net-next: unitialized lock

net-next: unitialized lock

[Stephen Hemminger]

Looks like locks on qdisc aren't initialized properly after
Dave's conversion to MQ.

# brctl addbr br0
# ifconfig br0 10.1.1.1
# ifconfig br0 down
------------------

[  146.937241] br0: Dropping NETIF_F_UFO since no NETIF_F_HW_CSUM feature.
[  253.874538] BUG: spinlock bad magic on CPU#2, ifconfig/7861
[  253.874548]  lock: ffffffff806c0558, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
[  253.874552] Pid: 7861, comm: ifconfig Not tainted 2.6.26 #12
[  253.874557] 
[  253.874557] Call Trace:
[  253.874566]  [<ffffffff803884cf>] spin_bug+0xef/0x100
[  253.874571]  [<ffffffff803886ff>] _raw_spin_lock+0x9f/0x190
[  253.874579]  [<ffffffff8050a822>] _spin_lock_bh+0x32/0x40
[  253.874584]  [<ffffffff8048f197>] dev_deactivate_queue+0x37/0x70
[  253.874591]  [<ffffffff8048ee10>] dev_deactivate+0x40/0x150
[  253.874596]  [<ffffffff8047c18a>] dev_close+0x4a/0xa0
[  253.874602]  [<ffffffff8047bdb1>] dev_change_flags+0xa1/0x1d0
[  253.874609]  [<ffffffff804cba73>] devinet_ioctl+0x5b3/0x760
[  253.874619]  [<ffffffff804cc5fd>] inet_ioctl+0x6d/0x90
[  253.874624]  [<ffffffff8046f446>] sock_ioctl+0x56/0x240
[  253.874630]  [<ffffffff802cbc91>] vfs_ioctl+0x31/0x90
[  253.874635]  [<ffffffff802cbf5b>] do_vfs_ioctl+0x26b/0x2d0
[  253.874640]  [<ffffffff8050a391>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[  253.874646]  [<ffffffff802cc042>] sys_ioctl+0x82/0xa0
[  253.874653]  [<ffffffff8020c518>] system_call_after_swapgs+0x88/0x8d
[  253.874660] 

Re: net-next: unitialized lock

[David Miller]

From: Stephen Hemminger <shemminger@vyatta.com>
Date: Fri, 18 Jul 2008 20:19:45 -0700

> Looks like locks on qdisc aren't initialized properly after
> Dave's conversion to MQ.
> 
> # brctl addbr br0
> # ifconfig br0 10.1.1.1
> # ifconfig br0 down

The noqueue_qdisc is missing some initialization, the following
should fix it.

pkt_sched: Fix noqueue_qdisc initialization.

Like noop_qdisc, it needs a dummy backpointer and
explicit qdisc->q.lock initialization.

Based upon a report by Stephen Hemminger.

Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 14cc443..522a41a 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -340,12 +340,19 @@ static struct Qdisc_ops noqueue_qdisc_ops __read_mostly = {
 	.owner		=	THIS_MODULE,
 };
 
+static struct Qdisc noqueue_qdisc;
+static struct netdev_queue noqueue_netdev_queue = {
+	.qdisc		=	&noqueue_qdisc,
+};
+
 static struct Qdisc noqueue_qdisc = {
 	.enqueue	=	NULL,
 	.dequeue	=	noop_dequeue,
 	.flags		=	TCQ_F_BUILTIN,
 	.ops		=	&noqueue_qdisc_ops,
 	.list		=	LIST_HEAD_INIT(noqueue_qdisc.list),
+	.q.lock		=	__SPIN_LOCK_UNLOCKED(noqueue_qdisc.q.lock),
+	.dev_queue	=	&noqueue_netdev_queue,
 };