On 01/18/2013 04:22 AM, Carlos O'Donell wrote: > On Thu, Jan 17, 2013 at 11:20 PM, Mike Frysinger <vapier(a)gentoo.org&gt; wrote: >> On Wednesday 16 January 2013 22:15:38 David Miller wrote: >>> From: Carlos O'Donell <carlos(a)systemhalted.org&gt; >>> Date: Wed, 16 Jan 2013 21:15:03 -0500 >>> >>>> +/* If a glibc-based userspace has already included in.h, then we will >>>> not + * define in6_addr (nor the defines), sockaddr_in6, or ipv6_mreq. >>>> The + * ABI used by the kernel and by glibc match exactly. Neither the >>>> kernel + * nor glibc should break this ABI without coordination. >>>> + */ >>>> +#ifndef _NETINET_IN_H >>>> + >>> >>> I think we should shoot for a non-glibc-centric solution. >>> >>> I can't imagine that other libc's won't have the same exact problem >>> with their netinet/in.h conflicting with the kernel's, redefining >>> structures like in6_addr, that we'd want to provide a protection >>> scheme for here as well. >> >> yes, the kernel's use of __GLIBC__ in exported headers has already caused >> problems in the past. fortunately, it's been reduced down to just one case >> now (stat.h). let's not balloon it back up. >> -mike > > I also see coda.h has grown a __GLIBC__ usage. > > In the next revision of the patch I created a single libc-compat.h header > which encompasses the logic for any libc that wants to coordinate with > the kernel headers. > It's simple enough to move all of the __GLIBC__ uses into libc-compat.h, > then you control userspace libc coordination from one file. How about just deciding on a single macro/symbol both the kernel and libc (any libc that needs this) define? Something like both the kernel and userland doing: #ifndef __IPV6_BITS_DEFINED #define __IPV6_BITS_DEFINED ... define in6_addr, sockaddr_in6, ipv6_mreq, whatnot #endif So whichever the application includes first, wins. Too naive? I didn't see this option being discarded, so not sure it was considered.

>>> It's simple enough to move all of the __GLIBC__ uses into libc-compat.h, >>> then you control userspace libc coordination from one file. >> >> How about just deciding on a single macro/symbol both the >> kernel and libc (any libc that needs this) define? Something >> like both the kernel and userland doing: >> >> #ifndef __IPV6_BITS_DEFINED >> #define __IPV6_BITS_DEFINED >> ... >> define in6_addr, sockaddr_in6, ipv6_mreq, whatnot >> #endif Hmm, how should we handle future structs/enums then? For example, if I want to have in6_flowlabel_req{} defined in glibc, what should we do?