Bug 447426

Summary: Unable to unlock screen after USB keyboard was disconnected and re-connected
Product: [Plasma] kwin Reporter: Rob Sanders <rob>
Component: libinputAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED WORKSFORME    
Severity: critical CC: aleixpol, bshah, kde, nate
Priority: NOR    
Version First Reported In: 5.23.3   
Target Milestone: ---   
Platform: Fedora RPMs   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Rob Sanders 2021-12-23 12:51:48 UTC 
I use USB switch and often switch my mouse/keyboard between my KDE desktop and my work PC. Upon returning to my desktop I'm greeted with screenlocker but my keyboard does not seem to be working. I can move my mouse around but cannot type any password as the password prompt does not appear. ALT+CTRL+Fx doesn't work either. The only way to resolve it is hard reset.

Importantly, this only happens when I run plasma on Wayland session. This behaviour is not present with plasma on X11.

Based on my limited knowledge I cannot say if the kscreenlocker is responsible here or there's an underlying problem somewhere else in wider input handling under wayland.

STEPS TO REPRODUCE
1.  Login to desktop session (plasma on Wayland)
2.  disconnect USB keyboard/mouse
3.  leave for ~30min (not sure about the exact time required)
4. re-connect the keyboard/mouse


OBSERVED RESULT
No keyboard events are processed. Unable to unlock the screen

EXPECTED RESULT
Keyboard events are processed and screen can be unlocked

SOFTWARE/OS VERSIONS
Linux/KDE Plasma:  5.23.3 from Fedora 35 repos. This has been observed for a very long time so it's not a new regression.
(available in About System)
KDE Plasma Version:  5.23.3
KDE Frameworks Version:  5.89.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
As mentioned before, this only happens on Wayland and not on X11
Comment 1 Aleix Pol 2022-04-21 00:00:01 UTC 
Moving to KWin, although realistically this is possibly a problem with linux input handling.

Do you remember if you had upgraded your kernel and didn't reboot? it could be that the kernel module got unloaded and wasn't found again.

Can you still reproduce the problem?
Comment 2 David Edmundson 2022-05-03 13:00:46 UTC 
marking as needsinfo
Comment 3 Bug Janitor Service 2022-05-18 04:35:26 UTC 
Dear Bug Submitter,

This bug has been in NEEDSINFO status with no change for at least
15 days. Please provide the requested information as soon as
possible and set the bug status as REPORTED. Due to regular bug
tracker maintenance, if the bug is still in NEEDSINFO status with
no change in 30 days the bug will be closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

If you have already provided the requested information, please
mark the bug as REPORTED so that the KDE team knows that the bug is
ready to be confirmed.

Thank you for helping us make KDE software even better for everyone!
Comment 4 Bug Janitor Service 2022-06-02 04:35:47 UTC 
This bug has been in NEEDSINFO status with no change for at least
30 days. The bug is now closed as RESOLVED > WORKSFORME
due to lack of needed information.

For more information about our bug triaging procedures please read the
wiki located here:
https://community.kde.org/Guidelines_and_HOWTOs/Bug_triaging

Thank you for helping us make KDE software even better for everyone!