RE: [PATCH v5 bpf-next 3/3] selftests/bpf: add raw_tp_test_run

Song Liu wrote:

This test runs test_run for raw_tracepoint program. The test covers ctx
input, retval output, and running on correct cpu.

Signed-off-by: Song Liu <redacted>
---

[...]

+void test_raw_tp_test_run(void)
+{
+	struct bpf_prog_test_run_attr test_attr = {};
+	int comm_fd = -1, err, nr_online, i, prog_fd;
+	__u64 args[2] = {0x1234ULL, 0x5678ULL};
+	int expected_retval = 0x1234 + 0x5678;
+	struct test_raw_tp_test_run *skel;
+	char buf[] = "new_name";
+	bool *online = NULL;
+
+	err = parse_cpu_mask_file("/sys/devices/system/cpu/online", &online,
+				  &nr_online);
+	if (CHECK(err, "parse_cpu_mask_file", "err %d\n", err))
+		return;
+
+	skel = test_raw_tp_test_run__open_and_load();
+	if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+		goto cleanup;
+
+	err = test_raw_tp_test_run__attach(skel);
+	if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
+		goto cleanup;
+
+	comm_fd = open("/proc/self/comm", O_WRONLY|O_TRUNC);
+	if (CHECK(comm_fd < 0, "open /proc/self/comm", "err %d\n", errno))
+		goto cleanup;
+
+	err = write(comm_fd, buf, sizeof(buf));
+	CHECK(err < 0, "task rename", "err %d", errno);
+
+	CHECK(skel->bss->count == 0, "check_count", "didn't increase\n");
+	CHECK(skel->data->on_cpu != 0xffffffff, "check_on_cpu", "got wrong value\n");
+
+	prog_fd = bpf_program__fd(skel->progs.rename);
+	test_attr.prog_fd = prog_fd;
+	test_attr.ctx_in = args;
+	test_attr.ctx_size_in = sizeof(__u64);
+
+	err = bpf_prog_test_run_xattr(&test_attr);
+	CHECK(err == 0, "test_run", "should fail for too small ctx\n");
+
+	test_attr.ctx_size_in = sizeof(args);
+	err = bpf_prog_test_run_xattr(&test_attr);
+	CHECK(err < 0, "test_run", "err %d\n", errno);
+	CHECK(test_attr.retval != expected_retval, "check_retval",
+	      "expect 0x%x, got 0x%x\n", expected_retval, test_attr.retval);
+
+	for (i = 0; i < nr_online; i++) {
+		if (online[i]) {
+			DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
+				.ctx_in = args,
+				.ctx_size_in = sizeof(args),
+				.flags = BPF_F_TEST_RUN_ON_CPU,
+				.retval = 0,
+				.cpu = i,
+			);
+
+			err = bpf_prog_test_run_opts(prog_fd, &opts);
+			CHECK(err < 0, "test_run_opts", "err %d\n", errno);
+			CHECK(skel->data->on_cpu != i, "check_on_cpu",
+			      "expect %d got %d\n", i, skel->data->on_cpu);
+			CHECK(opts.retval != expected_retval,
+			      "check_retval", "expect 0x%x, got 0x%x\n",
+			      expected_retval, opts.retval);
+
+			if (i == 0) {
+				/* invalid cpu ID should fail with ENXIO */
+				opts.cpu = 0xffffffff;
+				err = bpf_prog_test_run_opts(prog_fd, &opts);
+				CHECK(err != -1 || errno != ENXIO,
+				      "test_run_opts_fail",
+				      "should failed with ENXIO\n");
+			} else {

One more request...

How about pull this if/else branch out of the for loop here? It feels a bit
clumsy as-is imo. Also is it worthwhile to bang on the else branch for evey
cpu I would think testing for any non-zero value should be sufficient.

+				/* non-zero cpu w/o BPF_F_TEST_RUN_ON_CPU
+				 * should fail with EINVAL
+				 */
+				opts.flags = 0;
+				err = bpf_prog_test_run_opts(prog_fd, &opts);
+				CHECK(err != -1 || errno != EINVAL,
+				      "test_run_opts_fail",
+				      "should failed with EINVAL\n");
+			}
+		}
+	}
+cleanup:
+	close(comm_fd);
+	test_raw_tp_test_run__destroy(skel);
+	free(online);
+}