address all -Wunused-const warnings

[PATCH 18/34] lib: checksum: hide unused expected_csum_ipv6_magic[]

Posted by Arnd Bergmann 1 year, 10 months ago

From: Arnd Bergmann <arnd@arndb.de>

When CONFIG_NET is disabled, an extra warning shows up for this
unused variable:

lib/checksum_kunit.c:218:18: error: 'expected_csum_ipv6_magic' defined but not used [-Werror=unused-const-variable=]

Hide it under the same #ifdef as the reference to it.

Fixes: f24a70106dc1 ("lib: checksum: Fix build with CONFIG_NET=n")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 lib/checksum_kunit.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/checksum_kunit.c b/lib/checksum_kunit.c
index bf70850035c7..80dd1e1b71ba 100644
--- a/lib/checksum_kunit.c
+++ b/lib/checksum_kunit.c
@@ -215,6 +215,7 @@ static const u32 init_sums_no_overflow[] = {
 	0xffff0000, 0xfffffffb,
 };
 
+#ifdef CONFIG_NET
 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,
@@ -240,6 +241,7 @@ static const u16 expected_csum_ipv6_magic[] = {
 	0x99aa, 0xb06b, 0xee19, 0xcc2c, 0xf34c, 0x7c49, 0xdac3, 0xa71e, 0xc988,
 	0x3845, 0x1014
 };
+#endif
 
 static const u16 expected_fast_csum[] = {
 	0xda83, 0x45da, 0x4f46, 0x4e4f, 0x34e,	0xe902, 0xa5e9, 0x87a5, 0x7187,
-- 
2.39.2

Re: [PATCH 18/34] lib: checksum: hide unused expected_csum_ipv6_magic[]

Posted by Christophe Leroy 1 year, 10 months ago


Le 03/04/2024 à 10:06, Arnd Bergmann a écrit :
> From: Arnd Bergmann <arnd@arndb.de>
> 
> When CONFIG_NET is disabled, an extra warning shows up for this
> unused variable:
> 
> lib/checksum_kunit.c:218:18: error: 'expected_csum_ipv6_magic' defined but not used [-Werror=unused-const-variable=]
> 
> Hide it under the same #ifdef as the reference to it.
> 
> Fixes: f24a70106dc1 ("lib: checksum: Fix build with CONFIG_NET=n")

I think that commit introduced unjustified #ifdef in a C file.

Refer 
https://docs.kernel.org/process/coding-style.html#conditional-compilation

The fix should be:

diff --git a/lib/checksum_kunit.c b/lib/checksum_kunit.c
index bf70850035c7..1354953c8942 100644
--- a/lib/checksum_kunit.c
+++ b/lib/checksum_kunit.c
@@ -594,7 +594,6 @@ static void test_ip_fast_csum(struct kunit *test)

  static void test_csum_ipv6_magic(struct kunit *test)
  {
-#if defined(CONFIG_NET)
  	const struct in6_addr *saddr;
  	const struct in6_addr *daddr;
  	unsigned int len;
@@ -608,6 +607,9 @@ static void test_csum_ipv6_magic(struct kunit *test)
  	const int csum_offset = sizeof(struct in6_addr) + sizeof(struct 
in6_addr) +
  			    sizeof(int) + sizeof(char);

+	if (!IS_ENABLED(CONFIG_NET))
+		return;
+
  	for (int i = 0; i < NUM_IPv6_TESTS; i++) {
  		saddr = (const struct in6_addr *)(random_buf + i);
  		daddr = (const struct in6_addr *)(random_buf + i +
@@ -618,7 +620,6 @@ static void test_csum_ipv6_magic(struct kunit *test)
  		CHECK_EQ(to_sum16(expected_csum_ipv6_magic[i]),
  			 csum_ipv6_magic(saddr, daddr, len, proto, csum));
  	}
-#endif /* !CONFIG_NET */
  }

  static struct kunit_case __refdata checksum_test_cases[] = {


> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>   lib/checksum_kunit.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/lib/checksum_kunit.c b/lib/checksum_kunit.c
> index bf70850035c7..80dd1e1b71ba 100644
> --- a/lib/checksum_kunit.c
> +++ b/lib/checksum_kunit.c
> @@ -215,6 +215,7 @@ static const u32 init_sums_no_overflow[] = {
>   	0xffff0000, 0xfffffffb,
>   };
>   
> +#ifdef CONFIG_NET
>   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,
> @@ -240,6 +241,7 @@ static const u16 expected_csum_ipv6_magic[] = {
>   	0x99aa, 0xb06b, 0xee19, 0xcc2c, 0xf34c, 0x7c49, 0xdac3, 0xa71e, 0xc988,
>   	0x3845, 0x1014
>   };
> +#endif
>   
>   static const u16 expected_fast_csum[] = {
>   	0xda83, 0x45da, 0x4f46, 0x4e4f, 0x34e,	0xe902, 0xa5e9, 0x87a5, 0x7187,

Re: [PATCH 18/34] lib: checksum: hide unused expected_csum_ipv6_magic[]

Posted by Arnd Bergmann 1 year, 10 months ago

On Wed, Apr 3, 2024, at 10:41, Christophe Leroy wrote:
> Le 03/04/2024 à 10:06, Arnd Bergmann a écrit :
>> From: Arnd Bergmann <arnd@arndb.de>
>> 
>> When CONFIG_NET is disabled, an extra warning shows up for this
>> unused variable:
>> 
>> lib/checksum_kunit.c:218:18: error: 'expected_csum_ipv6_magic' defined but not used [-Werror=unused-const-variable=]
>> 
>> Hide it under the same #ifdef as the reference to it.
>> 
>> Fixes: f24a70106dc1 ("lib: checksum: Fix build with CONFIG_NET=n")
>
> I think that commit introduced unjustified #ifdef in a C file.

