[Spice-devel] [PATCH v3 1/7] Add red_qxl_destroy function

[Jonathon Jongsma]

On Fri, 2016-12-02 at 10:51 -0500, Frediano Ziglio wrote:
> > 
> > 
> > On Fri, 2016-12-02 at 03:35 -0500, Frediano Ziglio wrote:
> > > 
> > > > 
> > > > 
> > > > 
> > > > On Thu, 2016-12-01 at 11:09 +0000, Frediano Ziglio wrote:
> > > > > 
> > > > > 
> > > > > Allows to destroy a QXL object
> > > > > 
> > > > > Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> > > > > ---
> > > > >  server/red-qxl.c    | 25 ++++++++++++++++++++++---
> > > > >  server/red-qxl.h    |  1 +
> > > > >  server/red-worker.c | 35 ++++++++++++++++++++++++++++++++++-
> > > > >  server/red-worker.h |  1 +
> > > > >  4 files changed, 58 insertions(+), 4 deletions(-)
> > > > > 
> > > > > diff --git a/server/red-qxl.c b/server/red-qxl.c
> > > > > index 19cff95..de0546f 100644
> > > > > --- a/server/red-qxl.c
> > > > > +++ b/server/red-qxl.c
> > > > > @@ -58,6 +58,7 @@ struct QXLState {
> > > > >      QXLDevSurfaceCreate surface_create;
> > > > >      unsigned int max_monitors;
> > > > >      RedsState *reds;
> > > > > +    RedWorker *worker;
> > > > >  
> > > > >      pthread_mutex_t scanout_mutex;
> > > > >      SpiceMsgDisplayGlScanoutUnix scanout;
> > > > > @@ -1006,11 +1007,29 @@ void red_qxl_init(RedsState *reds,
> > > > > QXLInstance *qxl)
> > > > >      client_display_cbs.disconnect =
> > > > > red_qxl_disconnect_display_peer;
> > > > >      client_display_cbs.migrate = red_qxl_display_migrate;
> > > > >  
> > > > > -    // TODO: reference and free
> > > > > -    RedWorker *worker = red_worker_new(qxl,
> > > > > &client_cursor_cbs,
> > > > > +    qxl_state->worker = red_worker_new(qxl,
> > > > > &client_cursor_cbs,
> > > > >                                         &client_display_cbs);
> > > > >  
> > > > > -    red_worker_run(worker);
> > > > > +    red_worker_run(qxl_state->worker);
> > > > > +}
> > > > > +
> > > > > +void red_qxl_destroy(QXLInstance *qxl)
> > > > > +{
> > > > > +    spice_return_if_fail(qxl->st != NULL && qxl->st-
> > > > > >dispatcher
> > > > > !=
> > > > > NULL);
> > > > > +
> > > > > +    QXLState *qxl_state = qxl->st;
> > > > > +
> > > > > +    /* send message to close thread */
> > > > > +    RedWorkerMessageClose message;
> > > > > +    dispatcher_send_message(qxl_state->dispatcher,
> > > > > +                            RED_WORKER_MESSAGE_CLOSE_WORKER,
> > > > > +                            &message);
> > > > > +    red_worker_free(qxl_state->worker);
> > > > 
> > > > Is this safe? You're sending a CLOSE_WORKER message and then
> > > > freeing
> > > > the worker. But the CLOSE_WORKER handler (handle_dev_close())
> > > > also
> > > > uses
> > > > the worker (via 'opaque'). I don't think we can guarantee that
> > > > the
> > > > RedWorker's handler has executed already, can we?
> > > > 
> > > 
> > > red_worker_free calls pthread_join to make sure consistency.
> > 
> > Hmm, somehow I missed that. Thanks. Is it worth asserting or
> > warning if
> > red_worker_free() is called from the worker thread?
> > 
> > Acked-by: Jonathon Jongsma <jjongsma at redhat.com>
> > 
> 
> Maybe some comments would be better. It's true that RedQxl and
> RedWorker
> are quite close friends and only RedQxl should use RedWorker.
> I'll try to write the comment:
> 
> > 
> > 
> > > 
> > >  
> > > > 
> > > > 
> > > > > 
> > > > > 
> > > > > +    g_object_unref(qxl_state->dispatcher);
> > > > > +    /* this must be done after calling red_worker_free */
> > > > > +    qxl->st = NULL;
> > > > > +    pthread_mutex_destroy(&qxl_state->scanout_mutex);
> > > > > +    free(qxl_state);
> > > > >  }
> > > > >  
> > > > >  Dispatcher *red_qxl_get_dispatcher(QXLInstance *qxl)
> > > > > diff --git a/server/red-qxl.h b/server/red-qxl.h
> > > > > index 65357b1..7743124 100644
> > > > > --- a/server/red-qxl.h
> > > > > +++ b/server/red-qxl.h
> > > > > @@ -24,6 +24,7 @@
> > > > >  typedef struct AsyncCommand AsyncCommand;
> > > > >  
> > > > >  void red_qxl_init(SpiceServer *reds, QXLInstance *qxl);
> > > > > +void red_qxl_destroy(QXLInstance *qxl);
> > > > >  
> > > > >  void red_qxl_on_ic_change(QXLInstance *qxl,
> > > > > SpiceImageCompression
> > > > > ic);
> > > > >  void red_qxl_on_sv_change(QXLInstance *qxl, int sv);
> > > > > diff --git a/server/red-worker.c b/server/red-worker.c
> > > > > index d699bd6..5dac0ec 100644
> > > > > --- a/server/red-worker.c
> > > > > +++ b/server/red-worker.c
> > > > > @@ -1410,7 +1410,6 @@ static void *red_worker_main(void *arg)
> > > > >      g_main_loop_unref(loop);
> > > > >      worker->loop = NULL;
> > > > >  
> > > > > -    /* FIXME: free worker, and join threads */
> > > > >      return NULL;
> > > > >  }
> > > > >  
> > > > > @@ -1435,3 +1434,37 @@ bool red_worker_run(RedWorker *worker)
> > > > >  
> > > > >      return r == 0;
> > > > >  }
> > > > > +
> > > > > +static void red_worker_close_channel(RedChannel *channel)
> > > > > +{
> > > > > +    red_channel_reset_thread_id(channel);
> > > > > +    red_channel_destroy(channel);
> > > > > +}
> > > > > +
> 
> /*
>  * Free the worker thread. This function should be called by RedQxl
>  * after sending a RED_WORKER_MESSAGE_CLOSE_WORKER message;
>  * failing to do so will cause a deadlock.
>  */

