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

----- On Sep 3, 2015, at 11:36 PM, Michael Ellerman mpe@ellerman.id.au wrote:

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

quoted

----- On Sep 3, 2015, at 5:33 AM, Michael Ellerman mpe@ellerman.id.au 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?

After some investigation, I noticed the following:

1) I first ran make headers_install as root, which installed the
headers within my build tree. I later tried it again as user, and
it failed due to permission issues (my bad). This is where I tried
to install it into my system rather than under my build directory,
which caused a mess.

2) Since make kselftest should be run as root (according to make
help), this means that all the output files generated by the build
are owned by root. It leads to permissions issues when trying to
rebuild the tests as user afterward. Perhaps we could introduce a
distinction between make kselftest_build and make kselftest_run ?
The former could be executed as user, and the latter as root.

quoted

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).

OK, trying it out.

quoted

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?

When doing make headers_install, it indeed installs
membarrier.h where we expect it under the build output
dir:

$ ls usr/include/linux/membarrier.h 
usr/include/linux/membarrier.h

However, if I issue 

$ make -C tools/testing/selftests TARGETS=membarrier
make: Entering directory `/home/efficios/git/linux-next/tools/testing/selftests'
for TARGET in membarrier; do \
		make -C $TARGET; \
	done;
make[1]: Entering directory `/home/efficios/git/linux-next/tools/testing/selftests/membarrier'
gcc     membarrier_test.c   -o membarrier_test
membarrier_test.c:2:30: fatal error: linux/membarrier.h: No such file or directory
 #include <linux/membarrier.h>

This is after applying the modifications you requested
(see patch attached). Perhaps I did something wrong ?

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

I'm not using anything special here. My src tree is my obj
output directory.

Thanks,

Mathieu

cheers

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com