Re: [Qemu-devel] [PATCH 3/6] qtest: add C version of test infrastructure

[Stefan Hajnoczi]

On Fri, Jan 13, 2012 at 6:32 PM, Anthony Liguori <address@hidden> wrote:
> +    pid = fork();
> +    if (pid == 0) {
> +        command = g_strdup_printf("%s "
> +                                  "-qtest unix:%s,server,nowait "
> +                                  "-qtest-log /dev/null "
> +                                  "-pidfile %s "
> +                                  "-machine accel=qtest "
> +                                  "%s", qemu_binary, socket_path,
> +                                  pid_file,
> +                                  extra_args ?: "");
> +
> +        ret = system(command);

qtest_init() launches qemu with a pidfile so that we can send SIGTERM
later.  But we never get around to doing that if g_assert() fails - it
calls abort(3).  The result is a run-away qemu process.  I find the
qemu process consumes 100% in send_all() trying to write to the closed
qtest socket and SIGTERM no longer works since we're stuck in a tight
loop that never runs the event loop.

A simple solution is to handle SIGABRT in tests/libqtest.c and sent
SIGTERM to qemu when the test aborts.  The downside is that this only
covers the abort(3) case - a segfault or other abnormal termination
would still leave the run-away qemu process.

I was wondering about a qemu-side solution where a closed qtest socket
means we need to shut down, but am not sure if the chardev code lets
us do that.  (Really we want POLLHUP but we only seem to have
POLLIN/POLLOUT handlers.)

Thoughts?

Stefan