[CrystalSpace] #974: Race in csThreadManager::PushToQueue

#974: Race in csThreadManager::PushToQueue
---------------------------+------------------------------------------------
 Reporter:  ralphcampbell  |       Owner:  admin
     Type:  defect         |      Status:  new  
 Priority:  major          |   Milestone:       
Component:  libs           |     Version:  V2.1 
 Keywords:                 |  
---------------------------+------------------------------------------------
 The mutex lock is not held while scanning the array of waitingThreads.
 This can lead to the array boundary assertion being hit if an entry is
 deleted while scanning the array (when CS_DEBUG is enabled).
 Since the NotifyAll() sets a condition variable, it seems safe to
 me to be called while holding the waitingThreadsLock.
 The suggested fix is to make the lock cover the for loop.

 I found this while running planeshift and the background loader hit the
 array assertion. I made the suggested fix and it seems to be
 working better.


 {{{
 Index: include/csutil/threadmanager.h
 ===================================================================
 --- include/csutil/threadmanager.h      (revision 39160)
 +++ include/csutil/threadmanager.h      (working copy)
 @@ -73,11 +73,8 @@
    {
      if(queueType == THREADED || queueType == THREADEDL)
      {
 -      {
 -        CS::Threading::MutexScopedLock lock(waitingThreadsLock);
 -        threadQueue->Enqueue(job);
 -      }
 -
 +      CS::Threading::MutexScopedLock lock(waitingThreadsLock);
 +      threadQueue->Enqueue(job);
        for(size_t i=0; i<waitingThreads.GetSize(); ++i)
        {
          waitingThreads[i]->NotifyAll();
 }}}

-- 
Ticket URL: <http://www.crystalspace3d.org/trac/CS/ticket/974>
CrystalSpace <http://www.crystalspace3d.org/>
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