[PATCH bpf-next 2/2] selftests/bpf: Skip libarena on kernels with too many possible CPUs

[Qiliang Yuan]

serial_test_libarena runs every test program of libarena, most of them
after resetting the buddy allocator with arena_buddy_reset.

The buddy allocator takes an arena spin lock, which fails with
-EOPNOTSUPP on kernels built with more than 1024 possible CPUs, as
distributions commonly configure them. Every test then fails at
arena_buddy_reset, while the arena_spin_lock test already skips in that
case.

Reset the allocator once before running the tests, and skip them when
that returns -EOPNOTSUPP.

Fixes: b1487dc1b181 ("selftests/bpf: Add selftests for libarena buddy allocator")
Signed-off-by: Qiliang Yuan <odys.yuan@xxxxxxxxx>
---
 tools/testing/selftests/bpf/prog_tests/libarena.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/libarena.c b/tools/testing/selftests/bpf/prog_tests/libarena.c
index daade4150af66..070a08856ee04 100644
--- a/tools/testing/selftests/bpf/prog_tests/libarena.c
+++ b/tools/testing/selftests/bpf/prog_tests/libarena.c
@@ -240,6 +240,15 @@ void serial_test_libarena(void)
 	if (!ASSERT_OK(ret, "arena_alloc_reserve"))
 		goto out;
 
+	/* Skip on kernels with more possible CPUs than arena spin locks support */
+	ret = libarena_run_prog(bpf_program__fd(skel->progs.arena_buddy_reset));
+	if (ret == -EOPNOTSUPP) {
+		test__skip();
+		goto out;
+	}
+	if (!ASSERT_OK(ret, "arena_buddy_reset"))
+		goto out;
+
 	bpf_object__for_each_program(prog, skel->obj) {
 		const char *name = bpf_program__name(prog);
 

-- 
2.43.0