On Fri, Feb 18, 2022 at 4:30 PM Mykola Lysenko <mykolal@xxxxxx> wrote:
>
> In send_signal, replace sleep with dummy cpu intensive computation
> to increase probability of child process being scheduled. Add few
> more asserts.
How often do we see the test fail because the child process is not
scheduled?
[...]
> static void sigusr1_handler(int signum)
> {
> - sigusr1_received++;
> + sigusr1_received = 1;
> }
>
> static void test_send_signal_common(struct perf_event_attr *attr,
> @@ -42,7 +43,9 @@ static void test_send_signal_common(struct perf_event_attr *attr,
> int old_prio;
>
> /* install signal handler and notify parent */
> + errno = 0;
> signal(SIGUSR1, sigusr1_handler);
> + ASSERT_OK(errno, "signal");
>
> close(pipe_c2p[0]); /* close read */
> close(pipe_p2c[1]); /* close write */
> @@ -63,9 +66,12 @@ static void test_send_signal_common(struct perf_event_attr *attr,
> ASSERT_EQ(read(pipe_p2c[0], buf, 1), 1, "pipe_read");
>
> /* wait a little for signal handler */
> - sleep(1);
> + for (int i = 0; i < 1000000000; i++)
> + volatile_variable++;
>
> buf[0] = sigusr1_received ? '2' : '0';
^^^^ this "? :" seems useless as we assert sigusr1_received == 1. Let's fix it.
> + ASSERT_EQ(sigusr1_received, 1, "sigusr1_received");
> +
> ASSERT_EQ(write(pipe_c2p[1], buf, 1), 1, "pipe_write");
>
> /* wait for parent notification and exit */
> @@ -110,9 +116,9 @@ static void test_send_signal_common(struct perf_event_attr *attr,
> ASSERT_EQ(read(pipe_c2p[0], buf, 1), 1, "pipe_read");
>
> /* trigger the bpf send_signal */
> + skel->bss->signal_thread = signal_thread;
> skel->bss->pid = pid;
> skel->bss->sig = SIGUSR1;
> - skel->bss->signal_thread = signal_thread;
Does the order matter here?
