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    Subject[PATCH 3.16 171/366] xen-netfront: avoid crashing on resume after a failure in talk_to_netback()
    3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Vitaly Kuznetsov <vkuznets@redhat.com>

    commit d86b5672b1adb98b4cdd6fbf0224bbfb03db6e2e upstream.

    Unavoidable crashes in netfront_resume() and netback_changed() after a
    previous fail in talk_to_netback() (e.g. when we fail to read MAC from
    xenstore) were discovered. The failure path in talk_to_netback() does
    unregister/free for netdev but we don't reset drvdata and we try accessing
    it after resume.

    Fix the bug by removing the whole xen device completely with
    device_unregister(), this guarantees we won't have any calls into netfront
    after a failure.

    Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    drivers/net/xen-netfront.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    --- a/drivers/net/xen-netfront.c
    +++ b/drivers/net/xen-netfront.c
    @@ -1980,8 +1980,7 @@ abort_transaction_no_dev_fatal:
    xennet_disconnect_backend(info);
    xennet_destroy_queues(info);
    out:
    - unregister_netdev(info->netdev);
    - xennet_free_netdev(info->netdev);
    + device_unregister(&dev->dev);
    return err;
    }

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