> Refer 
> https://docs.kernel.org/process/coding-style.html#conditional-compilation
>
> The fix should be:
>
> +	if (!IS_ENABLED(CONFIG_NET))
> +		return;
> +
>   	for (int i = 0; i < NUM_IPv6_TESTS; i++) {
>   		saddr = (const struct in6_addr *)(random_buf + i);
>   		daddr = (const struct in6_addr *)(random_buf + i +
> @@ -618,7 +620,6 @@ static void test_csum_ipv6_magic(struct kunit *test)
>   		CHECK_EQ(to_sum16(expected_csum_ipv6_magic[i]),
>   			 csum_ipv6_magic(saddr, daddr, len, proto, csum));
>   	}
> -#endif /* !CONFIG_NET */

Yes, I usually prefer that approach, and I think I tried it first
but ran into compile-time problems because csum_ipv6_magic()
is declared conditionally. Let me try again, maybe I misremember
what I did or I can remove some more #ifdef checks for this.

       Arnd

Re: [PATCH 18/34] lib: checksum: hide unused expected_csum_ipv6_magic[]

Posted by Christophe Leroy 1 year, 10 months ago


Le 03/04/2024 à 10:58, Arnd Bergmann a écrit :
> On Wed, Apr 3, 2024, at 10:41, Christophe Leroy wrote:
>> Le 03/04/2024 à 10:06, Arnd Bergmann a écrit :
>>> From: Arnd Bergmann <arnd@arndb.de>
>>>
>>> When CONFIG_NET is disabled, an extra warning shows up for this
>>> unused variable:
>>>
>>> lib/checksum_kunit.c:218:18: error: 'expected_csum_ipv6_magic' defined but not used [-Werror=unused-const-variable=]
>>>
>>> Hide it under the same #ifdef as the reference to it.
>>>
>>> Fixes: f24a70106dc1 ("lib: checksum: Fix build with CONFIG_NET=n")
>>
>> I think that commit introduced unjustified #ifdef in a C file.
> 
>> Refer
>> https://docs.kernel.org/process/coding-style.html#conditional-compilation
>>
>> The fix should be:
>>
>> +	if (!IS_ENABLED(CONFIG_NET))
>> +		return;
>> +
>>    	for (int i = 0; i < NUM_IPv6_TESTS; i++) {
>>    		saddr = (const struct in6_addr *)(random_buf + i);
>>    		daddr = (const struct in6_addr *)(random_buf + i +
>> @@ -618,7 +620,6 @@ static void test_csum_ipv6_magic(struct kunit *test)
>>    		CHECK_EQ(to_sum16(expected_csum_ipv6_magic[i]),
>>    			 csum_ipv6_magic(saddr, daddr, len, proto, csum));
>>    	}
>> -#endif /* !CONFIG_NET */
> 
> Yes, I usually prefer that approach, and I think I tried it first
> but ran into compile-time problems because csum_ipv6_magic()
> is declared conditionally. Let me try again, maybe I misremember
> what I did or I can remove some more #ifdef checks for this.

FWIW, before replying I did a build check with pmac32_defconfig 
(powerpc) with CONFIG_NET removed. I was able to build 
lib/checksum_kunit.o and objdump shown there was no reference to 
csum_ipv6_magic() inside it.

Christophe

Re: [PATCH 18/34] lib: checksum: hide unused expected_csum_ipv6_magic[]

Posted by Arnd Bergmann 1 year, 10 months ago

On Wed, Apr 3, 2024, at 11:03, Christophe Leroy wrote:
> Le 03/04/2024 à 10:58, Arnd Bergmann a écrit :
>
>> On Wed, Apr 3, 2024, at 10:41, Christophe Leroy wrote:
>> Yes, I usually prefer that approach, and I think I tried it first
>> but ran into compile-time problems because csum_ipv6_magic()
>> is declared conditionally. Let me try again, maybe I misremember
>> what I did or I can remove some more #ifdef checks for this.
>
> FWIW, before replying I did a build check with pmac32_defconfig 
> (powerpc) with CONFIG_NET removed. I was able to build 
> lib/checksum_kunit.o and objdump shown there was no reference to 
> csum_ipv6_magic() inside it.

Right, got it now. I was confused a bit by CONFIG_NET vs CONFIG_IPV6
given that the common definition for csum_ipv6_magic() is in
net/ipv6 but unlike other files there still gets build when IPV6
is disabled but NET remains turned on.

I've done a little more randconfig testing to verify it,
sending v2 now.

      Arnd