[PATCH net-next] af_unix: fix a fatal race with bit fields

[Stephen Hemminger]

On Tue, 30 Apr 2013 22:04:32 -0700
Eric Dumazet <eric.dumazet at gmail.com> wrote:

> On Wed, 2013-05-01 at 13:24 +0930, Alan Modra wrote:
> > On Tue, Apr 30, 2013 at 07:24:20PM -0700, Eric Dumazet wrote:
> > > 	li 11,1
> > > 	ld 0,0(9)
> > > 	rldimi 0,11,31,32
> > > 	std 0,0(9)
> > > 	blr
> > > 	.ident	"GCC: (GNU) 4.6.3"
> > > 
> > > You can see "ld 0,0(9)" is used : its a 64 bit load.
> > 
> > Yup.  This is not a powerpc64 specific problem.  See
> > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52080
> > Fixed in 4.8.0 and 4.7.3.
> 
> Ah thanks.
> 
> This seems a pretty serious issue, is it documented somewhere that
> ppc64, sparc64 and others need such compiler version ?
> 
> These kind of errors are pretty hard to find, its a pity to spend time
> on them.

There is a checkbin target inside arch/powerpc/Makefile
Shouldn't a check be added there to block building kernel with known
bad GCC versions?