Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/net/rose/rose_loopback.c b/net/rose/rose_loopback.c
index 7af4f99..7b09427 100644
--- a/net/rose/rose_loopback.c
+++ b/net/rose/rose_loopback.c
@@ -1,8 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
 /*
- * 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 (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
  */
@@ -16,6 +13,7 @@
 #include <linux/init.h>
 
 static struct sk_buff_head loopback_queue;
+#define ROSE_LOOPBACK_LIMIT 1000
 static struct timer_list loopback_timer;
 
 static void rose_set_loopback_timer(void);
@@ -35,29 +33,27 @@
 
 int rose_loopback_queue(struct sk_buff *skb, struct rose_neigh *neigh)
 {
-	struct sk_buff *skbn;
+	struct sk_buff *skbn = NULL;
 
-	skbn = skb_clone(skb, GFP_ATOMIC);
+	if (skb_queue_len(&loopback_queue) < ROSE_LOOPBACK_LIMIT)
+		skbn = skb_clone(skb, GFP_ATOMIC);
 
-	kfree_skb(skb);
-
-	if (skbn != NULL) {
+	if (skbn) {
+		consume_skb(skb);
 		skb_queue_tail(&loopback_queue, skbn);
 
 		if (!rose_loopback_running())
 			rose_set_loopback_timer();
+	} else {
+		kfree_skb(skb);
 	}
 
 	return 1;
 }
 
-
 static void rose_set_loopback_timer(void)
 {
-	del_timer(&loopback_timer);
-
-	loopback_timer.expires  = jiffies + 10;
-	add_timer(&loopback_timer);
+	mod_timer(&loopback_timer, jiffies + 10);
 }
 
 static void rose_loopback_timer(struct timer_list *unused)
@@ -68,8 +64,12 @@
 	struct sock *sk;
 	unsigned short frametype;
 	unsigned int lci_i, lci_o;
+	int count;
 
-	while ((skb = skb_dequeue(&loopback_queue)) != NULL) {
+	for (count = 0; count < ROSE_LOOPBACK_LIMIT; count++) {
+		skb = skb_dequeue(&loopback_queue);
+		if (!skb)
+			return;
 		if (skb->len < ROSE_MIN_LEN) {
 			kfree_skb(skb);
 			continue;
@@ -106,6 +106,8 @@
 			kfree_skb(skb);
 		}
 	}
+	if (!skb_queue_empty(&loopback_queue))
+		mod_timer(&loopback_timer, jiffies + 1);
 }
 
 void __exit rose_loopback_clear(void)