Work around LVM/cryptsetup errors like:

  semid 32768: semop failed for cookie 0xd4d41f4: incorrect semaphore state
  Failed to set a proper state for notification semaphore identified by cookie value 223166964 (0xd4d41f4) to initialize waiting for incoming notifications.

and (when running "cryptsetup --debug"):

  Uevent not generated! Calling udev_complete internally to avoid process lock-up.

Here for some reason libdm *thinks* that the uevent hasn't been
emitted, so it calls udev_complete.  But the uevent actually *has*
been emitted, so udev calls ‘dmsetup udevcomplete’ as well, leading to
a race.

This is probably a reoccurence of the problem described here:

  http://www.redhat.com/archives/dm-devel/2011-August/msg00075.html
  http://www.redhat.com/archives/linux-lvm/2011-September/msg00023.html

which was fixed in the kernel, so it's not clear why it's surfacing
again.  Maybe netlink_broadcast_filtered() has started returning some
other bogus error code.
  
diff -ru -x '*~' LVM2.2.02.98/libdm/ioctl/libdm-iface.c LVM2.2.02.98-new/libdm/ioctl/libdm-iface.c
--- LVM2.2.02.98/libdm/ioctl/libdm-iface.c	2012-10-15 10:24:58.000000000 -0400
+++ LVM2.2.02.98-new/libdm/ioctl/libdm-iface.c	2012-10-15 14:19:06.774363736 -0400
@@ -1754,9 +1754,12 @@
 
 	if (ioctl_with_uevent && dm_udev_get_sync_support() &&
 	    !_check_uevent_generated(dmi)) {
+		log_debug("warning: Uevent might not be generated!");
+#if 0
 		log_debug("Uevent not generated! Calling udev_complete "
 			  "internally to avoid process lock-up.");
 		_udev_complete(dmt);
+#endif
 	}
 
 	if (!_dm_ioctl_unmangle_names(dmt->type, dmi))