https://bugs.kde.org/show_bug.cgi?id=508478
Bug ID: 508478
Summary: Plasma Mobile: Rare boot issue with empty desktop and
app drawer due to duplicate homescreen instance
Classification: Plasma
Product: plasma-mobile
Version First unspecified
Reported In:
Platform: Other
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: Shell
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
SUMMARY
Rare race condition on boot causes empty desktop due to duplicate homescreen
instance from invalid currentActivity.
STEPS TO REPRODUCE
1.Use a device running Plasma Mobile.
2.Reboot the device repeatedly.
3.The issue occurs statistically approximately once every 1000 reboots. It is a
race condition and is not reliably triggered by specific user actions.
OBSERVED RESULT
After boot, the user is presented with an empty desktop (no wallpaper, panels,
or widgets) and an empty application launcher. The system is otherwise
operational. Investigation of the source code shows that an extra instance of
the homescreen class is created because
KActivities::Controller::currentActivity() returns a null UUID
("00000000-0000-0000-0000-000000000000") during the screen loading process.
EXPECTED RESULT
The device should boot consistently every time, loading the default Plasma
Mobile desktop with the correct wallpaper, panels, widgets, and a functional
application launcher. The currentActivity() method should always return a valid
activity ID, preventing the creation of duplicate homescreen instances.
SOFTWARE/OS VERSIONS
Windows:
macOS:
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma:
KDE Plasma Version:
KDE Frameworks Version:
Qt Version:
ADDITIONAL INFORMATION
I am using Plasma Mobile on my smartphone for a home project and have
encountered a strange, intermittent issue. Approximately once in every 1000
reboots (a very rough estimate), the system boots to an empty desktop and an
empty application launcher.
I investigated the source code and found that during initialization, an extra
instance of the homescreen class is created. The root cause appears to be that
when the load() method is called, KActivities::Controller::currentActivity()
returns a null UUID ("00000000-0000-0000-0000-000000000000") at the stage when
the screens are being loaded. This incorrect activity ID leads to the creation
of a duplicate homescreen.
Furthermore, I looked at the checkActivities() method, which is called earlier
in the same function. I believe the logic there is flawed. You correctly check
the serviceStatus, but then the code contains:
cpp
Q_ASSERT_X(!existingActivities.isEmpty(), "isEmpty", "There are no activities,
and the service is running");
Q_ASSERT_X(existingActivities[0] !=
QLatin1String("00000000-0000-0000-0000-000000000000"), "null uuid", "There is a
nulluuid activity present");
This is where the problem lies. In this specific race condition, the
existingActivities list contains valid activities, but the currentActivity()
remains invalid (null UUID). This leads to a very subtle and hard-to-reproduce
bug that I can only trigger with fairly specific methods.
Please feel free to contact me via email or another method so we can work
together to find a solution. I can provide more details on my environment and
the specific steps I use to model the problem.
--
You are receiving this mail because:
You are watching all bug changes.
