linux-kernel - Re: [PATCH 1/3] PM / sleep: New flag to speed up suspend-resume of suspended devices

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <Pine.LNX.4.44L0.1402271001190.1150-100000@iolanthe.rowland.org>
Date:	Thu, 27 Feb 2014 10:02:05 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
cc:	Linux PM list <linux-pm@...r.kernel.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Aaron Lu <aaron.lu@...el.com>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] PM / sleep: New flag to speed up suspend-resume of
 suspended devices

On Thu, 27 Feb 2014, Rafael J. Wysocki wrote:

> > If the child knows about the problem beforehand, it can runtime-resume 
> > the parent during its ->suspend.
> 
> Well, it even should do that in those cases.  We may need to deal with children
> that don't do that, though.
> 
> > > Well, if power.fast_suspend set guarantees that ->suspend_late, ->suspend_noirq,
> > > ->resume_noirq, and ->resume_early will be skipped for a device, then we may
> > > restrict setting it for devices whose children have it set (or that have no
> > > children).  Initially, that will be equivalent to setting it for leaf devices
> > > only, but it might be extended over time in a natural way.
> > 
> > Initially, maybe.
> 
> Of course initially.
> 
> > But it's the wrong approach in general.
> 
> In the long run - I agree.
> 
> > The right approach is to restrict setting fast_suspend for devices whose
> > children don't mind their parent being suspended when their resume callbacks 
> > run -- not for devices whose children also have fast_suspend set.
> 
> I agree, but we need to know which children are OK with the parent being
> suspended.  Having fast_suspend set is a good indication of that. :-)
> 
> Of course, we may introduce a separate flag for that just fine if you prefer.
> 
> > That's the point I've been trying to express all along.
> 
> I see.

Okay.  I'll wait to see the next version.

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/