Re: [PATCH] selftests: use LDLIBS for libraries instead of LDFLAGS

From: shuah
Date: Thu Feb 13 2020 - 15:24:25 EST


On 2/12/20 11:15 AM, shuah wrote:
On 2/12/20 7:00 AM, Dmitry Safonov wrote:
While building selftests, the following errors were observed:
tools/testing/selftests/timens'
gcc -Wall -Werror -pthread -lrt -ldl timens.c -o tools/testing/selftests/timens/timens
/usr/bin/ld: /tmp/ccGy5CST.o: in function `check_config_posix_timers':
timens.c:(.text+0x65a): undefined reference to `timer_create'
collect2: error: ld returned 1 exit status

Quoting commit 870f193d48c2 ("selftests: net: use LDLIBS instead of
LDFLAGS"):

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,
âldâ, 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, âldâ. LOADLIBES is a deprecated (but still supported) alternative to
LDLIBS. Non-library linker flags, such as -L, should go in the LDFLAGS
variable.

While at here, correct other selftests, not only timens ones.

Reported-by: Shuah Khan <skhan@xxxxxxxxxx>
Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>
---
 tools/testing/selftests/futex/functional/Makefile | 2 +-
 tools/testing/selftests/net/Makefile | 4 ++--
 tools/testing/selftests/rtc/Makefile | 2 +-
 tools/testing/selftests/timens/Makefile | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)



Looks good. Thanks for fixing it quickly.

Please split these into 4 patches and send one for each test.

For timens:

Tested-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>


In the interest of getting this fix in, I applied it to

git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git fixes branch.

No need to do anything.

thanks,
-- Shuah