From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932073AbdA3SHl (ORCPT ); Mon, 30 Jan 2017 13:07:41 -0500 Received: from mail-pg0-f65.google.com ([74.125.83.65]:35647 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750948AbdA3SHi (ORCPT ); Mon, 30 Jan 2017 13:07:38 -0500 Message-ID: <1485799651.6360.101.camel@edumazet-glaptop3.roam.corp.google.com> Subject: Re: [PATCH] xen-netfront: Delete rx_refill_timer in xennet_disconnect_backend() From: Eric Dumazet To: Boris Ostrovsky Cc: jgross@suse.com, xen-devel@lists.xenproject.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, vineethp@amazon.com, wei.liu2@citrix.com, paul.durrant@citrix.com, stable@vger.kernel.org Date: Mon, 30 Jan 2017 10:07:31 -0800 In-Reply-To: <1485798346-4425-1-git-send-email-boris.ostrovsky@oracle.com> References: <1485798346-4425-1-git-send-email-boris.ostrovsky@oracle.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > CC: stable@vger.kernel.org > --- > 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. > 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); > } >