From fcbb6fed85ea9ff4feb4f1ebd4f0f235fdaf06b6 Mon Sep 17 00:00:00 2001
From: David Heidelberger <david.heidelberger@ixit.cz>
Date: Mon, 29 Jun 2015 16:53:03 +0200
Subject: [PATCH 3/3] uapi/if_ether.h: prevent redefinition of struct ethhdr

Musl provides its own ethhdr struct definition. Add a guard to prevent
its definition of the appropriate musl header has already been included.

Signed-off-by: John Spencer <maillist-linux@barfooze.de>
Tested-by: David Heidelberger <david.heidelberger@ixit.cz>
Signed-off-by: Jonas Gorski <jogo@openwrt.org>
---
 include/uapi/linux/if_ether.h    |  3 +++
 include/uapi/linux/libc-compat.h | 11 +++++++++++
 2 files changed, 14 insertions(+)

--- a/include/uapi/linux/if_ether.h
+++ b/include/uapi/linux/if_ether.h
@@ -22,6 +22,7 @@
 #define _UAPI_LINUX_IF_ETHER_H
 
 #include <linux/types.h>
+#include <linux/libc-compat.h>
 
 /*
  *	IEEE 802.3 Ethernet magic constants.  The frame sizes omit the preamble
@@ -134,11 +135,13 @@
  *	This is an Ethernet frame header.
  */
 
+#if __UAPI_DEF_ETHHDR
 struct ethhdr {
 	unsigned char	h_dest[ETH_ALEN];	/* destination eth addr	*/
 	unsigned char	h_source[ETH_ALEN];	/* source ether addr	*/
 	__be16		h_proto;		/* packet type ID field	*/
 } __attribute__((packed));
+#endif
 
 
 #endif /* _UAPI_LINUX_IF_ETHER_H */
--- a/include/uapi/linux/libc-compat.h
+++ b/include/uapi/linux/libc-compat.h
@@ -51,6 +51,14 @@
 /* We have included libc headers... */
 #if !defined(__KERNEL__)
 
+/* musl defines the ethhdr struct itself in its netinet/if_ether.h.
+ * Glibc just includes the kernel header and uses a different guard. */
+#if defined(_NETINET_IF_ETHER_H)
+#define __UAPI_DEF_ETHHDR		0
+#else
+#define __UAPI_DEF_ETHHDR		1
+#endif
+
 /* Coordinate with libc netinet/in.h header. */
 #if defined(_NETINET_IN_H)
 
@@ -117,6 +125,9 @@
  * that we need. */
 #else /* defined(__KERNEL__) */
 
+/* Definitions for if_ether.h */
+#define __UAPI_DEF_ETHHDR 		1
+
 /* Definitions for in.h */
 #define __UAPI_DEF_IN_ADDR		1
 #define __UAPI_DEF_IN_IPPROTO		1
