Re: [linux-next:master 1875/2100] include/linux/jump_label.h:122:2: error: implicit declaration of function 'atomic_read'

[Stephen Rothwell <sfr@canb.auug.org.au>]

Hi Vlastimil,

On Fri, 29 Jan 2016 11:28:59 +0100 Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 01/29/2016 08:06 AM, kbuild test robot wrote:
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > head:   735cfa51151aeae6df04074165aa36b42481df86
> > commit: e8bd33570a656979c09ce66a11ca8864fda8ad0c [1875/2100] mm, printk: introduce new format string for flags-fix
> > config: s390-allyesconfig (attached as .config)
> > reproduce:
> >         wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
> >         chmod +x ~/bin/make.cross
> >         git checkout e8bd33570a656979c09ce66a11ca8864fda8ad0c
> >         # save the attached .config to linux build tree
> >         make.cross ARCH=s390 
> > 
> > All errors (new ones prefixed by >>):
> > 
> >    In file included from include/linux/static_key.h:1:0,
> >                     from include/linux/tracepoint-defs.h:11,
> >                     from include/linux/mmdebug.h:6,
> >                     from arch/s390/include/asm/cmpxchg.h:10,
> >                     from arch/s390/include/asm/atomic.h:19,
> >                     from include/linux/atomic.h:4,
> >                     from include/linux/debug_locks.h:5,
> >                     from include/linux/lockdep.h:23,
> >                     from include/linux/hardirq.h:5,
> >                     from include/linux/kvm_host.h:10,
> >                     from arch/s390/kernel/asm-offsets.c:10:
> >    include/linux/jump_label.h: In function 'static_key_count':  
> >>> include/linux/jump_label.h:122:2: error: implicit declaration of function 'atomic_read' [-Werror=implicit-function-declaration]  
> >      return atomic_read(&key->enabled);  
> 
> Sigh.
> 
> I don't get it, there's "#include <linux/atomic.h>" in jump_label.h right before
> it gets used. So, what implicit declaration?

But we are in the process of reading linux/atomic.h already, and the
#include in jump_label.h will just not read it then (because of the
include guards) so the body of linux/atomic.h has not yet been read
when we process static_key_count().  i.e. we have a circular inclusion.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au

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