4.4 backport request: perf tools: Fix build failure on perl script context

4.4 backport request: perf tools: Fix build failure on perl script context

[Tuomas Tynkkynen]

Hi Greg,

Please apply the following commit from 4.8 to 4.4.y. It fixes a perf
build failure on distros with modern Perl:

commit b581c01fff646b5075d65359c8667de9c667da9e
Author: Namhyung Kim <namhyung@kernel.org>
Date:   Tue Aug 2 11:43:17 2016 +0900

    perf tools: Fix build failure on perl script context
    
    On my Archlinux machine, perf faild to build like below:
    
        CC       scripts/perl/Perf-Trace-Util/Context.o
      In file included from /usr/lib/perl5/core/perl/CORE/perl.h:3905:0,
                       from Context.xs:23:
      /usr/lib/perl5/core/perl/CORE/inline.h: In function :
      /usr/lib/perl5/core/perl/CORE/cop.h:612:13: warning: declaration of 'av'
                                      shadows a previous local [-Werror-shadow]
                 AV *av =3D GvAV(PL_defgv);
                     ^
      /usr/lib/perl5/core/perl/CORE/inline.h:526:5: note: in expansion of
                                      macro 'CX_POP_SAVEARRAY'
             CX_POP_SAVEARRAY(cx);
             ^~~~~~~~~~~~~~~~
      In file included from /usr/lib/perl5/core/perl/CORE/perl.h:5853:0,
                       from Context.xs:23:
      /usr/lib/perl5/core/perl/CORE/inline.h:518:9: note:
                                      shadowed declaration is here
             AV *av;
                 ^~
    
    What I did to fix is adding '-Wno-shadow' as the error message said it's
    the cause of the failure.  Since it's from the perl (not perf) code
    base, we don't have the control so I just wanted to ignore the warning
    when compiling perl scripting code.
    
    Committer note:
    
    This also fixes the build on Fedora Rawhide.
    
    Signed-off-by: Namhyung Kim <namhyung@kernel.org>
    Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Link: http://lkml.kernel.org/r/20160802024317.31725-1-namhyung@kernel.org
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Thanks.

Re: 4.4 backport request: perf tools: Fix build failure on perl script context

[Greg Kroah-Hartman]

On Thu, Nov 02, 2017 at 02:07:28AM +0200, Tuomas Tynkkynen wrote:
> Hi Greg,
> 
> Please apply the following commit from 4.8 to 4.4.y. It fixes a perf
> build failure on distros with modern Perl:

Now queued up.

But how are you getting past this error when building perf on Arch
Linux:

~/linux/stable/linux-4.4.y/tools/perf $ make
  BUILD:   Doing 'make -j4' parallel build
config/Makefile:448: Missing perl devel files. Disabling perl scripting support, please install perl-ExtUtils-Embed/libperl-dev
make[3]: *** No rule to make target '/usr/lib/gcc/x86_64-pc-linux-gnu/7.1.1/include/stddef.h', needed by 'fixdep.o'.  Stop.
make[2]: *** [Makefile:36: fixdep-in.o] Error 2
make[1]: *** [/home/gregkh/linux/stable/linux-4.4.y/tools/build/Makefile.include:7: fixdep] Error 2
make: *** [Makefile:69: all] Error 2

And yes, ExtUtils:Embed is installed :(

thanks,

greg k-h