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_HELO_NONE,SPF_PASS 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 1005BC31E44 for ; Mon, 17 Jun 2019 08:16:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E1F6621C38 for ; Mon, 17 Jun 2019 08:16:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727478AbfFQIQe (ORCPT ); Mon, 17 Jun 2019 04:16:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59592 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725837AbfFQIQd (ORCPT ); Mon, 17 Jun 2019 04:16:33 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8E8E33082E70; Mon, 17 Jun 2019 08:16:33 +0000 (UTC) Received: from [10.72.12.67] (ovpn-12-67.pek2.redhat.com [10.72.12.67]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3A8CE101F96B; Mon, 17 Jun 2019 08:16:30 +0000 (UTC) Subject: Re: [PATCH] Fix tun: wake up waitqueues after IFF_UP is set From: Jason Wang To: Fei Li , davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: zhengfeiran@bytedance.com, duanxiongchun@bytedance.com References: <20190617073320.69015-1-lifei.shirley@bytedance.com> <28bef625-ce70-20a1-7d8b-296cd43015c4@redhat.com> Message-ID: <2d05dce3-e19a-2f0f-8b74-8defae38640d@redhat.com> Date: Mon, 17 Jun 2019 16:16:28 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <28bef625-ce70-20a1-7d8b-296cd43015c4@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Mon, 17 Jun 2019 08:16:33 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/6/17 下午4:10, Jason Wang wrote: > > On 2019/6/17 下午3:33, Fei Li wrote: >> Currently after setting tap0 link up, the tun code wakes tx/rx waited >> queues up in tun_net_open() when .ndo_open() is called, however the >> IFF_UP flag has not been set yet. If there's already a wait queue, it >> would fail to transmit when checking the IFF_UP flag in tun_sendmsg(). >> Then the saving vhost_poll_start() will add the wq into wqh until it >> is waken up again. Although this works when IFF_UP flag has been set >> when tun_chr_poll detects; this is not true if IFF_UP flag has not >> been set at that time. Sadly the latter case is a fatal error, as >> the wq will never be waken up in future unless later manually >> setting link up on purpose. >> >> Fix this by moving the wakeup process into the NETDEV_UP event >> notifying process, this makes sure IFF_UP has been set before all >> waited queues been waken up. Btw, the title needs some tweak. E.g you need use "net" as prefix since it's a fix for net.git and "Fix" could be removed like: [PATCH net] tun: wake up waitqueues after IFF_UP is set. Thanks >> >> Signed-off-by: Fei Li >> --- >>   drivers/net/tun.c | 17 +++++++++-------- >>   1 file changed, 9 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/net/tun.c b/drivers/net/tun.c >> index c452d6d831dd..a3c9cab5a4d0 100644 >> --- a/drivers/net/tun.c >> +++ b/drivers/net/tun.c >> @@ -1015,17 +1015,9 @@ static void tun_net_uninit(struct net_device >> *dev) >>   static int tun_net_open(struct net_device *dev) >>   { >>       struct tun_struct *tun = netdev_priv(dev); >> -    int i; >>         netif_tx_start_all_queues(dev); >>   -    for (i = 0; i < tun->numqueues; i++) { >> -        struct tun_file *tfile; >> - >> -        tfile = rtnl_dereference(tun->tfiles[i]); >> - tfile->socket.sk->sk_write_space(tfile->socket.sk); >> -    } >> - >>       return 0; >>   } >>   @@ -3634,6 +3626,7 @@ static int tun_device_event(struct >> notifier_block *unused, >>   { >>       struct net_device *dev = netdev_notifier_info_to_dev(ptr); >>       struct tun_struct *tun = netdev_priv(dev); >> +    int i; >>         if (dev->rtnl_link_ops != &tun_link_ops) >>           return NOTIFY_DONE; >> @@ -3643,6 +3636,14 @@ static int tun_device_event(struct >> notifier_block *unused, >>           if (tun_queue_resize(tun)) >>               return NOTIFY_BAD; >>           break; >> +    case NETDEV_UP: >> +        for (i = 0; i < tun->numqueues; i++) { >> +            struct tun_file *tfile; >> + >> +            tfile = rtnl_dereference(tun->tfiles[i]); >> + tfile->socket.sk->sk_write_space(tfile->socket.sk); >> +        } >> +        break; >>       default: >>           break; >>       } > > > Acked-by: Jason Wang