4 files changed, 30 insertions, 5 deletions

diff --git a/drivers/net/ixgbe/ixgbe_main.c b/drivers/net/ixgbe/ixgbe_main.c
index a0b33165b989..7b5d9764f317 100644
--- a/drivers/net/ixgbe/ixgbe_main.c
+++ b/drivers/net/ixgbe/ixgbe_main.c
@@ -4001,7 +4001,7 @@ static void ixgbe_set_num_queues(struct ixgbe_adapter *adapter)
 
 done:
         /* Notify the stack of the (possibly) reduced Tx Queue count. */
-        adapter->netdev->real_num_tx_queues = adapter->num_tx_queues;
+        netif_set_real_num_tx_queues(adapter->netdev, adapter->num_tx_queues);
 }
 
 static void ixgbe_acquire_msix_vectors(struct ixgbe_adapter *adapter,
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 40291f375024..5e6188d9f017 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1656,6 +1656,9 @@ static inline int netif_is_multiqueue(const struct net_device *dev)
         return (dev->num_tx_queues > 1);
 }
 
+extern void netif_set_real_num_tx_queues(struct net_device *dev,
+                                         unsigned int txq);
+
 /* Use this variant when it is known for sure that it
  * is executing from hardware interrupt context or with hardware interrupts
  * disabled.
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index ba749be1e354..433604bb3fe8 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -313,13 +313,12 @@ extern void qdisc_calculate_pkt_len(struct sk_buff *skb,
 extern void tcf_destroy(struct tcf_proto *tp);
 extern void tcf_destroy_chain(struct tcf_proto **fl);
 
-/* Reset all TX qdiscs of a device.  */
-static inline void qdisc_reset_all_tx(struct net_device *dev)
+/* Reset all TX qdiscs greater then index of a device.  */
+static inline void qdisc_reset_all_tx_gt(struct net_device *dev, unsigned int i)
 {
-        unsigned int i;
         struct Qdisc *qdisc;
 
-        for (i = 0; i < dev->num_tx_queues; i++) {
+        for (; i < dev->num_tx_queues; i++) {
                 qdisc = netdev_get_tx_queue(dev, i)->qdisc;
                 if (qdisc) {
                         spin_lock_bh(qdisc_lock(qdisc));
@@ -329,6 +328,11 @@ static inline void qdisc_reset_all_tx(struct net_device *dev)
         }
 }
 
+static inline void qdisc_reset_all_tx(struct net_device *dev)
+{
+        qdisc_reset_all_tx_gt(dev, 0);
+}
+
 /* Are all TX queues of the device empty?  */
 static inline bool qdisc_all_tx_empty(const struct net_device *dev)
 {
diff --git a/net/core/dev.c b/net/core/dev.c
index 2b3bf53bc687..723a34710ad4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1553,6 +1553,24 @@ static void dev_queue_xmit_nit(struct sk_buff *skb, struct net_device *dev)
         rcu_read_unlock();
 }
 
+/*
+ * Routine to help set real_num_tx_queues. To avoid skbs mapped to queues
+ * greater then real_num_tx_queues stale skbs on the qdisc must be flushed.
+ */
+void netif_set_real_num_tx_queues(struct net_device *dev, unsigned int txq)
+{
+        unsigned int real_num = dev->real_num_tx_queues;
+
+        if (unlikely(txq > dev->num_tx_queues))
+                ;
+        else if (txq > real_num)
+                dev->real_num_tx_queues = txq;
+        else if (txq < real_num) {
+                dev->real_num_tx_queues = txq;
+                qdisc_reset_all_tx_gt(dev, txq);
+        }
+}
+EXPORT_SYMBOL(netif_set_real_num_tx_queues);
 
 static inline void __netif_reschedule(struct Qdisc *q)
 {