'Review Request: Fix a VLC crash by delaying object deletion to avoid'

[prev in list] [next in list] [prev in thread] [next in thread] 

List:       kde-core-devel
Subject:    Review Request: Fix a VLC crash by delaying object deletion to avoid
From:       "Dawit Alemayehu" <adawit () kde ! org>
Date:       2011-02-05 17:39:35
Message-ID: 20110205173935.5545.13037 () vidsolbach ! de
[Download RAW message or body]

-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
http://git.reviewboard.kde.org/r/100577/
-----------------------------------------------------------

Review request for kdelibs.


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


[Attachment #3 (text/html)]

<html>
 <body>
  <div style="font-family: Verdana, Arial, Helvetica, Sans-Serif;">
   <table bgcolor="#f9f3c9" width="100%" cellpadding="8" style="border: 1px #c9c399 \
solid;">  <tr>
     <td>
      This is an automatically generated e-mail. To reply, visit:
      <a href="http://git.reviewboard.kde.org/r/100577/">http://git.reviewboard.kde.org/r/100577/</a>
  </td>
    </tr>
   </table>
   <br />


<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="8" \
style="background-image: \
url('http://git.reviewboard.kde.orgrb/images/review_request_box_top_bg.png'); \
background-position: left top; background-repeat: repeat-x; border: 1px black \
solid;">  <tr>
  <td>

<div>Review request for kdelibs.</div>
<div>By Dawit Alemayehu.</div>





<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0">  <tr>
  <td>
   <pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">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.</pre>  </td>
 </tr>
</table>




<div style="margin-top: 1.5em;">
 <b style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Bugs: </b>


 <a href="http://bugs.kde.org/show_bug.cgi?id=234484">234484</a>


</div>


<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">

 <li>kio/kio/scheduler.cpp <span style="color: grey">(d5fab85)</span></li>

 <li>kio/bookmarks/kbookmarkmanager.cc <span style="color: \
grey">(9086fd2)</span></li>

 <li>kio/kio/fileundomanager.cpp <span style="color: grey">(ca1cbbb)</span></li>

</ul>

<p><a href="http://git.reviewboard.kde.org/r/100577/diff/" style="margin-left: \
3em;">View Diff</a></p>




  </td>
 </tr>
</table>




  </div>
 </body>
</html>



[prev in list] [next in list] [prev in thread] [next in thread]
Configure | About | News | Add a list | Sponsored by KoreLogic