Bug 18465 - X crashes when disabling compositing in kwin
Summary: X crashes when disabling compositing in kwin
Alias: None
Product: xorg
Classification: Unclassified
Component: * Other (show other bugs)
Version: 7.4 (2008.09)
Hardware: x86 (IA32) Linux (All)
: medium normal
Assignee: Xorg Project Team
QA Contact: Xorg Project Team
Depends on:
Reported: 2008-11-10 05:41 UTC by Gábor Lehel
Modified: 2009-09-01 01:54 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:

X log (24.64 KB, text/plain)
2008-11-10 05:42 UTC, Gábor Lehel
no flags Details
backtrace of the server crash (2.06 KB, text/plain)
2008-11-14 11:13 UTC, Magnus Kessler
no flags Details
avoid calling DRIGetDrawableInfo with NULL pScreen (439 bytes, patch)
2008-11-14 11:17 UTC, Magnus Kessler
no flags Details | Splinter Review

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Description Gábor Lehel 2008-11-10 05:41:30 UTC
KWin in KDE4 has a shortcut to toggle compositing on and off. Sometimes (not always) when I toggle compositing off with this, X crashes. Dunno if this is a bug in kwin or X, so I'm reporting it in both places. Attaching the X log. There's a not-too-useful backtrace near the end.
Comment 1 Gábor Lehel 2008-11-10 05:42:19 UTC
Created attachment 20179 [details]
X log
Comment 2 Gábor Lehel 2008-11-11 10:11:53 UTC
A workaround for this was just committed to kwin: http://bugs.kde.org/show_bug.cgi?id=174782#c1 (includes what looks like more info about the bug itself)
Comment 3 Magnus Kessler 2008-11-14 11:13:04 UTC
Created attachment 20310 [details]
backtrace of the server crash
Comment 4 Magnus Kessler 2008-11-14 11:17:48 UTC
Created attachment 20311 [details] [review]
avoid calling DRIGetDrawableInfo with NULL pScreen

This patch adds an extra check for a NULL pScreen pointer into glxdri.c getDrawableInfo(), in line with an existing check for a NULL pDraw pointer.
Comment 5 Michel Dänzer 2008-11-14 12:28:40 UTC
The patch is a hack and won't always help I'm afraid. The problem is that pDraw is a stale pointer.
Comment 6 Michel Dänzer 2009-09-01 01:54:06 UTC
This should be fixed in xserver

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