Re: [Qemu-devel] [Spice-devel] [PATCH] server: don't call reds_stream_free from worker thread context

[Alon Levy]

On Fri, Sep 02, 2011 at 05:19:54PM +0200, Gerd Hoffmann wrote:
> reds_stream_free() may call the channel_event callback which is not
> supposed to be callsed from worker thread context.  This patch moves
> the reds_stream_free call for the display channel from the worker to
> the dispatcher to fix this issue.
> 

Looks good. I told Luiz that this would be harder to fix in spice-server,
and so I take it back - seems to be easier to fix in spice-server actually.

But still the possible problem of other users in qemu of monitor that don't
make sure to use the main thread remains.

> [ Note: not tested yet, against 0.8 branch, sending out for review &
>         comments nevertheless ]
> 
> Signed-off-by: Gerd Hoffmann <address@hidden>
> ---
>  server/red_dispatcher.c |    5 +++++
>  server/red_worker.c     |    3 +--
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/server/red_dispatcher.c b/server/red_dispatcher.c
> index f74b13e..801a575 100644
> --- a/server/red_dispatcher.c
> +++ b/server/red_dispatcher.c
> @@ -51,6 +51,7 @@ struct RedDispatcher {
>      int y_res;
>      int use_hardware_cursor;
>      RedDispatcher *next;
> +    RedsStream *stream;
>      RedWorkerMessage async_message;
>      pthread_mutex_t  async_lock;
>      QXLDevSurfaceCreate surface_create;
> @@ -81,6 +82,7 @@ static void red_dispatcher_set_peer(Channel *channel, 
> RedsStream *stream, int mi
>  
>      red_printf("");
>      dispatcher = (RedDispatcher *)channel->data;
> +    dispatcher->stream = stream;
>      RedWorkerMessage message = RED_WORKER_MESSAGE_DISPLAY_CONNECT;
>      write_message(dispatcher->channel, &message);
>      send_data(dispatcher->channel, &stream, sizeof(RedsStream *));
> @@ -93,6 +95,9 @@ static void red_dispatcher_shutdown_peer(Channel *channel)
>      red_printf("");
>      RedWorkerMessage message = RED_WORKER_MESSAGE_DISPLAY_DISCONNECT;
>      write_message(dispatcher->channel, &message);
> +    read_message(dispatcher->channel, &message);
> +    ASSERT(message == RED_WORKER_MESSAGE_READY);
> +    reds_stream_free(dispatcher->stream);
>  }
>  
>  static void red_dispatcher_migrate(Channel *channel)
> diff --git a/server/red_worker.c b/server/red_worker.c
> index 5f07803..f77b0f2 100644
> --- a/server/red_worker.c
> +++ b/server/red_worker.c
> @@ -8486,8 +8486,6 @@ static void red_disconnect_channel(RedChannel *channel)
>  {
>      channel_release_res(channel);
>      red_pipe_clear(channel);
> -    reds_stream_free(channel->stream);
> -    channel->stream = NULL;
>      channel->send_data.blocked = FALSE;
>      channel->send_data.size = channel->send_data.pos = 0;
>      spice_marshaller_reset(channel->send_data.marshaller);
> @@ -10060,6 +10058,7 @@ static void handle_dev_input(EventListener *listener, 
> uint32_t events)
>      case RED_WORKER_MESSAGE_CURSOR_DISCONNECT:
>          red_printf("cursor disconnect");
>          red_disconnect_cursor((RedChannel *)worker->cursor_channel);
> +        write_ready = 1;
>          break;
>      case RED_WORKER_MESSAGE_CURSOR_MIGRATE:
>          red_printf("cursor migrate");
> -- 
> 1.7.1
> 
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