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Date: Wed, 17 Nov 2021 06:40:50 -0700
From: Shuah Khan <skhan@...uxfoundation.org>
To: Anders Roxell <anders.roxell@...aro.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Shuah Khan <shuah@...nel.org>
Cc: fenghua.yu@...el.com, reinette.chatre@...el.com,
john.stultz@...aro.org, tglx@...utronix.de,
akpm@...ux-foundation.org, nathan@...nel.org,
linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
linux-mm@...ck.org, llvm@...ts.linux.dev,
Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCHv2] selftests: kselftest.h: mark functions with 'noreturn'
On 11/17/21 4:01 AM, Anders Roxell wrote:
> On Wed, 3 Nov 2021 at 19:38, Nick Desaulniers <ndesaulniers@...gle.com> wrote:
>>
>> On Wed, Nov 3, 2021 at 2:47 AM Anders Roxell <anders.roxell@...aro.org> wrote:
>>>
>>> When building kselftests/capabilities the following warning shows up:
>>>
>>> clang -O2 -g -std=gnu99 -Wall test_execve.c -lcap-ng -lrt -ldl -o test_execve
>>> test_execve.c:121:13: warning: variable 'have_outer_privilege' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
>>> } else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) {
>>> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> test_execve.c:136:9: note: uninitialized use occurs here
>>> return have_outer_privilege;
>>> ^~~~~~~~~~~~~~~~~~~~
>>> test_execve.c:121:9: note: remove the 'if' if its condition is always true
>>> } else if (unshare(CLONE_NEWUSER | CLONE_NEWNS) == 0) {
>>> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> test_execve.c:94:27: note: initialize the variable 'have_outer_privilege' to silence this warning
>>> bool have_outer_privilege;
>>> ^
>>> = false
>>>
>>> Rework so all the ksft_exit_*() functions have attribue
>>> '__attribute__((noreturn))' so the compiler knows that there wont be
>>> any return from the function. That said, without
>>> '__attribute__((noreturn))' the compiler warns about the above issue
>>> since it thinks that it will get back from the ksft_exit_skip()
>>> function, which it wont.
>>> Cleaning up the callers that rely on ksft_exit_*() return code, since
>>> the functions ksft_exit_*() have never returned anything.
>>>
>>> Signed-off-by: Anders Roxell <anders.roxell@...aro.org>
>>> ---
>>> tools/testing/selftests/clone3/clone3.c | 4 +++-
>>> .../testing/selftests/clone3/clone3_clear_sighand.c | 2 +-
>>> tools/testing/selftests/clone3/clone3_set_tid.c | 4 +++-
>>> tools/testing/selftests/ipc/msgque.c | 10 +++++-----
>>> tools/testing/selftests/kcmp/kcmp_test.c | 2 +-
>>> tools/testing/selftests/kselftest.h | 12 ++++++------
>>> .../membarrier/membarrier_test_multi_thread.c | 2 +-
>>> .../membarrier/membarrier_test_single_thread.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 | 2 +-
>>> 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/clocksource-switch.c | 4 ++--
>>> tools/testing/selftests/timers/freq-step.c | 4 ++--
>>> tools/testing/selftests/timers/inconsistency-check.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/nanosleep.c | 4 ++--
>>> tools/testing/selftests/timers/nsleep-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/vm/madv_populate.c | 2 +-
>>> 35 files changed, 80 insertions(+), 74 deletions(-)
>>>
>>> diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c
>>> index 42be3b925830..ede5da0c67b4 100644
>>> --- a/tools/testing/selftests/clone3/clone3.c
>>> +++ b/tools/testing/selftests/clone3/clone3.c
>>> @@ -191,5 +191,7 @@ int main(int argc, char *argv[])
>>> test_clone3(CLONE_NEWPID, getpagesize() + 8, -E2BIG,
>>> CLONE3_ARGS_NO_TEST);
>>>
>>> - return !ksft_get_fail_cnt() ? ksft_exit_pass() : ksft_exit_fail();
>>> + if (ksft_get_fail_cnt())
>>> + ksft_exit_fail();
>>> + ksft_exit_pass();
>>> }
>>> diff --git a/tools/testing/selftests/clone3/clone3_clear_sighand.c b/tools/testing/selftests/clone3/clone3_clear_sighand.c
>>> index 47a8c0fc3676..dcd9448eaeec 100644
>>> --- a/tools/testing/selftests/clone3/clone3_clear_sighand.c
>>> +++ b/tools/testing/selftests/clone3/clone3_clear_sighand.c
>>> @@ -124,5 +124,5 @@ int main(int argc, char **argv)
>>>
>>> test_clone3_clear_sighand();
>>>
>>> - return ksft_exit_pass();
>>> + ksft_exit_pass();
>>> }
>>> diff --git a/tools/testing/selftests/clone3/clone3_set_tid.c b/tools/testing/selftests/clone3/clone3_set_tid.c
>>> index 0229e9ebb995..a755fcd3af89 100644
>>> --- a/tools/testing/selftests/clone3/clone3_set_tid.c
>>> +++ b/tools/testing/selftests/clone3/clone3_set_tid.c
>>> @@ -393,5 +393,7 @@ int main(int argc, char *argv[])
>>> out:
>>> ret = 0;
>>>
>>> - return !ret ? ksft_exit_pass() : ksft_exit_fail();
>>> + if (ret)
>>> + ksft_exit_fail();
>>> + ksft_exit_pass();
>>
>> This case is weird (pre-existing-ly) and looks broken. The assignment
>> to ret should probably occur _before_ the out: label. Honestly, I'd
>> remove the use of goto from this function and just call either
>> ksft_exit_pass() or ksft_exit_fail().
>
> I can do that in a followup patch.
>
Let's fold this change in. Please send me v3 with.
thanks,
-- Shuah
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