linux-kernel - Re: [PATCH] bitops: simplify get_count_order

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Date:   Wed, 27 May 2020 22:45:42 +0000
From:   Wei Yang <richard.weiyang@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Wei Yang <richard.weiyang@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        christian.brauner@...ntu.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] bitops: simplify get_count_order_long()

On Mon, May 25, 2020 at 03:31:46PM -0700, Andrew Morton wrote:
>On Mon, 25 May 2020 21:57:41 +0000 Wei Yang <richard.weiyang@...il.com> wrote:
>
>> I see the patch just merged, so I suppose to add the above test code into that
>> one?
>
>Well, that's not really test code.
>
>But yes, something which tests both the 32-bit and 64-bit functions would be
>nice, sometime.

Mimic the test_bitops.c, I wrote a test like this:

/* a tiny module only meant to test get_count_order/long */
unsigned int order_comb[][2] = {
	{0x00000003,  2},
	{0x00000004,  2},
	{0x00001fff, 13},
	{0x00002000, 13},
	{0x50000000, 32},
	{0x80000000, 32},
};

static int __init test_getorder_startup(void)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(order_comb); i++) {
		if (order_comb[i][1] != get_count_order(order_comb[i][0]))
			pr_warn("get_count_order wrong for %lx\n",
					order_comb[i][0]);
	}

	return 0;
}

Since I don't get a way to iterate all the possibilities, some random
combination is chosen. Is this one looks good?

-- 
Wei Yang
Help you, Help me