Re: panic 2.6.27-rc3-git2, qdisc_dequeue_head

[Jarek Poplawski <jarkao2@gmail.com>]

On Sat, Aug 16, 2008 at 09:15:16PM +0300, Denys Fedoryshchenko wrote:
> Yes, i did apply fix for another problem.
> 
> Other patches applied:
> [PATCH] pkt_sched: Fix unlocking in tc_ctl_tfilter()
> [PATCH] pkt_sched: Add lockdep annotation for qdisc locks

These patches shouldn't change so much. I meant: was this last patch
(with previous one ie. take #3) tested the same as earlier take #3
alone? (There were warnings only, no oopses.)

BTW, here is a patch with another way of fixing this. I would be glad
if you could try this too. The previous patch should be reverted, so
we need only: "take #3", this one and these two you mentioned above.

Jarek P.

---

 include/linux/netdevice.h |    1 +
 include/net/sch_generic.h |    5 ++++-
 net/core/dev.c            |    1 +
 3 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 488c56e..7041c2c 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -445,6 +445,7 @@ struct netdev_queue {
 	struct net_device	*dev;
 	struct Qdisc		*qdisc;
 	unsigned long		state;
+	spinlock_t		qdisc_lock;
 	spinlock_t		_xmit_lock;
 	int			xmit_lock_owner;
 	struct Qdisc		*qdisc_sleeping;
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index a7abfda..f84e96c 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -185,7 +185,10 @@ static inline struct qdisc_skb_cb *qdisc_skb_cb(struct sk_buff *skb)
 
 static inline spinlock_t *qdisc_lock(struct Qdisc *qdisc)
 {
-	return &qdisc->q.lock;
+	if (unlikely(qdisc->flags & TCQ_F_BUILTIN))
+		return &qdisc->q.lock;
+
+	return &qdisc->dev_queue->qdisc_lock;
 }
 
 static inline struct Qdisc *qdisc_root(struct Qdisc *qdisc)
diff --git a/net/core/dev.c b/net/core/dev.c
index 600bb23..9ec20e0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3859,6 +3859,7 @@ static void __netdev_init_queue_locks_one(struct net_device *dev,
 					  void *_unused)
 {
 	spin_lock_init(&dev_queue->_xmit_lock);
+	spin_lock_init(&dev_queue->qdisc_lock);
 	netdev_set_xmit_lockdep_class(&dev_queue->_xmit_lock, dev->type);
 	dev_queue->xmit_lock_owner = -1;
 }