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Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in user space

From Mikko Rapeli <mikko.rapeli@iki.fi>
Newsgroups linux.kernel
Subject Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in user space
Date 2017-08-07 00:00 +0200
Message-ID <ubBKy-7CQ-7@gated-at.bofh.it> (permalink)
References (2 earlier) <ubAls-6Rf-21@gated-at.bofh.it> <ubAOu-72y-17@gated-at.bofh.it> <ubBhw-7tc-21@gated-at.bofh.it> <ubBrc-7wm-29@gated-at.bofh.it> <ubBAR-7zG-17@gated-at.bofh.it>
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On Sun, Aug 06, 2017 at 05:42:13PM -0400, Willem de Bruijn wrote:
> On Sun, Aug 6, 2017 at 5:33 PM, Mikko Rapeli <mikko.rapeli@iki.fi> wrote:
> > On Sun, Aug 06, 2017 at 05:24:20PM -0400, Willem de Bruijn wrote:
> >> >> > +#ifdef __KERNEL__
> >> >> > +#include <linux/time.h>
> >> >> > +#else
> >> >> > +#include <time.h>
> >> >> > +#endif /* __KERNEL__ */
> >> >>
> >> >> This will break applications that include <linux/time.h> manually.
> >> >> I previously sent a patch to use libc-compat to make compilation succeed
> >> >> when both are included in the case where <linux/time.h> is included after
> >> >> <time.h>.
> >> >>
> >> >>   https://lkml.org/lkml/2016/9/12/872
> >> >>
> >> >> The inverse will require changes to the libc header to avoid redefining
> >> >> symbols already defined by <linux/time.h>
> >> >>
> >> >> The second patch in that 2-patch set included <linux/time.h>
> >> >> unconditionally after the fix. This broke builds that also included
> >> >> <time.h> in the wrong order. I did not resubmit the first patch as a
> >> >> stand-alone, as it is not sufficient to avoid breakage.
> >> >
> >> > I wasn't aware of your change, but I was about to send this to fix the
> >> > case when glibc <time.h> is included before <linux/time.h>:
> >> >
> >> > https://github.com/mcfrisk/linux/commit/f3952a27b8a21c6478d26e6246055383483f6a66
> >>
> >> There are a few differences between the two. Including <time.h> does not
> >> unconditionally define all the symbols. Some are conditional on additional
> >> state, such as __timespec_defined.
> >
> > Yep, your patch seems better for libc-compat.h. Could you send it again?
> 
> Okay. Or feel free to include it in the patchset if that helps resolve
> dependencies.

If you don't have the time, I will send tomorrow a new version of this
patch which fixes the commit topic and before that your libc-compat.h change
so both could be applied together.

Feel free to be faster :)

> >> > I don't like leaving a few dozen non-compiling header files into uapi.
> >>
> >> I agree, but I do not see a simple solution.
> >>
> >> Unless libc has the analogous change, including either <time.h> or
> >> <linux/time.h> in userspace can unfortunately cause breakage.
> >>
> >> The added include if __KERNEL__ is defined should be safe, though.
> >
> > Yes, for the kernel side, but your libc-compat change would nice for
> > userspace, where something will break for sure, but providing source
> > API compatibility is sometimes impossible.
> >
> > To summarize, this change from me, and your libc-compat.c for time.h, or?
> 
> I'm still afraid that this patch as is will break builds that include
> <linux/time.h> first.

I agree, but I also want uapi headers to cleanly compile. I know this might
break stuff on userspace side which rely on these broken header file
dependencies, but if the fix to just re-order include
statements I'm fine with it, also when the complaints hit my inbox.

If I had the CPU time, memory and disk space, I'd do a full yocto distro
build to see how badly userspace could break but I don't at home.

