[PATCH] uapi glibc compat: fix build if libc defines IFF_ECHO

[Hauke Mehrtens]

musl 1.1.15 defines IFF_ECHO and the other net_device_flags options.
When a user application includes linux/if.h and net/if.h the compile
will fail.

Activate __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO only when
it is needed. This should also make this work in case glibc will add
these defines.

Signed-off-by: Hauke Mehrtens <hauke@xxxxxxxxxx>
---
 include/uapi/linux/libc-compat.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/uapi/linux/libc-compat.h b/include/uapi/linux/libc-compat.h
index 44b8a6bd5fe1..dbf16a3de4d2 100644
--- a/include/uapi/linux/libc-compat.h
+++ b/include/uapi/linux/libc-compat.h
@@ -64,9 +64,11 @@
 /* Everything up to IFF_DYNAMIC, matches net/if.h until glibc 2.23 */
 #define __UAPI_DEF_IF_NET_DEVICE_FLAGS 0
 /* For the future if glibc adds IFF_LOWER_UP, IFF_DORMANT and IFF_ECHO */
+#ifndef 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 /* __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO */
+#endif /* IFF_ECHO */
 
 #else /* _NET_IF_H */
 
-- 
2.11.0