xen-netfront: Delete rx_refill_timer in xennet_disconnect_backend()

rx_refill_timer should be deleted as soon as we disconnect from the
backend since otherwise it is possible for the timer to go off before
we get to xennet_destroy_queues(). If this happens we may dereference
queue->rx.sring which is set to NULL in xennet_disconnect_backend().

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
CC: stable@vger.kernel.org
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index d3812581c6c0..1e4125a98291 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -1387,6 +1387,8 @@ static void xennet_disconnect_backend(struct netfront_info *info)
         for (i = 0; i < num_queues && info->queues; ++i) {
                 struct netfront_queue *queue = &info->queues[i];
 
+                del_timer_sync(&queue->rx_refill_timer);
+
                 if (queue->tx_irq && (queue->tx_irq == queue->rx_irq))
                         unbind_from_irqhandler(queue->tx_irq, queue);
                 if (queue->tx_irq && (queue->tx_irq != queue->rx_irq)) {
@@ -1741,7 +1743,6 @@ static void xennet_destroy_queues(struct netfront_info *info)
 
                 if (netif_running(info->netdev))
                         napi_disable(&queue->napi);
-                del_timer_sync(&queue->rx_refill_timer);
                 netif_napi_del(&queue->napi);
         }