Bug 291390

we need a backtrace for a crash

Created attachment 67753 [details]
New crash information added by DrKonqi

kwin (4.7.97 (4.8 RC2 (4.7.97)) on KDE Platform 4.7.97 (4.8 RC2 (4.7.97) using Qt 4.7.4

- What I was doing when the application crashed:

Enabled "explosion" desktop effect while opengl2 shaders were disabled

-- Backtrace (Reduced):
#7  0xb64c8d1b in KWin::GLShader::uniformLocation (this=0x0, name=0xad62128d "screenTransformation") at ../../../kwin/libkwineffects/kwinglutils.cpp:429
#8  0xb64c955e in KWin::GLShader::getUniformMatrix4x4 (this=0x0, name=0xad62128d "screenTransformation") at ../../../kwin/libkwineffects/kwinglutils.cpp:584
#9  0xad600e40 in KWin::ExplosionEffect::paintWindow (this=0xa1b8fb8, w=0x985e630, mask=38, region=..., data=...) at ../../../kwin/effects/explosion/explosion.cpp:150
#10 0xb76cb4c8 in KWin::EffectsHandlerImpl::paintWindow (this=0x9a78018, w=0x985e630, mask=38, region=..., data=...) at ../../kwin/effects.cpp:246
#11 0xad58c74c in KWin::FadeEffect::paintWindow (this=0x9ad6fc8, w=0x985e630, mask=38, region=..., data=...) at ../../../kwin/effects/fade/fade.cpp:150

Created attachment 67754 [details]
New crash information added by DrKonqi

kwin (4.7.97 (4.8 RC2 (4.7.97)) on KDE Platform 4.7.97 (4.8 RC2 (4.7.97) using Qt 4.7.4

- What I was doing when the application crashed:

Kwin crashed when "opengl2 shaders" are disabled and "explosion" effect is enabled

-- Backtrace (Reduced):
#7  0xb64f9d1b in KWin::GLShader::uniformLocation (this=0x0, name=0xad63428d "screenTransformation") at ../../../kwin/libkwineffects/kwinglutils.cpp:429
#8  0xb64fa55e in KWin::GLShader::getUniformMatrix4x4 (this=0x0, name=0xad63428d "screenTransformation") at ../../../kwin/libkwineffects/kwinglutils.cpp:584
#9  0xad613e40 in KWin::ExplosionEffect::paintWindow (this=0xa339af8, w=0xa4c36d0, mask=38, region=..., data=...) at ../../../kwin/effects/explosion/explosion.cpp:150
#10 0xb76fc4c8 in KWin::EffectsHandlerImpl::paintWindow (this=0xa278b00, w=0xa4c36d0, mask=38, region=..., data=...) at ../../kwin/effects.cpp:246
#11 0xad59f646 in KWin::FadeEffect::paintWindow (this=0xa2e5a88, w=0xa4c36d0, mask=38, region=..., data=...) at ../../../kwin/effects/fade/fade.cpp:140

please try this patch:

diff --git a/kwin/effects/explosion/explosion.cpp b/kwin/effects/explosion/explosion.cpp
index bdff254..a2e523f 100644
--- a/kwin/effects/explosion/explosion.cpp
+++ b/kwin/effects/explosion/explosion.cpp
@@ -136,7 +136,7 @@ void ExplosionEffect::paintWindow(EffectWindow* w, int mask, QRegion region, Win
 {
     // Make sure we have OpenGL compositing and the window is vidible and not a
     //  special window
-    bool useshader = (mValid && mWindows.contains(w));
+    bool useshader = (mValid && mWindows.contains(w)) && ShaderManager::instance()->isValid();
     if (useshader) {
         double maxscaleadd = 1.5f;
         double scale = 1 + maxscaleadd * mWindows[w];

I am sorry, I am still relativly new to linux so I still don't know how to patch something :( If it is not complicated, please point me to some patching guide/wiki and I will try tommorow. I am on Kubuntu 11.10 KDE 4.8rc2.

Git commit edd5726eb6f53fbffedadff68a913f07431d40db by Martin Gräßlin.
Committed on 13/01/2012 at 09:01.
Pushed by graesslin into branch 'KDE/4.8'.

Check whether the ShaderManager is valid in Explosion effect

The effect did not check whether the ShaderManager is valid causing
a null pointer access when trying to use the shader.

Additionally this change moves the Shader init into the close window
slot as close window referrenced windows without checking whether the
effect would work. If the effect would not work each closed window
would be referrenced without any chance to being unreffed again as this
code is in a block checking whether the effect is valid.
FIXED-IN: 4.8.0

M  +9    -2    kwin/effects/explosion/explosion.cpp

http://commits.kde.org/kde-workspace/edd5726eb6f53fbffedadff68a913f07431d40db