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From: Nathan Chancellor <nathan@kernel.org>
Subject: [PATCH v2 00/10] selftests: Make ksft_exit functions return void
 instead of int
Date: Wed, 24 Apr 2024 10:24:03 -0700
Message-Id: <20240424-ksft-exit-int-to-void-v2-0-c35f3b8c9ca0@kernel.org>
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To: shuah@kernel.org
Cc: linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, 
 Muhammad Usama Anjum <usama.anjum@collabora.com>, 
 Thomas Gleixner <tglx@linutronix.de>, Nathan Chancellor <nathan@kernel.org>, 
 brauner@kernel.org, akpm@linux-foundation.org, linux-mm@kvack.org, 
 fenghua.yu@intel.com, reinette.chatre@intel.com, anna-maria@linutronix.de, 
 frederic@kernel.org, jstultz@google.com, sboyd@kernel.org

Hi all,

Commit f7d5bcd35d42 ("selftests: kselftest: Mark functions that
unconditionally call exit() as __noreturn") marked functions that call
exit() as __noreturn but it did not change the return type of these
functions from 'void' to 'int' like it should have (since a noreturn
function by definition cannot return an integer because it does not
return...) because there are many tests that return the result of the
ksft_exit function, even though it has never been used due to calling
exit().

Prior to adding __noreturn, the compiler would not know that the functions
that call exit() will not return, so code like

  void ksft_exit_fail(void)
  {
    exit(1);
  }

  void ksft_exit_pass(void)
  {
    exit(0);
  }

  int main(void)
  {
    int ret;

    ret = foo();
    if (ret)
      ksft_exit_fail();
    ksft_exit_pass();
  }

would cause the compiler to complain that main() does not return an
integer, even though when ksft_exit_pass() is called, exit() will cause
the program to terminate. So ksft_exit_...() returns int to make the
compiler happy.

  int ksft_exit_fail(void)
  {
    exit(1);
  }

  int ksft_exit_pass(void)
  {
    exit(0);
  }

  int main(void)
  {
    int ret;

    ret = foo();
    if (ret)
      return ksft_exit_fail();
    return ksft_exit_pass();
  }

While this results in no warnings, it is weird semantically and it has
issues as noted in the aforementioned __noreturn change. Now that
__noreturn has been added to these functions, it is much cleaner to
change the functions to 'void' and eliminate the return statements, as
it has been made clear to the compiler that these functions terminate
the program. Drop the return before all instances of ksft_exit_...() in
a mostly mechanical way.

---
Changes in v2:
- Split series into individual patches per subsystem at Shuah's
  request and CC maintainers for subsystems that have one.
- Rewrite commit messages for new patches and move previous commit
  message into cover letter to high level explain all changes.
- Carry forward Thomas and Muhammad's review on patch split, as there
  were no functional changes, please holler if this was inappropriate.
- Link to v1: https://lore.kernel.org/r/20240417-ksft-exit-int-to-void-v1-1-eff48fdbab39@kernel.org

---
Nathan Chancellor (10):
      selftests/clone3: ksft_exit functions do not return
      selftests/ipc: ksft_exit functions do not return
      selftests: membarrier: ksft_exit_pass() does not return
      selftests/mm: ksft_exit functions do not return
      selftests: pidfd: ksft_exit functions do not return
      selftests/resctrl: ksft_exit_skip() does not return
      selftests: sync: ksft_exit_pass() does not return
      selftests: timers: ksft_exit functions do not return
      selftests: x86: ksft_exit_pass() does not return
      selftests: kselftest: Make ksft_exit functions return void instead of int

 tools/testing/selftests/clone3/clone3_clear_sighand.c        |  2 +-
 tools/testing/selftests/clone3/clone3_set_tid.c              |  4 +++-
 tools/testing/selftests/ipc/msgque.c                         | 11 +++++------
 tools/testing/selftests/kselftest.h                          | 12 ++++++------
 .../selftests/membarrier/membarrier_test_multi_thread.c      |  2 +-
 .../selftests/membarrier/membarrier_test_single_thread.c     |  2 +-
 tools/testing/selftests/mm/compaction_test.c                 |  6 +++---
 tools/testing/selftests/mm/cow.c                             |  2 +-
 tools/testing/selftests/mm/gup_longterm.c                    |  2 +-
 tools/testing/selftests/mm/gup_test.c                        |  4 ++--
 tools/testing/selftests/mm/ksm_functional_tests.c            |  2 +-
 tools/testing/selftests/mm/madv_populate.c                   |  2 +-
 tools/testing/selftests/mm/mkdirty.c                         |  2 +-
 tools/testing/selftests/mm/pagemap_ioctl.c                   |  4 ++--
 tools/testing/selftests/mm/soft-dirty.c                      |  2 +-
 tools/testing/selftests/pidfd/pidfd_fdinfo_test.c            |  2 +-
 tools/testing/selftests/pidfd/pidfd_open_test.c              |  4 +++-
 tools/testing/selftests/pidfd/pidfd_poll_test.c              |  2 +-
 tools/testing/selftests/pidfd/pidfd_test.c                   |  2 +-
 tools/testing/selftests/resctrl/resctrl_tests.c              |  6 +++---
 tools/testing/selftests/sync/sync_test.c                     |  3 +--
 tools/testing/selftests/timers/adjtick.c                     |  4 ++--
 tools/testing/selftests/timers/alarmtimer-suspend.c          |  4 ++--
 tools/testing/selftests/timers/change_skew.c                 |  4 ++--
 tools/testing/selftests/timers/freq-step.c                   |  4 ++--
 tools/testing/selftests/timers/leap-a-day.c                  | 10 +++++-----
 tools/testing/selftests/timers/leapcrash.c                   |  4 ++--
 tools/testing/selftests/timers/mqueue-lat.c                  |  4 ++--
 tools/testing/selftests/timers/posix_timers.c                | 12 ++++++------
 tools/testing/selftests/timers/raw_skew.c                    |  6 +++---
 tools/testing/selftests/timers/set-2038.c                    |  4 ++--
 tools/testing/selftests/timers/set-tai.c                     |  4 ++--
 tools/testing/selftests/timers/set-timer-lat.c               |  4 ++--
 tools/testing/selftests/timers/set-tz.c                      |  4 ++--
 tools/testing/selftests/timers/skew_consistency.c            |  4 ++--
 tools/testing/selftests/timers/threadtest.c                  |  2 +-
 tools/testing/selftests/timers/valid-adjtimex.c              |  6 +++---
 tools/testing/selftests/x86/lam.c                            |  2 +-
 38 files changed, 81 insertions(+), 79 deletions(-)
---
base-commit: 0e275f65f3ef9c662b678655c70aca555fbde304
change-id: 20240416-ksft-exit-int-to-void-5aa9db381379

Best regards,
-- 
Nathan Chancellor <nathan@kernel.org>