[PATCH 1/4] selftests/cgroup: fix clang build failures for abs() calls

John Hubbard
2024-05-03T03:51:12Z

First of all, in order to build with clang at all, one must first apply
Valentin Obst's build fix for LLVM [1]. Once that is done, then when
building with clang, via:

make LLVM=1 -C tools/testing/selftests

...clang is pickier than gcc, about which version of abs(3) to call,
depending on the argument type:

int abs(int j);
long labs(long j);
long long llabs(long long j);

...and this is causing both build failures and warnings, when running:

make LLVM=1 -C tools/testing/selftests

Fix this by calling labs() in value_close(), because the arguments are
unambiguously "long" type.

[1] https://lore.kernel.org/all/20240329-selftests-libmk-llvm-rfc-v1-1-2f9ed7d1c49f@valentinobst.de/

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
tools/testing/selftests/cgroup/cgroup_util.h | 2 +-
tools/testing/selftests/cgroup/test_kmem.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h
index 1df7f202214a..239633e936df 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.h
+++ b/tools/testing/selftests/cgroup/cgroup_util.h
@@ -18,7 +18,7 @@
*/
static inline int values_close(long a, long b, int err)
{
- return abs(a - b) <= (a + b) / 100 * err;
+ return labs(a - b) <= (a + b) / 100 * err;
}

extern int cg_find_unified_root(char *root, size_t len);
diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c
index c82f974b85c9..d21d3d280ca2 100644
--- a/tools/testing/selftests/cgroup/test_kmem.c
+++ b/tools/testing/selftests/cgroup/test_kmem.c
@@ -192,7 +192,7 @@ static int test_kmem_memcg_deletion(const char *root)
goto cleanup;

sum = anon + file + kernel + sock;
- if (abs(sum - current) < MAX_VMSTAT_ERROR) {
+ if (labs(sum - current) < MAX_VMSTAT_ERROR) {
ret = KSFT_PASS;
} else {
printf("memory.current = %ld\n", current);
@@ -380,7 +380,7 @@ static int test_percpu_basic(const char *root)
current = cg_read_long(parent, "memory.current");
percpu = cg_read_key_long(parent, "memory.stat", "percpu ");

- if (current > 0 && percpu > 0 && abs(current - percpu) <
+ if (current > 0 && percpu > 0 && labs(current - percpu) <
MAX_VMSTAT_ERROR)
ret = KSFT_PASS;
else
--
2.45.0