No lock screen after suspend from ayatana indicator

[stephematician]

Expected behaviour

Screen/session should be locked after awaking from suspend

Actual behaviour

Session is unlocked.

Steps to reproduce the behaviour

1. UbuntuMATE 24.04.1 clean install or live boot.
2. Select ⏻ -> Suspend
3. Wake up laptop.

MATE general version

mate-desktop: 1.26.2-1.1build3

Package version

mate-session-manager: 1.26.1-2build2
ayatana-indicator-session: 24.2.0-1build2

Linux Distribution

Ubuntu MATE 24.04.1

Link to bugreport of your Distribution (requirement)

https://bugs.launchpad.net/ubuntu-mate/+bug/2085580
AyatanaIndicators/ayatana-indicator-session#101

[lukefromdc]

This implies the applet itself may be having trouble communicating with the screensaver. It might have to be fixed there. If mate-panel's built-in "shutdown" panel applet is able to suspend the session and trigger the screensaver's lock screen function but the indicator cannot, the problem is in the indicator.

Can you add the "shutdown" applet to the panel, suspend from there, and report back what happens? I don't know much about the screensaver code but this could determine if the problem is here or in the indicator, and if the problem also occurs with the shutdown button's suspend function it could help someone else here to work on it.

[stephematician]

The shutdown applet does work. Similarly, from the indicator, you can get the correct behaviour by selecting 'Shutdown...' which also launches the Shutdown applet.

[lukefromdc]

OK, that tells me the indicator probably is not communicating fully with the session manager, or with the screensaver. I do not know if the screensaver's lock screen is invoked by the session manager or is invoked directly, but in either case it looks like the indicator's the problem and we cannot fix it here

[stephematician]

The indicator invokes the suspend here: https://github.com/AyatanaIndicators/ayatana-indicator-session/blob/dff9e06e57069e3095f1289fa640124010554be8/src/backend-dbus/actions.c#L474

  login1_manager_call_suspend (p->login1_manager,
                               FALSE,
                               p->login1_manager_cancellable,
                               NULL,
                               NULL);

Unfortunately, I'm really out of my depth as to what happens between that call and this session manager.

[lukefromdc]

We don't have that code in mate-session manager. Looks from nearby code like this indicator is trying to talk to gnome-session-manager as the word "gnome" appears.

[stephematician]

I don't think it's calling gnome session manager for suspend (and its not installed on my system anyway yet the suspend does 'work' other than not locking). From what I can see in my dbus-monitor output, it calls org.freedesktop.login1, which is the d-bus interface for systemd-logind.

mc  1732151682.842798   159 :1.79   :1.11   /org/freedesktop/login1 org.freedesktop.login1.Manager  Suspend

So, if I understand, this means that when ayatana-indicator-session builds its menu, the 'Suspend' item will totally bypass the session manager?

[lukefromdc]

I really don't know enough about dbus to answer that. I do believe the problem is somewhere in the indicator and not in MATE's code,given that the indicator does call a function we don't have by name. What's going on with the menu I don't know.