Currently, _GNU_SOURCE is defined in resctrl.h. Defining _GNU_SOURCE
has a large impact on what gets defined when including headers either
before or after it. This can result in compile failures if .c file
decides to include a standard header file before resctrl.h.

It is safer to define _GNU_SOURCE in Makefile so it is always defined
regardless of in which order includes are done.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: <stable@vger.kernel.org>
---
 tools/testing/selftests/resctrl/Makefile  | 2 +-
 tools/testing/selftests/resctrl/resctrl.h | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/testing/selftests/resctrl/Makefile b/tools/testing/selftests/resctrl/Makefile
index 5073dbc96125..2deac2031de9 100644
--- a/tools/testing/selftests/resctrl/Makefile
+++ b/tools/testing/selftests/resctrl/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-CFLAGS = -g -Wall -O2 -D_FORTIFY_SOURCE=2
+CFLAGS = -g -Wall -O2 -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE
 CFLAGS += $(KHDR_INCLUDES)
 
 TEST_GEN_PROGS := resctrl_tests
diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index dd07463cdf48..d9b5df95849d 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -1,5 +1,4 @@
 /* SPDX-License-Identifier: GPL-2.0 */
-#define _GNU_SOURCE
 #ifndef RESCTRL_H
 #define RESCTRL_H
 #include <stdio.h>
-- 
2.30.2

Hi Ilpo,

On 9/15/2023 8:44 AM, Ilpo Järvinen wrote:
> Currently, _GNU_SOURCE is defined in resctrl.h. Defining _GNU_SOURCE

nitpick: If you do submit a new version, could you please drop the
"Currently".

> has a large impact on what gets defined when including headers either
> before or after it. This can result in compile failures if .c file
> decides to include a standard header file before resctrl.h.
> 
> It is safer to define _GNU_SOURCE in Makefile so it is always defined
> regardless of in which order includes are done.
> 
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
> Cc: <stable@vger.kernel.org>

Thank you.

Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>

Reinette