Switching to -O2 when building the mm tests has the unexpected side effect of triggering many unused-result warnings on certain distros like Ubuntu, where GCC is configured so that -O2 implies -D_FORTIFY_SOURCE.
Explicitly disable FORTIFY_SOURCE to avoid those warnings. This has no effect on upstream toolchains where FORTIFY_SOURCE is not implicitly enabled.
Suggested-by: Ryan Roberts ryan.roberts@arm.com Signed-off-by: Kevin Brodsky kevin.brodsky@arm.com ---
Hi Andrew,
Could you please take this fixup patch for "selftests/mm: Build with -O2" in mm-unstable? Ryan found that building the mm kselftests on Ubuntu yields a bunch of warnings, this patch suppresses them.
Cheers, - Kevin
Cc: aruna.ramakrishna@oracle.com Cc: catalin.marinas@arm.com Cc: dave.hansen@linux.intel.com Cc: joey.gouly@arm.com Cc: keith.lucas@oracle.com Cc: shuah@kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kselftest@vger.kernel.org Cc: linux-mm@kvack.org Cc: x86@kernel.org --- tools/testing/selftests/mm/Makefile | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index fce194a92cad..d633d6b6a6e1 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -36,6 +36,13 @@ MAKEFLAGS += --no-builtin-rules CFLAGS = -Wall -O2 -I $(top_srcdir) $(EXTRA_CFLAGS) $(KHDR_INCLUDES) $(TOOLS_INCLUDES) LDLIBS = -lrt -lpthread -lm
+# Some distributions (such as Ubuntu) configure GCC so that _FORTIFY_SOURCE is +# automatically enabled at -O1 or above. This triggers various unused-result +# warnings where functions such as read() or write() are called and their +# return value is not checked. Disable _FORTIFY_SOURCE to silence those +# warnings. +CFLAGS += -U_FORTIFY_SOURCE + KDIR ?= /lib/modules/$(shell uname -r)/build ifneq (,$(wildcard $(KDIR)/Module.symvers)) ifneq (,$(wildcard $(KDIR)/include/linux/page_frag_cache.h))