We recently got the following warning after setting up a vlan device on
top of an offloaded bridge and executing 'bridge link':

WARNING: CPU: 0 PID: 18566 at drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c:81 mlxsw_sp_port_orig_get.part.9+0x55/0x70 [mlxsw_spectrum]
[...]
 CPU: 0 PID: 18566 Comm: bridge Not tainted 4.8.0-rc7 #1
 Hardware name: Mellanox Technologies Ltd. Mellanox switch/Mellanox switch, BIOS 4.6.5 05/21/2015
  0000000000000286 00000000e64ab94f ffff880406e6f8f0 ffffffff8135eaa3
  0000000000000000 0000000000000000 ffff880406e6f930 ffffffff8108c43b
  0000005106e6f988 ffff8803df398840 ffff880403c60108 ffff880406e6f990
 Call Trace:
  [<ffffffff8135eaa3>] dump_stack+0x63/0x90
  [<ffffffff8108c43b>] __warn+0xcb/0xf0
  [<ffffffff8108c56d>] warn_slowpath_null+0x1d/0x20
  [<ffffffffa01420d5>] mlxsw_sp_port_orig_get.part.9+0x55/0x70 [mlxsw_spectrum]
  [<ffffffffa0142195>] mlxsw_sp_port_attr_get+0xa5/0xb0 [mlxsw_spectrum]
  [<ffffffff816f151f>] switchdev_port_attr_get+0x4f/0x140
  [<ffffffff816f15d0>] switchdev_port_attr_get+0x100/0x140
  [<ffffffff816f15d0>] switchdev_port_attr_get+0x100/0x140
  [<ffffffff816f1d6b>] switchdev_port_bridge_getlink+0x5b/0xc0
  [<ffffffff816f2680>] ? switchdev_port_fdb_dump+0x90/0x90
  [<ffffffff815f5427>] rtnl_bridge_getlink+0xe7/0x190
  [<ffffffff8161a1b2>] netlink_dump+0x122/0x290
  [<ffffffff8161b0df>] __netlink_dump_start+0x15f/0x190
  [<ffffffff815f5340>] ? rtnl_bridge_dellink+0x230/0x230
  [<ffffffff815fab46>] rtnetlink_rcv_msg+0x1a6/0x220
  [<ffffffff81208118>] ? __kmalloc_node_track_caller+0x208/0x2c0
  [<ffffffff815f5340>] ? rtnl_bridge_dellink+0x230/0x230
  [<ffffffff815fa9a0>] ? rtnl_newlink+0x890/0x890
  [<ffffffff8161cf54>] netlink_rcv_skb+0xa4/0xc0
  [<ffffffff815f56f8>] rtnetlink_rcv+0x28/0x30
  [<ffffffff8161c92c>] netlink_unicast+0x18c/0x240
  [<ffffffff8161ccdb>] netlink_sendmsg+0x2fb/0x3a0
  [<ffffffff815c5a48>] sock_sendmsg+0x38/0x50
  [<ffffffff815c6031>] SYSC_sendto+0x101/0x190
  [<ffffffff815c7111>] ? __sys_recvmsg+0x51/0x90
  [<ffffffff815c6b6e>] SyS_sendto+0xe/0x10
  [<ffffffff817017f2>] entry_SYSCALL_64_fastpath+0x1a/0xa4

The problem is that the 8021q module propagates the call to
ndo_bridge_getlink() via switchdev ops, but the switch driver doesn't
recognize the netdev, as it's not offloaded.

While we can ignore calls being made to non-bridge ports inside the
driver, a better fix would be to push this check up to the switchdev
layer.

Note that these ndos can be called for non-bridged netdev, but this only
happens in certain PF drivers which don't call the corresponding
switchdev functions anyway.

Fixes: 99f44bb3 ("mlxsw: spectrum: Enable L3 interfaces on top of bridge devices")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Tamir Winetroub <tamirw@mellanox.com>
Tested-by: Tamir Winetroub <tamirw@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>