Re: [RFC][PATCH -mm 3/3] PM: Disable _request_firmware before hibernation/suspend

Pavel Machek
2007-06-04T11:00:52Z

Hi!

> > > The theoretical answer is that it behaves the way we want. The kernel
> > > thread does selective resumes in response to device requests. If such
> > > a request comes in while the system is asleep it will awaken the
> > > system; so it's only logical that a request coming in while the system
> > > is in the process of going to sleep should abort the suspend.
> >
> > I'd say that it shows ppc being broken. User wanted to suspend the
> > system, and now unrelated task did lsusb... and system will not sleep.
> >
> > AFAICT it is DoS issue -- if one of your users keeps doing lsusb, root
> > will not be able to suspend the system.
>
> This is a matter of one's philosophy. In suspend-to-RAM, should tasks
> be frozen or should I/O queues be frozen?
>
> With the USB subsystem I have followed the approach taken by the PM
> core, which is that tasks are frozen. But one can -- and Linus has on
> at least one occasion -- make a good case that tasks should be left
> running while only I/O is frozen. This would require the subsystem to
> distinguish between a selective device suspend and a system-wide
> suspend-to-RAM, so that selective resume could be enabled on demand in
> one case but not the other.
>
> It's quite doable in principle -- it's just not the technique I used.

I guess we need to do that. Random user should not be able to prevent
machine from sleeping.

--
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