From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alan Stern <stern@rowland.harvard.edu>
Subject: Re: question on freeze and aio
Date: Fri, 9 Feb 2007 17:03:21 -0500 (EST)
Message-ID: <Pine.LNX.4.44L0.0702091700450.4557-100000@iolanthe.rowland.org>
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To: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: linux-pm@lists.osdl.org
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On Sat, 10 Feb 2007, Nigel Cunningham wrote:

> Hi.
> =

> On Fri, 2007-02-09 at 17:04 +0100, Oliver Neukum wrote:
> > Hi,
> > =

> > can there be running aio requests if all tasks are frozen?
> =

> Since tasks are frozen, no new aio requests would be submitted. We do a
> sync to ssek to complete existing requests; I haven't looked to see
> whether that would need extending to flush aio as well, but don't think
> that would be the case. Given everyone else's silence, so far, you might
> be better to ask the author(s) of the aio code.

I believe Nigel is basically correct.  However sync will only flush aio =

for block devices.  Other types of aio will remain active.

aio callbacks are interrupt-driven and execute in a workqueue (see
fs/aio.c), and as far as I can tell that workqueue doesn't freeze.  =

Unless some general facility freezes all workqueues...

Alan Stern