[linux-pm] [RFC][PATCH] PM: Introduce new top level suspend and hibernation callbacks (rev. 3)
Alan Stern
stern at rowland.harvard.edu
Tue Mar 25 07:24:03 PDT 2008
On Tue, 25 Mar 2008, Oliver Neukum wrote:
> Am Dienstag, 25. März 2008 13:40:53 schrieb Rafael J. Wysocki:
> > On Tuesday, 25 of March 2008, Oliver Neukum wrote:
> > > Am Montag 24 März 2008 schrieb Rafael J. Wysocki:
>
> > > > + * after @prepare() returns. If @prepare() detects a situation it cannot
> > > > + * handle (e.g. registration of a child already in progress), it may return
> > > > + * -EAGAIN, so that the PM core can execute it once again (e.g. after the
> > > > + * new child has been registered) to recover from the race condition. This
> > > > + * method is executed for all kinds of suspend transitions and is followed
> > > > + * by one of the suspend callbacks: @suspend(), @freeze(), or @poweroff().
> > >
> > > This could be understood so that disconnect() cannot be called.
> >
> > At what time exactly?
>
> I see no locking that would would prevent disconnect() in the window between
> prepare() and suspend()/...
There is no such locking. It's perfectly legal for a device to be
unregistered between prepare() and suspend(). I suppose it wouldn't
hurt to add a general comment explaining that a device can be
unregistered at any time except when one of its methods is running.
Alan Stern
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