Re: [PATCH] selftest/timerns: fix clang build failures for abs() calls

[Dmitry Safonov]

On Fri, May 3, 2024 at 4:30 AM John Hubbard <jhubbard@xxxxxxxxxx> wrote:
>
> First of all, in order to build with clang at all, one must first apply
> Valentin Obst's build fix for LLVM [1]. Once that is done, then when
> building with clang, via:
>
>     make LLVM=1 -C tools/testing/selftests
>
> ...then clang warns about mismatches between the expected and required
> integer length being supplied to abs(3).
>
> Fix this by using the correct variant of abs(3): labs(3) or llabs(3), in
> these cases.
>
> [1] https://lore.kernel.org/all/20240329-selftests-libmk-llvm-rfc-v1-1-2f9ed7d1c49f@xxxxxxxxxxxxxxx/
>
> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>

LGTM, even potentially fixes the testing post-2038.

Reviewed-by: Dmitry Safonov <dima@xxxxxxxxxx>

> ---
>  tools/testing/selftests/timens/exec.c       | 6 +++---
>  tools/testing/selftests/timens/timer.c      | 2 +-
>  tools/testing/selftests/timens/timerfd.c    | 2 +-
>  tools/testing/selftests/timens/vfork_exec.c | 4 ++--
>  4 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/tools/testing/selftests/timens/exec.c b/tools/testing/selftests/timens/exec.c
> index e40dc5be2f66..d12ff955de0d 100644
> --- a/tools/testing/selftests/timens/exec.c
> +++ b/tools/testing/selftests/timens/exec.c
> @@ -30,7 +30,7 @@ int main(int argc, char *argv[])
>
>                 for (i = 0; i < 2; i++) {
>                         _gettime(CLOCK_MONOTONIC, &tst, i);
> -                       if (abs(tst.tv_sec - now.tv_sec) > 5)
> +                       if (labs(tst.tv_sec - now.tv_sec) > 5)
>                                 return pr_fail("%ld %ld\n", now.tv_sec, tst.tv_sec);
>                 }
>                 return 0;
> @@ -50,7 +50,7 @@ int main(int argc, char *argv[])
>
>         for (i = 0; i < 2; i++) {
>                 _gettime(CLOCK_MONOTONIC, &tst, i);
> -               if (abs(tst.tv_sec - now.tv_sec) > 5)
> +               if (labs(tst.tv_sec - now.tv_sec) > 5)
>                         return pr_fail("%ld %ld\n",
>                                         now.tv_sec, tst.tv_sec);
>         }
> @@ -70,7 +70,7 @@ int main(int argc, char *argv[])
>                 /* Check that a child process is in the new timens. */
>                 for (i = 0; i < 2; i++) {
>                         _gettime(CLOCK_MONOTONIC, &tst, i);
> -                       if (abs(tst.tv_sec - now.tv_sec - OFFSET) > 5)
> +                       if (labs(tst.tv_sec - now.tv_sec - OFFSET) > 5)
>                                 return pr_fail("%ld %ld\n",
>                                                 now.tv_sec + OFFSET, tst.tv_sec);
>                 }
> diff --git a/tools/testing/selftests/timens/timer.c b/tools/testing/selftests/timens/timer.c
> index 5e7f0051bd7b..5b939f59dfa4 100644
> --- a/tools/testing/selftests/timens/timer.c
> +++ b/tools/testing/selftests/timens/timer.c
> @@ -56,7 +56,7 @@ int run_test(int clockid, struct timespec now)
>                         return pr_perror("timerfd_gettime");
>
>                 elapsed = new_value.it_value.tv_sec;
> -               if (abs(elapsed - 3600) > 60) {
> +               if (llabs(elapsed - 3600) > 60) {
>                         ksft_test_result_fail("clockid: %d elapsed: %lld\n",
>                                               clockid, elapsed);
>                         return 1;
> diff --git a/tools/testing/selftests/timens/timerfd.c b/tools/testing/selftests/timens/timerfd.c
> index 9edd43d6b2c1..a4196bbd6e33 100644
> --- a/tools/testing/selftests/timens/timerfd.c
> +++ b/tools/testing/selftests/timens/timerfd.c
> @@ -61,7 +61,7 @@ int run_test(int clockid, struct timespec now)
>                         return pr_perror("timerfd_gettime(%d)", clockid);
>
>                 elapsed = new_value.it_value.tv_sec;
> -               if (abs(elapsed - 3600) > 60) {
> +               if (llabs(elapsed - 3600) > 60) {
>                         ksft_test_result_fail("clockid: %d elapsed: %lld\n",
>                                               clockid, elapsed);
>                         return 1;
> diff --git a/tools/testing/selftests/timens/vfork_exec.c b/tools/testing/selftests/timens/vfork_exec.c
> index beb7614941fb..5b8907bf451d 100644
> --- a/tools/testing/selftests/timens/vfork_exec.c
> +++ b/tools/testing/selftests/timens/vfork_exec.c
> @@ -32,7 +32,7 @@ static void *tcheck(void *_args)
>
>         for (i = 0; i < 2; i++) {
>                 _gettime(CLOCK_MONOTONIC, &tst, i);
> -               if (abs(tst.tv_sec - now->tv_sec) > 5) {
> +               if (labs(tst.tv_sec - now->tv_sec) > 5) {
>                         pr_fail("%s: in-thread: unexpected value: %ld (%ld)\n",
>                                 args->tst_name, tst.tv_sec, now->tv_sec);
>                         return (void *)1UL;
> @@ -64,7 +64,7 @@ static int check(char *tst_name, struct timespec *now)
>
>         for (i = 0; i < 2; i++) {
>                 _gettime(CLOCK_MONOTONIC, &tst, i);
> -               if (abs(tst.tv_sec - now->tv_sec) > 5)
> +               if (labs(tst.tv_sec - now->tv_sec) > 5)
>                         return pr_fail("%s: unexpected value: %ld (%ld)\n",
>                                         tst_name, tst.tv_sec, now->tv_sec);
>         }
>
> base-commit: f03359bca01bf4372cf2c118cd9a987a5951b1c8
> prerequisite-patch-id: b901ece2a5b78503e2fb5480f20e304d36a0ea27
> --
> 2.45.0
>