[PATCH AUTOSEL 6.6 24/35] selftests/futex: pass _GNU_SOURCE without a value to the compiler

Sasha Levin
2024-06-17T13:24:11Z

From: John Hubbard <jhubbard@nvidia.com>

[ Upstream commit cb708ab9f584f159798b60853edcf0c8b67ce295 ]

It's slightly better to set _GNU_SOURCE in the source code, but if one
must do it via the compiler invocation, then the best way to do so is
this:

$(CC) -D_GNU_SOURCE=

...because otherwise, if this form is used:

$(CC) -D_GNU_SOURCE

...then that leads the compiler to set a value, as if you had passed in:

$(CC) -D_GNU_SOURCE=1

That, in turn, leads to warnings under both gcc and clang, like this:

futex_requeue_pi.c:20: warning: "_GNU_SOURCE" redefined

Fix this by using the "-D_GNU_SOURCE=" form.

Reviewed-by: Edward Liaw <edliaw@google.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/futex/functional/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/futex/functional/Makefile b/tools/testing/selftests/futex/functional/Makefile
index a392d0917b4e5..994fa3468f170 100644
--- a/tools/testing/selftests/futex/functional/Makefile
+++ b/tools/testing/selftests/futex/functional/Makefile
@@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
INCLUDES := -I../include -I../../ $(KHDR_INCLUDES)
-CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE -pthread $(INCLUDES) $(KHDR_INCLUDES)
+CFLAGS := $(CFLAGS) -g -O2 -Wall -D_GNU_SOURCE= -pthread $(INCLUDES) $(KHDR_INCLUDES)
LDLIBS := -lpthread -lrt

LOCAL_HDRS := \
--
2.43.0