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Bug 422472 - "Lock re-entrance in TimerThread, deadlock" [p=honzab@allpeers.com (Honza Bambas [mayhemer]) r=bsmedberg sr=brendan a1.9=damons]

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This commit is contained in:
reed@reedloden.com 2008-03-14 09:25:14 -07:00
parent 785b599a30
commit b7588b43ad
2 changed files with 24 additions and 7 deletions
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30
xpcom/threads/TimerThread.cpp
View File

@ -154,6 +154,7 @@ nsresult TimerThread::Shutdown()
if (!mThread)
return NS_ERROR_NOT_INITIALIZED;
nsVoidArray timers;
{ // lock scope
nsAutoLock lock(mLock);
@ -163,12 +164,22 @@ nsresult TimerThread::Shutdown()
if (mCondVar && mWaiting)
PR_NotifyCondVar(mCondVar);
nsTimerImpl *timer;
for (PRInt32 i = mTimers.Count() - 1; i >= 0; i--) {
timer = static_cast<nsTimerImpl*>(mTimers[i]);
timer->ReleaseCallback();
RemoveTimerInternal(timer);
}
// Need to copy content of mTimers array to a local array
// because call to timers' ReleaseCallback() (and release its self)
// must not be done under the lock. Destructor of a callback
// might potentially call some code reentering the same lock
// that leads to unexpected behavior or deadlock.
// See bug 422472.
PRBool rv = timers.AppendElements(mTimers);
NS_ASSERTION(rv, "Could not copy timers array, remaining timers will not be released");
mTimers.Clear();
}
PRInt32 timersCount = timers.Count();
for (PRInt32 i = 0; i < timersCount; i++) {
nsTimerImpl *timer = static_cast<nsTimerImpl*>(timers[i]);
timer->ReleaseCallback();
ReleaseTimerInternal(timer);
}
mThread->Shutdown(); // wait for the thread to die
@ -434,10 +445,15 @@ PRBool TimerThread::RemoveTimerInternal(nsTimerImpl *aTimer)
if (!mTimers.RemoveElement(aTimer))
return PR_FALSE;
ReleaseTimerInternal(aTimer);
return PR_TRUE;
}
void TimerThread::ReleaseTimerInternal(nsTimerImpl *aTimer)
{
// Order is crucial here -- see nsTimerImpl::Release.
aTimer->mArmed = PR_FALSE;
NS_RELEASE(aTimer);
return PR_TRUE;
}
void TimerThread::DoBeforeSleep()

1
xpcom/threads/TimerThread.h
View File

@ -91,6 +91,7 @@ private:
// list, or -1 if it failed.
PRInt32 AddTimerInternal(nsTimerImpl *aTimer);
PRBool RemoveTimerInternal(nsTimerImpl *aTimer);
void ReleaseTimerInternal(nsTimerImpl *aTimer);
nsCOMPtr<nsIThread> mThread;
PRLock *mLock;