bridge: flush br's address entry in fdb when remove the

 bridge dev

When the following commands are executed:

brctl addbr br0
ifconfig br0 hw ether <addr>
rmmod bridge

The calltrace will occur:

[  563.312114] device eth1 left promiscuous mode
[  563.312188] br0: port 1(eth1) entered disabled state
[  563.468190] kmem_cache_destroy bridge_fdb_cache: Slab cache still has objects
[  563.468197] CPU: 6 PID: 6982 Comm: rmmod Tainted: G           O 3.12.0-0.7-default+ #9
[  563.468199] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
[  563.468200]  0000000000000880 ffff88010f111e98 ffffffff814d1c92 ffff88010f111eb8
[  563.468204]  ffffffff81148efd ffff88010f111eb8 0000000000000000 ffff88010f111ec8
[  563.468206]  ffffffffa062a270 ffff88010f111ed8 ffffffffa063ac76 ffff88010f111f78
[  563.468209] Call Trace:
[  563.468218]  [<ffffffff814d1c92>] dump_stack+0x6a/0x78
[  563.468234]  [<ffffffff81148efd>] kmem_cache_destroy+0xfd/0x100
[  563.468242]  [<ffffffffa062a270>] br_fdb_fini+0x10/0x20 [bridge]
[  563.468247]  [<ffffffffa063ac76>] br_deinit+0x4e/0x50 [bridge]
[  563.468254]  [<ffffffff810c7dc9>] SyS_delete_module+0x199/0x2b0
[  563.468259]  [<ffffffff814e0922>] system_call_fastpath+0x16/0x1b
[  570.377958] Bridge firewalling registered

--------------------------- cut here -------------------------------

The reason is that when the bridge dev's address is changed, the
br_fdb_change_mac_address() will add new address in fdb, but when
the bridge was removed, the address entry in the fdb did not free,
the bridge_fdb_cache still has objects when destroy the cache, Fix
this by flushing the bridge address entry when removing the bridge.

v2: according to the Toshiaki Makita and Vlad's suggestion, I only
    delete the vlan0 entry, it still have a leak here if the vlan id
    is other number, so I need to call fdb_delete_by_port(br, NULL, 1)
    to flush all entries whose dst is NULL for the bridge.

Suggested-by: Toshiaki Makita <toshiaki.makita1@gmail.com>
Suggested-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>