linux-kernel - Re: [PATCH net] kunit: Fix again checksum tests on big endian CPUs

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Date: Fri, 23 Feb 2024 12:05:45 -0800
From: Charlie Jenkins <charlie@...osinc.com>
To: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: "David S. Miller" <davem@...emloft.net>,
	Jakub Kicinski <kuba@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Guenter Roeck <linux@...ck-us.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Erhard Furtner <erhard_f@...lbox.org>
Subject: Re: [PATCH net] kunit: Fix again checksum tests on big endian CPUs

On Fri, Feb 23, 2024 at 06:15:16PM +0000, Christophe Leroy wrote:
> 
> 
> Le 23/02/2024 à 18:57, Charlie Jenkins a écrit :
> > 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 <erhard_f@...lbox.org>
> >> Fixes: 6f4c45cbcb00 ("kunit: Add tests for csum_ipv6_magic and ip_fast_csum")
> >> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
> >> ---
> >>   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/20240221-fix_sparse_errors_checksum_tests-v9-2-bff4d73ab9d1@rivosinc.com/.
> > 
> 
> The idea here is to provide a fix which is similar to the one done 
> previously and that uses the same approach and reuses the same helpers.
> 
> This is to keep the code homogeneous.
> 
> Christophe

htons makes more sense here since this is networking code, but I don't
care enough to argue the point. I tested it on big endian SPARC and on
riscv. I'll base my alignment patch on this.

Tested-by: Charlie Jenkins <charlie@...osinc.com>