https://bugs.kde.org/show_bug.cgi?id=487388
Bug ID: 487388
Summary: Cannot load kamera in kcmshell
Classification: Frameworks and Libraries
Product: frameworks-kcmutils
Version: 6.2.0
Platform: openSUSE
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
Nothing happens when trying to load kamera in kcmshell
STEPS TO REPRODUCE
1. Open Konsole and type `kcmshell6 kcm_kamera` (no camera connected)
OBSERVED RESULT
Kamera icon appears in taskbar, but nothing more
EXPECTED RESULT
Should open Kamera (as is possible in systemsettings)
SOFTWARE/OS VERSIONSDistribution:
openSUSE Tumbleweed 20240520
Linux: 6.9.1-1-default (64-bit)
KDE Plasma Version: 6.0.4
KDE Frameworks Version: 6.2.0
Qt Version: 6.7.0
gPhoto: 2.5.28
ADDITIONAL INFORMATION
I tried to look into it and I think that I understood the root cause.
I set two breakpoints with GDB:
Breakpoint 1at KCMultiDialogPrivate::clientChanged()
Breakpoint 2 at KKameraConfig::load()
When I ran kcmshell6, I noticed that KCMultiDialogPrivate::clientChanged() is
called three times before is called KKameraConfig::load(). Consequently many 0s
timer are lauched. The first will ultimately call KKameraConfig::load() which
uses gphoto functions, which call the cancel callback, which let the event-loop
run and call again the KKameraConfig::load() from inside the previous one as
demonstrated in this trace:
#0 KKameraConfig::load() (this=0x555555b52ed0) at
/usr/src/debug/kamera-24.02.2/kcontrol/kamera.cpp:182
#1 0x00007ffff7f91930 in operator() (__closure=<optimized out>) at
/usr/src/debug/kcmutils-6.2.0/src/kcmultidialog.cpp:130
#2 QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void,
KCMultiDialogPrivate::clientChanged()::<lambda()> >::call
(arg=<optimized out>, f=<optimized out>) at
/usr/include/qt6/QtCore/qobjectdefs_impl.h:137
#3
QtPrivate::FunctorCallable<KCMultiDialogPrivate::clientChanged()::<lambda()>
>::call<QtPrivate::List<>, void>
(arg=<optimized out>, f=<optimized out>) at
/usr/include/qt6/QtCore/qobjectdefs_impl.h:345
#4
QtPrivate::QCallableObject<KCMultiDialogPrivate::clientChanged()::<lambda()>,
QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *,
void **, bool *) (which=<optimized out>, this_=0x555555c3a730, r=<optimized
out>, a=<optimized out>, ret=<optimized out>)
at /usr/include/qt6/QtCore/qobjectdefs_impl.h:555
#5 0x00007ffff61d232e in QObject::event(QEvent*) (this=0x555555997820,
e=0x555555c09d20)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qobject.cpp:1446
#6 0x00007ffff73c2f1e in QApplicationPrivate::notify_helper(QObject*, QEvent*)
() at /lib64/libQt6Widgets.so.6
#7 0x00007ffff618f060 in QCoreApplication::notifyInternal2(QObject*, QEvent*)
(receiver=0x555555997820, event=0x555555c09d20)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qcoreapplication.cpp:1134
#8 0x00007ffff618f099 in QCoreApplication::sendEvent(QObject*, QEvent*)
(receiver=<optimized out>, event=<optimized out>)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qcoreapplication.cpp:1575
#9 0x00007ffff618f3c0 in QCoreApplicationPrivate::sendPostedEvents(QObject*,
int, QThreadData*) (receiver=0x0, event_type=0, data=0x555555593360)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qcoreapplication.cpp:1932
#10 0x00007ffff63c2053 in postEventSourceDispatch(GSource*, GSourceFunc,
gpointer) (s=0x555555599750)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qeventdispatcher_glib.cpp:244
#11 0x00007ffff5b12740 in () at /lib64/libglib-2.0.so.0
#12 0x00007ffff5b14388 in () at /lib64/libglib-2.0.so.0
#13 0x00007ffff5b14a3c in g_main_context_iteration () at
/lib64/libglib-2.0.so.0
#14 0x00007ffff63c0b0c in
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>)
