selftests 'make install' crashing due to bpf makefile bug

selftests 'make install' crashing due to bpf makefile bug

[Veronika Kabatova]

Hi,

we've been working on adding selftests to CI for bpf-next and ran into
problems when running 'make install'.

Steps to reproduce:

make -C tools/testing/selftests install TARGETS="bpf"

The underlying build completes fine but the install step crashes with
following error:

rsync: link_stat "/kernel/bpf-next/tools/testing/selftests/bpf/runqslower"
       failed: No such file or directory (2)

lib.mk expects all TEST_GEN_PROGS_EXTENDED to be present in the subsystem
selftests directory, while runqslower is located in tools subdirectory
instead [0].

The directory override was originally added together with the runqslower
target in [1] a few months ago. The issue was most likely overlooked for
two reasons:
- people don't use 'make install' for bpf selftests
- kselftest_install.sh script happily continues after errors so while
  the same error is present, it is easy to overlook. runqslower is
  "simply" not present in the created kselftest_install/bpf


We currently see two potential solutions:
a) Remove "OUTPUT=$(SCRATCH_DIR)/" from runqslower target
   - Tested this for our use case but it has a potential of breaking
     workflows
b) Add a copy from bpf/tools to the bpf directory at the end of the target

Which one of them is preferred? Or does anyone have an alternative idea?
I'm willing to post a proper patch if needed (once we agree on the proper
fix) or test any proposals in our environment.


[0]: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/tree/tools/testing/selftests/bpf/Makefile#n143
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3a0d3092a4edbbc

Thanks,
Veronika

Re: selftests 'make install' crashing due to bpf makefile bug

[Andrii Nakryiko]

On Fri, Apr 24, 2020 at 9:29 AM Veronika Kabatova <vkabatov@redhat.com> wrote:
>
>
> Hi,
>
> we've been working on adding selftests to CI for bpf-next and ran into
> problems when running 'make install'.
>
> Steps to reproduce:
>
> make -C tools/testing/selftests install TARGETS="bpf"
>
> The underlying build completes fine but the install step crashes with
> following error:

I assume "crashes" means fails here, not really core-dumping process, right?

>
> rsync: link_stat "/kernel/bpf-next/tools/testing/selftests/bpf/runqslower"
>        failed: No such file or directory (2)
>
> lib.mk expects all TEST_GEN_PROGS_EXTENDED to be present in the subsystem
> selftests directory, while runqslower is located in tools subdirectory
> instead [0].
>
> The directory override was originally added together with the runqslower
> target in [1] a few months ago. The issue was most likely overlooked for
> two reasons:
> - people don't use 'make install' for bpf selftests
> - kselftest_install.sh script happily continues after errors so while
>   the same error is present, it is easy to overlook. runqslower is
>   "simply" not present in the created kselftest_install/bpf
>
>
> We currently see two potential solutions:
> a) Remove "OUTPUT=$(SCRATCH_DIR)/" from runqslower target
>    - Tested this for our use case but it has a potential of breaking
>      workflows
> b) Add a copy from bpf/tools to the bpf directory at the end of the target

We don't want to do a) to keep runqslower completely isolated from
selftest build. Doing b) should be fine, though.

>
> Which one of them is preferred? Or does anyone have an alternative idea?
> I'm willing to post a proper patch if needed (once we agree on the proper
> fix) or test any proposals in our environment.
>
>
> [0]: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/tree/tools/testing/selftests/bpf/Makefile#n143
> [1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3a0d3092a4edbbc
>
> Thanks,
> Veronika
>