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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Fri, 15 Mar 2019 21:30:25 +0100
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Subject: Re: [PATCH] y2038: fix socket.h header inclusion
To:     Florian Weimer <fw@deneb.enyo.de>
Cc:     "David S . Miller" <davem@davemloft.net>,
        Deepa Dinamani <deepa.kernel@gmail.com>,
        Willem de Bruijn <willemb@google.com>,
        alpha <linux-alpha@vger.kernel.org>,
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        linux-mips@vger.kernel.org,
        Parisc List <linux-parisc@vger.kernel.org>,
        sparclinux <sparclinux@vger.kernel.org>,
        Laura Abbott <labbott@redhat.com>,
        Networking <netdev@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
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On Thu, Mar 14, 2019 at 7:41 PM Florian Weimer <fw@deneb.enyo.de> wrote:
>
> * Arnd Bergmann:
>
> > diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
> > index 0d0fddb7e738..976e89b116e5 100644
> > --- a/arch/alpha/include/uapi/asm/socket.h
> > +++ b/arch/alpha/include/uapi/asm/socket.h
> > @@ -2,8 +2,8 @@
> >  #ifndef _UAPI_ASM_SOCKET_H
> >  #define _UAPI_ASM_SOCKET_H
> >
> > +#include <linux/posix_types.h>
> >  #include <asm/sockios.h>
> > -#include <asm/bitsperlong.h>
>
> This breaks POSIX conformance in glibc because the
> <linux/posix_types.h> header is not namespace clean.  It contains the
> identifiers fds_bits and val:
>
>         unsigned long fds_bits[__FD_SETSIZE / (8 * sizeof(long))];
>
>         int     val[2];

What is problematic about the struct members here? I had thought that
only the struct names have to be in a namespace to be usable here,
but not the members.

The only part that might be problematic is

#undef __FD_SETSIZE
#define __FD_SETSIZE    1024

but we already get that from a number of other inclusions of
linux/posix_types.h. Is this what you mean?

> We could duplicate some of the SO_* constants for POSIX mode in glibc,
> but it would be nice to avoid that.
>
> Is there a different way of fixing this on the kernel side that avoids
> including <linux/posix_types.h>?

We could use asm/posix_types.h instead of linux/posix_types.h,
would that address your concern?

       Arnd