v4.19.13 snapshot.
diff --git a/net/netrom/nr_loopback.c b/net/netrom/nr_loopback.c
new file mode 100644
index 0000000..215ad22
--- /dev/null
+++ b/net/netrom/nr_loopback.c
@@ -0,0 +1,77 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Copyright Tomi Manninen OH2BNS (oh2bns@sral.fi)
+ */
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/socket.h>
+#include <linux/timer.h>
+#include <net/ax25.h>
+#include <linux/skbuff.h>
+#include <net/netrom.h>
+#include <linux/init.h>
+
+static void nr_loopback_timer(struct timer_list *);
+
+static struct sk_buff_head loopback_queue;
+static DEFINE_TIMER(loopback_timer, nr_loopback_timer);
+
+void __init nr_loopback_init(void)
+{
+ skb_queue_head_init(&loopback_queue);
+}
+
+static inline int nr_loopback_running(void)
+{
+ return timer_pending(&loopback_timer);
+}
+
+int nr_loopback_queue(struct sk_buff *skb)
+{
+ struct sk_buff *skbn;
+
+ if ((skbn = alloc_skb(skb->len, GFP_ATOMIC)) != NULL) {
+ skb_copy_from_linear_data(skb, skb_put(skbn, skb->len), skb->len);
+ skb_reset_transport_header(skbn);
+
+ skb_queue_tail(&loopback_queue, skbn);
+
+ if (!nr_loopback_running())
+ mod_timer(&loopback_timer, jiffies + 10);
+ }
+
+ kfree_skb(skb);
+ return 1;
+}
+
+static void nr_loopback_timer(struct timer_list *unused)
+{
+ struct sk_buff *skb;
+ ax25_address *nr_dest;
+ struct net_device *dev;
+
+ if ((skb = skb_dequeue(&loopback_queue)) != NULL) {
+ nr_dest = (ax25_address *)(skb->data + 7);
+
+ dev = nr_dev_get(nr_dest);
+
+ if (dev == NULL || nr_rx_frame(skb, dev) == 0)
+ kfree_skb(skb);
+
+ if (dev != NULL)
+ dev_put(dev);
+
+ if (!skb_queue_empty(&loopback_queue) && !nr_loopback_running())
+ mod_timer(&loopback_timer, jiffies + 10);
+ }
+}
+
+void __exit nr_loopback_clear(void)
+{
+ del_timer_sync(&loopback_timer);
+ skb_queue_purge(&loopback_queue);
+}