[root@localhost wacom]# gdb /usr/libexec/gnome-settings-daemon 6285
GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-80.el7
Copyright (C) 2013 Free Software Foundation, Inc.

......cut.....cut....

Program received signal SIGSEGV, Segmentation fault.
XSetDeviceMode (dpy=0xaa61a0, dev=dev@entry=0x0, mode=mode@entry=1)
    at XSetMode.c:80
80	    req->deviceid = dev->device_id;
(gdb) bt
#0  0x00007fcce4331b80 in XSetDeviceMode (dpy=0xaa61a0, dev=dev@entry=0x0, mode=mode@entry=1) at XSetMode.c:80
#1  0x00007fccbf2abfe8 in set_absolute (device=0x7fcc8c0052b0, is_absolute=<optimized out>) at gsd-wacom-manager.c:360
#2  0x00007fccbf2ace26 in wacom_settings_changed (settings=0x7fcccc0138d0, key=0xd4a7d4 "is-absolute", device=0x7fcc8c0052b0) at gsd-wacom-manager.c:848
#3  0x00007fcce5cc6e38 in g_closure_invoke () at /lib64/libgobject-2.0.so.0
#4  0x00007fcce5cd875d in signal_emit_unlocked_R ()
    at /lib64/libgobject-2.0.so.0
#5  0x00007fcce5ce04c1 in g_signal_emit_valist () at /lib64/libgobject-2.0.so.0
#6  0x00007fcce5ce077f in g_signal_emit () at /lib64/libgobject-2.0.so.0
#7  0x00007fcce6b6fbfc in g_settings_real_change_event ()
    at /lib64/libgio-2.0.so.0
#8  0x00007fcce3092dac in ffi_call_unix64 () at /lib64/libffi.so.6
#9  0x00007fcce30926d5 in ffi_call () at /lib64/libffi.so.6
#10 0x00007fcce5cc7ad5 in g_cclosure_marshal_generic_va ()
    at /lib64/libgobject-2.0.so.0
#11 0x00007fcce5cc7067 in _g_closure_invoke_va () at /lib64/libgobject-2.0.so.0
#12 0x00007fcce5cdfb27 in g_signal_emit_valist () at /lib64/libgobject-2.0.so.0
#13 0x00007fcce5ce077f in g_signal_emit () at /lib64/libgobject-2.0.so.0
#14 0x00007fcce6b70388 in settings_backend_path_changed ()
    at /lib64/libgio-2.0.so.0
#15 0x00007fcce6b6b20a in g_settings_backend_invoke_closure ()
---Type <return> to continue, or q <return> to quit---
    at /lib64/libgio-2.0.so.0
#16 0x00007fcce59c97aa in g_main_context_dispatch () at /lib64/libglib-2.0.so.0
#17 0x00007fcce59c9af8 in g_main_context_iterate.isra.24 ()
    at /lib64/libglib-2.0.so.0
#18 0x00007fcce59c9dca in g_main_loop_run () at /lib64/libglib-2.0.so.0
#19 0x00007fcce74d4045 in gtk_main () at /lib64/libgtk-3.so.0
#20 0x00000000004037c1 in main (argc=1, argv=0x7ffe1639e4e8) at main.c:427
(gdb) p dev
$1 = (XDevice *) 0x0
(gdb) list
75		return (NoSuchExtension);
76	
77	    GetReq(SetDeviceMode, req);
78	    req->reqType = info->codes->major_opcode;
79	    req->ReqType = X_SetDeviceMode;
80	    req->deviceid = dev->device_id;
81	    req->mode = mode;
82	
83	    (void)_XReply(dpy, (xReply *) & rep, 0, xTrue);
84	    UnlockDisplay(dpy);
(gdb) list XSetDeviceMode
63	int
64	XSetDeviceMode(
65	    register Display	*dpy,
66	    XDevice		*dev,
67	    int			 mode)
68	{
69	    xSetDeviceModeReq *req;
70	    xSetDeviceModeReply rep;
71	    XExtDisplayInfo *info = XInput_find_display(dpy);
72	
(gdb) 
73	    LockDisplay(dpy);
74	    if (_XiCheckExtInit(dpy, XInput_Initial_Release, info) == -1)
75		return (NoSuchExtension);
76	
77	    GetReq(SetDeviceMode, req);
78	    req->reqType = info->codes->major_opcode;
79	    req->ReqType = X_SetDeviceMode;
80	    req->deviceid = dev->device_id;
81	    req->mode = mode;
82	
(gdb) 
83	    (void)_XReply(dpy, (xReply *) & rep, 0, xTrue);
84	    UnlockDisplay(dpy);
85	    SyncHandle();
86	    return (rep.status);
87	}
(gdb) list set_absolute
350	}
351	
352	static void
353	set_absolute (GsdWacomDevice  *device,
354	              gint             is_absolute)
355	{
356		XDevice *xdev;
357	
358		xdev = open_device (device);
359		gdk_error_trap_push ();
(gdb) 
360		XSetDeviceMode (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), xdev, is_absolute ? Absolute : Relative);
361		if (gdk_error_trap_pop ())
362			g_error ("Failed to set mode \"%s\" for \"%s\".",
363				 is_absolute ? "Absolute" : "Relative", gsd_wacom_device_get_tool_name (device));
364		xdevice_close (xdev);
365	}
366	
367	static void
368	compute_aspect_area (gint monitor,
369	                     gint *area,
(gdb) frame 1
#1  0x00007fccbf2abfe8 in set_absolute (device=0x7fcc8c0052b0, 
    is_absolute=<optimized out>) at gsd-wacom-manager.c:360
360		XSetDeviceMode (GDK_DISPLAY_XDISPLAY (gdk_display_get_default ()), xdev, is_absolute ? Absolute : Relative);
(gdb) p xdev
$2 = (XDevice *) 0x0
(gdb) list gdk_error_trap_push
(gdb) list open_device
file: "gsd-device-mapper.c", line number: 140
file: "gsd-wacom-manager.c", line number: 167

