Messages in this thread | | | Date | Wed, 3 Jul 2013 08:11:04 +0200 | From | Thomas Zeitlhofer <> | Subject | Re: tuntap regression in v3.9.8 and v3.10 |
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Hello Jason,
On Wed, Jul 03, 2013 at 10:44:32AM +0800, Jason Wang wrote: > On 07/03/2013 06:06 AM, Thomas Zeitlhofer wrote: > > On Tue, Jul 02, 2013 at 06:01:12PM -0300, Fabio Estevam wrote: > >> On Tue, Jul 2, 2013 at 4:59 PM, Thomas Zeitlhofer > >> <thomas.zeitlhofer@nt.tuwien.ac.at> 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). > > Yes, commit "tuntap: set SOCK_ZEROCOPY flag during open" just re-enable > the zerocopy capability of tuntap. I believe it just uncover other > zerocopy bugs. > > Which regression did you see?
a kernel panic on the host machine. The details are in the first message of this thread: http://lkml.org/lkml/2013/7/2/499
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