linux-kernel - Re: [RFC][PATCH] PM: Make PM core handle device registrations concurrent with suspend/hibernation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 6 Mar 2008 15:28:26 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
cc:	pm list <linux-pm@...ts.linux-foundation.org>,
	Alexey Starikovskiy <astarikovskiy@...e.de>,
	Pavel Machek <pavel@....cz>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCH] PM: Make PM core handle device registrations
 concurrent with suspend/hibernation

On Thu, 6 Mar 2008, Rafael J. Wysocki wrote:

> On Thursday, 6 of March 2008, Alan Stern wrote:
> > On Thu, 6 Mar 2008, Rafael J. Wysocki wrote:
> > 
> > > > I thought of one more thing you might want to add: device_pm_add() 
> > > > doesn't handle the case where dev->parent is NULL.
> > > 
> > > I'm not sure what you mean.
> > > 
> > > If dev->parent is NULL, we get into the "successful" branch where the device is
> > > added to dpm_active.  Do you think we should add any extra handling of this
> > > case?
> > 
> > If a device is registered after dpm_suspend() has returned, the
> > device won't be suspended properly before the system goes to sleep.  
> > 
> > If the device has a parent then you're okay, because the parent must
> > already be suspended and so device_pm_add() will fail.  But if the
> > device doesn't have a parent then device_pm_add() will succeed, which
> > you don't want.
> 
> Well, can it happen in practice?  If it can, then what way can it happen?

Yes, it can happen in practice when a new module is loaded.  In some 
ways, modules' init routines are like probe methods.

Maybe it can happen some other ways too, but I don't know of any.

> It seems to me that we're discussing purely academic stuff here.  If it turns
> out to be of any practical relevance, it will be trivial to add the handling of
> it in the future.

To be safe, I think we should make system sleep mutually exclusive with 
module loading.

Alan Stern

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/