Public bug reported:

gdm3 version: 42.0-1ubuntu7.22.04.2
Ubuntu version: Ubuntu 22.04.2 LTS

[Description]
Installing or removing snap packages through NICE DCV on AWS will cause the 
user to be kicked out of their session. The issue happens on machines running 
nvidia GPUs (passed through to a VM) with the GRID driver installed as well as 
the normal nvidia driver.

[Steps to reproduce]
Simply install or remove any snap through the snap store will trigger the 
issue, for example:
$ snap install skype

also running any of the following commands will also trigger the issue:
$ snap connect skype:opengl :opengl
$ snap disconnect skype:opengl :opengl
$ snap connect skype:camera :camera
$ snap disconnect skype:camera :camera

After further investigation I was able to pin down the issue to udev and could 
reproduce the issue by running the following command:
$ sudo udevadm trigger 
--parent-match=/sys/devices/pci0000:00/0000:00:1e.0/drm/card0

where "/sys/devices/pci0000:00/0000:00:1e.0/drm/card0" corresponds to
the nvidia GPU of my instance.

A more generic way of triggering the issue would be running:
$ sudo udevadm trigger

[Solution]

I have investigated the issue and discovered that it lies within GDM3 in the 
"udev_is_settled" function (daemon/gdm-local-display-factory.c).
In the case where the udev is settled the line "g_clear_signal_handler 
(&factory->uevent_handler_id, factory->gudev_client);" at the end of the 
function is triggered however this is not the case when the function returns 
early and will lead to the user being logged out. In its current implementation 
there are three different return points before "g_clear_signal_handler" is 
executed where the udev devices would already have settled.

I have written a patch that fixes this issue by making sure the function
"g_clear_signal_handler" is executed in all cases for which the udev is
settled.

** Affects: gdm3 (Ubuntu)
     Importance: High
     Assignee: Ghadi Rahme (ghadi-rahme)
         Status: New


** Tags: patch

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https://bugs.launchpad.net/bugs/2020641

Title:
  Installing or removing apps through snap-store launches another gdm
  session

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