netdev: Fix lockdep warnings in multiqueue configurations.

When support for multiple TX queues were added, the
netif_tx_lock() routines we converted to iterate over
all TX queues and grab each queue's spinlock.

This causes heartburn for lockdep and it's not a healthy
thing to do with lots of TX queues anyways.

So modify this to use a top-level lock and a "frozen"
state for the individual TX queues.

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

5 files changed, 16 insertions, 8 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 63d6bcd..69320a5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4200,6 +4200,7 @@ static void netdev_init_queues(struct net_device *dev)
 {
 	netdev_init_one_queue(dev, &dev->rx_queue, NULL);
 	netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
+	spin_lock_init(&dev->tx_global_lock);
 }
 
 /**
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index c127208..6c7af39 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -70,6 +70,7 @@ static void queue_process(struct work_struct *work)
 		local_irq_save(flags);
 		__netif_tx_lock(txq, smp_processor_id());
 		if (netif_tx_queue_stopped(txq) ||
+		    netif_tx_queue_frozen(txq) ||
 		    dev->hard_start_xmit(skb, dev) != NETDEV_TX_OK) {
 			skb_queue_head(&npinfo->txq, skb);
 			__netif_tx_unlock(txq);
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index c7d484f..3284605 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3305,6 +3305,7 @@ static __inline__ void pktgen_xmit(struct pktgen_dev *pkt_dev)
 
 	txq = netdev_get_tx_queue(odev, queue_map);
 	if (netif_tx_queue_stopped(txq) ||
+	    netif_tx_queue_frozen(txq) ||
 	    need_resched()) {
 		idle_start = getCurUs();
 
@@ -3320,7 +3321,8 @@ static __inline__ void pktgen_xmit(struct pktgen_dev *pkt_dev)
 
 		pkt_dev->idle_acc += getCurUs() - idle_start;
 
-		if (netif_tx_queue_stopped(txq)) {
+		if (netif_tx_queue_stopped(txq) ||
+		    netif_tx_queue_frozen(txq)) {
 			pkt_dev->next_tx_us = getCurUs();	/* TODO */
 			pkt_dev->next_tx_ns = 0;
 			goto out;	/* Try the next interface */
@@ -3352,7 +3354,8 @@ static __inline__ void pktgen_xmit(struct pktgen_dev *pkt_dev)
 	txq = netdev_get_tx_queue(odev, queue_map);
 
 	__netif_tx_lock_bh(txq);
-	if (!netif_tx_queue_stopped(txq)) {
+	if (!netif_tx_queue_stopped(txq) &&
+	    !netif_tx_queue_frozen(txq)) {
 
 		atomic_inc(&(pkt_dev->skb->users));
 	      retry_now:
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 345838a..9c9cd4d 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -135,7 +135,8 @@ static inline int qdisc_restart(struct Qdisc *q)
 	txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
 
 	HARD_TX_LOCK(dev, txq, smp_processor_id());
-	if (!netif_subqueue_stopped(dev, skb))
+	if (!netif_tx_queue_stopped(txq) &&
+	    !netif_tx_queue_frozen(txq))
 		ret = dev_hard_start_xmit(skb, dev, txq);
 	HARD_TX_UNLOCK(dev, txq);
 
@@ -162,7 +163,8 @@ static inline int qdisc_restart(struct Qdisc *q)
 		break;
 	}
 
-	if (ret && netif_tx_queue_stopped(txq))
+	if (ret && (netif_tx_queue_stopped(txq) ||
+		    netif_tx_queue_frozen(txq)))
 		ret = 0;
 
 	return ret;
diff --git a/net/sched/sch_teql.c b/net/sched/sch_teql.c
index 5372236..2c35c67 100644
--- a/net/sched/sch_teql.c
+++ b/net/sched/sch_teql.c
@@ -305,10 +305,11 @@ restart:
 
 		switch (teql_resolve(skb, skb_res, slave)) {
 		case 0:
-			if (netif_tx_trylock(slave)) {
-				if (!__netif_subqueue_stopped(slave, subq) &&
+			if (__netif_tx_trylock(slave_txq)) {
+				if (!netif_tx_queue_stopped(slave_txq) &&
+				    !netif_tx_queue_frozen(slave_txq) &&
 				    slave->hard_start_xmit(skb, slave) == 0) {
-					netif_tx_unlock(slave);
+					__netif_tx_unlock(slave_txq);
 					master->slaves = NEXT_SLAVE(q);
 					netif_wake_queue(dev);
 					master->stats.tx_packets++;
@@ -316,7 +317,7 @@ restart:
 						qdisc_pkt_len(skb);
 					return 0;
 				}
-				netif_tx_unlock(slave);
+				__netif_tx_unlock(slave_txq);
 			}
 			if (netif_queue_stopped(dev))
 				busy = 1;