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    SubjectRe: [Xen-devel][PATCH] xen/netfront: Remove unneeded .resume callback
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    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@epam.com>
    >>>
    >>> 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
    >>> cannot
    >>>    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
    >>> communication
    >>>    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
    >> connectivity?
    > 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().

    -boris


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