[PATCH 1/1] tools feature gettid: Undef _GNU_SOURCE before defining it

[PATCH 1/1] tools feature gettid: Undef _GNU_SOURCE before defining it

[Arnaldo Carvalho de Melo]

Since most of tools/build/feature/test-*.c feature tests are included in
tools/build/feature/test-all.c, we can't just define _GNU_SOURCE as it
may already been defined and this will break the build with:

  acme@alta:~$ cat /tmp/build/perf-tools-next/feature/test-all.make.output
  In file included from test-all.c:26:
  test-gettid.c:3:9: error: "_GNU_SOURCE" redefined [-Werror]
      3 | #define _GNU_SOURCE
        |         ^~~~~~~~~~~
  In file included from /usr/include/python3.13/pyconfig.h:9,
                   from /usr/include/python3.13/Python.h:14,
                   from test-python-module.c:2,
                   from test-all.c:14:
  /usr/include/aarch64-linux-gnu/python3.13/pyconfig.h:1810:10: note: this is the location of the previous definition
   1810 | # define _GNU_SOURCE 1
        |          ^~~~~~~~~~~
  cc1: all warnings being treated as errors
  acme@alta:~$

I.e. pyconfig.h is included by the new test-python-module.c, that is at
the start of test-all.c, defines _GNU_SOURCE, noticed on Debian 13
(/usr/include/aarch64-linux-gnu/python3.13/pyconfig.h, libpython
3.13.5-2+deb13u5), and then test-all.c includes test-gettid.c that was
defining it as well, undef it first as does several other tests.

Fixes: 1b7e0280e247b93d ("perf Makefile: Update Python script installation path")
Cc: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/build/feature/test-gettid.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/build/feature/test-gettid.c b/tools/build/feature/test-gettid.c
index ef24e42d3f1b877d..a8fdb26196697b66 100644
--- a/tools/build/feature/test-gettid.c
+++ b/tools/build/feature/test-gettid.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (C) 2019, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
+#undef _GNU_SOURCE
 #define _GNU_SOURCE
 #include <unistd.h>
 
-- 
2.55.0

Re: [PATCH 1/1] tools feature gettid: Undef _GNU_SOURCE before defining it

[sashiko-bot]

> Since most of tools/build/feature/test-*.c feature tests are included in
> tools/build/feature/test-all.c, we can't just define _GNU_SOURCE as it
> may already been defined and this will break the build with:
> 
>   acme@alta:~$ cat /tmp/build/perf-tools-next/feature/test-all.make.output
>   In file included from test-all.c:26:
>   test-gettid.c:3:9: error: "_GNU_SOURCE" redefined [-Werror]
>       3 | #define _GNU_SOURCE
>         |         ^~~~~~~~~~~
>   In file included from /usr/include/python3.13/pyconfig.h:9,
>                    from /usr/include/python3.13/Python.h:14,
>                    from test-python-module.c:2,
>                    from test-all.c:14:
>   /usr/include/aarch64-linux-gnu/python3.13/pyconfig.h:1810:10: note: this is the location of the previous definition
>    1810 | # define _GNU_SOURCE 1
>         |          ^~~~~~~~~~~
>   cc1: all warnings being treated as errors
>   acme@alta:~$
> 
> I.e. pyconfig.h is included by the new test-python-module.c, that is at
> the start of test-all.c, defines _GNU_SOURCE, noticed on Debian 13
> (/usr/include/aarch64-linux-gnu/python3.13/pyconfig.h, libpython
> 3.13.5-2+deb13u5), and then test-all.c includes test-gettid.c that was
> defining it as well, undef it first as does several other tests.
> 
> Fixes: 1b7e0280e247b93d ("perf Makefile: Update Python script installation path")
> Cc: Ian Rogers <irogers@google.com>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/arpXYeRUu3B-ouqB@x2?part=1

Re: [PATCH 1/1] tools feature gettid: Undef _GNU_SOURCE before defining it

[Arnaldo Carvalho de Melo]

On Mon, Sep 28, 2026 at 02:02:45PM +0200, Arnaldo Carvalho de Melo wrote:
> Since most of tools/build/feature/test-*.c feature tests are included in
> tools/build/feature/test-all.c, we can't just define _GNU_SOURCE as it
> may already been defined and this will break the build with:
> 
>   acme@alta:~$ cat /tmp/build/perf-tools-next/feature/test-all.make.output
>   In file included from test-all.c:26:
>   test-gettid.c:3:9: error: "_GNU_SOURCE" redefined [-Werror]
>       3 | #define _GNU_SOURCE
>         |         ^~~~~~~~~~~
>   In file included from /usr/include/python3.13/pyconfig.h:9,
>                    from /usr/include/python3.13/Python.h:14,
>                    from test-python-module.c:2,
>                    from test-all.c:14:
>   /usr/include/aarch64-linux-gnu/python3.13/pyconfig.h:1810:10: note: this is the location of the previous definition
>    1810 | # define _GNU_SOURCE 1
>         |          ^~~~~~~~~~~
>   cc1: all warnings being treated as errors
>   acme@alta:~$
> 
> I.e. pyconfig.h is included by the new test-python-module.c, that is at
> the start of test-all.c, defines _GNU_SOURCE, noticed on Debian 13
> (/usr/include/aarch64-linux-gnu/python3.13/pyconfig.h, libpython
> 3.13.5-2+deb13u5), and then test-all.c includes test-gettid.c that was

Noticed as well on fedora:

make: Leaving directory '/home/acme/git/perf-tools-next/tools/perf'
105: 'import perf' in python                                                                                   : Ok

