VirtViewerSessionSpice creates a reference-holding VirtViewerDisplay
array and associates it with the display SpiceChannel with
g_object_set_data(channel, "virt-viewer-displays").
When virt_viewer_session_spice_channel_destroy() is called and the display
channel is being destroyed, we should ensure these VirtViewerDisplay
references are dropped or the displays could outlive the session.
In my testing (start qemu with a f20 live cd, connect to it, when the
kernel has started booting and qxl is initialized (4 displays listed in the
display submenu), kill qemu), I was getting "invalid unclassed pointer in
cast to 'VirtViewerSessionSpice'" warnings through
#0 0x00000035bac504e9 in g_logv (log_domain=0x35bb039aa4 "GLib-GObject",
log_level=G_LOG_LEVEL_WARNING, format=<optimized out>,
args=args@entry=0x7fffffffc7c0) at gmessages.c:989
#1 0x00000035bac5063f in g_log (
log_domain=log_domain@entry=0x35bb039aa4 "GLib-GObject",
log_level=log_level@entry=G_LOG_LEVEL_WARNING,
format=format@entry=0x35bb041010 "invalid unclassed pointer in cast to '%s'")
at gmessages.c:1025
#2 0x00000035bb032e09 in g_type_check_instance_cast (type_instance=0x665580,
iface_type=<optimized out>) at gtype.c:4025
#3 0x0000000000426e9f in get_main (self=0x894190) at virt-viewer-display-spice.c:92
#4 0x0000000000426ece in show_hint_changed (self=0x894190)
at virt-viewer-display-spice.c:100
#5 0x00000035bb010298 in g_closure_invoke (closure=0x9f47c0,
return_value=return_value@entry=0x0, n_param_values=2,
param_values=param_values@entry=0x7fffffffcad0,
invocation_hint=invocation_hint@entry=0x7fffffffca70) at gclosure.c:777
#6 0x00000035bb02235d in signal_emit_unlocked_R (node=node@entry=0x651f60,
detail=detail@entry=1782, instance=instance@entry=0x894190,
emission_return=emission_return@entry=0x0,
instance_and_params=instance_and_params@entry=0x7fffffffcad0) at gsignal.c:3586
#7 0x00000035bb02a0f2 in g_signal_emit_valist (instance=<optimized out>,
signal_id=<optimized out>, detail=<optimized out>,
var_args=var_args@entry=0x7fffffffcc60) at gsignal.c:3330
#8 0x00000035bb02a3af in g_signal_emit (instance=<optimized out>,
signal_id=<optimized out>, detail=<optimized out>) at gsignal.c:3386
#9 0x00000035bb014945 in g_object_dispatch_properties_changed (object=0x894190,
n_pspecs=92, pspecs=0x0) at gobject.c:1047
#10 0x00000035bb017019 in g_object_notify_by_spec_internal (pspec=<optimized out>,
object=0x894190) at gobject.c:1141
#11 g_object_notify (object=0x894190, property_name=<optimized out>) at gobject.c:1183
#12 0x000000000041b617 in virt_viewer_display_set_show_hint (self=0x894190, mask=1,
enable=0) at virt-viewer-display.c:659
#13 0x000000000042712c in update_display_ready (self=0x894190)
at virt-viewer-display-spice.c:156
#14 0x00000035bb010298 in g_closure_invoke (closure=0x6ba480,
return_value=return_value@entry=0x0, n_param_values=2,
param_values=param_values@entry=0x7fffffffcfb0,
invocation_hint=invocation_hint@entry=0x7fffffffcf50) at gclosure.c:777
#15 0x00000035bb02235d in signal_emit_unlocked_R (node=node@entry=0x651f60,
detail=detail@entry=1798, instance=instance@entry=0xa2c250,
emission_return=emission_return@entry=0x0,
instance_and_params=instance_and_params@entry=0x7fffffffcfb0) at gsignal.c:3586
#16 0x00000035bb02a0f2 in g_signal_emit_valist (instance=<optimized out>,
signal_id=<optimized out>, detail=<optimized out>,
var_args=var_args@entry=0x7fffffffd140) at gsignal.c:3330
#17 0x00000035bb02a3af in g_signal_emit (instance=<optimized out>,
