The combination of two commits:
commit 8e4e1713
("openvswitch: Simplify datapath locking.")
commit 2537b4dd
("openvswitch:: link upper device for port devices")

introduced a bug where upper_dev wasn't unlinked upon
netdev_unregister notification

The following steps:

  modprobe openvswitch
  ovs-dpctl add-dp test
  ip tuntap add dev tap1 mode tap
  ovs-dpctl add-if test tap1
  ip tuntap del dev tap1 mode tap

are causing multiple warnings:

[   62.747557] gre: GRE over IPv4 demultiplexor driver
[   62.749579] openvswitch: Open vSwitch switching datapath
[   62.755087] device test entered promiscuous mode
[   62.765911] device tap1 entered promiscuous mode
[   62.766033] IPv6: ADDRCONF(NETDEV_UP): tap1: link is not ready
[   62.769017] ------------[ cut here ]------------
[   62.769022] WARNING: CPU: 1 PID: 3267 at net/core/dev.c:5501 rollback_registered_many+0x20f/0x240()
[   62.769023] Modules linked in: openvswitch gre vxlan ip_tunnel libcrc32c ip6table_filter ip6_tables ebtable_nat ebtables nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack xt_CHECKSUM iptable_mangle ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp llc vhost_net macvtap macvlan vhost kvm_intel kvm dm_crypt iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi hid_generic mxm_wmi eeepc_wmi asus_wmi sparse_keymap dm_multipath psmouse serio_raw usbhid hid parport_pc ppdev firewire_ohci lpc_ich firewire_core e1000e crc_itu_t binfmt_misc igb dca ptp pps_core mac_hid wmi lp parport i2o_config i2o_block video
[   62.769051] CPU: 1 PID: 3267 Comm: ip Not tainted 3.12.0-rc3+ #60
[   62.769052] Hardware name: System manufacturer System Product Name/P8Z77 WS, BIOS 3007 07/26/2012
[   62.769053]  0000000000000009 ffff8807f25cbd28 ffffffff8175e575 0000000000000006
[   62.769055]  0000000000000000 ffff8807f25cbd68 ffffffff8105314c ffff8807f25cbd58
[   62.769057]  ffff8807f2634000 ffff8807f25cbdc8 ffff8807f25cbd88 ffff8807f25cbdc8
[   62.769059] Call Trace:
[   62.769062]  [<ffffffff8175e575>] dump_stack+0x55/0x76
[   62.769065]  [<ffffffff8105314c>] warn_slowpath_common+0x8c/0xc0
[   62.769067]  [<ffffffff8105319a>] warn_slowpath_null+0x1a/0x20
[   62.769069]  [<ffffffff8162a04f>] rollback_registered_many+0x20f/0x240
[   62.769071]  [<ffffffff8162a101>] rollback_registered+0x31/0x40
[   62.769073]  [<ffffffff8162a488>] unregister_netdevice_queue+0x58/0x90
[   62.769075]  [<ffffffff8154f900>] __tun_detach+0x140/0x340
[   62.769077]  [<ffffffff8154fb36>] tun_chr_close+0x36/0x60
[   62.769080]  [<ffffffff811bddaf>] __fput+0xff/0x260
[   62.769082]  [<ffffffff811bdf5e>] ____fput+0xe/0x10
[   62.769084]  [<ffffffff8107b515>] task_work_run+0xb5/0xe0
[   62.769087]  [<ffffffff810029b9>] do_notify_resume+0x59/0x80
[   62.769089]  [<ffffffff813a41fe>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[   62.769091]  [<ffffffff81770f5a>] int_signal+0x12/0x17
[   62.769093] ---[ end trace 838756c62e156ffb ]---
[   62.769481] ------------[ cut here ]------------
[   62.769485] WARNING: CPU: 1 PID: 92 at fs/sysfs/inode.c:325 sysfs_hash_and_remove+0xa9/0xb0()
