Comment # 16 on bug 933858 from Wolfgang Bauer

(In reply to Andreas Fueglistaler from comment #14)
> as requested the Xorg.0.log file after a login attempt

Well, the reason for your problems is obvious I think.
You do indeed use nouveau, but have nvidia's libglx installed:
[   116.248] (II) Loading /usr/lib64/xorg/modules/extensions/libglx.so
[   116.263] (II) Module glx: vendor="NVIDIA Corporation"
[   116.263]     compiled for 4.0.2, module version = 1.0.0
[   116.263]     Module class: X.Org Server Extension
[   116.263] (II) NVIDIA GLX Module  340.76  Thu Jan 22 11:24:42 PST 2015

If you want to use nouveau, you have to remove the nvidia driver from your
system, as it replaces some system components (libglx and libGL in particular)
with its own versions which don't work with the open source drivers (and it
even breaks Mesa's software renderer, which is why you have the same problems
in recovery mode).
Just switching to nouveau in xorg.conf (which you apparently did according to
the Xorg.0.log) is not enough.

If you added the (13.2?) nvidia repo to your system, remove it, or the driver
might get installed automatically.

Or maybe you installed nvidia but it broke with a kernel update?
You have to recompile the kernel module after each such update.

Btw, there is no such thing as "openSUSE 13.2 Tumbleweed". You either use 13.2
or Tumbleweed.
According to the Xorg and Kernel versions, it seems to be the latter.

But make sure that you have no 13.2 repos on your system. In case you missed
it, Tumbleweed is no longer an addon repo to the latest openSUSE release, but a
completely separate (rolling) distribution (since November already)...