Re: [Qemu-devel] [PATCH 1/3] colo-compare: serialize compare thread's initialization with main thread

[Hailiang Zhang]

On 2017/4/24 12:10, Jason Wang wrote:
> On 2017年04月20日 15:46, zhanghailiang wrote:
> > We call qemu_chr_fe_set_handlers() in colo-compare thread, it is used
> > to detach watched fd from default main context, so it has chance to
> > handle the same watched fd with main thread concurrently, which will
> > trigger an error report:
> > "qemu-char.c:918: io_watch_poll_finalize: Assertion `iwp->src == ((void *)0)' 
> > failed."
> Anyway to prevent fd from being handled by main thread before creating
> colo thread? Using semaphore seems not elegant.

So how about calling qemu_mutex_lock_iothread() before 
qemu_chr_fe_set_handlers() ?

> Thanks
>
> > Fix it by serializing compare thread's initialization with main thread.
> >
> > Signed-off-by: zhanghailiang <address@hidden>
> > ---
> >    net/colo-compare.c | 6 ++++++
> >    1 file changed, 6 insertions(+)
> >
> > diff --git a/net/colo-compare.c b/net/colo-compare.c
> > index 54e6d40..a6bf419 100644
> > --- a/net/colo-compare.c
> > +++ b/net/colo-compare.c
> > @@ -83,6 +83,7 @@ typedef struct CompareState {
> >        GHashTable *connection_track_table;
> >        /* compare thread, a thread for each NIC */
> >        QemuThread thread;
> > +    QemuSemaphore thread_ready;
> >    
> >        GMainContext *worker_context;
> >        GMainLoop *compare_loop;
> > @@ -557,6 +558,8 @@ static void *colo_compare_thread(void *opaque)
> >                              (GSourceFunc)check_old_packet_regular, s, NULL);
> >        g_source_attach(timeout_source, s->worker_context);
> >    
> > +    qemu_sem_post(&s->thread_ready);
> > +
> >        g_main_loop_run(s->compare_loop);
> >    
> >        g_source_unref(timeout_source);
> > @@ -707,12 +710,15 @@ static void colo_compare_complete(UserCreatable *uc, 
> > Error **errp)
> >                                                          connection_key_equal,
> >                                                          g_free,
> >                                                          connection_destroy);
> > +    qemu_sem_init(&s->thread_ready, 0);
> >    
> >        sprintf(thread_name, "colo-compare %d", compare_id);
> >        qemu_thread_create(&s->thread, thread_name,
> >                           colo_compare_thread, s,
> >                           QEMU_THREAD_JOINABLE);
> >        compare_id++;
> > +    qemu_sem_wait(&s->thread_ready);
> > +    qemu_sem_destroy(&s->thread_ready);
> >    
> >        return;
> >    }
>
> .