Re: [linux-pm] question on resume()
- From: Pavel Machek <pavel@xxxxxx>
- Date: Wed, 31 Jan 2007 10:36:53 +0100
Hi!
Yes, it will. The process freezer can only return success if there are no more
TASK_UNINTERRUPTIBLE tasks. Otherwise it fails (after a timeout).
So, this means, on suspend():
1. Don't worry about TASK_UNINTERRUPTIBLE
2. Do worry about TASK_INTERRUPTIBLE
We have to cease IO and must not call wake_up_interruptible()
"cease IO"? No, I believe it is enough not to start new I/O. Userspace
is frozen at that point, it can't ask you to do I/O.
Isn't that a race until suspend() is called?
I do not think so.
On resume():
1. Don't worry about TASK_UNINTERRUPTIBLE
2. Do not restart IO that may call wake_up_interruptible()
When do we restart such IO?
We reuse signal handling code to do that for us. It is same situation
as when someone signals task doing I/O.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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