Re: [PATCH 1/2] selftests: timens: use 'llabs()' over 'abs()'

[Shuah Khan <skhan@linuxfoundation.org>]

On 11/5/21 2:26 PM, Nick Desaulniers wrote:
> On Fri, Nov 5, 2021 at 9:31 AM Anders Roxell <anders.roxell@linaro.org> wrote:
>>
>> When building selftests/timens with clang, the compiler warn about the
>> function abs() see below:
>>
>> timerfd.c:64:7: error: absolute value function 'abs' given an argument of type 'long long' but has parameter of type 'int' which may cause truncation of value [-Werror,-Wabsolute-value]
>>                  if (abs(elapsed - 3600) > 60) {
>>                      ^
>> timerfd.c:64:7: note: use function 'llabs' instead
>>                  if (abs(elapsed - 3600) > 60) {
>>                      ^~~
>>                      llabs
>>
>> The note indicates what to do, Rework to use the function 'llabs()'.
>>
>> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> 
> Thanks for the patch!
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> 
>> ---
>>   tools/testing/selftests/timens/timer.c   | 2 +-
>>   tools/testing/selftests/timens/timerfd.c | 2 +-
>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> 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;
>> --
>> 2.33.0
>>
> 
> 

Same comment on llabs() define in stdlib.h made earlier in the context
of timer test changes.

thanks,
-- Shuah