[Spice-devel] [PATCH] spicec-x11: Fix going into a never ending loop upon xrandr event (#628573) (v2)

[Alon Levy]

----- "Hans de Goede" <hdegoede at redhat.com> wrote:

> When handling an xrandr event the
> event_listener->on_monitors_change()
> callback destroys and re-creates the monitor object(s) which results
> in the DynamicScreen or MultyMonconstructor being called, which
> triggers
> more xrandr events. This causes a never ending event handling loop
> making
> spicec hang, and eventually making the X-server crash as a backlog
> of events builds up and it oom's.
> 
> This patches this by explictly processing the xrandr event caused
> by the constructor inside the constructor surrounded by the already
> present guard code against recursive xrandr events.
> ---
>  client/x11/platform.cpp |   10 ++++++++++
>  1 files changed, 10 insertions(+), 0 deletions(-)
> 
> diff --git a/client/x11/platform.cpp b/client/x11/platform.cpp
> index 8292d44..cc1502b 100644
> --- a/client/x11/platform.cpp
> +++ b/client/x11/platform.cpp
> @@ -778,6 +778,11 @@ DynamicScreen::DynamicScreen(Display* display,
> int screen, int& next_mon_id)
>      platform_win = XCreateSimpleWindow(display, RootWindow(display,
> screen), 0, 0, 1, 1, 0, 0, 0);
>      XSelectInput(display, platform_win, StructureNotifyMask);
>      XRRSelectInput(display, platform_win, RRScreenChangeNotifyMask);
> +
> +    Monitor::self_monitors_change++;
> +    process_monitor_configure_events(platform_win);
> +    Monitor::self_monitors_change--;
> +
>      XPlatform::set_win_proc(platform_win, root_win_proc);
>      intern_clipboard_atoms();
>      X_DEBUG_SYNC(display);
> @@ -1046,6 +1051,11 @@ MultyMonScreen::MultyMonScreen(Display*
> display, int screen, int& next_mon_id)
>      X_DEBUG_SYNC(get_display());
>      intern_clipboard_atoms();
>      XPlatform::set_win_proc(root_window, root_win_proc);
> +
> +    XMonitor::inc_change_ref();
> +    process_monitor_configure_events(root_window);
> +    XMonitor::dec_change_ref();
> +
>      X_DEBUG_SYNC(get_display());
>      //
>      //platform_win = XCreateSimpleWindow(display, RootWindow(display,
> screen), 0, 0, 1, 1, 0, 0, 0);
> -- 
> 1.7.2.2
> 

This is a little magic, I can't see anyone looking at this later and understanding (except by doing git blame). Still, ACK.

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