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 1BD5FC43441 for ; Fri, 12 Oct 2018 08:24:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DF8A92087D for ; Fri, 12 Oct 2018 08:24:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DF8A92087D 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 S1727995AbeJLPzW (ORCPT ); Fri, 12 Oct 2018 11:55:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55284 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727506AbeJLPzV (ORCPT ); Fri, 12 Oct 2018 11:55:21 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0C7B59D411; Fri, 12 Oct 2018 08:24:03 +0000 (UTC) Received: from [10.72.12.161] (ovpn-12-161.pek2.redhat.com [10.72.12.161]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EF29B84942; Fri, 12 Oct 2018 08:23:53 +0000 (UTC) Subject: Re: [PATCH] virtio_net: enable tx after resuming from suspend To: ake Cc: "Michael S. Tsirkin" , "David S. Miller" , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20181011075127.2608-1-ake@igel.co.jp> <7e87b140-79ae-c79e-40ed-dc76b38eeae4@igel.co.jp> From: Jason Wang Message-ID: <4918ed7c-4c63-6f19-530b-8e16b0c496d4@redhat.com> Date: Fri, 12 Oct 2018 16:23:48 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 12 Oct 2018 08:24:03 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018年10月12日 12:30, ake wrote: > > On 2018年10月11日 22:06, Jason Wang wrote: >> >> On 2018年10月11日 18:22, ake wrote: >>> On 2018年10月11日 18:44, Jason Wang wrote: >>>> On 2018年10月11日 15:51, Ake Koomsin wrote: >>>>> commit 713a98d90c5e ("virtio-net: serialize tx routine during reset") >>>>> disabled the virtio tx before going to suspend to avoid a use after >>>>> free. >>>>> However, after resuming, it causes the virtio_net device to lose its >>>>> network connectivity. >>>>> >>>>> To solve the issue, we need to enable tx after resuming. >>>>> >>>>> Fixes commit 713a98d90c5e ("virtio-net: serialize tx routine during >>>>> reset") >>>>> Signed-off-by: Ake Koomsin >>>>> --- >>>>>    drivers/net/virtio_net.c | 1 + >>>>>    1 file changed, 1 insertion(+) >>>>> >>>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>>>> index dab504ec5e50..3453d80f5f81 100644 >>>>> --- a/drivers/net/virtio_net.c >>>>> +++ b/drivers/net/virtio_net.c >>>>> @@ -2256,6 +2256,7 @@ static int virtnet_restore_up(struct >>>>> virtio_device *vdev) >>>>>        } >>>>>          netif_device_attach(vi->dev); >>>>> +    netif_start_queue(vi->dev); >>>> I believe this is duplicated with netif_tx_wake_all_queues() in >>>> netif_device_attach() above? >>> Thank you for your review. >>> >>> If both netif_tx_wake_all_queues() and netif_start_queue() result in >>> clearing __QUEUE_STATE_DRV_XOFF, then is it possible that some >>> conditions in netif_device_attach() is not satisfied? >> Yes, maybe. One case I can see now is when the device is down, in this >> case netif_device_attach() won't try to wakeup the queue. >> >>>   Without >>> netif_start_queue(), the virtio_net device does not resume properly >>> after waking up. >> How do you trigger the issue? Just do suspend/resume? > Yes, simply suspend and resume. > > Here is how I trigger the issue: > > 1) Start the Virtual Machine Manager GUI program. > 2) Create a guest Linux OS. Make sure that the guest OS kernel is > >= 4.12. Make sure that it uses virtio_net as its network device. > In addition, make sure that the video adapter is VGA. Otherwise, > waking up with the virtual power button does not work. > 3) After installing the guest OS, log in, and test the network > connectivity by ping the host machine. > 4) Suspend. After this, the screen is blank. > 5) Resume by hitting the virtual power button. The login screen > appears again. > 6) Log in again. The guest loses its network connection. > > In my test: > Guest: Ubuntu 16.04/18.04 with kernel 4.15.0-36-generic > Host: Ubuntu 16.04 with kernel 4.15.0-36-generic/4.4.0-137-generic I can not reproduce this issue if virtio-net interface is up in guest before the suspend. I'm using net-next.git and qemu master. But I do reproduce when virtio-net interface is down in guest before suspend, after resume, even if I make it up, the network is still lost. I think the interface is up in your case, but please confirm this. > >>> Is it better to report this as a bug first? >> Nope, you're very welcome to post patch directly. >> >>> If I am to do more >>> investigation, what areas should I look into? >> As you've figured out, you can start with why netif_tx_wake_all_queues() >> were not executed? >> >> (Btw, does the issue disappear if you move netif_tx_disable() under the >> check of netif_running() in virtnet_freeze_down()?) > The issue disappears if I move netif_tx_disable() under the check of > netif_running() in virtnet_freeze_down(). Moving netif_tx_disable() > is probably better as its logic is consistent with > netif_device_attach() implementation. If you are OK with this idea, > I will submit another patch. I think the it helps for the case when interface is down before suspend. But it's still unclear why it help even if the interface is up (netif_running() is true). Please submit a patch but we should figure out why it help for a up interface as well. Thanks > >> Thanks >> >>> Best Regards >>> Ake Koomsin >>> > Best Regards