Adding test to verify that once we attach module's trampoline,
the module can't be unloaded.

Acked-by: Andrii Nakryiko <and...@kernel.org>
Signed-off-by: Jiri Olsa <jo...@kernel.org>
---
 .../selftests/bpf/prog_tests/module_attach.c  | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/module_attach.c 
b/tools/testing/selftests/bpf/prog_tests/module_attach.c
index 5bc53d53d86e..d85a69b7ce44 100644
--- a/tools/testing/selftests/bpf/prog_tests/module_attach.c
+++ b/tools/testing/selftests/bpf/prog_tests/module_attach.c
@@ -45,12 +45,18 @@ static int trigger_module_test_write(int write_sz)
        return 0;
 }
 
+static int delete_module(const char *name, int flags)
+{
+       return syscall(__NR_delete_module, name, flags);
+}
+
 void test_module_attach(void)
 {
        const int READ_SZ = 456;
        const int WRITE_SZ = 457;
        struct test_module_attach* skel;
        struct test_module_attach__bss *bss;
+       struct bpf_link *link;
        int err;
 
        skel = test_module_attach__open();
@@ -84,6 +90,23 @@ void test_module_attach(void)
        ASSERT_EQ(bss->fexit_ret, -EIO, "fexit_tet");
        ASSERT_EQ(bss->fmod_ret_read_sz, READ_SZ, "fmod_ret");
 
+       test_module_attach__detach(skel);
+
+       /* attach fentry/fexit and make sure it get's module reference */
+       link = bpf_program__attach(skel->progs.handle_fentry);
+       if (!ASSERT_OK_PTR(link, "attach_fentry"))
+               goto cleanup;
+
+       ASSERT_ERR(delete_module("bpf_testmod", 0), "delete_module");
+       bpf_link__destroy(link);
+
+       link = bpf_program__attach(skel->progs.handle_fexit);
+       if (!ASSERT_OK_PTR(link, "attach_fexit"))
+               goto cleanup;
+
+       ASSERT_ERR(delete_module("bpf_testmod", 0), "delete_module");
+       bpf_link__destroy(link);
+
 cleanup:
        test_module_attach__destroy(skel);
 }
-- 
2.30.2

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