Under network load, doing :

tc qdisc del dev eth0 root

triggers :

[  167.193087] BUG: spinlock bad magic on CPU#3, udpflood/4928
[  167.193139]  lock: c15bc324, .magic: 00000000, .owner:
<none>/-1, .owner_cpu: -1
[  167.193193] Pid: 4928, comm: udpflood Not tainted
2.6.36-rc7-11417-g215340c-dirty #323
[  167.193245] Call Trace:
[  167.193292]  [<c13abaa0>] ? printk+0x18/0x20
[  167.193342]  [<c11afb53>] spin_bug+0xa3/0xf0
[  167.193389]  [<c11afcdd>] do_raw_spin_lock+0x7d/0x160
[  167.193440]  [<c1313d4e>] ? __dev_xmit_skb+0x27e/0x2b0
[  167.193496]  [<c107382b>] ? trace_hardirqs_on+0xb/0x10
[  167.193545]  [<c13ae99a>] _raw_spin_lock+0x3a/0x40
[  167.193593]  [<c1313d4e>] ? __dev_xmit_skb+0x27e/0x2b0
[  167.193641]  [<c1313d4e>] __dev_xmit_skb+0x27e/0x2b0

commit 79640a4c (add additional lock to qdisc to increase
throughput) forgot to initialize  noop_qdisc and noqueue_qdisc busylock
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>