=== Test Summary ===
Passed main tests : 1
Passed subtests   : 0
Skipped tests     : 0
Failed tests      : 0
In file included from test-all.c:26:
test-gettid.c:3:9: error: ‘_GNU_SOURCE’ redefined [-Werror]
    3 | #define _GNU_SOURCE
      |         ^~~~~~~~~~~
In file included from /usr/include/python3.14/pyconfig.h:6,
                 from /usr/include/python3.14/Python.h:14,
                 from test-python-module.c:2,
                 from test-all.c:14:
/usr/include/python3.14/pyconfig-64.h:1879:10: note: this is the location of the previous definition
 1879 | # define _GNU_SOURCE 1
      |          ^~~~~~~~~~~
cc1: all warnings being treated as errors
⬢ [acme@toolbx perf-tools-next]$ head /etc/os-release
NAME="Fedora Linux"
VERSION="44 (Toolbx Container Image)"
RELEASE_TYPE=stable
ID=fedora
VERSION_ID=44
VERSION_CODENAME=""
PRETTY_NAME="Fedora Linux 44 (Toolbx Container Image)"
ANSI_COLOR="0;38;2;60;110;180"
LOGO=fedora-logo-icon
CPE_NAME="cpe:/o:fedoraproject:fedora:44"
⬢ [acme@toolbx perf-tools-next]$

Re: [PATCH 1/1] tools feature gettid: Undef _GNU_SOURCE before defining it

[Ian Rogers]

On Mon, Sep 28, 2026 at 5:02 AM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> Since most of tools/build/feature/test-*.c feature tests are included in
> tools/build/feature/test-all.c, we can't just define _GNU_SOURCE as it
> may already been defined and this will break the build with:
>
>   acme@alta:~$ cat /tmp/build/perf-tools-next/feature/test-all.make.output
>   In file included from test-all.c:26:
>   test-gettid.c:3:9: error: "_GNU_SOURCE" redefined [-Werror]
>       3 | #define _GNU_SOURCE
>         |         ^~~~~~~~~~~
>   In file included from /usr/include/python3.13/pyconfig.h:9,
>                    from /usr/include/python3.13/Python.h:14,
>                    from test-python-module.c:2,
>                    from test-all.c:14:
>   /usr/include/aarch64-linux-gnu/python3.13/pyconfig.h:1810:10: note: this is the location of the previous definition
>    1810 | # define _GNU_SOURCE 1
>         |          ^~~~~~~~~~~
>   cc1: all warnings being treated as errors
>   acme@alta:~$
>
> I.e. pyconfig.h is included by the new test-python-module.c, that is at
> the start of test-all.c, defines _GNU_SOURCE, noticed on Debian 13
> (/usr/include/aarch64-linux-gnu/python3.13/pyconfig.h, libpython
> 3.13.5-2+deb13u5), and then test-all.c includes test-gettid.c that was
> defining it as well, undef it first as does several other tests.
>
> Fixes: 1b7e0280e247b93d ("perf Makefile: Update Python script installation path")
> Cc: Ian Rogers <irogers@google.com>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks!
Ian

> ---
>  tools/build/feature/test-gettid.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/tools/build/feature/test-gettid.c b/tools/build/feature/test-gettid.c
> index ef24e42d3f1b877d..a8fdb26196697b66 100644
> --- a/tools/build/feature/test-gettid.c
> +++ b/tools/build/feature/test-gettid.c
> @@ -1,5 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0
>  // Copyright (C) 2019, Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
> +#undef _GNU_SOURCE
>  #define _GNU_SOURCE
>  #include <unistd.h>
>
> --
> 2.55.0
>

Re: [PATCH 1/1] tools feature gettid: Undef _GNU_SOURCE before defining it

[Arnaldo Carvalho de Melo]

On Mon, Sep 28, 2026 at 08:12:45AM -0700, Ian Rogers wrote:
> On Mon, Sep 28, 2026 at 5:02 AM Arnaldo Carvalho de Melo
> <acme@kernel.org> wrote:
> >
> > Since most of tools/build/feature/test-*.c feature tests are included in
> > tools/build/feature/test-all.c, we can't just define _GNU_SOURCE as it
> > may already been defined and this will break the build with:
> >
> >   acme@alta:~$ cat /tmp/build/perf-tools-next/feature/test-all.make.output
> >   In file included from test-all.c:26:
> >   test-gettid.c:3:9: error: "_GNU_SOURCE" redefined [-Werror]
> >       3 | #define _GNU_SOURCE
> >         |         ^~~~~~~~~~~
> >   In file included from /usr/include/python3.13/pyconfig.h:9,
> >                    from /usr/include/python3.13/Python.h:14,
> >                    from test-python-module.c:2,
> >                    from test-all.c:14:
> >   /usr/include/aarch64-linux-gnu/python3.13/pyconfig.h:1810:10: note: this is the location of the previous definition
> >    1810 | # define _GNU_SOURCE 1
> >         |          ^~~~~~~~~~~
> >   cc1: all warnings being treated as errors
> >   acme@alta:~$
> >
> > I.e. pyconfig.h is included by the new test-python-module.c, that is at
> > the start of test-all.c, defines _GNU_SOURCE, noticed on Debian 13
> > (/usr/include/aarch64-linux-gnu/python3.13/pyconfig.h, libpython
> > 3.13.5-2+deb13u5), and then test-all.c includes test-gettid.c that was
> > defining it as well, undef it first as does several other tests.
> >
> > Fixes: 1b7e0280e247b93d ("perf Makefile: Update Python script installation path")
> > Cc: Ian Rogers <irogers@google.com>
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> 
> Reviewed-by: Ian Rogers <irogers@google.com>

Thanks, applied to perf-tools-next, for v7.4.

- Arnaldo