From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pavel Machek <pavel@ucw.cz>
Subject: Re: question on resume()
Date: Wed, 31 Jan 2007 10:36:53 +0100
Message-ID: <20070131093653.GA19643@elf.ucw.cz>
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To: Oliver Neukum <oneukum@suse.de>
Cc: pm list <linux-pm@lists.osdl.org>, Oliver Neukum <oliver@neukum.name>, linux-kernel@vger.kernel.org
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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
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