Re: [Xen-devel][PATCH] xen/netfront: Remove unneeded .resume callback
- Date: Thu, 14 Mar 2019 11:02:12 -0400
- From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
- Subject: Re: [Xen-devel][PATCH] xen/netfront: Remove unneeded .resume callback
On 3/14/19 10:52 AM, Oleksandr Andrushchenko wrote:
> On 3/14/19 4:47 PM, Boris Ostrovsky wrote:
>> On 3/14/19 9:17 AM, Oleksandr Andrushchenko wrote:
>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
>>> Currently on driver resume we remove all the network queues and
>>> destroy shared Tx/Rx rings leaving the driver in its current state
>>> and never signaling the backend of this frontend's state change.
>>> This leads to the number of consequences:
>>> - when frontend withdraws granted references to the rings etc. it
>>> be cleanly done as the backend still holds those (it was not told to
>>> free the resources)
>>> - it is not possible to resume driver operation as all the
>>> means with the backned were destroyed by the frontend, thus
>>> making the frontend appear to the guest OS as functional, but
>>> not really.
>> What do you mean? Are you saying that after resume you lose
> Exactly, if you take a look at the .resume callback as it is now
> what it does it destroys the rings etc. and never notifies the backend
> of that, e.g. it stays in, say, connected state with communication
> channels destroyed. It never goes into any other Xen bus state, so
> there is
> no way its state machine can help recovering.
My tree is about a month old so perhaps there is some sort of regression
but this certainly works for me. After resume netfront gets
XenbusStateInitWait from backend which causes xennet_connect().