From patchwork Mon Jan 28 10:11:11 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 216151 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id F0E572C007C for ; Mon, 28 Jan 2013 21:07:11 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755628Ab3A1KHI (ORCPT ); Mon, 28 Jan 2013 05:07:08 -0500 Received: from mx1.redhat.com ([209.132.183.28]:62402 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754205Ab3A1KHF (ORCPT ); Mon, 28 Jan 2013 05:07:05 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r0SA70k0024204 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Mon, 28 Jan 2013 05:07:00 -0500 Received: from redhat.com (vpn-200-18.tlv.redhat.com [10.35.200.18]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id r0SA6sRO021642; Mon, 28 Jan 2013 05:06:56 -0500 Date: Mon, 28 Jan 2013 12:11:11 +0200 From: "Michael S. Tsirkin" To: Jason Wang Cc: Toralf =?iso-8859-1?Q?F=F6rster?= , netdev@vger.kernel.org, Linux Kernel , David Miller Subject: [PATCH] tun: fix carrier on/off status Message-ID: <20130128101111.GB5337@redhat.com> References: <5103B01D.5070303@gmx.de> <3592886.xagLc7Uij9@jason-thinkpad-t430s> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <3592886.xagLc7Uij9@jason-thinkpad-t430s> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Commit c8d68e6be1c3b242f1c598595830890b65cea64a removed carrier off call from tun_detach since it's now called on queue disable and not only on tun close. This confuses userspace which used this flag to detect a free tun. To fix, move on/off calls to setiff/close respectively. Signed-off-by: Michael S. Tsirkin --- On Mon, Jan 28, 2013 at 05:38:24PM +0800, Jason Wang wrote: > On Saturday, January 26, 2013 11:29:49 AM Toralf Förster wrote: > > Re: How to find an unused TAP device with kernel 3.8 ? > > With kernel 3.8. I just realized that all pre-defined TAP devices are > > RUNNING even if no virtual linux system is using it. Now I'm wondering > > whether this is a new feature of the upcoming kernel, a bug of the old - > > and how I can avoid that. > > > > Background : When I start a user mode linux instance, I currently grep > > for the next free tap device in this way : > > > > Code: > > for t in $(ifconfig | grep "^tap" | cut -f1 -d:) > > do > > ethtool $t | grep -q 'Link detected: no' > > if [[ $? -eq 0 ]]; then > > NET="tuntap,$t" > > break > > fi > > done > > > > but this doesn't work now anymore. > > > > Here is the diff in dmesg > > > > $ diff 3.7.1 3.8.0-rc1+ | grep UP > > > > < br0: flags=4355 mtu 1500 > > > > > br0: flags=4419 mtu 1500 > > > > < tap0: flags=4099 mtu 1500 > > > > > tap0: flags=4163 mtu 1500 > > > > more details : http://forums.gentoo.org/viewtopic-p-7211498.html#7211498 > > Looks like something wrong with the carrier detection of tap. > > Please try the following patch to see if it helps. > > Thanks. > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > index cc09b67..d8a53c3 100644 > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -438,6 +438,9 @@ static void __tun_detach(struct tun_file *tfile, bool clean) > sock_put(&tfile->sk); > } > > + if (tun && tun->numqueues == 0) > + netif_carrier_off(tun->dev); > + > if (clean) { > if (tun && tun->numqueues == 0 && tun->numdisabled == 0 && > !(tun->flags & TUN_PERSIST)) > @@ -473,6 +476,7 @@ static void tun_detach_all(struct net_device *dev) > BUG_ON(tun->numqueues != 0); > > synchronize_net(); > + netif_carrier_off(dev); > for (i = 0; i < n; i++) { > tfile = rtnl_dereference(tun->tfiles[i]); > /* Drop read queue */ > @@ -531,6 +535,7 @@ static int tun_attach(struct tun_struct *tun, struct file *file) > sock_hold(&tfile->sk); > > tun_set_real_num_queues(tun); > + netif_carrier_on(tun->dev); > > /* device is allowed to go away first, so no need to hold extra > * refcnt. This will set carrier off if all queues are disabled, which I think is a problem as it would confuse the script. How about the following instead: diff --git a/drivers/net/tun.c b/drivers/net/tun.c index af372d0..00dfdad 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1644,10 +1644,10 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) device_create_file(&tun->dev->dev, &dev_attr_owner) || device_create_file(&tun->dev->dev, &dev_attr_group)) pr_err("Failed to create tun sysfs files\n"); - - netif_carrier_on(tun->dev); } + netif_carrier_on(tun->dev); + tun_debug(KERN_INFO, tun, "tun_set_iff\n"); if (ifr->ifr_flags & IFF_NO_PI) @@ -2124,6 +2124,8 @@ static int tun_chr_close(struct inode *inode, struct file *file) struct tun_file *tfile = file->private_data; struct net *net = tfile->net; + netif_carrier_off(tun->dev); + tun_detach(tfile, true); put_net(net);