[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <200803251437.17268.oliver@neukum.org>
Date: Tue, 25 Mar 2008 14:37:16 +0100
From: Oliver Neukum <oliver@...kum.org>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: Alan Stern <stern@...land.harvard.edu>,
pm list <linux-pm@...ts.linux-foundation.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Greg KH <greg@...ah.com>, Len Brown <lenb@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
Alexey Starikovskiy <astarikovskiy@...e.de>,
David Brownell <david-b@...bell.net>,
Pavel Machek <pavel@....cz>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [RFC][PATCH] PM: Introduce new top level suspend and hibernation callbacks (rev. 3)
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()/...
> > > + * The PM core executes @prepare() for all devices before starting to
> > > + * execute suspend callbacks for any of them, so drivers may assume all of
> > > + * the other devices to be present and functional while @prepare() is being
> > > + * executed. However, they may NOT assume anything about the availability
> > > + * of the user space at that time.
> >
> > Probably it should be mentioned that this is the time to allocate memory
> > if you have to.
>
> Well, not exactly. Afterwards you cannot use GFP_KERNEL allocations, but
> GFP_NOIO should still work, although for hibernation it's quite possible that
> they'll fail if substantial amounts of memory are requested.
>
> > And it is too late to request firmware.
>
> Yes.
This is better documented explicitly.
Regards
Oliver
--
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/
Powered by blists - more mailing lists