[   62.769486] sysfs: can not remove 'master', no directory
[   62.769486] Modules linked in: openvswitch gre vxlan ip_tunnel libcrc32c ip6table_filter ip6_tables ebtable_nat ebtables nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack xt_CHECKSUM iptable_mangle ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp llc vhost_net macvtap macvlan vhost kvm_intel kvm dm_crypt iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi hid_generic mxm_wmi eeepc_wmi asus_wmi sparse_keymap dm_multipath psmouse serio_raw usbhid hid parport_pc ppdev firewire_ohci lpc_ich firewire_core e1000e crc_itu_t binfmt_misc igb dca ptp pps_core mac_hid wmi lp parport i2o_config i2o_block video
[   62.769514] CPU: 1 PID: 92 Comm: kworker/1:2 Tainted: G        W    3.12.0-rc3+ #60
[   62.769515] Hardware name: System manufacturer System Product Name/P8Z77 WS, BIOS 3007 07/26/2012
[   62.769518] Workqueue: events ovs_dp_notify_wq [openvswitch]
[   62.769519]  0000000000000009 ffff880807ad3ac8 ffffffff8175e575 0000000000000006
[   62.769521]  ffff880807ad3b18 ffff880807ad3b08 ffffffff8105314c ffff880807ad3b28
[   62.769523]  0000000000000000 ffffffff81a87a1f ffff8807f2634000 ffff880037038500
[   62.769525] Call Trace:
[   62.769528]  [<ffffffff8175e575>] dump_stack+0x55/0x76
[   62.769529]  [<ffffffff8105314c>] warn_slowpath_common+0x8c/0xc0
[   62.769531]  [<ffffffff81053236>] warn_slowpath_fmt+0x46/0x50
[   62.769533]  [<ffffffff8123e7e9>] sysfs_hash_and_remove+0xa9/0xb0
[   62.769535]  [<ffffffff81240e96>] sysfs_remove_link+0x26/0x30
[   62.769538]  [<ffffffff81631ef7>] __netdev_adjacent_dev_remove+0xf7/0x150
[   62.769540]  [<ffffffff81632037>] __netdev_adjacent_dev_unlink_lists+0x27/0x50
[   62.769542]  [<ffffffff8163213a>] __netdev_adjacent_dev_unlink_neighbour+0x3a/0x50
[   62.769544]  [<ffffffff8163218d>] netdev_upper_dev_unlink+0x3d/0x140
[   62.769548]  [<ffffffffa033c2db>] netdev_destroy+0x4b/0x80 [openvswitch]
[   62.769550]  [<ffffffffa033b696>] ovs_vport_del+0x46/0x60 [openvswitch]
[   62.769552]  [<ffffffffa0335314>] ovs_dp_detach_port+0x44/0x60 [openvswitch]
[   62.769555]  [<ffffffffa0336574>] ovs_dp_notify_wq+0xb4/0x150 [openvswitch]
[   62.769557]  [<ffffffff81075c28>] process_one_work+0x1d8/0x6a0
[   62.769559]  [<ffffffff81075bc8>] ? process_one_work+0x178/0x6a0
[   62.769562]  [<ffffffff8107659b>] worker_thread+0x11b/0x370
[   62.769564]  [<ffffffff81076480>] ? rescuer_thread+0x350/0x350
[   62.769566]  [<ffffffff8107f44a>] kthread+0xea/0xf0
[   62.769568]  [<ffffffff8107f360>] ? flush_kthread_worker+0x150/0x150
[   62.769570]  [<ffffffff81770bac>] ret_from_fork+0x7c/0xb0
[   62.769572]  [<ffffffff8107f360>] ? flush_kthread_worker+0x150/0x150
[   62.769573] ---[ end trace 838756c62e156ffc ]---
[   62.769574] ------------[ cut here ]------------
[   62.769576] WARNING: CPU: 1 PID: 92 at fs/sysfs/inode.c:325 sysfs_hash_and_remove+0xa9/0xb0()
[   62.769577] sysfs: can not remove 'upper_test', no directory
