Re: [PATCH bpf-next v3 3/4] selftests/bpf: Add selftest for attaching tracing programs to functions in deny list

On 7/22/25 8:34 AM, KaFai Wan wrote:

The result:

$ tools/testing/selftests/bpf/test_progs -t tracing_failure/tracing_deny #468/3 tracing_failure/tracing_deny:OK #468 tracing_failure:OK Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: KaFai Wan kafai.wan@linux.dev

LGTM but see a nit below.

Acked-by: Yonghong Song yonghong.song@linux.dev

---

.../bpf/prog_tests/tracing_failure.c | 33 +++++++++++++++++++ .../selftests/bpf/progs/tracing_failure.c | 6 ++++ 2 files changed, 39 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c index a222df765bc3..140fb0d175cf 100644 --- a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c +++ b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c @@ -28,10 +28,43 @@ static void test_bpf_spin_lock(bool is_spin_lock) tracing_failure__destroy(skel); } +static void test_tracing_deny(void) +{

• struct tracing_failure *skel;
• char log_buf[256];
• int btf_id, err;
• /* migrate_disable depends on CONFIG_SMP */
• btf_id = libbpf_find_vmlinux_btf_id("migrate_disable", BPF_TRACE_FENTRY);
• if (btf_id <= 0) {

• test__skip();
  

• return;
  

• }

There is a discussion about inlining migrate_disable(). See https://lore.kernel.org/bpf/CAADnVQ+Afov4E=9t=3M=zZmO9z4ZqT6imWD5xijDHshTf3J...

Maybe trying to find a different function? Otherwise, if migrate_disable is inlined and this test will become useless.

• skel = tracing_failure__open();
• if (!ASSERT_OK_PTR(skel, "tracing_failure__open"))

• return;
  

• bpf_program__set_autoload(skel->progs.tracing_deny, true);
• bpf_program__set_log_buf(skel->progs.tracing_deny, log_buf, sizeof(log_buf));
• err = tracing_failure__load(skel);
• if (!ASSERT_ERR(err, "tracing_failure__load"))

• goto out;
  

• ASSERT_HAS_SUBSTR(log_buf,

• 	  "Attaching tracing programs to function 'migrate_disable' is rejected.",
  

• 	  "log_buf");
  

+out:

• tracing_failure__destroy(skel);

+}

• void test_tracing_failure(void) { if (test__start_subtest("bpf_spin_lock")) test_bpf_spin_lock(true); if (test__start_subtest("bpf_spin_unlock")) test_bpf_spin_lock(false);
• if (test__start_subtest("tracing_deny"))

• test_tracing_deny();
  

  }

diff --git a/tools/testing/selftests/bpf/progs/tracing_failure.c b/tools/testing/selftests/bpf/progs/tracing_failure.c index d41665d2ec8c..dfa152e8194e 100644 --- a/tools/testing/selftests/bpf/progs/tracing_failure.c +++ b/tools/testing/selftests/bpf/progs/tracing_failure.c @@ -18,3 +18,9 @@ int BPF_PROG(test_spin_unlock, struct bpf_spin_lock *lock) { return 0; }

+SEC("?fentry/migrate_disable") +int BPF_PROG(tracing_deny) +{

• return 0;

+}