Hi, On Sun, Nov 12, 2017 at 01:30:17PM -0500, Felix Janda wrote: > libc-compat.h aims to prevent symbol collisions between uapi and libc > headers for each supported libc. This requires continuous coordination > between them. > > The goal of this commit is to improve the situation for libcs (such as > musl) which are not yet supported and/or do not wish to be explicitly > supported, while not affecting supported libcs. More precisely, with > this commit, unsupported libcs can request the suppression of any > specific uapi definition by defining the correspondings _UAPI_DEF_* > macro as 0. This can fix symbol collisions for them, as long as the > libc headers are included before the uapi headers. Inclusion in the > other order is outside the scope of this commit. > > All infrastructure in order to enable this fallback for unsupported > libcs is already in place, except that libc-compat.h unconditionally > defines all _UAPI_DEF_* macros to 1 for all unsupported libcs so that > any previous definitions are ignored. In order to fix this, this commit > merely makes these definitions conditional. > > This commit together with the musl libc commit > > http://git.musl-libc.org/cgit/musl/commit/?id=04983f2272382af92eb8f8838964ff944fbb8258 > > fixes for example the following compiler errors when <linux/in6.h> is > included after musl's <netinet/in.h>: > > ./linux/in6.h:32:8: error: redefinition of 'struct in6_addr' > ./linux/in6.h:49:8: error: redefinition of 'struct sockaddr_in6' > ./linux/in6.h:59:8: error: redefinition of 'struct ipv6_mreq' > > Signed-off-by: Felix Janda <felix.janda@xxxxxxxxx> > Reviewed-by: Hauke Mehrtens <hauke@xxxxxxxxxx> > --- > v3: Fix typos, add a comment to the file and use #ifndef. > v2: The only change to the previous version is the commit title and > message. > --- > include/uapi/linux/libc-compat.h | 55 +++++++++++++++++++++++++++++++++++++++- > 1 file changed, 54 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/libc-compat.h b/include/uapi/linux/libc-compat.h > index 44b8a6bd5fe1..65db6b26d790 100644 > --- a/include/uapi/linux/libc-compat.h > +++ b/include/uapi/linux/libc-compat.h > @@ -167,46 +167,99 @@ > > /* 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 Please double-check that mentioning glibc in comments of this !__GLIBC__ section is relevant. > > /* 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__ */ As most of affected macros are related to networking (in fact, all except __UAPI_DEF_XATTR affect uapi/linux/{if.h,in.h,in6.h,ipv6.h,ipx.h} only), I think this patch should be submitted to netdev. -- ldv
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