powerpc/selftests: Use timersub() for gettimeofday()

Use timersub() function to simplify the code.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220816105106.82666-1-ye.xingchen@zte.com.cn

diff --git a/tools/testing/selftests/powerpc/benchmarks/gettimeofday.c b/tools/testing/selftests/powerpc/benchmarks/gettimeofday.c
index 6b41568..580fcac 100644 (file)
--- a/tools/testing/selftests/powerpc/benchmarks/gettimeofday.c
+++ b/tools/testing/selftests/powerpc/benchmarks/gettimeofday.c
@@ -12,7 +12,7 @@ static int test_gettimeofday(void)
 {
        int i;
 
-       struct timeval tv_start, tv_end;
+       struct timeval tv_start, tv_end, tv_diff;
 
        gettimeofday(&tv_start, NULL);
 
@@ -20,7 +20,9 @@ static int test_gettimeofday(void)
                gettimeofday(&tv_end, NULL);
        }
 
-       printf("time = %.6f\n", tv_end.tv_sec - tv_start.tv_sec + (tv_end.tv_usec - tv_start.tv_usec) * 1e-6);
+       timersub(&tv_start, &tv_end, &tv_diff);
+
+       printf("time = %.6f\n", tv_diff.tv_sec + (tv_diff.tv_usec) * 1e-6);
 
        return 0;
 }