On Tue, Feb 21, 2017 at 12:10:22PM -0500, David Miller wrote: > From: "Dmitry V. Levin" <l...@altlinux.org> > Date: Mon, 20 Feb 2017 14:58:41 +0300 > > > Include <sys/socket.h> (guarded by ifndef __KERNEL__) to fix > > the following linux/if.h userspace compilation errors: > > Wouldn't it be so much better to do this in include/uapi/linux/socket.h?
Yes, it would be nicer if we could afford it. However, changing uapi/linux/socket.h to include <sys/socket.h> is less conservative than changing every uapi header that fails to compile because of its use of struct sockaddr. It's risky because <sys/socket.h> pulls in other types that might conflict with definitions provided by uapi headers. I've checked all uapi headers that have no compilation errors whether inclusion of <sys/socket.h> before them causes any issues, and found that linux/time.h and linux/uio.h (and their users) stop compiling because of type conflicts: $ gcc -S -o/dev/null -xc /dev/null -include /usr/include/sys/socket.h -include /usr/include/linux/time.h In file included from <command-line>:32:0: /usr/include/linux/time.h:9:8: error: redefinition of 'struct timespec' struct timespec { ^~~~~~~~ In file included from /usr/include/sys/select.h:45:0, from /usr/include/sys/types.h:219, from /usr/include/sys/uio.h:23, from /usr/include/sys/socket.h:26, from <command-line>:32: /usr/include/time.h:120:8: note: originally defined here struct timespec ^~~~~~~~ In file included from <command-line>:32:0: /usr/include/linux/time.h:15:8: error: redefinition of 'struct timeval' struct timeval { ^~~~~~~ In file included from /usr/include/sys/select.h:47:0, from /usr/include/sys/types.h:219, from /usr/include/sys/uio.h:23, from /usr/include/sys/socket.h:26, from <command-line>:32: /usr/include/bits/time.h:30:8: note: originally defined here struct timeval ^~~~~~~ $ gcc -S -o/dev/null -xc /dev/null -include /usr/include/sys/socket.h -include /usr/include/linux/uio.h In file included from <command-line>:32:0: /usr/include/linux/uio.h:16:8: error: redefinition of 'struct iovec' struct iovec ^~~~~ In file included from /usr/include/sys/uio.h:28:0, from /usr/include/sys/socket.h:26, from <command-line>:32: /usr/include/bits/uio.h:43:8: note: originally defined here struct iovec ^~~~~ We can try to workaround these ancient <time.h> against <linux/time.h> and <sys/uio.h> against <linux/uio.h> conflicts on uapi side by introducing __UAPI_DEF_TIMESPEC, __UAPI_DEF_TIMEVAL, and __UAPI_DEF_IOVEC guards, but these workarounds will work only one way (when libc headers are included before uapi ones) until glibc catches up, and the latter may take a lot of time. > I mean, look at the comment right by the change you are making: > > > @@ -24,6 +24,10 @@ > > #include <linux/socket.h> /* for "struct sockaddr" et al */ > > Anyone including linux/socket.h is trying to obtain that type. I think this comment is true for #ifdef __KERNEL__ code only. -- ldv
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