Looks fine to me.

Jonathon


> 
> > 
> > > 
> > > > 
> > > > > 
> > > > > +void red_worker_free(RedWorker *worker)
> > > > > +{
> > > > > +    RedsState *reds = red_qxl_get_server(worker->qxl->st);
> > > > > +
> > > > > +    /* prevent any possible future attempt to connect to new
> > > > > clients
> > > > > */
> > > > > +    reds_unregister_channel(reds, RED_CHANNEL(worker-
> > > > > > 
> > > > > > 
> > > > > > cursor_channel));
> > > > > +    reds_unregister_channel(reds, RED_CHANNEL(worker-
> > > > > > 
> > > > > > 
> > > > > > display_channel));
> > > > > +
> > > > > +    pthread_join(worker->thread, NULL);
> > > > > +
> > > > > +    red_worker_close_channel(RED_CHANNEL(worker-
> > > > > > 
> > > > > > cursor_channel));
> > > > > +    worker->cursor_channel = NULL;
> > > > > +    red_worker_close_channel(RED_CHANNEL(worker-
> > > > > > 
> > > > > > display_channel));
> > > > > +    worker->display_channel = NULL;
> > > > > +
> > > > > +    if (worker->dispatch_watch) {
> > > > > +        worker->core.watch_remove(&worker->core, worker-
> > > > > > 
> > > > > > 
> > > > > > dispatch_watch);
> > > > > +    }
> > > > > +
> > > > > +    g_main_context_unref(worker->core.main_context);
> > > > > +
> > > > > +    if (worker->record) {
> > > > > +        red_record_free(worker->record);
> > > > > +    }
> > > > > +    memslot_info_destroy(&worker->mem_slots);
> > > > > +    free(worker);
> > > > > +}
> > > > > diff --git a/server/red-worker.h b/server/red-worker.h
> > > > > index 53b92b3..d5b5a78 100644
> > > > > --- a/server/red-worker.h
> > > > > +++ b/server/red-worker.h
> > > > > @@ -29,5 +29,6 @@ RedWorker* red_worker_new(QXLInstance *qxl,
> > > > >                            const ClientCbs
> > > > > *client_cursor_cbs,
> > > > >                            const ClientCbs
> > > > > *client_display_cbs);
> > > > >  bool       red_worker_run(RedWorker *worker);
> > > > > +void red_worker_free(RedWorker *worker);
> > > > >  
> > > > >  #endif
> > > > 
> > > 
> 
> Frediano