linux-kernel - [PATCHv2] selftests: timens: exec: use 'labs()' over 'abs()'

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Message-Id: <20211110180359.2338349-1-anders.roxell@linaro.org>
Date:   Wed, 10 Nov 2021 19:03:59 +0100
From:   Anders Roxell <anders.roxell@...aro.org>
To:     shuah@...nel.org
Cc:     nathan@...nel.org, ndesaulniers@...gle.com,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Anders Roxell <anders.roxell@...aro.org>,
        Arnd Bergmann <arnd@...db.de>
Subject: [PATCHv2] selftests: timens: exec: use 'labs()' over 'abs()'

When building selftests/timens with clang, the compiler warn about the
function abs() see below:

exec.c:33:8: error: absolute value function 'abs' given an argument of type 'long' but has parameter of type 'int' which may cause truncation of value [-Werror,-Wabsolute-value]
                        if (abs(tst.tv_sec - now.tv_sec) > 5)
                            ^
exec.c:33:8: note: use function 'labs' instead
                        if (abs(tst.tv_sec - now.tv_sec) > 5)
                            ^~~
                            labs

Rework to store the time difference in a 'long long' and pass that to
llabs(), since the variable can be an 'int', 'long' or 'long long'
depending on the architecture and C library.

Suggested-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Anders Roxell <anders.roxell@...aro.org>
---
 tools/testing/selftests/timens/exec.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/timens/exec.c b/tools/testing/selftests/timens/exec.c
index e40dc5be2f66..04439e6ac8a2 100644
--- a/tools/testing/selftests/timens/exec.c
+++ b/tools/testing/selftests/timens/exec.c
@@ -21,6 +21,7 @@
 int main(int argc, char *argv[])
 {
 	struct timespec now, tst;
+	long long timediff;
 	int status, i;
 	pid_t pid;
 
@@ -30,7 +31,8 @@ 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)
+			timediff = tst.tv_sec - now.tv_sec;
+			if (llabs(timediff) > 5)
 				return pr_fail("%ld %ld\n", now.tv_sec, tst.tv_sec);
 		}
 		return 0;
@@ -50,7 +52,8 @@ 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)
+		timediff = tst.tv_sec - now.tv_sec;
+		if (llabs(timediff) > 5)
 			return pr_fail("%ld %ld\n",
 					now.tv_sec, tst.tv_sec);
 	}
@@ -70,7 +73,8 @@ 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)
+			timediff = tst.tv_sec - now.tv_sec - OFFSET;
+			if (llabs(timediff) > 5)
 				return pr_fail("%ld %ld\n",
 						now.tv_sec + OFFSET, tst.tv_sec);
 		}
-- 
2.33.0