Re: 2.4.0-test13-pre1 lockup: run_task_queue or tty_io are wrong

From: Jamie Lokier (lk@tantalophile.demon.co.uk)
Date: Mon Dec 18 2000 - 20:32:40 EST


Linus Torvalds wrote:
> > I wasn't clear. The sentinel is a local structure on the stack, and
> > only exists while run_task_queue is executing. Another name for this is
> > "deletion-safe pointer".
>
> Yes, except run_task_queue removes every object it finds. So two
> concurrent run_task_queues would be bad.

That could work, but forget it. I've just looked at Andrew's patch and
it's much nicer :-)

If you put a spinlock around the list operations in Andrew's version,
you'd have safe tqueue deletions again (if you felt that was worth
having). Some tricks and you can make it a different spinlock, but I
doubt that would be a net benefit.

-- Jamie
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