From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nigel Cunningham <ncunningham@cyclades.com>
Subject: Re: Re: Hotplug events during sleep transition
Date: Sat, 24 Dec 2005 08:09:56 +1000
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References: <20051223172057.GA15357@elf.ucw.cz>
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	<20051223212827.GA17350@kroah.com>
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To: Greg KH <greg@kroah.com>
Cc: Linux-pm mailing list <linux-pm@lists.osdl.org>, Pavel Machek <pavel@ucw.cz>
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Hi.

On Sat, 2005-12-24 at 07:28, Greg KH wrote:
> On Fri, Dec 23, 2005 at 04:22:44PM -0500, Alan Stern wrote:
> > On Fri, 23 Dec 2005, Pavel Machek wrote:
> > 
> > > Well, if you can find some elegant solution in the core, I think thats
> > > the best way.
> > > 
> > > You could set system_state to "suspending" or something like that, and
> > > just if() out notifications in that case.
> > 
> > How about simply adding a call to try_to_freeze() somewhere inside 
> > kernel/kmod.c:____call_usermodehelper()?  That ought to do pretty much 
> > what I want, in theory.  The hotplug processes would get frozen before 
> > /sbin/hotplug is exec'ed.
> 
> On modern distros, /sbin/hotplug is set to NULL, so this isn't an issue.
> We use netlink to send the data out, so this might not even be a problem
> anymore...

At resume time, prior to copying back the original kernel data, events
can and do occur.

FWIW, I've been using "if(freezer_is_on()) return 0" for a while in
call_usermodehelper_keys, to good effect.

Regards,

Nigel


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