Musl defines its own struct ethhdr and thus defines __UAPI_DEF_ETHHDR to
zero. To avoid struct redefinition errors, user space is therefore
supposed to include netinet/if_ether.h before (or instead of)
linux/if_ether.h. To relieve them from this burden, include the libc
header here if not building for kernel space.

Reported-by: Alyssa Ross <hi@alyssa.is>
Suggested-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 include/uapi/linux/netfilter_bridge.h | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/netfilter_bridge.h b/include/uapi/linux/netfilter_bridge.h
index 1610fdbab98d..d4440e56da60 100644
--- a/include/uapi/linux/netfilter_bridge.h
+++ b/include/uapi/linux/netfilter_bridge.h
@@ -5,16 +5,17 @@
 /* bridge-specific defines for netfilter. 
  */
 
+#ifndef __KERNEL__
+#include <limits.h>		/* for INT_MIN, INT_MAX */
+#include <netinet/if_ether.h>	/* for __UAPI_DEF_ETHHDR if defined */
+#endif
+
 #include <linux/in.h>
 #include <linux/netfilter.h>
 #include <linux/if_ether.h>
 #include <linux/if_vlan.h>
 #include <linux/if_pppox.h>
 
-#ifndef __KERNEL__
-#include <limits.h> /* for INT_MIN, INT_MAX */
-#endif
-
 /* Bridge Hooks */
 /* After promisc drops, checksum checks. */
 #define NF_BR_PRE_ROUTING	0
-- 
2.51.0