Subject: Re: [PATCH net] kunit: Fix again checksum tests on big endian CPUs

From: Charlie Jenkins <[email-masked]>
Date: Fri, 23 Feb 2024 09:57:50 -0800

On Fri, Feb 23, 2024 at 11:41:52AM +0100, Christophe Leroy wrote:
> Commit b38460bc463c ("kunit: Fix checksum tests on big endian CPUs")
> fixed endianness issues with kunit checksum tests, but then
> commit 6f4c45cbcb00 ("kunit: Add tests for csum_ipv6_magic and
> ip_fast_csum") introduced new issues on big endian CPUs. Those issues
> are once again reflected by the warnings reported by sparse.
> 
> So, fix them with the same approach, perform proper conversion in
> order to support both little and big endian CPUs. Once the conversions
> are properly done and the right types used, the sparse warnings are
> cleared as well.
> 
> Reported-by: Erhard Furtner <[email-masked]>
> Fixes: 6f4c45cbcb00 ("kunit: Add tests for csum_ipv6_magic and ip_fast_csum")
> Signed-off-by: Christophe Leroy <[email-masked]>
> ---
>  lib/checksum_kunit.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/lib/checksum_kunit.c b/lib/checksum_kunit.c
> index 225bb7701460..bf70850035c7 100644
> --- a/lib/checksum_kunit.c
> +++ b/lib/checksum_kunit.c
> @@ -215,7 +215,7 @@ static const u32 init_sums_no_overflow[] = {
>  	0xffff0000, 0xfffffffb,
>  };
>  
> -static const __sum16 expected_csum_ipv6_magic[] = {
> +static const u16 expected_csum_ipv6_magic[] = {
>  	0x18d4, 0x3085, 0x2e4b, 0xd9f4, 0xbdc8, 0x78f,	0x1034, 0x8422, 0x6fc0,
>  	0xd2f6, 0xbeb5, 0x9d3,	0x7e2a, 0x312e, 0x778e, 0xc1bb, 0x7cf2, 0x9d1e,
>  	0xca21, 0xf3ff, 0x7569, 0xb02e, 0xca86, 0x7e76, 0x4539, 0x45e3, 0xf28d,
> @@ -241,7 +241,7 @@ static const __sum16 expected_csum_ipv6_magic[] = {
>  	0x3845, 0x1014
>  };
>  
> -static const __sum16 expected_fast_csum[] = {
> +static const u16 expected_fast_csum[] = {
>  	0xda83, 0x45da, 0x4f46, 0x4e4f, 0x34e,	0xe902, 0xa5e9, 0x87a5, 0x7187,
>  	0x5671, 0xf556, 0x6df5, 0x816d, 0x8f81, 0xbb8f, 0xfbba, 0x5afb, 0xbe5a,
>  	0xedbe, 0xabee, 0x6aac, 0xe6b,	0xea0d, 0x67ea, 0x7e68, 0x8a7e, 0x6f8a,
> @@ -577,7 +577,8 @@ static void test_csum_no_carry_inputs(struct kunit *test)
>  
>  static void test_ip_fast_csum(struct kunit *test)
>  {
> -	__sum16 csum_result, expected;
> +	__sum16 csum_result;
> +	u16 expected;
>  
>  	for (int len = IPv4_MIN_WORDS; len < IPv4_MAX_WORDS; len++) {
>  		for (int index = 0; index < NUM_IP_FAST_CSUM_TESTS; index++) {
> @@ -586,7 +587,7 @@ static void test_ip_fast_csum(struct kunit *test)
>  				expected_fast_csum[(len - IPv4_MIN_WORDS) *
>  						   NUM_IP_FAST_CSUM_TESTS +
>  						   index];
> -			CHECK_EQ(expected, csum_result);
> +			CHECK_EQ(to_sum16(expected), csum_result);
>  		}
>  	}
>  }
> @@ -598,7 +599,7 @@ static void test_csum_ipv6_magic(struct kunit *test)
>  	const struct in6_addr *daddr;
>  	unsigned int len;
>  	unsigned char proto;
> -	unsigned int csum;
> +	__wsum csum;
>  
>  	const int daddr_offset = sizeof(struct in6_addr);
>  	const int len_offset = sizeof(struct in6_addr) + sizeof(struct in6_addr);
> @@ -611,10 +612,10 @@ static void test_csum_ipv6_magic(struct kunit *test)
>  		saddr = (const struct in6_addr *)(random_buf + i);
>  		daddr = (const struct in6_addr *)(random_buf + i +
>  						  daddr_offset);
> -		len = *(unsigned int *)(random_buf + i + len_offset);
> +		len = le32_to_cpu(*(__le32 *)(random_buf + i + len_offset));
>  		proto = *(random_buf + i + proto_offset);
> -		csum = *(unsigned int *)(random_buf + i + csum_offset);
> -		CHECK_EQ(expected_csum_ipv6_magic[i],
> +		csum = *(__wsum *)(random_buf + i + csum_offset);
> +		CHECK_EQ(to_sum16(expected_csum_ipv6_magic[i]),
>  			 csum_ipv6_magic(saddr, daddr, len, proto, csum));
>  	}
>  #endif /* !CONFIG_NET */
> -- 
> 2.43.0
> 

There is no need to duplicate efforts here. This has already been
resolved by
https://lore.kernel.org/lkml/[email-masked]/.

- Charlie