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Message-ID: <20170806205654.GF28459@lakka.kapsi.fi>
Date: Sun, 6 Aug 2017 23:56:54 +0300
From: Mikko Rapeli <mikko.rapeli@....fi>
To: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Linux API <linux-api@...r.kernel.org>,
Willem de Bruijn <willemb@...gle.com>,
Soheil Hassas Yeganeh <soheil@...gle.com>,
Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH v06 18/36] uapi linux/errqueue.h: include linux/time.h in
user space
On Sun, Aug 06, 2017 at 04:23:16PM -0400, Willem de Bruijn wrote:
> On Sun, Aug 6, 2017 at 12:44 PM, Mikko Rapeli <mikko.rapeli@....fi> wrote:
> > linux/time.h conflicts with user space header time.h. Try to be compatible
> > with both.
> >
> > Fixes userspace compilation error:
> >
> > error: array type has incomplete element type
> > struct timespec ts[3];
> >
> > Signed-off-by: Mikko Rapeli <mikko.rapeli@....fi>
> > Cc: Willem de Bruijn <willemb@...gle.com>
> > Cc: Soheil Hassas Yeganeh <soheil@...gle.com>
> > Cc: netdev@...r.kernel.org
> > ---
> > include/uapi/linux/errqueue.h | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/include/uapi/linux/errqueue.h b/include/uapi/linux/errqueue.h
> > index 07bdce1f444a..b310b2c6d94f 100644
> > --- a/include/uapi/linux/errqueue.h
> > +++ b/include/uapi/linux/errqueue.h
> > @@ -3,6 +3,12 @@
> >
> > #include <linux/types.h>
> >
> > +#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
but you also ran into problems where <linux/time.h> is included before
<time.h> which need fixes in libc header side.
So how to proceed with these?
I don't like leaving a few dozen non-compiling header files into uapi.
-Mikko
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