-Mikko

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[PATCH v06 00/36] Userspace compile test and fixes for exported uapi header files Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:10 +0200
  [PATCH v06 16/36] uapi linux/dlm_netlink.h: include linux/dlmconstants.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:10 +0200
  [PATCH v06 34/36] uapi: break dependency loop between <linux/hdlc/ioctl.h> and <linux/if.h> Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:10 +0200
  [PATCH v06 12/36] x86 uapi asm/signal.h: use __kernel_size_t instead of size_t Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:10 +0200
    Re: [PATCH v06 12/36] x86 uapi asm/signal.h: use __kernel_size_t  instead of size_t Arnd Bergmann <arnd@arndb.de> - 2017-08-07 16:40 +0200
    Re: [PATCH v06 12/36] x86 uapi asm/signal.h: use __kernel_size_t  instead of size_t "Dmitry V. Levin" <ldv@altlinux.org> - 2017-08-09 01:00 +0200
  [PATCH v06 22/36] uapi linux/reiserfs_xattr.h: use __kernel_size_t instead of size_t Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:10 +0200
    Re: [PATCH v06 22/36] uapi linux/reiserfs_xattr.h: use  __kernel_size_t instead of size_t "Dmitry V. Levin" <ldv@altlinux.org> - 2017-08-09 01:20 +0200
      Re: [PATCH v06 05/36] uapi linux/sysctl.h: use __kernel_size_t  instead of size_t Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-09 09:30 +0200
  [PATCH v06 14/36] arm uapi asm/signal.h: include <stddef.h> for size_t in userspace Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:20 +0200
    Re: [PATCH v06 14/36] arm uapi asm/signal.h: include <stddef.h> for  size_t in userspace "Dmitry V. Levin" <ldv@altlinux.org> - 2017-08-09 01:00 +0200
      Re: [PATCH v06 14/36] arm uapi asm/signal.h: include <stddef.h> for  size_t in userspace Arnd Bergmann <arnd@arndb.de> - 2017-08-09 14:50 +0200
        Re: [PATCH v06 14/36] arm uapi asm/signal.h: include <stddef.h> for  size_t in userspace "Dmitry V. Levin" <ldv@altlinux.org> - 2017-08-09 15:00 +0200
  [PATCH v06 33/36] uapi linux/fsmap.h: use __kernel_size_t instead of size_t Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:20 +0200
    Re: [PATCH v06 33/36] uapi linux/fsmap.h: use __kernel_size_t  instead of size_t "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-07 18:00 +0200
      Re: [PATCH v06 33/36] uapi linux/fsmap.h: use __kernel_size_t instead  of size_t Arnd Bergmann <arnd@arndb.de> - 2017-08-07 18:10 +0200
        Re: [PATCH v06 33/36] uapi linux/fsmap.h: use __kernel_size_t  instead of size_t "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-07 18:50 +0200
          Re: [PATCH v06 33/36] uapi linux/fsmap.h: use __kernel_size_t instead  of size_t Arnd Bergmann <arnd@arndb.de> - 2017-08-07 22:30 +0200
            Re: [PATCH v06 33/36] uapi linux/fsmap.h: use __kernel_size_t  instead of size_t "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-09 01:10 +0200
              Re: [PATCH v06 33/36] uapi linux/fsmap.h: use __kernel_size_t instead  of size_t Arnd Bergmann <arnd@arndb.de> - 2017-08-09 10:30 +0200
  [PATCH v06 01/36] Add scripts/headers_compile_test.sh: compile test for exported uapi headers Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:20 +0200
  [PATCH v06 20/36] uapi linux/scc.h: include linux/sockios.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:20 +0200
  [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in user space Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
    Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in  user space Willem de Bruijn <willemdebruijn.kernel@gmail.com> - 2017-08-06 22:30 +0200
      Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in  user space Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 23:00 +0200
    Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in  user space Willem de Bruijn <willemdebruijn.kernel@gmail.com> - 2017-08-06 22:30 +0200
      Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in  user space Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 23:00 +0200
        Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in  user space Willem de Bruijn <willemdebruijn.kernel@gmail.com> - 2017-08-06 23:30 +0200
          Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in  user space Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 23:40 +0200
            Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in  user space Willem de Bruijn <willemdebruijn.kernel@gmail.com> - 2017-08-06 23:50 +0200
              Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in  user space Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-07 00:00 +0200
                Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in  user space Willem de Bruijn <willemdebruijn.kernel@gmail.com> - 2017-08-07 00:10 +0200
  [PATCH v06 36/36] uapi linux/kfd_ioctl.h: use __u32 and __u64 instead of uint32_t and uint64_t Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
    Re: [PATCH v06 36/36] uapi linux/kfd_ioctl.h: use __u32 and __u64  instead of uint32_t and uint64_t Arnd Bergmann <arnd@arndb.de> - 2017-08-07 17:10 +0200
  [PATCH v06 06/36] uapi asm-generic/ipcbuf.h: include linux/posix_types.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 17/36] uapi linux/sctp.h: use __u8, __u16 and __u32 from linux/types.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 07/36] uapi asm-generic/msgbuf.h: include asm/ipcbuf.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 25/36] uapi linux/android/binder.h: use __kernel_pid_t and __kernel_uid_t Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 02/36] uapi scsi/scsi_bsg_fc.h: use __u8, __u32 and __u64 from linux/types.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 11/36] uapi asm-generic/ucontext.h: include asm/signal.h and asm/sigcontext.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 10/36] uapi asm-generic/signal.h: use __kernel_size_t instead of size_t Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 24/36] uapi linux/coda_psdev.h: move upc_req definition from uapi to kernel side headers Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 09/36] uapi asm-generic/sembuf.h: include asm/posix_types.h and asm/ipcbuf.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
    Re: [PATCH v06 09/36] uapi asm-generic/sembuf.h: include  asm/posix_types.h and asm/ipcbuf.h "Dmitry V. Levin" <ldv@altlinux.org> - 2017-08-09 00:50 +0200
  [PATCH v06 27/36] uapi xen/gntdev.h: include xen/privcmd.h and define grant_ref_t Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 30/36] uapi rdma/rdma_user_rxe.h: include in.h and in6.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
    Re: [PATCH v06 30/36] uapi rdma/rdma_user_rxe.h: include in.h and  in6.h Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-08-09 01:20 +0200
      Re: [PATCH v06 30/36] uapi rdma/rdma_user_rxe.h: include in.h and in6.h Moni Shoua <monis@mellanox.com> - 2017-08-09 15:50 +0200
        Re: [PATCH v06 30/36] uapi rdma/rdma_user_rxe.h: include in.h and  in6.h Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-08-09 18:00 +0200
          Re: [PATCH v06 30/36] uapi rdma/rdma_user_rxe.h: include in.h and  in6.h "Dmitry V. Levin" <ldv@altlinux.org> - 2017-08-10 04:50 +0200
            Re: [PATCH v06 30/36] uapi rdma/rdma_user_rxe.h: include in.h and  in6.h Jason Gunthorpe <jgunthorpe@obsidianresearch.com> - 2017-08-10 18:20 +0200
  [PATCH v06 13/36] x86 uapi asm/sembuf.h: include linux/types.h and linux/ipc.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
    Re: [PATCH v06 13/36] x86 uapi asm/sembuf.h: include linux/types.h  and linux/ipc.h "Dmitry V. Levin" <ldv@altlinux.org> - 2017-08-09 01:00 +0200
  [PATCH v06 26/36] uapi xen/privcmd.h: fix compilation in userspace Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200
  [PATCH v06 28/36] uapi xen/evtchn.h: include xen/privcmd.h Mikko Rapeli <mikko.rapeli@iki.fi> - 2017-08-06 19:30 +0200

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