On 01/30/2017 01:07 PM, Eric Dumazet wrote: > On Mon, 2017-01-30 at 12:45 -0500, Boris Ostrovsky wrote: >> 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@xxxxxxxxxx> >> CC: stable@xxxxxxxxxxxxxxx >> --- >> drivers/net/xen-netfront.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c >> index 8315fe7..722fe9f 100644 >> --- a/drivers/net/xen-netfront.c >> +++ b/drivers/net/xen-netfront.c >> @@ -1379,6 +1379,8 @@ 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 napi_disable() was not called before this del_timer_sync(), another > RX might come here and rearm rx_refill_timer. We do netif_carrier_off() first thing in xennet_disconnect_backend() and the only place where the timer is rearmed is xennet_alloc_rx_buffers(), which is guarded by netif_carrier_ok() check. -boris > >> 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)) { >> @@ -1733,7 +1735,6 @@ 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); >> } >> > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html