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Date: Fri, 28 Sep 2012 17:50:43 -0700
From: Josh Triplett <josh@joshtriplett.org>
To: Daniel Santos <daniel.santos@pobox.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Andi Kleen <ak@linux.intel.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
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        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH 7/10] compiler{,-gcc4}.h: Introduce __flatten function
 attribute
Message-ID: <20120929005043.GD14293@jtriplet-mobl1>
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On Fri, Sep 28, 2012 at 07:38:32PM -0500, Daniel Santos wrote:
> On 09/28/2012 07:26 PM, Josh Triplett wrote:
> > On Fri, Sep 28, 2012 at 06:20:08PM -0500, Daniel Santos wrote:
> >> --- a/include/linux/compiler-gcc4.h
> >> +++ b/include/linux/compiler-gcc4.h
> >> @@ -15,7 +15,12 @@
> >>  
> >>  #if GCC_VERSION >= 40102
> >>  # define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
> >> -#endif
> >> +
> >> +/* flatten introduced in 4.1, but broken in 4.6.0 (gcc bug #48731)*/
> >> +# if GCC_VERSION != 40600
> >> +#  define __flatten __attribute__((flatten))
> >> +# endif
> >> +#endif /* GCC_VERSION >= 40102 */
> > Same comment as before: why 40102 rather than 40100?
> Again, I'm presuming building with 4.1.0 or 4.1.1 will always have the
> build broken earlier.  I don't have any objections to changing this, but
> it would seem that the issue with the __weak attribute needs to be resolved.

That issue doesn't relate to __flatten, though; it only relates to
__weak.  Since __flatten (and __compiletime_object_size) will work fine
on 4.1.0 and 4.1.1, don't exclude them just because the definition for
__weak elsewhere in the file excludes them.  That just makes it harder
for anyone who might want to work on the issue with __weak.

- Josh Triplett