Re: [Xen-devel][PATCH] Input: xen-kbdfront - signal the backend that we disconnect

[Oleksandr Andrushchenko]

On 3/22/19 1:03 PM, Juergen Gross wrote:
> On 15/03/2019 10:23, Oleksandr Andrushchenko wrote:
> > From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> >
> > While disconnecting from the backend we clean up shared resources
> > (event channel, ring buffer), but never let the backend know about
> > that. This may lead to inconsistent backend state and/or shared
> > resources use.
> > Fix this by explicitly letting the backend know that frontend has
> > destroyed shared resources by changing its Xen bus state accordingly.
> >
> > Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> > ---
> >   drivers/input/misc/xen-kbdfront.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/input/misc/xen-kbdfront.c b/drivers/input/misc/xen-kbdfront.c
> > index 24bc5c5d876f..ecb6e719e0e2 100644
> > --- a/drivers/input/misc/xen-kbdfront.c
> > +++ b/drivers/input/misc/xen-kbdfront.c
> > @@ -488,6 +488,8 @@ static int xenkbd_connect_backend(struct xenbus_device *dev,
> >   
> >   static void xenkbd_disconnect_backend(struct xenkbd_info *info)
> >   {
> > +	xenbus_switch_state(info->xbdev, XenbusStateClosing);
> > +
> >   	if (info->irq >= 0)
> >   		unbind_from_irqhandler(info->irq, info);
> >   	info->irq = -1;
> As already stated for the related netfront patch: I'm not sure this
> is really what we want. Have you tested xl save/restore or migration
> of the guest with your patch applied?
Well, it comes out that this is not enough and needs much more work,
so please let's abandon this patch
> Juergen
Thank you,
Oleksandr