[NET_SCHED]: Avoid requeue warning on dev_deactivate

When we relinquish queue_lock in qdisc_restart and then retake it for
requeueing, we might race against dev_deactivate and end up requeueing
onto noop_qdisc.  This causes a warning to be printed.

This patch fixes this by checking this before we requeue.  As an added
bonus, we can remove the same check in __qdisc_run which was added to
prevent dev->gso_skb from being requeued when we're shutting down.

Even though we've had to add a new conditional in its place, it's better
because it only happens on requeues rather than every single time that
qdisc_run is called.

For this to work we also need to move the clearing of gso_skb up in
dev_deactivate as now qdisc_restart can occur even after we wait for
__LINK_STATE_QDISC_RUNNING to clear (but it won't do anything as long
as the queue and gso_skb is already clear).

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 816d311db40fbb5531efbf529ddf2d1421490997..f28bb2dc58d0af3f17c7430eafe9d110ec6cba31 100644 (file)
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -162,7 +162,9 @@ static inline int qdisc_restart(struct net_device *dev)
                 */
 
 requeue:
-               if (skb->next)
+               if (unlikely(q == &noop_qdisc))
+                       kfree_skb(skb);
+               else if (skb->next)
                        dev->gso_skb = skb;
                else
                        q->ops->requeue(skb, q);
@@ -177,15 +179,11 @@ out:
 
 void __qdisc_run(struct net_device *dev)
 {
-       if (unlikely(dev->qdisc == &noop_qdisc))
-               goto out;
-
        do {
                if (!qdisc_restart(dev))
                        break;
        } while (!netif_queue_stopped(dev));
 
-out:
        clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
 }
 
@@ -547,6 +545,7 @@ void dev_activate(struct net_device *dev)
 void dev_deactivate(struct net_device *dev)
 {
        struct Qdisc *qdisc;
+       struct sk_buff *skb;
 
        spin_lock_bh(&dev->queue_lock);
        qdisc = dev->qdisc;
@@ -554,8 +553,12 @@ void dev_deactivate(struct net_device *dev)
 
        qdisc_reset(qdisc);
 
+       skb = dev->gso_skb;
+       dev->gso_skb = NULL;
        spin_unlock_bh(&dev->queue_lock);
 
+       kfree_skb(skb);
+
        dev_watchdog_down(dev);
 
        /* Wait for outstanding dev_queue_xmit calls. */
@@ -564,11 +567,6 @@ void dev_deactivate(struct net_device *dev)
        /* Wait for outstanding qdisc_run calls. */
        while (test_bit(__LINK_STATE_QDISC_RUNNING, &dev->state))
                yield();
-
-       if (dev->gso_skb) {
-               kfree_skb(dev->gso_skb);
-               dev->gso_skb = NULL;
-       }
 }
 
 void dev_init_scheduler(struct net_device *dev)