| Message ID | 1389634880-4138-2-git-send-email-dborkman@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Mon, 13 Jan 2014 18:41:19 +0100 Daniel Borkmann <dborkman@redhat.com> wrote: > We can create a vxlan device with an explicit underlying carrier. > In that case, when the carrier link is being deleted from the > system (e.g. due to module unload) we should also clean up all > created vxlan devices on top of it since otherwise we're in an > inconsistent state in vxlan device. In that case, the user needs > to remove all such devices, while in case of other virtual devs > that sit on top of physical ones, it is usually the case that > these devices do unregister automatically as well and do not > leave the burden on the user. > > This work is not necessary when vxlan device was not created with > a real underlying device, as connections can resume in that case > when driver is plugged again. But at least for the other cases, > we should go ahead and do the cleanup on removal. > > We don't register the notifier during vxlan_newlink() here since > I consider this event rather rare, and therefore we should not > bloat vxlan's core structure unecessary. Also, we can simply make > use of unregister_netdevice_many() to batch that. fdb is flushed > upon ndo_stop(). > > E.g. `ip -d link show vxlan13` after carrier removal before > this patch: > > 5: vxlan13: <BROADCAST,MULTICAST> mtu 1450 qdisc noop state DOWN mode DEFAULT group default > link/ether 1e:47:da:6d:4d:99 brd ff:ff:ff:ff:ff:ff promiscuity 0 > vxlan id 13 group 239.0.0.10 dev 2 port 32768 61000 ageing 300 > ^^^^^ > Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Since vxlan is running over UDP socket. I wonder if this could be done better by implementing something equivalent to SO_BINDTODEVICE. What happens to a user land application which has a UDP socket and has done SO_BINDTODEVICE and device is removed? Is there an asynchronous error, can the application recover? Why can't vxlan use the same mechanism? -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 01/14/2014 03:22 AM, Stephen Hemminger wrote: > On Mon, 13 Jan 2014 18:41:19 +0100 > Daniel Borkmann <dborkman@redhat.com> wrote: > >> We can create a vxlan device with an explicit underlying carrier. >> In that case, when the carrier link is being deleted from the >> system (e.g. due to module unload) we should also clean up all >> created vxlan devices on top of it since otherwise we're in an >> inconsistent state in vxlan device. In that case, the user needs >> to remove all such devices, while in case of other virtual devs >> that sit on top of physical ones, it is usually the case that >> these devices do unregister automatically as well and do not >> leave the burden on the user. >> >> This work is not necessary when vxlan device was not created with >> a real underlying device, as connections can resume in that case >> when driver is plugged again. But at least for the other cases, >> we should go ahead and do the cleanup on removal. >> >> We don't register the notifier during vxlan_newlink() here since >> I consider this event rather rare, and therefore we should not >> bloat vxlan's core structure unecessary. Also, we can simply make >> use of unregister_netdevice_many() to batch that. fdb is flushed >> upon ndo_stop(). >> >> E.g. `ip -d link show vxlan13` after carrier removal before >> this patch: >> >> 5: vxlan13: <BROADCAST,MULTICAST> mtu 1450 qdisc noop state DOWN mode DEFAULT group default >> link/ether 1e:47:da:6d:4d:99 brd ff:ff:ff:ff:ff:ff promiscuity 0 >> vxlan id 13 group 239.0.0.10 dev 2 port 32768 61000 ageing 300 >> ^^^^^ >> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> > > Since vxlan is running over UDP socket. I wonder if this could be > done better by implementing something equivalent to SO_BINDTODEVICE. > > What happens to a user land application which has a UDP socket > and has done SO_BINDTODEVICE and device is removed? Is there an asynchronous > error, can the application recover? Why can't vxlan use the same mechanism? Interesting point. What seems to happen with UDP sockets and SO_BINDTODEVICE in case the device was present during the setsockopt(2), and module was unloaded at time of sendto(2)/recvfrom(2), that at least senders give an error of ENODEV in such cases while receivers seem not to notice as far as I can