[PATCH] xwayland: Clear pending cursor frame callbacks on pointer enter

[Bryce Harrington]

On Wed, Feb 03, 2016 at 04:14:09PM +0100, Rui Matos wrote:
> The last cursor frame we commited before the pointer left one of our
> surfaces might not have been shown. In that case we'll have a cursor
> surface frame callback pending which we need to clear so that we can
> continue submitting new cursor frames.
> 
> Signed-off-by: Rui Matos <tiagomatos at gmail.com>
> ---
> 
> On Wed, Feb 3, 2016 at 9:30 AM, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> > Xwayland commits a wl_buffer to a cursor wl_surface with a frame
> > callback, and the frame callback may never be emitted by the
> > compositor, right?
> >
> > Is Xwayland waiting for any previous frame callback to be signalled
> > before it commits a buffer or re-sets the cursor role on the
> > wl_surface? Even if the commit and re-set is caused by wl_pointer.enter?
> >
> > Would it be a better fix to destroy any pending frame callback and
> > commit and re-set the role unconditionally on wl_pointer.enter?
> 
> Yes, this seems like the proper fix indeed. Thanks,
> 
> Rui
> 
>  hw/xwayland/xwayland-input.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/hw/xwayland/xwayland-input.c b/hw/xwayland/xwayland-input.c
> index 61ca70b..f9e3255 100644
> --- a/hw/xwayland/xwayland-input.c
> +++ b/hw/xwayland/xwayland-input.c
> @@ -267,6 +267,16 @@ pointer_handle_enter(void *data, struct wl_pointer *pointer,
>      for (i = 0; i < dev->button->numButtons; i++)
>          if (BitIsOn(dev->button->down, i))
>              QueuePointerEvents(dev, ButtonRelease, i, 0, &mask);
> +
> +    /* The last cursor frame we commited before the pointer left one
> +     * of our surfaces might not have been shown. In that case we'll
> +     * have a cursor surface frame callback pending which we need to
> +     * clear so that we can continue submitting new cursor frames. */
> +    if (xwl_seat->cursor_frame_cb) {
> +        wl_callback_destroy(xwl_seat->cursor_frame_cb);
> +        xwl_seat->cursor_frame_cb = NULL;
> +        xwl_seat_set_cursor(xwl_seat);
> +    }
>  }
>  
>  static void

Reviewed-by: Bryce Harrington <bryce at osg.samsung.com>

How noticeable/severe is this problem?  Can this be left to 1.11?