net: Clean up explicit ->tx_queue references in link watch.

First, we add a qdisc_tx_changing() helper which returns true if the
qdisc attachment is in transition.

Second, we remove an assertion warning which is of limited value and
is hard to express precisely in a multiqueue environment.

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

include/net/sch_generic.h

@@ -242,6 +242,14 @@ static inline bool qdisc_all_tx_empty(const struct net_device *dev)
 	return (q->q.qlen == 0);
 }
 
+/* Are any of the TX qdiscs changing?  */
+static inline bool qdisc_tx_changing(struct net_device *dev)
+{
+	struct netdev_queue *txq = &dev->tx_queue;
+
+	return (txq->qdisc != txq->qdisc_sleeping);
+}
+
 static inline int __qdisc_enqueue_tail(struct sk_buff *skb, struct Qdisc *sch,
 				       struct sk_buff_head *list)
 {

net/core/link_watch.c

@@ -77,12 +77,10 @@ static void rfc2863_policy(struct net_device *dev)
 }
 
 
-static int linkwatch_urgent_event(struct net_device *dev)
+static bool linkwatch_urgent_event(struct net_device *dev)
 {
-	struct netdev_queue *txq = &dev->tx_queue;
-
 	return netif_running(dev) && netif_carrier_ok(dev) &&
-	       txq->qdisc != txq->qdisc_sleeping;
+		qdisc_tx_changing(dev);
 }
 
 
@@ -182,12 +180,9 @@ static void __linkwatch_run_queue(int urgent_only)
 
 		rfc2863_policy(dev);
 		if (dev->flags & IFF_UP) {
-			if (netif_carrier_ok(dev)) {
-				struct netdev_queue *txq = &dev->tx_queue;
-
-				WARN_ON(txq->qdisc_sleeping == &noop_qdisc);
+			if (netif_carrier_ok(dev))
 				dev_activate(dev);
-			} else
+			else
 				dev_deactivate(dev);
 
 			netdev_state_change(dev);
@@ -218,7 +213,7 @@ static void linkwatch_event(struct work_struct *dummy)
 
 void linkwatch_fire_event(struct net_device *dev)
 {
-	int urgent = linkwatch_urgent_event(dev);
+	bool urgent = linkwatch_urgent_event(dev);
 
 	if (!test_and_set_bit(__LINK_STATE_LINKWATCH_PENDING, &dev->state)) {
 		dev_hold(dev);