Date: Tue, 2 Jun 2020 17:37:05 -0400 From: Rich Felker <dalias@...c.org> To: musl@...ts.openwall.com Cc: libc-alpha@...rceware.org, linux-kernel@...r.kernel.org Subject: sys/sysinfo.h clash with linux/kernel.h linux/kernel.h is a uapi header that does almost nothing but define some internal-use alignment macros and -- oddly -- include linux/sysinfo.h to provide a definition of struct sysinfo. It's included only from 6 places in the kernel uapi headers: include/uapi/linux/lightnvm.h include/uapi/linux/ethtool.h include/uapi/linux/sysctl.h include/uapi/linux/netlink.h include/uapi/linux/netfilter/x_tables.h include/uapi/linux/mroute6.h However, it's also included from glibc's sys/sysinfo.h to provide struct sysinfo (glibc depends on the kernel for the definition). On musl, this produces a conflicting definition if both sys/sysinfo.h and any of the above 6 headers are included in the same file. I think the underlying problem here is that the same header is used for two very disjoint purposes: by glibc as the provider of struct sysinfo, and by other kernel headers as provider of the alignment macros. The glibc use is effectively a permanent contract that can't be changed, so what I'd like to do is move the macros out to a separate header (maybe linux/something_macros.h?) and have linux/kernel.h and the above 6 uapi headers all include that. Then nothing but linux/kernel.h would pull in linux/sysinfo.h. Note that in practice this is a rather hard issue to hit since almost nothing needs sysinfo() at the same time as the above uapi interfaces. However it did come up in toybox, which is how I first (just today) learned about the conflict, so it seems like something that should be fixed. Rich
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