1 files changed, 60 insertions, 1 deletions

diff --git a/include/uapi/linux/libc-compat.h b/include/uapi/linux/libc-compat.h
index 282875cf8056..fc29efaa918c 100644
--- a/include/uapi/linux/libc-compat.h
+++ b/include/uapi/linux/libc-compat.h
@@ -168,47 +168,106 @@
 
 /* If we did not see any headers from any supported C libraries,
  * or we are being included in the kernel, then define everything
- * that we need. */
+ * that we need. Check for previous __UAPI_* definitions to give
+ * unsupported C libraries a way to opt out of any kernel definition. */
 #else /* !defined(__GLIBC__) */
 
 /* Definitions for if.h */
+#ifndef __UAPI_DEF_IF_IFCONF
 #define __UAPI_DEF_IF_IFCONF 1
+#endif
+#ifndef __UAPI_DEF_IF_IFMAP
 #define __UAPI_DEF_IF_IFMAP 1
+#endif
+#ifndef __UAPI_DEF_IF_IFNAMSIZ
 #define __UAPI_DEF_IF_IFNAMSIZ 1
+#endif
+#ifndef __UAPI_DEF_IF_IFREQ
 #define __UAPI_DEF_IF_IFREQ 1
+#endif
 /* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
+#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS
 #define __UAPI_DEF_IF_NET_DEVICE_FLAGS 1
+#endif
 /* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
+#ifndef __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO
 #define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
+#endif
 
 /* Definitions for in.h */
+#ifndef __UAPI_DEF_IN_ADDR
 #define __UAPI_DEF_IN_ADDR              1
+#endif
+#ifndef __UAPI_DEF_IN_IPPROTO
 #define __UAPI_DEF_IN_IPPROTO           1
+#endif
+#ifndef __UAPI_DEF_IN_PKTINFO
 #define __UAPI_DEF_IN_PKTINFO           1
+#endif
+#ifndef __UAPI_DEF_IP_MREQ
 #define __UAPI_DEF_IP_MREQ              1
+#endif
+#ifndef __UAPI_DEF_SOCKADDR_IN
 #define __UAPI_DEF_SOCKADDR_IN          1
+#endif
+#ifndef __UAPI_DEF_IN_CLASS
 #define __UAPI_DEF_IN_CLASS             1
+#endif
 
 /* Definitions for in6.h */
+#ifndef __UAPI_DEF_IN6_ADDR
 #define __UAPI_DEF_IN6_ADDR             1
+#endif
+#ifndef __UAPI_DEF_IN6_ADDR_ALT
 #define __UAPI_DEF_IN6_ADDR_ALT         1
+#endif
+#ifndef __UAPI_DEF_SOCKADDR_IN6
 #define __UAPI_DEF_SOCKADDR_IN6         1
+#endif
+#ifndef __UAPI_DEF_IPV6_MREQ
 #define __UAPI_DEF_IPV6_MREQ            1
+#endif
+#ifndef __UAPI_DEF_IPPROTO_V6
 #define __UAPI_DEF_IPPROTO_V6           1
+#endif
+#ifndef __UAPI_DEF_IPV6_OPTIONS
 #define __UAPI_DEF_IPV6_OPTIONS         1
+#endif
+#ifndef __UAPI_DEF_IN6_PKTINFO
 #define __UAPI_DEF_IN6_PKTINFO          1
+#endif
+#ifndef __UAPI_DEF_IP6_MTUINFO
 #define __UAPI_DEF_IP6_MTUINFO          1
+#endif
 
 /* Definitions for ipx.h */
+#ifndef __UAPI_DEF_SOCKADDR_IPX
 #define __UAPI_DEF_SOCKADDR_IPX                 1
+#endif
+#ifndef __UAPI_DEF_IPX_ROUTE_DEFINITION
 #define __UAPI_DEF_IPX_ROUTE_DEFINITION         1
+#endif
+#ifndef __UAPI_DEF_IPX_INTERFACE_DEFINITION
 #define __UAPI_DEF_IPX_INTERFACE_DEFINITION     1
+#endif
+#ifndef __UAPI_DEF_IPX_CONFIG_DATA
 #define __UAPI_DEF_IPX_CONFIG_DATA              1
+#endif
+#ifndef __UAPI_DEF_IPX_ROUTE_DEF
 #define __UAPI_DEF_IPX_ROUTE_DEF                1
+#endif
 
 /* Definitions for xattr.h */
+#ifndef __UAPI_DEF_XATTR
 #define __UAPI_DEF_XATTR                1
+#endif
 
 #endif /* __GLIBC__ */
 
+/* Definitions for if_ether.h */
+/* allow libcs like musl to deactivate this, glibc does not implement this. */
+#ifndef __UAPI_DEF_ETHHDR
+#define __UAPI_DEF_ETHHDR               1
+#endif
+
 #endif /* _UAPI_LIBC_COMPAT_H */