Re: [PATCH V2 10/10] selftests: vm: remove dependecy from internal kernel macros

[Alistair Popple <apopple@nvidia.com>]

Reviewed-by: Alistair Popple <apopple@nvidia.com>

On Wednesday, 19 January 2022 9:15:31 PM AEDT Muhammad Usama Anjum wrote:
> The defination of swap() is used from kernel's internal header when this
> test is built in source tree. The build fails when this test is built
> out of source tree as defination of swap() isn't found. Selftests
> shouldn't depend on kernel's internal header files. They can only depend
> on uapi header files. Add the defination of swap() to fix the build
> error:
> 
> 	gcc -Wall  -I/linux_mainline2/build/usr/include -no-pie    userfaultfd.c -lrt -lpthread -o /linux_mainline2/build/kselftest/vm/userfaultfd
> 	userfaultfd.c: In function ‘userfaultfd_stress’:
> 	userfaultfd.c:1530:3: warning: implicit declaration of function ‘swap’; did you mean ‘swab’? [-Wimplicit-function-declaration]
> 	 1530 |   swap(area_src, area_dst);
> 	      |   ^~~~
> 	      |   swab
> 	/usr/bin/ld: /tmp/cclUUH7V.o: in function `userfaultfd_stress':
> 	userfaultfd.c:(.text+0x4d64): undefined reference to `swap'
> 	/usr/bin/ld: userfaultfd.c:(.text+0x4d82): undefined reference to `swap'
> 	collect2: error: ld returned 1 exit status
> 
> Fixes: 2c769ed7137a ("tools/testing/selftests/vm/userfaultfd.c: use swap() to make code cleaner")
> Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
> ---
>  tools/testing/selftests/vm/userfaultfd.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
> index d3fd24f9fae8..d2480ab93037 100644
> --- a/tools/testing/selftests/vm/userfaultfd.c
> +++ b/tools/testing/selftests/vm/userfaultfd.c
> @@ -119,6 +119,9 @@ struct uffd_stats {
>  				 ~(unsigned long)(sizeof(unsigned long long) \
>  						  -  1)))
>  
> +#define swap(a, b) \
> +	do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0)
> +
>  const char *examples =
>      "# Run anonymous memory test on 100MiB region with 99999 bounces:\n"
>      "./userfaultfd anon 100 99999\n\n"
>