tell. When we reload the module and device appears again with the same name, then sendto(2), still fails with ENODEV, since we, of course, work with indexes, that is, sk->sk_bound_dev_if. The only chance user space would have is to try to redo the setsockopt(2) with SO_BINDTODEVICE on the same device _name_, but different new index now, in the hope that this would be the same underlying NIC. It seems, however not recommended to do so [1]. Anyway, so I'm not sure how useful this would be, I guess just doing what this patch here does should be appropriate to do. [1] http://ftp.riken.go.jp/Linux/kernel/v2.0/patch-html/patch-2.0.31/linux_Documentation_networking_so_bindtodevice.txt.html -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 481f85d..81c553f 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -2656,6 +2656,44 @@ static struct rtnl_link_ops vxlan_link_ops __read_mostly = { .fill_info = vxlan_fill_info, }; +static void vxlan_handle_lowerdev_unregister(struct vxlan_net *vn, + struct net_device *dev) +{ + struct vxlan_dev *vxlan, *next; + LIST_HEAD(list_kill); + + list_for_each_entry_safe(vxlan, next, &vn->vxlan_list, next) { + struct vxlan_rdst *dst = &vxlan->default_dst; + + /* In case we created vxlan device with carrier + * and we loose the carrier due to module unload + * we also need to remove vxlan device. In other + * cases, it's not necessary and remote_ifindex + * is 0 here, so no matches. + */ + if (dst->remote_ifindex == dev->ifindex) + vxlan_dellink(vxlan->dev, &list_kill); + } + + unregister_netdevice_many(&list_kill); +} + +static int vxlan_lowerdev_event(struct notifier_block *unused, + unsigned long event, void *ptr) +{ + struct net_device *dev = netdev_notifier_info_to_dev(ptr); + struct vxlan_net *vn = net_generic(dev_net(dev), vxlan_net_id); + + if (event == NETDEV_UNREGISTER) + vxlan_handle_lowerdev_unregister(vn, dev); + + return NOTIFY_DONE; +} + +static struct notifier_block vxlan_notifier_block __read_mostly = { + .notifier_call = vxlan_lowerdev_event, +}; + static __net_init int vxlan_init_net(struct net *net) { struct vxlan_net *vn = net_generic(net, vxlan_net_id); @@ -2704,12 +2742,17 @@ static int __init vxlan_init_module(void) if (rc) goto out1; - rc = rtnl_link_register(&vxlan_link_ops); + rc = register_netdevice_notifier(&vxlan_notifier_block); if (rc) goto out2; - return 0; + rc = rtnl_link_register(&vxlan_link_ops); + if (rc) + goto out3; + return 0; +out3: + unregister_netdevice_notifier(&vxlan_notifier_block); out2: unregister_pernet_device(&vxlan_net_ops); out1: @@ -2721,6 +2764,7 @@ late_initcall(vxlan_init_module); static void __exit vxlan_cleanup_module(void) { rtnl_link_unregister(&vxlan_link_ops); + unregister_netdevice_notifier(&vxlan_notifier_block); destroy_workqueue(vxlan_wq); unregister_pernet_device(&vxlan_net_ops); rcu_barrier();
We can create a vxlan device with an explicit underlying carrier. In that case, when the carrier link is being deleted from the system (e.g. due to module unload) we should also clean up all created vxlan devices on top of it since otherwise we're in an inconsistent state in vxlan device. In that case, the user needs to remove all such devices, while in case of other virtual devs that sit on top of physical ones, it is usually the case that these devices do unregister automatically as well and do not leave the burden on the user. This work is not necessary when vxlan device was not created with a real underlying device, as connections can resume in that case when driver is plugged again. But at least for the other cases, we should go ahead and do the cleanup on removal. We don't register the notifier during vxlan_newlink() here since I consider this event rather rare, and therefore we should not bloat vxlan's core structure unecessary. Also, we can simply make use of unregister_netdevice_many() to batch that. fdb is flushed upon ndo_stop(). E.g. `ip -d link show vxlan13` after carrier removal before this patch: 5: vxlan13: <BROADCAST,MULTICAST> mtu 1450 qdisc noop state DOWN mode DEFAULT group default link/ether 1e:47:da:6d:4d:99 brd ff:ff:ff:ff:ff:ff promiscuity 0 vxlan id 13 group 239.0.0.10 dev 2 port 32768 61000 ageing 300 ^^^^^ Signed-off-by: Daniel Borkmann <dborkman@redhat.com> --- drivers/net/vxlan.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 46 insertions(+), 2 deletions(-)