selftests: net: use LDLIBS instead of LDFLAGS
authorFathi Boudra <fathi.boudra@linaro.org>
Wed, 16 Jan 2019 17:43:18 +0000 (11:43 -0600)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 13 Mar 2019 21:02:29 +0000 (14:02 -0700)
commitc68cf0831b25b55b058bf180682c9bd7f476475c
treeb8503b8a280121b9dbd0071ddc7eba3338d3eb70
parenteda52fa18e4f8e8764cf27bf8398789a40704187
selftests: net: use LDLIBS instead of LDFLAGS

[ Upstream commit 870f193d48c25a97d61a8e6c04e3c29a2c606850 ]

reuseport_bpf_numa fails to build due to undefined reference errors:

 aarch64-linaro-linux-gcc
 --sysroot=/build/tmp-rpb-glibc/sysroots/hikey -Wall
 -Wl,--no-as-needed -O2 -g -I../../../../usr/include/  -Wl,-O1
 -Wl,--hash-style=gnu -Wl,--as-needed -lnuma  reuseport_bpf_numa.c
 -o
 /build/tmp-rpb-glibc/work/hikey-linaro-linux/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/net/reuseport_bpf_numa
 /tmp/ccfUuExT.o: In function `send_from_node':
 /build/tmp-rpb-glibc/work/hikey-linaro-linux/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/net/reuseport_bpf_numa.c:138:
 undefined reference to `numa_run_on_node'
 /tmp/ccfUuExT.o: In function `main':
 /build/tmp-rpb-glibc/work/hikey-linaro-linux/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/net/reuseport_bpf_numa.c:230:
 undefined reference to `numa_available'
 /build/tmp-rpb-glibc/work/hikey-linaro-linux/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/net/reuseport_bpf_numa.c:233:
 undefined reference to `numa_max_node'

It's GNU Make and linker specific.

The default Makefile rule looks like:

$(CC) $(CFLAGS) $(LDFLAGS) $@ $^ $(LDLIBS)

When linking is done by gcc itself, no issue, but when it needs to be passed
to proper ld, only LDLIBS follows and then ld cannot know what libs to link
with.

More detail:
https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html

LDFLAGS
Extra flags to give to compilers when they are supposed to invoke the linker,
‘ld’, such as -L. Libraries (-lfoo) should be added to the LDLIBS variable
instead.

LDLIBS
Library flags or names given to compilers when they are supposed to invoke the
linker, ‘ld’. LOADLIBES is a deprecated (but still supported) alternative to
LDLIBS. Non-library linker flags, such as -L, should go in the LDFLAGS
variable.

https://lkml.org/lkml/2010/2/10/362

tools/perf: libraries must come after objects

Link order matters, use LDLIBS instead of LDFLAGS to properly link against
libnuma.

Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>
Signed-off-by: Shuah Khan <shuah@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tools/testing/selftests/net/Makefile