Hi
On Thu, Feb 21, 2019 at 9:00 AM Peter Xu <pet...@redhat.com> wrote:
>
> On Wed, Feb 20, 2019 at 05:06:25PM +0100, Marc-André Lureau wrote:
> > Another thread may acquire the glib context (temporarily) before
> > g_main_context_push_thread_default().
> >
> > This can happen with the following qemu_chr_fe_set_handlers()
> > modifications.
> >
> > Unfortunately, g_main_context_wait() is deprecated in glib
> > 2.58 (apparently it was a broken interface). Use a polling loop.
> >
> > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> > ---
> > iothread.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/iothread.c b/iothread.c
> > index e615b7ae52..93cc3aa875 100644
> > --- a/iothread.c
> > +++ b/iothread.c
> > @@ -70,6 +70,11 @@ static void *iothread_run(void *opaque)
> > if (iothread->running && atomic_read(&iothread->worker_context)) {
> > GMainLoop *loop;
> >
> > + /* we may race with another thread acquiring the context */
> > + while (!g_main_context_acquire(iothread->worker_context)) {
> > + g_usleep(10000);
> > + }
>
> Could you help explain why need this explicitly? Since AFAIU
> g_main_loop_run() below will do context acquire too so IIUC you're
> taking it twice (while g_main_context_acquire should allow it to
> happen, though)?
>
We call g_main_context_push_thread_default() before run(). It will
fail if the context is not acquirable.
> > +
> > g_main_context_push_thread_default(iothread->worker_context);
> > iothread->main_loop =
> > g_main_loop_new(iothread->worker_context, TRUE);
> > @@ -80,6 +85,8 @@ static void *iothread_run(void *opaque)
> > g_main_loop_unref(loop);
> >
> > g_main_context_pop_thread_default(iothread->worker_context);
> > +
> > + g_main_context_release(iothread->worker_context);
> > }
> > }
> >
> > --
> > 2.21.0.rc1
> >
> >
>
> Regards,
>
> --
> Peter Xu
