Re: [PATCH v1 net-next] selftests: net: af_unix: Fix a build error of unix_connect.c.

[Jakub Kicinski <kuba@kernel.org>]

On Mon, 18 Jul 2022 09:23:50 -0700 Kuniyuki Iwashima wrote:
> This patch fixes a build error reported in the link. [0]
> 
>   unix_connect.c: In function ‘unix_connect_test’:
>   unix_connect.c:115:55: error: expected identifier before ‘(’ token
>    #define offsetof(type, member) ((size_t)&((type *)0)->(member))
>                                                        ^
>   unix_connect.c:128:12: note: in expansion of macro ‘offsetof’
>     addrlen = offsetof(struct sockaddr_un, sun_path) + variant->len;
>               ^~~~~~~~

Can we delete this define and use stddef.h instead?  man offsetof
This is not kernel code the C standard lib is at our disposal.

> The checkpatch.pl will complain about this change, but the root cause of
> the build failure is that I fixed this in the v2 -> v3 change. [1]
> 
>   CHECK: Macro argument 'member' may be better as '(member)' to avoid precedence issues
>   #33: FILE: tools/testing/selftests/net/af_unix/unix_connect.c:115:
>   +#define offsetof(type, member) ((size_t)&((type *)0)->member)
> 
> [0]: https://lore.kernel.org/linux-mm/202207182205.FrkMeDZT-lkp@intel.com/
> [1]: https://lore.kernel.org/netdev/20220702154818.66761-1-kuniyu@amazon.com/
> 
> Fixes: e95ab1d85289 ("selftests: net: af_unix: Test connect() with different netns.")
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
> ---
>  tools/testing/selftests/net/af_unix/unix_connect.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/net/af_unix/unix_connect.c b/tools/testing/selftests/net/af_unix/unix_connect.c
> index 157e44ef7f37..5b231d8c4683 100644
> --- a/tools/testing/selftests/net/af_unix/unix_connect.c
> +++ b/tools/testing/selftests/net/af_unix/unix_connect.c
> @@ -112,7 +112,7 @@ FIXTURE_TEARDOWN(unix_connect)
>  		remove("test");
>  }
>  
> -#define offsetof(type, member) ((size_t)&((type *)0)->(member))
> +#define offsetof(type, member) ((size_t)&((type *)0)->member)
>  
>  TEST_F(unix_connect, test)
>  {