Review Request: Fix a VLC crash by delaying object deletion to avoid invalid access by QtDBus...

[Thiago Macieira]

I can't reproduce the crash anymore.

I'm getting a different error with Qt 4.8. It seems VLC is now trying to 
closeAllWindows after QApplication is gone.

Em terça-feira, 12 de abril de 2011, às 22:22:10, Dawit Alemayehu escreveu:
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/100577/
> -----------------------------------------------------------
> 
> (Updated April 12, 2011, 10:22 p.m.)
> 
> 
> Review request for kdelibs and Thiago Macieira.
> 
> 
> Changes
> -------
> 
> Thiago,
> 
> A reminder for you to look into this crash when you get a chance[1].
> Otherwise, we would have to commit the workaround patch posted in this
> review.
> 
> [1] http://lists.kde.org/?l=kde-core-devel&m=129693527318658&w=2
> 
> 
> Summary
> -------
> 
> As described in the bug report when opening the file dialog, canceling it
> and exiting VLC causes the application to seg fault. The backtraces posted
> in the bug report shows that the crash happens somewhere in QtDBus and I
> get a similar backtrace when using v1.1.7 of this application.
> 
> When I looked into this issue what I discovered was that only KIO classes
> that register themselves with QtDBus cause the crash. I only found that out
> because fixing the crash in KIO::Scheduler by defering its deletion using
> deleteLater() did not prevent the application from still crashing on exit.
> However, the crash had moved to another location, KBookmarkManager. The
> only common thing between the crash at KBookmarkmanager and KIO::Scheduler
> was that in both cases the backtrace shows QtDBus attempting to invoke or
> access some method or slot in the object that was just destroyed. At this
> point I decided to check how many other classes in KIO register themselves
> with QtDBS and found only one and applied the same change to all three,
> defer deletion of any object registered with QtDBus using
> QObject::deleteLater.
> 
> Anyhow, I have no idea why the crashes are only seen with this application.
> I was not able to duplicate the crash using the same sequences in another
> Qt only app, Arora and none of the KDE applications I tried.
> 
> 
> This addresses bug 234484.
>     http://bugs.kde.org/show_bug.cgi?id=234484
> 
> 
> Diffs
> -----
> 
>   kio/kio/scheduler.cpp d5fab85
>   kio/bookmarks/kbookmarkmanager.cc 9086fd2
>   kio/kio/fileundomanager.cpp ca1cbbb
> 
> Diff: http://git.reviewboard.kde.org/r/100577/diff
> 
> 
> Testing
> -------
> 
> 
> Thanks,
> 
> Dawit
-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
      PGP/GPG: 0x6EF45358; fingerprint:
      E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358
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