Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 6894976..0abe9a4 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
 /*
  *	Definitions for the 'struct ptr_ring' datastructure.
  *
@@ -6,11 +7,6 @@
  *
  *	Copyright (C) 2016 Red Hat, Inc.
  *
- *	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.
- *
  *	This is a limited-size FIFO maintaining pointers in FIFO order, with
  *	one CPU producing entries and another consuming entries from a FIFO.
  *
@@ -26,7 +22,6 @@
 #include <linux/cache.h>
 #include <linux/types.h>
 #include <linux/compiler.h>
-#include <linux/cache.h>
 #include <linux/slab.h>
 #include <asm/errno.h>
 #endif
@@ -573,6 +568,8 @@
 		else if (destroy)
 			destroy(ptr);
 
+	if (producer >= size)
+		producer = 0;
 	__ptr_ring_set_size(r, size);
 	r->producer = producer;
 	r->consumer_head = 0;