signal_id=<optimized out>, detail=<optimized out>) at gsignal.c:3386
#18 0x00000035bb014945 in g_object_dispatch_properties_changed (object=0xa2c250,
n_pspecs=92, pspecs=0x0) at gobject.c:1047
#19 0x00000035bb017019 in g_object_notify_by_spec_internal (pspec=<optimized out>,
object=0xa2c250) at gobject.c:1141
#20 g_object_notify (object=0xa2c250, property_name=<optimized out>) at gobject.c:1183
#21 0x00007ffff7044d9a in update_ready (display=0xa2c250) at spice-widget.c:257
#22 0x00007ffff7044df0 in set_monitor_ready (self=0xa2c250, ready=0)
at spice-widget.c:265
#23 0x00007ffff7049bb3 in primary_destroy (channel=0x9f40b0, data=0xa2c250)
at spice-widget.c:2131
#24 0x00007ffff704afd5 in channel_destroy (s=0x892880, channel=0x9f40b0, data=0xa2c250)
at spice-widget.c:2444
#25 0x00000035bb010298 in g_closure_invoke (closure=0xa27850,
return_value=return_value@entry=0x0, n_param_values=2,
param_values=param_values@entry=0x7fffffffd570,
invocation_hint=invocation_hint@entry=0x7fffffffd510) at gclosure.c:777
#26 0x00000035bb02235d in signal_emit_unlocked_R (node=node@entry=0x7cf600,
detail=detail@entry=0, instance=instance@entry=0x892880,
emission_return=emission_return@entry=0x0,
instance_and_params=instance_and_params@entry=0x7fffffffd570) at gsignal.c:3586
#27 0x00000035bb02a0f2 in g_signal_emit_valist (instance=<optimized out>,
signal_id=<optimized out>, detail=<optimized out>,
var_args=var_args@entry=0x7fffffffd700) at gsignal.c:3330
#28 0x00000035bb02a3af in g_signal_emit (instance=<optimized out>,
signal_id=<optimized out>, detail=<optimized out>) at gsignal.c:3386
#29 0x00007ffff6ceba87 in spice_session_channel_destroy (session=0x892880,
channel=0x9f40b0) at spice-session.c:1923
#30 0x00007ffff6cecf05 in spice_channel_dispose (gobject=0x9f40b0)
at spice-channel.c:149
#31 0x00007ffff6cf912c in spice_display_channel_dispose (object=0x9f40b0)
at channel-display.c:136
#32 0x00000035bb014ee8 in g_object_unref (_object=0x9f40b0) at gobject.c:3160
#33 0x00007ffff6cf300c in spice_channel_delayed_unref (data=0x9f40b0)
at spice-channel.c:2135
#34 0x00000035bac492a6 in g_main_dispatch (context=0x67a6b0) at gmain.c:3066
#35 g_main_context_dispatch (context=context@entry=0x67a6b0) at gmain.c:3642
#36 0x00000035bac49628 in g_main_context_iterate (context=0x67a6b0,
block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>)
at gmain.c:3713
#37 0x00000035bac49a3a in g_main_loop_run (loop=0x7baf60) at gmain.c:3907
#38 0x00000035bfdaa2d5 in gtk_main () at gtkmain.c:1158
#39 0x000000000042caf1 in main (argc=1, argv=0x7fffffffdc78) at remote-viewer-main.c:179
In that backtrace, the last ref to the VirtViewerDisplay instances is held by the
SpiceChannel:virt-viewer-displays object data which will only be released after
completion of spice_display_channel_dispose()
---
src/virt-viewer-session-spice.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/src/virt-viewer-session-spice.c b/src/virt-viewer-session-spice.c
index 3c9e765..25a7f8c 100644
--- a/src/virt-viewer-session-spice.c
+++ b/src/virt-viewer-session-spice.c
@@ -776,6 +776,7 @@ virt_viewer_session_spice_channel_destroy(G_GNUC_UNUSED SpiceSession *s,
if (SPICE_IS_DISPLAY_CHANNEL(channel)) {
DEBUG_LOG("zap display channel (#%d)", id);
+ g_object_set_data(G_OBJECT(channel), "virt-viewer-displays", NULL);
}
if (SPICE_IS_PLAYBACK_CHANNEL(channel) && self->priv->audio) {
--
1.8.4.2
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