Merge lp:~afrantzis/ubuntu-touch-session/fix-1642360 into lp:ubuntu-touch-session

[Alexandros Frantzis]

Fix potential upstart job race between lightdm and keep-display-on-during-boot (LP: #1642360)

If lightdm happens to start before keep-display-on-during-boot, then keep-display-on-during-boot will never receive the "started lightdm" event, and will therefore never release the display-on lock.

This MP ensures that the keep-display-on-during-boot job does not acquire a display-on lock if lightdm is already running, thus avoiding the scenario described above.

Fix potential upstart job race between lightdm and keep-display-on-during-boot (LP: #1642360)

If lightdm happens to start before keep-display-on-during-boot, then keep-display-on-during-boot will never receive the "started lightdm" event, and will therefore never release the display-on lock.

This MP ensures that the keep-display-on-during-boot job does not acquire a display-on lock if lightdm is already running, thus avoiding the scenario described above.

[Pat McGowan (pat-mcgowan)]

I tried to reproduce this using the suggestion in the linked bug report but could not manage to.
I added this to /etc/init/repowerd.conf

pre-start script
    sleep 30
end script

but the screen still turned off. I tried on both rc and rc-proposed

[Alexandros Frantzis (afrantzis)]

> I tried to reproduce this using the suggestion in the linked bug report but could not manage to.

Pat, do you mean that you cannot reproduce the issue without the fix applied, or that you can't reproduce it with the fix applied (i.e. that the fix works)?

I just tried this (added the pre-start script to repowerd.conf) on a freshly flashed krillin with rc-proposed/bq-aquaris.en, and I am able to reproduce the problem easily.

[Łukasz Zemczak (sil2100)]

Ok, too bad we have to use such measures to make sure this is not executed when lightdm is running already. But in overall, +1.

review: Approve

[Pat McGowan (pat-mcgowan)]

I had a bad conf file, reproduced the issue and saw the fix resolve it.

review: Approve

=== modified file 'keep-display-on-during-boot.conf'
--- keep-display-on-during-boot.conf	2016-10-07 12:20:58 +0000
+++ keep-display-on-during-boot.conf	2016-11-16 20:58:32 +0000
@@ -13,4 +13,11 @@
 start on started repowerd
 stop on started lightdm
 
+pre-start script
+    if status lightdm | grep running;
+    then
+        stop; exit 0
+    fi
+end script
+
 exec repowerd-cli display on