Re: [PATCH 2/3] selftests: add membarrier syscall test

On Thu, 2015-09-03 at 15:47 +0000, Mathieu Desnoyers wrote:

----- On Sep 3, 2015, at 5:33 AM, Michael Ellerman mpe-Gsx/Oe8HsFggBc27wqDAHg@public.gmane.org wrote:

quoted

On Tue, 2015-09-01 at 11:32 -0700, Andy Lutomirski wrote:

quoted

On Tue, Sep 1, 2015 at 10:11 AM, Mathieu Desnoyers
[off-list ref] wrote:

quoted

Just to make sure I understand: should we expect that
everyone will issue "make headers_install" on their system
before doing a make kselftest ?

I see that a few selftests (e.g. memfd) are adding the
source tree include paths to the compiler include paths,
which I guess is to ensure that the kselftest will
work even if the system headers are not up to date.

It would be really nice if there were a clean way for selftests to
include the kernel headers.

What's wrong with make headers_install?

Or do you mean when writing the tests? That we could fix by adding the
../../../../usr/include path to CFLAGS in lib.mk. And fixing all the tests that
overwrite CFLAGS to append to CFLAGS.

quoted

Perhaps make should build the exportable headers somewhere as a dependency of
kselftests.

Yeah the top-level kselftest target could do that I think.

Folks who don't want the headers installed can just run the selftests Makefile
directly.

Does this work for you?

diff --git a/Makefile b/Makefile
index c361593..c8841d3 100644
--- a/Makefile
+++ b/Makefile

@@ -1080,7 +1080,7 @@ headers_check: headers_install

# Kernel selftest

PHONY += kselftest
-kselftest:
+kselftest: headers_install
       $(Q)$(MAKE) -C tools/testing/selftests run_tests

My personal experience is that make headers_install does not necessarily play
well with the distribution header file hierarchy, which requires some tweaks
to be done by the users (e.g. asm vs x86_64-linux-gnu).

OK, I've never had issues. What exactly are you doing and how is it going wrong?

Also, headers_install typically expects a INSTALL_HDR_PATH. 

You can specify it, but the default is just usr/, ie. in the kernel directory,
that is what I was proposing. (Actually it's $(objtree)/usr).

It would be interesting if we could install the kernel headers into a
specific location that is then re-used by kselftest, so using it without too
much manual configuration does not require to overwrite the distribution
header files to run tests.

I think we can do that now, ie:

  $ ls /usr/include/linux/membarrier.h
  ls: cannot access /usr/include/linux/membarrier.h: No such file or directory

  $ cd linux-next
  $ make mrproper
  $ make headers_install
  ...
  $ ls usr/include/linux/membarrier.h
  usr/include/linux/membarrier.h
  $ make -C tools/testing/selftests TARGETS=membarrier
  make: Entering directory '/home/michael/work/topics/selftests/linux-next/tools/testing/selftests'
  for TARGET in membarrier; do \
  	make -C $TARGET; \
  done;
  make[1]: Entering directory '/home/michael/work/topics/selftests/linux-next/tools/testing/selftests/membarrier'
  gcc -g -I../../../../usr/include/ membarrier_test.c -o membarrier_test
  make[1]: Leaving directory '/home/michael/work/topics/selftests/linux-next/tools/testing/selftests/membarrier'
  make: Leaving directory '/home/michael/work/topics/selftests/linux-next/tools/testing/selftests'

  $ ./tools/testing/selftests/membarrier/membarrier_test
  membarrier MEMBARRIER_CMD_QUERY failed. Function not implemented.
  $


So that seems to be working for me. Are you doing some different work flow, or
am I just missing something?

I guess it probably doesn't work if you're using O=.. ?

cheers