Messages in this thread Patch in this message | | | Date | Tue, 26 Nov 2013 11:45:52 -0500 | From | Konrad Rzeszutek Wilk <> | Subject | Re: [PATCH 3/4] xen/manage: Guard against user-space initiated poweroff and XenBus. |
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On Thu, Nov 21, 2013 at 11:09:52AM +0000, David Vrabel wrote: > On 08/11/13 17:38, Konrad Rzeszutek Wilk wrote: > > There is a race case where the user does 'poweroff' > > and at the same time the system admin does 'xl shutdown'. > > This isn't a Xen-specific problem is it? Wouldn't it be better to fix > this in generic code?
Possibly. I believe the reason for the reboot_notifier to exist is to provide a means to fix the race.
> > Especially since I don't think this patch actually fixes the race > completely. > > > --- a/drivers/xen/manage.c > > +++ b/drivers/xen/manage.c > [...] > > @@ -222,7 +230,7 @@ static void shutdown_handler(struct xenbus_watch *watch, > > }; > > static struct shutdown_handler *handler; > > > > - if (shutting_down != SHUTDOWN_INVALID) > > + if (atomic_read(&shutting_down) != SHUTDOWN_INVALID) > > return; > > In guest initiated poweroff at this time will still race with this > toolstack initiated poweroff.
No, b/c the reboot notifier would have set 'shutting_down' already.
> > David
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