(this=0x5555555afca0, flags=...)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qeventdispatcher_glib.cpp:394
#15 0x00007fffeb55559b in KKameraConfig::cbGPCancel(_GPContext*, void*)
(data=0x555555b52ed0) at /usr/include/qt6/QtCore/qflags.h:74
#16 0x00007fffe906e856 in () at /lib64/libgphoto2.so.6
#17 0x00007fffe906e9e0 in gp_abilities_list_load_dir () at
/lib64/libgphoto2.so.6
#18 0x00007fffe906ea29 in gp_abilities_list_load () at /lib64/libgphoto2.so.6
#19 0x00007fffeb55b303 in KKameraConfig::load() (this=0x555555b52ed0) at
/usr/src/debug/kamera-24.02.2/kcontrol/kamera.cpp:219
#20 0x00007ffff7f91930 in operator() (__closure=<optimized out>) at
/usr/src/debug/kcmutils-6.2.0/src/kcmultidialog.cpp:130
#21 QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void,
KCMultiDialogPrivate::clientChanged()::<lambda()> >::call
(arg=<optimized out>, f=<optimized out>) at
/usr/include/qt6/QtCore/qobjectdefs_impl.h:137
#22
QtPrivate::FunctorCallable<KCMultiDialogPrivate::clientChanged()::<lambda()>
>::call<QtPrivate::List<>, void>
(arg=<optimized out>, f=<optimized out>) at
/usr/include/qt6/QtCore/qobjectdefs_impl.h:345
#23
QtPrivate::QCallableObject<KCMultiDialogPrivate::clientChanged()::<lambda()>,
QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *,
void **, bool *) (which=<optimized out>, this_=0x555555b70120, r=<optimized
out>, a=<optimized out>, ret=<optimized out>)
at /usr/include/qt6/QtCore/qobjectdefs_impl.h:555
#24 0x00007ffff61d232e in QObject::event(QEvent*) (this=0x555555997820,
e=0x555555b701b0)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qobject.cpp:1446
#25 0x00007ffff73c2f1e in QApplicationPrivate::notify_helper(QObject*, QEvent*)
() at /lib64/libQt6Widgets.so.6
#26 0x00007ffff618f060 in QCoreApplication::notifyInternal2(QObject*, QEvent*)
(receiver=0x555555997820, event=0x555555b701b0)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qcoreapplication.cpp:1134
#27 0x00007ffff618f099 in QCoreApplication::sendEvent(QObject*, QEvent*)
(receiver=<optimized out>, event=<optimized out>)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qcoreapplication.cpp:1575
#28 0x00007ffff618f3c0 in QCoreApplicationPrivate::sendPostedEvents(QObject*,
int, QThreadData*) (receiver=0x0, event_type=0, data=0x555555593360)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qcoreapplication.cpp:1932
#29 0x00007ffff63c2053 in postEventSourceDispatch(GSource*, GSourceFunc,
gpointer) (s=0x555555599750)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qeventdispatcher_glib.cpp:244
#30 0x00007ffff5b12740 in () at /lib64/libglib-2.0.so.0
#31 0x00007ffff5b14388 in () at /lib64/libglib-2.0.so.0
#32 0x00007ffff5b14a3c in g_main_context_iteration () at
/lib64/libglib-2.0.so.0
#33 0x00007ffff63c0b0c in
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>)
(this=0x5555555afca0, flags=...)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/kernel/qeventdispatcher_glib.cpp:394
#34 0x00007ffff61997db in
QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7fffffffd610,
flags=...)
at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/global/qflags.h:34
#35 0x00007ffff6192fe6 in QCoreApplication::exec() () at
/usr/src/debug/qtbase-everywhere-src-6.7.0/src/corelib/global/qflags.h:74
#36 0x000055555555ae43 in main(int, char**) (argc=<optimized out>,
argv=<optimized out>) at
/usr/src/debug/kcmutils-6.2.0/src/kcmshell/main.cpp:236
The solution would be to ensure that the KCMultiDialogPrivate::clientChanged()
does not call the load() function of the kcm module many times. This can be
achieved by inverting lines 130 and 131 of kcmultidialog.cpp.
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