6lowpan: clean up fragments list if module unloaded

Clean all the pending fragments and relative timers if 6lowpan link
is going to be deleted.
Signed-off-by: NAlexander Smirnov <alex.bluesman.smirnov@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ieee802154/6lowpan.c

@@ -1177,11 +1177,20 @@ static void lowpan_dellink(struct net_device *dev, struct list_head *head)
 {
 	struct lowpan_dev_info *lowpan_dev = lowpan_dev_info(dev);
 	struct net_device *real_dev = lowpan_dev->real_dev;
-	struct lowpan_dev_record *entry;
-	struct lowpan_dev_record *tmp;
+	struct lowpan_dev_record *entry, *tmp;
+	struct lowpan_fragment *frame, *tframe;
 
 	ASSERT_RTNL();
 
+	spin_lock(&flist_lock);
+	list_for_each_entry_safe(frame, tframe, &lowpan_fragments, list) {
+		del_timer(&frame->timer);
+		list_del(&frame->list);
+		dev_kfree_skb(frame->skb);
+		kfree(frame);
+	}
+	spin_unlock(&flist_lock);
+
 	mutex_lock(&lowpan_dev_info(dev)->dev_list_mtx);
 	list_for_each_entry_safe(entry, tmp, &lowpan_devices, list) {
 		if (entry->ldev == dev) {