Bug 1267976 - application deadlock after monitor power on
application deadlock after monitor power on
Status: CLOSED EOL
Product: Fedora
Classification: Fedora
Component: libX11 (Show other bugs)
22
Unspecified Unspecified
unspecified Severity unspecified
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Assigned To: Adam Jackson
Fedora Extras Quality Assurance
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Reported: 2015-10-01 09:58 EDT by Dan Mossor [danofsatx]
Modified: 2016-07-19 14:04 EDT (History)
11 users (show)

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Doc Type: Bug Fix
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Last Closed: 2016-07-19 14:04:55 EDT
Type: Bug
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Attachments (Terms of Use)
bt of konversation when it was locked up (6.29 KB, text/plain)
2015-10-01 09:58 EDT, Dan Mossor [danofsatx]
no flags Details


External Trackers
Tracker ID Priority Status Summary Last Updated
KDE Software Compilation 338999 None None None Never
FreeDesktop.org 59361 None None None Never
Qt Bug Tracker QTBUG-42738 None None None Never

  None (edit)
Description Dan Mossor [danofsatx] 2015-10-01 09:58:01 EDT
Created attachment 1079121 [details]
bt of konversation when it was locked up

qt5-qtbase-5.5.0-15.fc22.x86_64
plasma-workspace-5.4.1-3.fc22.x86_64
libxcb-1.11-8.fc22.x86_64
libX11-1.6.3-1.fc22.x86_64
konversation-1.6-1.fc22.x86_64

When returning to my desk after an extended period, konversation is locked up when the system is unlocked.

The cause appears to be the powering on of the monitors - my monitors are physically powered off for "reasons" when I leave the desk, and the time stamps in konversation appear to stop at the approximate time the monitors are repowered.

The interesting data point is that konversation is the only application locked up. The plasmashell is working fine, the notification panel, konsole, and dolphin windows I have open all operate as normal. Konversation is the only application locked up.

The backtrace is attached to this bz, and rdieter was able to trace it back to a Freedesktop bug as a possible root cause. Related bugs are at bugs.kde.org  (338999) and bugreports.qt.io (42738)
Comment 1 Rex Dieter 2015-10-01 10:03:57 EDT
<nod>, according to the aforementioned bugs, this is a libX11 issue, triaging there.

According to a commenter on the freedesktop.org, they think it stems from this upstream commit,
http://cgit.freedesktop.org/xorg/lib/libX11/commit/?id=83e1ba59c48c79f8b0a7e7aa0b9c9cfd84fa403d

"The commit unlocks the display when an application-defined error handler is invoked, but re-locking the display requires re-syncing the sequence numbers which requires a remote call.

The commit author couldn't remember why the display lock was held while the error function was called - I guess the sequence number re-sync was the reason.

Reverting the commit fixes the problem."

We'll probably want a confirmation of this or deeper investigation before coming up with a plan to address this.
Comment 2 Rex Dieter 2015-10-01 12:25:02 EDT
Test libX11 build available in this copr,
https://copr.fedoraproject.org/coprs/rdieter/libxcb/

with the aforementioned commit reverted
Comment 3 Fedora End Of Life 2016-07-19 14:04:55 EDT
Fedora 22 changed to end-of-life (EOL) status on 2016-07-19. Fedora 22 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

If you can reproduce this bug against a currently maintained version of
Fedora please feel free to reopen this bug against that version. If you
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current release. If you experience problems, please add a comment to this
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