site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com --- At Tue, 15 Apr 2008 14:43:40 +1000, Godfrey van der Linden wrote:

The best IOKit aware equivalent to a condition variable is the IOCommandGate::commandSleep/commandWakeup APIs.

However the way you describe the problem the reference counting solution seems ideal. Especially as it is a data removal cleanup type of problem. I assume your problem is that you need to execute some code to do the data cleanup? Is that correct?

Can you describe the action you want to take on completion?

The fundamental problem is that the case that I am working with, the system is either going to sleep, shutting down, or in general going off- line. I can't return from the call that says "you're going off-line" until the other thread has completed and exited. The final stage of the exit of the other thread, records the information about why the thread exited so that it can be brought back up again appropriately. I'm using msleep() and it seems to be doing the job just great. Conveniently all the pieces were there in place; a variable to track the completion, and a mutex lock for that variable. Enter msleep() with a reasonable timeout and a wakeup() call at the end of the thread, and viola.

On 2008-04-15, at 1:45 , Duane Murphy wrote:

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--- At Mon, 14 Apr 2008 11:48:06 +1000, Godfrey van der Linden wrote:

...

There isn't really a 100% reliable way of waiting for a thread to terminate completely. However that isn't really a problem. The key is to recognise what you are really trying to do.

Presumably you are trying to clean up resources that the thread may be using?

In this case the correct kernel way of cleaning this up is just to reference count your resources. Then it doesn't matter exactly what order the objects get released in. There are a couple of other tricks but the OSObject reference counting will probably get you out of trouble.

Thanks for the idea. Unfortunately, in this case I think I need to wait for the thread to stop. The thread is processing data. The data is going to be removed and can't be removed until the processing has been halted and the removal noted. The waiting thread has received the notice that the data is going away and should clean up.

I'm going to use a condition variable to signal the end of the thread.

Now I need to work out how to do that. Any recommendations for a kernel condition variable?

Thanks for the ideas,

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On 2008-04-12, at 5:08 , Duane Murphy wrote:

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What is the equivalent of pthread_join() for a kernel thread?

I am using IOThreadCreate() to create a new thread. At some later point I indicate to that thread to stop. How do I detect that the thread as exited?

...Duane

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