From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net v2] ipv6: sr: fix user space compilation error with old glibc Date: Mon, 15 May 2017 10:09:22 -0400 (EDT) Message-ID: <20170515.100922.2194549018034831667.davem@davemloft.net> References: <20170515110320.23369-1-david.lebrun@uclouvain.be> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, daniel@iogearbox.net To: david.lebrun@uclouvain.be Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:35170 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932677AbdEOOJZ (ORCPT ); Mon, 15 May 2017 10:09:25 -0400 In-Reply-To: <20170515110320.23369-1-david.lebrun@uclouvain.be> Sender: netdev-owner@vger.kernel.org List-ID: From: David Lebrun Date: Mon, 15 May 2017 13:03:20 +0200 > When seg6.h is included in a user space program that also includes > netinet/in.h, it results in multiple definitions of structures such as > struct in6_addr. Recent glibc versions have a workaround that consists in > defining __USE_KERNEL_IPV6_DEFS to prevent duplicates. However, such a > program will fail to compile with older glibc versions. > > This patch ensures that including seg6.h will work in any case. > > v2: do not try to handle __USE_KERNEL_IPV6_DEFS case in seg6.h > > Fixes: ea3ebc73b46fbdb049dafd47543bb22efaa09c8e ("uapi: fix linux/seg6.h and linux/seg6_iptunnel.h userspace compilation errors") > Reported-by: Daniel Borkmann > Signed-off-by: David Lebrun Please, no. The reason we put together a method by which glibc and the kernel can stay out of eachother's way in header files is exactly so that we don't need ifdefs that conditionally do netinet/in.h vs. using the kernel header. There are more than a dozen other UAPI headers which make use of linux/in6.h and none of them jump through hoops like what is being proposed here, and that's on purpose. So special casing this one one header is really not the way to go.