| Summary: | Dead-lock with --help on Qt 5.6 | ||
|---|---|---|---|
| Product: | [Plasma] Breeze | Reporter: | Martin Flöser <mgraesslin> |
| Component: | QStyle | Assignee: | Hugo Pereira Da Costa <hugo.pereira.da.costa> |
| Status: | RESOLVED WORKSFORME | ||
| Severity: | grave | CC: | aleixpol, bhush94, cpigat242, heiko.becker, hugo.pereira.da.costa, kde |
| Priority: | NOR | ||
| Version: | 5.5.95 | ||
| Target Milestone: | --- | ||
| Platform: | Other | ||
| OS: | Linux | ||
| Latest Commit: | Version Fixed In: | ||
| Sentry Crash Report: | |||
| Attachments: | test patch (not to be committed) | ||
I noticed this problem before, but it vanishes for me if qtbase is built with this patch: https://codereview.qt-project.org/#/c/151496/ @Heiko Interesting. Indeed breeze does connect to some dbus signals in its constructor. @Martin, rather than patching Qt, maybe you can first try the following patch to breeze ? (which just comments the dbus connections) ? I cannot test here: do not have recent enough Qt5 (I have 5.5.1) Created attachment 97922 [details]
test patch (not to be committed)
yes, the patch solves the problem ok. So definitly related to the issue reported upstream. What should we do ? Close as upstream and wait for the patch to go in ? Find a workaround ? (no clue how) Comment out the code ? (in breeze and oxygen) ? The debus calls are necessary so that the widget style is updated "on fly" when the configuration is changes via system settings (or breeze-settings, or oxygen-settings) On one hand Locked application is somewhat a big deal, but on the other hand this only affects corner cases (--help) wdyt ? (In reply to Hugo Pereira Da Costa from comment #5) > On one hand Locked application is somewhat a big deal, but on the other hand > this only affects corner cases (--help) nah, it affects more. Every error handling case going directly to ::exit(). I assume it means that one cannot do a kwin_x11 --replace any more and similar things. What I wanted to try is whether an explicit disconnect in the dtor could help. (In reply to Martin Gräßlin from comment #6) > What I wanted to try is whether an explicit disconnect in the dtor could > help. nope, that just results in a crash. The Qt patch fixes the issue for me. This seems to be not true anymore. |
Running any application with --help will result in the following dead-lock: pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 185 ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S: No such file or directory. (gdb) bt #0 pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 #1 0x00007ffff324c10b in QWaitConditionPrivate::wait (time=18446744073709551615, this=0x6ba300) at thread/qwaitcondition_unix.cpp:136 #2 QWaitCondition::wait (this=this@entry=0x6a3a48, mutex=mutex@entry=0x6a3a40, time=time@entry=18446744073709551615) at thread/qwaitcondition_unix.cpp:208 #3 0x00007ffff324557b in QSemaphore::acquire (this=this@entry=0x7fffffffc660, n=n@entry=1) at thread/qsemaphore.cpp:137 #4 0x00007ffff3438dcf in QMetaObject::activate (sender=sender@entry=0x6a3130, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7fffffffc6e0) at kernel/qobject.cpp:3698 #5 0x00007ffff3439467 in QMetaObject::activate (sender=sender@entry=0x6a3130, m=m@entry=0x7ffff3652500 <QObject::staticMetaObject>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7fffffffc6e0) at kernel/qobject.cpp:3595 #6 0x00007ffff34394ff in QObject::destroyed (this=this@entry=0x6a3130, _t1=_t1@entry=0x6a3130) at .moc/moc_qobject.cpp:213 #7 0x00007ffff343ff95 in QObject::~QObject (this=<optimized out>, __in_chrg=<optimized out>) at kernel/qobject.cpp:913 #8 0x00007fffdc5e24fd in KStyle::~KStyle (this=0x6a3130, __in_chrg=<optimized out>) at /home/martin/src/kf5/frameworks/frameworkintegration/src/kstyle/kstyle.cpp:191 #9 0x00007fffdc82c233 in Breeze::Style::~Style (this=0x6a3130, __in_chrg=<optimized out>) at /home/martin/src/kf5/kde/workspace/breeze/kstyle/breezestyle.cpp:201 #10 0x00007fffdc82c262 in Breeze::Style::~Style (this=0x6a3130, __in_chrg=<optimized out>) at /home/martin/src/kf5/kde/workspace/breeze/kstyle/breezestyle.cpp:207 #11 0x00007fffdc850aeb in Breeze::StylePlugin::<lambda()>::operator()(void) const (__closure=0x7fffffffc820) at /home/martin/src/kf5/kde/workspace/breeze/kstyle/breezestyleplugin.cpp:43 #12 0x00007fffdc850e7a in QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, Breeze::StylePlugin::create(const QString&)::<lambda()> >::call(Breeze::StylePlugin::<lambda()>, void **) (f=..., arg=0x7fffffffc9e0) at /opt/qt5/include/QtCore/qobjectdefs_impl.h:495 #13 0x00007fffdc850e5b in QtPrivate::Functor<Breeze::StylePlugin::create(const QString&)::<lambda()>, 0>::call<QtPrivate::List<>, void>(Breeze::StylePlugin::<lambda()> &, void *, void **) (f=..., arg=0x7fffffffc9e0) at /opt/qt5/include/QtCore/qobjectdefs_impl.h:552 #14 0x00007fffdc850e20 in QtPrivate::QFunctorSlotObject<Breeze::StylePlugin::create(const QString&)::<lambda()>, 0, QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void **, bool *) (which=1, this_=0x6bba20, r=0x6a3130, a=0x7fffffffc9e0, ret=0x0) at /opt/qt5/include/QtCore/qobject_impl.h:192 #15 0x00007ffff3438ebe in QtPrivate::QSlotObjectBase::call (a=0x7fffffffc9e0, r=0x6a3130, this=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qobject_impl.h:124 #16 QMetaObject::activate (sender=sender@entry=0x6a84f0, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7fffffffc9e0) at kernel/qobject.cpp:3715 #17 0x00007ffff3439467 in QMetaObject::activate (sender=sender@entry=0x6a84f0, m=m@entry=0x7ffff3652500 <QObject::staticMetaObject>, local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7fffffffc9e0) at kernel/qobject.cpp:3595 #18 0x00007ffff34394ff in QObject::destroyed (this=this@entry=0x6a84f0, _t1=_t1@entry=0x6a84f0) at .moc/moc_qobject.cpp:213 #19 0x00007ffff343ff95 in QObject::~QObject (this=<optimized out>, __in_chrg=<optimized out>) at kernel/qobject.cpp:913 #20 0x00007fffdc850bfe in Breeze::StylePlugin::~StylePlugin (this=0x6a84f0, __in_chrg=<optimized out>) at /home/martin/src/kf5/kde/workspace/breeze/kstyle/breezestyleplugin.cpp:52 #21 0x00007fffdc850c2e in Breeze::StylePlugin::~StylePlugin (this=0x6a84f0, __in_chrg=<optimized out>) at /home/martin/src/kf5/kde/workspace/breeze/kstyle/breezestyleplugin.cpp:54 #22 0x00007ffff3403cd9 in QLibraryPrivate::unload (this=this@entry=0x6ba740, flag=flag@entry=QLibraryPrivate::UnloadSys) at plugin/qlibrary.cpp:551 #23 0x00007ffff33f9ec2 in QFactoryLoaderPrivate::~QFactoryLoaderPrivate (this=0x6ba530, __in_chrg=<optimized out>) at plugin/qfactoryloader.cpp:88 #24 0x00007ffff33f9ff9 in QFactoryLoaderPrivate::~QFactoryLoaderPrivate (this=0x6ba530, __in_chrg=<optimized out>) at plugin/qfactoryloader.cpp:91 #25 0x00007ffff344037c in QScopedPointerDeleter<QObjectData>::cleanup (pointer=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qscopedpointer.h:54 #26 QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> >::~QScopedPointer (this=0x7ffff42ce8c8 <(anonymous namespace)::Q_QGS_loader::innerFunction()::holder+8>, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qscopedpointer.h:101 #27 QObject::~QObject (this=<optimized out>, __in_chrg=<optimized out>) at kernel/qobject.cpp:893 #28 0x00007ffff33f9169 in QFactoryLoader::~QFactoryLoader (this=0x7ffff42ce8c0 <(anonymous namespace)::Q_QGS_loader::innerFunction()::holder>, __in_chrg=<optimized out>) at plugin/qfactoryloader.cpp:226 #29 0x00007ffff3e5a0a9 in (anonymous namespace)::Q_QGS_loader::Holder::~Holder (this=<optimized out>, __in_chrg=<optimized out>) at styles/qstylefactory.cpp:70 #30 0x00007ffff259be02 in __run_exit_handlers (status=status@entry=0, listp=0x7ffff2904698 <__exit_funcs>, run_list_atexit=run_list_atexit@entry=true) at exit.c:82 #31 0x00007ffff259be55 in __GI_exit (status=status@entry=0) at exit.c:104 #32 0x00007ffff325bdcf in QCommandLineParser::showHelp (this=this@entry=0x7fffffffce50, exitCode=exitCode@entry=0) at tools/qcommandlineparser.cpp:1010 #33 0x00007ffff325beb5 in QCommandLineParser::process (this=this@entry=0x7fffffffce50, arguments=...) at tools/qcommandlineparser.cpp:590 #34 0x00007ffff325bfcf in QCommandLineParser::process (this=0x7fffffffce50, app=...) at tools/qcommandlineparser.cpp:602 #35 0x0000000000415612 in main () I investigated a little bit and a problem seems to be that QFactoryLoader gained a dtor in 5.6 performing a QMutexLock and from destroying the Style another lock is invoked which results in the dead lock. Reproducible: Always Steps to Reproduce: 1. gdb --args kwrite --help 2. run 3. wait Actual Results: Application doesn't exit, interrupting in gdb gives backtrace as above Expected Results: application exits cleanly