vlan: fix GVRP at dismantle time

ip link add link eth2 eth2.103 type vlan id 103 gvrp on loose_binding on
ip link set eth2.103 up
rmmod tg3    # driver providing eth2

 BUG: unable to handle kernel NULL pointer dereference at           (null)
 IP: [<ffffffffa0030c9e>] garp_request_leave+0x3e/0xc0 [garp]
 PGD 11d251067 PUD 11b9e0067 PMD 0
 Oops: 0000 [#1] SMP
 last sysfs file: /sys/devices/virtual/net/eth2.104/ifindex
 CPU 0
 Modules linked in: tg3(-) 8021q garp nfsd lockd auth_rpcgss sunrpc libphy sg [last unloaded: x_tables]

 Pid: 11494, comm: rmmod Tainted: G        W   2.6.39-rc6-00261-gfd71257-dirty #580 HP ProLiant BL460c G6
 RIP: 0010:[<ffffffffa0030c9e>]  [<ffffffffa0030c9e>] garp_request_leave+0x3e/0xc0 [garp]
 RSP: 0018:ffff88007a19bae8  EFLAGS: 00010286
 RAX: 0000000000000000 RBX: ffff88011b5e2000 RCX: 0000000000000002
 RDX: 0000000000000000 RSI: 0000000000000175 RDI: ffffffffa0030d5b
 RBP: ffff88007a19bb18 R08: 0000000000000001 R09: ffff88011bd64a00
 R10: ffff88011d34ec00 R11: 0000000000000000 R12: 0000000000000002
 R13: ffff88007a19bc48 R14: ffff88007a19bb88 R15: 0000000000000001
 FS:  0000000000000000(0000) GS:ffff88011fc00000(0063) knlGS:00000000f77d76c0
 CS:  0010 DS: 002b ES: 002b CR0: 000000008005003b
 CR2: 0000000000000000 CR3: 000000011a675000 CR4: 00000000000006f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
 Process rmmod (pid: 11494, threadinfo ffff88007a19a000, task ffff8800798595c0)
 Stack:
  ffff88007a19bb36 ffff88011c84b800 ffff88011b5e2000 ffff88007a19bc48
  ffff88007a19bb88 0000000000000006 ffff88007a19bb38 ffffffffa003a5f6
  ffff88007a19bb38 670088007a19bba8 ffff88007a19bb58 ffffffffa00397e7
 Call Trace:
  [<ffffffffa003a5f6>] vlan_gvrp_request_leave+0x46/0x50 [8021q]
  [<ffffffffa00397e7>] vlan_dev_stop+0xb7/0xc0 [8021q]
  [<ffffffff8137e427>] __dev_close_many+0x87/0xe0
  [<ffffffff8137e507>] dev_close_many+0x87/0x110
  [<ffffffff8137e630>] rollback_registered_many+0xa0/0x240
  [<ffffffff8137e7e9>] unregister_netdevice_many+0x19/0x60
  [<ffffffffa00389eb>] vlan_device_event+0x53b/0x550 [8021q]
  [<ffffffff8143f448>] ? ip6mr_device_event+0xa8/0xd0
  [<ffffffff81479d03>] notifier_call_chain+0x53/0x80
  [<ffffffff81062539>] __raw_notifier_call_chain+0x9/0x10
  [<ffffffff81062551>] raw_notifier_call_chain+0x11/0x20
  [<ffffffff8137df82>] call_netdevice_notifiers+0x32/0x60
  [<ffffffff8137e69f>] rollback_registered_many+0x10f/0x240
  [<ffffffff8137e85f>] rollback_registered+0x2f/0x40
  [<ffffffff8137e8c8>] unregister_netdevice_queue+0x58/0x90
  [<ffffffff8137e9eb>] unregister_netdev+0x1b/0x30
  [<ffffffffa005d73f>] tg3_remove_one+0x6f/0x10b [tg3]

We should call vlan_gvrp_request_leave() from unregister_vlan_dev(),
not from vlan_dev_stop(), because vlan_gvrp_uninit_applicant()
is called right after unregister_netdevice_queue(). In batch mode,
unregister_netdevice_queue() doesn’t immediately call vlan_dev_stop().
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/8021q/vlan.c

@@ -124,6 +124,9 @@ void unregister_vlan_dev(struct net_device *dev, struct list_head *head)
 
 	grp->nr_vlans--;
 
+	if (vlan->flags & VLAN_FLAG_GVRP)
+		vlan_gvrp_request_leave(dev);
+
 	vlan_group_set_device(grp, vlan_id, NULL);
 	if (!grp->killall)
 		synchronize_net();

net/8021q/vlan_dev.c

@@ -487,9 +487,6 @@ static int vlan_dev_stop(struct net_device *dev)
 	struct vlan_dev_info *vlan = vlan_dev_info(dev);
 	struct net_device *real_dev = vlan->real_dev;
 
-	if (vlan->flags & VLAN_FLAG_GVRP)
-		vlan_gvrp_request_leave(dev);
-
 	dev_mc_unsync(real_dev, dev);
 	dev_uc_unsync(real_dev, dev);
 	if (dev->flags & IFF_ALLMULTI)