Re: kernel thread join?
Re: kernel thread join?
- Subject: Re: kernel thread join?
- From: Godfrey van der Linden <email@hidden>
- Date: Fri, 18 Apr 2008 10:54:01 +1000
msleep/wakeup & commandSleep/commandWakeup are basically equivalent.
The difference is the locking requirments. Presumably you are using a
roll-your-own locking mechanism rather than the IOKit::IOWorkLoop
mechanism. Anyway yes you have found the non-iokit solution to your
synchronisation problem. However if you do have a driver that is
using, or client of, a work loop you probably should change over from
msleep to commandSleep.
Cheers
Godfrey
On 2008-04-15, at 15:06 , Duane Murphy wrote:
--- 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:
--- 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,
On 2008-04-12, at 5:08 , Duane Murphy wrote:
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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...Duane
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