Re: intermittent hang, s390x host, bios-tables-test test, TPM

[Peter Maydell]

On Tue, 10 Jan 2023 at 19:25, Daniel P. Berrangé <berrange@redhat.com> wrote:
>
> On Fri, Jan 06, 2023 at 03:39:31PM +0000, Peter Maydell wrote:
> > Yeah. It would be good if we didn't deadlock without printing
> > the assertion, though...
> >
> > I guess we could improve qtest_kill_qemu() so it doesn't wait
> > indefinitely for QEMU to exit but instead sends a SIGKILL 20
> > seconds after the SIGTERM. (Annoyingly, there is no convenient
> > "waitpid but with a timeout" function...)
>
> We don't need to touch that. Instead the tpm-emu.c file needs to
> call  qtest_add_abrt_handler() passing a callback that will invoke
> qio_channel_close on its end of the socket. This will cause the
> QEMU process to get EOF on the other end of the socket. It then
> won't be stuck holding the iothread lock, and will be able to
> respond to SIGTERM.

That sounds straightforward and will fix this specific case
of "the QEMU process didn't exit on SIGTERM", but it would
be nice more generally if the test harness did not sit there
forever without printing the assertion in this situation.
"QEMU got permanently stuck" is something that can happen
in more than on way, after all...

thanks
-- PMM