int __init find_bit_test(void)
>  	get_random_bytes(bitmap, sizeof(bitmap));
>  	get_random_bytes(bitmap2, sizeof(bitmap2));
>  
> +	test_bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN);
>  	test_find_next_bit(bitmap, BITMAP_LEN);
>  	test_find_next_zero_bit(bitmap, BITMAP_LEN);
>  	test_find_last_bit(bitmap, BITMAP_LEN);
> @@ -181,6 +197,7 @@ static int __init find_bit_test(void)
>  		__set_bit(get_random_u32_below(BITMAP_LEN), bitmap2);
>  	}
>  
> +	test_bitmap_find_next_zero_area_off(bitmap, BITMAP_LEN);
>  	test_find_next_bit(bitmap, BITMAP_LEN);
>  	test_find_next_zero_bit(bitmap, BITMAP_LEN);
>  	test_find_last_bit(bitmap, BITMAP_LEN);
> diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
> index 69813c10e6c0..fad2b19760c2 100644
> --- a/lib/test_bitmap.c
> +++ b/lib/test_bitmap.c
> @@ -234,6 +234,34 @@ static void __init test_find_nth_bit(void)
>  	}
>  }
>  
> +static void __init
> +test_bitmap_find_next_zero_area_off(void)

warning: ‘test_bitmap_find_next_zero_area_off’ defined but not used [-Wunused-function]
  238 | test_bitmap_find_next_zero_area_off(void)

> +{
> +	int bmap_len = 64 * 3;
> +	DECLARE_BITMAP(bmap, bmap_len);

I believe, everyone can realize that 64*3 == 192, and we don't need a
variable for it.

> +	bitmap_set(bmap, 0, bmap_len);
> +
> +	bitmap_clear(bmap, 0, 8);
> +	__clear_bit(50, bmap);
> +	bitmap_clear(bmap, 60, 10);
> +	__clear_bit(80, bmap);
> +	bitmap_clear(bmap, 100, 10);
> +	__clear_bit(120, bmap);
> +	bitmap_clear(bmap, 160, 32);

Can you also test a 'dirty' region:

        bitmap_clear(60, 18);
        __set_bit(69);
        // find nothing
        bitmap_find_next_zero_area_off(bmap, bmap_len, 0, 10, 0, 0));

> +
> +	expect_eq_uint(0,
> +		bitmap_find_next_zero_area_off(bmap, bmap_len, 0, 8, 0, 0));
> +	expect_eq_uint(60,
> +		bitmap_find_next_zero_area_off(bmap, bmap_len, 1, 8, 0, 0));
> +	expect_eq_uint(60,
> +		bitmap_find_next_zero_area_off(bmap, bmap_len, 0, 10, 0, 0));
> +	expect_eq_uint(160,
> +		bitmap_find_next_zero_area_off(bmap, bmap_len, 0, 32, 0, 0));
> +	expect_eq_uint(1,
> +		!!(bitmap_find_next_zero_area_off(bmap, bmap_len, 0, 33, 0, 0) > bmap_len));

Two last parameters are zero in all cases. Doesn't sound like an
exhaustive testing. Real users provide non-zero alignments, so please
you do.

> +}
> +
>  static void __init test_fill_set(void)
>  {
>  	DECLARE_BITMAP(bmap, 1024);
> -- 
> 2.34.1