[   62.769577] Modules linked in: openvswitch gre vxlan ip_tunnel libcrc32c ip6table_filter ip6_tables ebtable_nat ebtables nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack xt_CHECKSUM iptable_mangle ipt_REJECT xt_tcpudp iptable_filter ip_tables x_tables bridge stp llc vhost_net macvtap macvlan vhost kvm_intel kvm dm_crypt iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi hid_generic mxm_wmi eeepc_wmi asus_wmi sparse_keymap dm_multipath psmouse serio_raw usbhid hid parport_pc ppdev firewire_ohci lpc_ich firewire_core e1000e crc_itu_t binfmt_misc igb dca ptp pps_core mac_hid wmi lp parport i2o_config i2o_block video
[   62.769603] CPU: 1 PID: 92 Comm: kworker/1:2 Tainted: G        W    3.12.0-rc3+ #60
[   62.769604] Hardware name: System manufacturer System Product Name/P8Z77 WS, BIOS 3007 07/26/2012
[   62.769606] Workqueue: events ovs_dp_notify_wq [openvswitch]
[   62.769607]  0000000000000009 ffff880807ad3ac8 ffffffff8175e575 0000000000000006
[   62.769609]  ffff880807ad3b18 ffff880807ad3b08 ffffffff8105314c ffff880807ad3b58
[   62.769611]  0000000000000000 ffff880807ad3bd9 ffff8807f2634000 ffff880037038500
[   62.769613] Call Trace:
[   62.769615]  [<ffffffff8175e575>] dump_stack+0x55/0x76
[   62.769617]  [<ffffffff8105314c>] warn_slowpath_common+0x8c/0xc0
[   62.769619]  [<ffffffff81053236>] warn_slowpath_fmt+0x46/0x50
[   62.769621]  [<ffffffff8123e7e9>] sysfs_hash_and_remove+0xa9/0xb0
[   62.769622]  [<ffffffff81240e96>] sysfs_remove_link+0x26/0x30
[   62.769624]  [<ffffffff81631f22>] __netdev_adjacent_dev_remove+0x122/0x150
[   62.769627]  [<ffffffff81632037>] __netdev_adjacent_dev_unlink_lists+0x27/0x50
[   62.769629]  [<ffffffff8163213a>] __netdev_adjacent_dev_unlink_neighbour+0x3a/0x50
[   62.769631]  [<ffffffff8163218d>] netdev_upper_dev_unlink+0x3d/0x140
[   62.769633]  [<ffffffffa033c2db>] netdev_destroy+0x4b/0x80 [openvswitch]
[   62.769636]  [<ffffffffa033b696>] ovs_vport_del+0x46/0x60 [openvswitch]
[   62.769638]  [<ffffffffa0335314>] ovs_dp_detach_port+0x44/0x60 [openvswitch]
[   62.769640]  [<ffffffffa0336574>] ovs_dp_notify_wq+0xb4/0x150 [openvswitch]
[   62.769642]  [<ffffffff81075c28>] process_one_work+0x1d8/0x6a0
[   62.769644]  [<ffffffff81075bc8>] ? process_one_work+0x178/0x6a0
[   62.769646]  [<ffffffff8107659b>] worker_thread+0x11b/0x370
[   62.769648]  [<ffffffff81076480>] ? rescuer_thread+0x350/0x350
[   62.769650]  [<ffffffff8107f44a>] kthread+0xea/0xf0
[   62.769652]  [<ffffffff8107f360>] ? flush_kthread_worker+0x150/0x150
[   62.769654]  [<ffffffff81770bac>] ret_from_fork+0x7c/0xb0
[   62.769656]  [<ffffffff8107f360>] ? flush_kthread_worker+0x150/0x150
[   62.769657] ---[ end trace 838756c62e156ffd ]---
[   62.769724] device tap1 left promiscuous mode

This patch also affects moving devices between net namespaces.

OVS used to ignore netns move notifications which caused problems.
Like:
  ovs-dpctl add-if test tap1
  ip link set tap1 netns 3512
and then removing tap1 inside the namespace will cause hang on missing dev_put.

With this patch OVS will detach dev upon receiving netns move event.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>