From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8522DECDE30 for ; Wed, 17 Oct 2018 15:09:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 54D2C21526 for ; Wed, 17 Oct 2018 15:09:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 54D2C21526 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727940AbeJQXF3 (ORCPT ); Wed, 17 Oct 2018 19:05:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49852 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727182AbeJQXF3 (ORCPT ); Wed, 17 Oct 2018 19:05:29 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CEB6230001E0; Wed, 17 Oct 2018 15:09:21 +0000 (UTC) Received: from redhat.com (ovpn-124-92.rdu2.redhat.com [10.10.124.92]) by smtp.corp.redhat.com (Postfix) with SMTP id D7B915C63B; Wed, 17 Oct 2018 15:09:20 +0000 (UTC) Date: Wed, 17 Oct 2018 11:09:20 -0400 From: "Michael S. Tsirkin" To: Ake Koomsin Cc: Jason Wang , "David S. Miller" , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] virtio_net: avoid using netif_tx_disable() for serializing tx routine Message-ID: <20181017110741-mutt-send-email-mst@kernel.org> References: <276ac5bb-90f7-5fb6-a826-0bb05ecfa069@redhat.com> <20181017104419.13003-1-ake@igel.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181017104419.13003-1-ake@igel.co.jp> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Wed, 17 Oct 2018 15:09:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 17, 2018 at 07:44:12PM +0900, Ake Koomsin wrote: > Commit 713a98d90c5e ("virtio-net: serialize tx routine during reset") > introduces netif_tx_disable() after netif_device_detach() in order to > avoid use-after-free of tx queues. However, there are two issues. > > 1) Its operation is redundant with netif_device_detach() in case the > interface is running. > 2) In case of the interface is not running before suspending and > resuming, the tx does not get resumed by netif_device_attach(). > This results in losing network connectivity. > > It is better to use netif_tx_lock_bh()/netif_tx_unlock_bh() instead for > serializing tx routine during reset. This also preserves the symmetry > of netif_device_detach() and netif_device_attach(). > > Fixes commit 713a98d90c5e ("virtio-net: serialize tx routine during reset") > Signed-off-by: Ake Koomsin Acked-by: Michael S. Tsirkin Thanks a lot for debugging! Seems like stable material to me, right? > --- > drivers/net/virtio_net.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 3f5aa59c37b7..3e2c041d76ac 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -2267,8 +2267,9 @@ static void virtnet_freeze_down(struct virtio_device *vdev) > /* Make sure no work handler is accessing the device */ > flush_work(&vi->config_work); > > + netif_tx_lock_bh(vi->dev); > netif_device_detach(vi->dev); > - netif_tx_disable(vi->dev); > + netif_tx_unlock_bh(vi->dev); > cancel_delayed_work_sync(&vi->refill); > > if (netif_running(vi->dev)) { > @@ -2304,7 +2305,9 @@ static int virtnet_restore_up(struct virtio_device *vdev) > } > } > > + netif_tx_lock_bh(vi->dev); > netif_device_attach(vi->dev); > + netif_tx_unlock_bh(vi->dev); > return err; > } > > -- > 2.19.1