Subject: [net-2.6 PATCH 1/2] sched: qdisc_reset_all_tx is calling qdisc_reset without qdisc_lock

From: Jeff Kirsher <[email-masked]>
Date: Thu, 01 Jul 2010 16:21:35 -0700

From: John Fastabend <[email-masked]>

When calling qdisc_reset() the qdisc lock needs to be held.  In
this case there is at least one driver i4l which is using this
without holding the lock.  Add the locking here.

Signed-off-by: John Fastabend <[email-masked]>
Signed-off-by: Jeff Kirsher <[email-masked]>
---

 include/net/sch_generic.h |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 03ca5d8..ba749be 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -317,8 +317,16 @@ extern void tcf_destroy_chain(struct tcf_proto **fl);
 static inline void qdisc_reset_all_tx(struct net_device *dev)
 {
 	unsigned int i;
-	for (i = 0; i < dev->num_tx_queues; i++)
-		qdisc_reset(netdev_get_tx_queue(dev, i)->qdisc);
+	struct Qdisc *qdisc;
+
+	for (i = 0; i < dev->num_tx_queues; i++) {
+		qdisc = netdev_get_tx_queue(dev, i)->qdisc;
+		if (qdisc) {
+			spin_lock_bh(qdisc_lock(qdisc));
+			qdisc_reset(qdisc);
+			spin_unlock_bh(qdisc_lock(qdisc));
+		}
+	}
 }
 
 /* Are all TX queues of the device empty?  */