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From:   Akemi Yagi <toracat@elrepo.org>
Date:   Sun, 5 Jan 2020 10:21:25 -0800
Message-ID: <CABA31DrtCwUj-wzPP+dwUP+=jTOHnt8eoS+d+N2yfAn22W19vA@mail.gmail.com>
Subject: Re: 4.9.208 regression in perf building
To:     Gordan Bobic <gordan@redsleeve.org>
Cc:     stable@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        ElRepo <contact@elrepo.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@kernel.org>
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Adding Arnaldo and Jiri to the CC list.

On Sun, Jan 5, 2020 at 9:01 AM Gordan Bobic <gordan@redsleeve.org> wrote:
>
> It looks like 4.9.208 introduces a build regression for perf:
>
> make -f /builddir/build/BUILD/kernel-4.9.208/linux-4.9.208-1.el7.x86_64/tools/build/Makefile.build
> dir=. obj=perf

>  -c -o builtin-report.o builtin-report.c
> builtin-report.c: In function ‘report__setup_sample_type’:
> builtin-report.c:296:6: error: ‘dwarf_callchain_users’ undeclared
> (first use in this function)
>   if (dwarf_callchain_users) {
>       ^
> builtin-report.c:296:6: note: each undeclared identifier is reported
> only once for each function it appears in
> mv: cannot stat ‘./.builtin-report.o.tmp’: No such file or directory
> make[3]: *** [builtin-report.o] Error 1
> make[2]: *** [perf-in.o] Error 2
> make[1]: *** [sub-make] Error 2
> make: *** [all] Error 2
>
> 4,9.207 works fine.

The regression was caused by the following patch:

https://lore.kernel.org/lkml/20191021133834.25998-7-acme@kernel.org/

To fix this, 'dwarf_callchain_users' needs to be declared.

Akemi