From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Zeitlhofer Subject: Re: tuntap regression in v3.9.8 and v3.10 Date: Wed, 3 Jul 2013 00:06:51 +0200 Message-ID: <20130702220651.GA23097@toau.bambla> References: <20130702195910.GA20271@toau.bambla> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, jasowang@redhat.com To: Fabio Estevam Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, Jul 02, 2013 at 06:01:12PM -0300, Fabio Estevam wrote: > On Tue, Jul 2, 2013 at 4:59 PM, Thomas Zeitlhofer > wrote: > > Commit "tuntap: set SOCK_ZEROCOPY flag during open" introduces a > > regression which is observed with live migration of qemu/kvm based > > virtual machines that are connected to an openvswitch bridge. > > > > Reverting this commit (b26c93c46a3dec25ed236d4ba6107eb4ed5d9401 in > > v3.9.8 and accordingly 19a6afb23e5d323e1245baa4e62755492b2f1200 in > > v3.10) fixes the following problem: > > Should the sock_set_flag stay in tun_set_iff as it was prior to 54f968d6efd? > > --- a/drivers/net/tun.c > +++ b/drivers/net/tun.c > @@ -1652,6 +1652,7 @@ static int tun_set_iff(struct net *net, struct > file *file, struct ifreq *ifr) > tun->txflt.count = 0; > tun->vnet_hdr_sz = sizeof(struct virtio_net_hdr); > > + sock_set_flag(&tfile->sk, SOCK_ZEROCOPY); > tun->filter_attached = false; > tun->sndbuf = tfile->socket.sk->sk_sndbuf; > > @@ -2159,8 +2160,6 @@ static int tun_chr_open(struct inode *inode, > struct file * file) > set_bit(SOCK_EXTERNALLY_ALLOCATED, &tfile->socket.flags); > INIT_LIST_HEAD(&tfile->next); > > - sock_set_flag(&tfile->sk, SOCK_ZEROCOPY); > - > return 0; > } I guess no, as this also leads to a kernel panic (tested against v3.10).