selftests/bpf: Add cookies check for tracing fill_link_info test

Adding tests for getting cookie with fill_link_info for tracing.

Signed-off-by: Tao Chen <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: Tao Chen

tools/testing/selftests/bpf/prog_tests/bpf_cookie.c

@@ -489,10 +489,28 @@ static void pe_subtest(struct test_bpf_cookie *skel)
 	bpf_link__destroy(link);
 }
 
+static int verify_tracing_link_info(int fd, u64 cookie)
+{
+	struct bpf_link_info info;
+	int err;
+	u32 len = sizeof(info);
+
+	err = bpf_link_get_info_by_fd(fd, &info, &len);
+	if (!ASSERT_OK(err, "get_link_info"))
+		return -1;
+
+	if (!ASSERT_EQ(info.type, BPF_LINK_TYPE_TRACING, "link_type"))
+		return -1;
+
+	ASSERT_EQ(info.tracing.cookie, cookie, "tracing_cookie");
+
+	return 0;
+}
+
 static void tracing_subtest(struct test_bpf_cookie *skel)
 {
 	__u64 cookie;
-	int prog_fd;
+	int prog_fd, err;
 	int fentry_fd = -1, fexit_fd = -1, fmod_ret_fd = -1;
 	LIBBPF_OPTS(bpf_test_run_opts, opts);
 	LIBBPF_OPTS(bpf_link_create_opts, link_opts);
@@ -507,6 +525,10 @@ static void tracing_subtest(struct test_bpf_cookie *skel)
 	if (!ASSERT_GE(fentry_fd, 0, "fentry.link_create"))
 		goto cleanup;
 
+	err = verify_tracing_link_info(fentry_fd, cookie);
+	if (!ASSERT_OK(err, "verify_tracing_link_info"))
+		goto cleanup;
+
 	cookie = 0x20000000000000L;
 	prog_fd = bpf_program__fd(skel->progs.fexit_test1);
 	link_opts.tracing.cookie = cookie;