Re: [PATCH] tst-process_madvise: Check process_madvise-syscall support.

[Florian Weimer <fweimer@redhat.com>]

* Stefan Liebler via Libc-alpha:

> So far this test checks if pidfd_open-syscall is supported,
> which was introduced with linux 5.3.
>
> The process_madvise-syscall was introduced with linux 5.10.
> Thus you'll get FAILs if you are running a kernel in between.
>
> This patch adds a check if the first process_madvise-syscall
> returns ENOSYS and in this case will fail with UNSUPPORTED.
> ---
>  sysdeps/unix/sysv/linux/tst-process_madvise.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/tst-process_madvise.c b/sysdeps/unix/sysv/linux/tst-process_madvise.c
> index a674e80b76..6fe5a79b1d 100644
> --- a/sysdeps/unix/sysv/linux/tst-process_madvise.c
> +++ b/sysdeps/unix/sysv/linux/tst-process_madvise.c
> @@ -101,8 +101,12 @@ do_test (void)
>  
>      /* We expect this to succeed in the target process because the mapping
>         is valid.  */
> -    TEST_COMPARE (process_madvise (pidfd, &iv, 1, MADV_COLD, 0),
> -		  2 * page_size);
> +    errno = 0;
> +    ssize_t ret = process_madvise (pidfd, &iv, 1, MADV_COLD, 0);
> +    if (ret == -1 && errno == ENOSYS)
> +      FAIL_UNSUPPORTED ("kernel does not support process_madvise, skipping"
> +			"test");
> +    TEST_COMPARE (ret, 2 * page_size);
>    }
>  
>    {

Assigning 0 to errno should not be necessary here.  But the patch looks
good otherwise.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

Thanks,
Florian