Re: [PATCH v2 1/4] userfaultfd: selftest: Fix checking of userfaultfd_open() result

From: Mike Rapoport
Date: Tue Aug 07 2018 - 02:50:38 EST


On Fri, Aug 03, 2018 at 07:00:43PM -0300, Thiago Jung Bauermann wrote:
> If the userfaultfd test is run on a kernel with CONFIG_USERFAULTFD=n, it
> will report that the system call is not available yet go ahead and continue
> anyway:
>
> # ./userfaultfd anon 30 1
> nr_pages: 480, nr_pages_per_cpu: 120
> userfaultfd syscall not available in this kernel
> bounces: 0, mode:, register failure
>
> This is because userfaultfd_open() returns 0 on success and 1 on error but
> all callers assume that it returns < 0 on error.
>
> Since the convention of the test as a whole is the one used by
> userfault_open(), fix its callers instead. Now the test behaves correctly:
>
> # ./userfaultfd anon 30 1
> nr_pages: 480, nr_pages_per_cpu: 120
> userfaultfd syscall not available in this kernel
>
> Signed-off-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>

Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>

> ---
> tools/testing/selftests/vm/userfaultfd.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
> index 7b8171e3128a..e4099afe7557 100644
> --- a/tools/testing/selftests/vm/userfaultfd.c
> +++ b/tools/testing/selftests/vm/userfaultfd.c
> @@ -859,7 +859,7 @@ static int userfaultfd_zeropage_test(void)
> if (uffd_test_ops->release_pages(area_dst))
> return 1;
>
> - if (userfaultfd_open(0) < 0)
> + if (userfaultfd_open(0))
> return 1;
> uffdio_register.range.start = (unsigned long) area_dst;
> uffdio_register.range.len = nr_pages * page_size;
> @@ -902,7 +902,7 @@ static int userfaultfd_events_test(void)
>
> features = UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_EVENT_REMAP |
> UFFD_FEATURE_EVENT_REMOVE;
> - if (userfaultfd_open(features) < 0)
> + if (userfaultfd_open(features))
> return 1;
> fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
>
> @@ -961,7 +961,7 @@ static int userfaultfd_sig_test(void)
> return 1;
>
> features = UFFD_FEATURE_EVENT_FORK|UFFD_FEATURE_SIGBUS;
> - if (userfaultfd_open(features) < 0)
> + if (userfaultfd_open(features))
> return 1;
> fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
>
> @@ -1027,7 +1027,7 @@ static int userfaultfd_stress(void)
> if (!area_dst)
> return 1;
>
> - if (userfaultfd_open(0) < 0)
> + if (userfaultfd_open(0))
> return 1;
>
> count_verify = malloc(nr_pages * sizeof(unsigned long long));

--
Sincerely yours,
Mike.