linux-kernel - Re: [PATCH 2/2] selftests: firmware: add CONFIG_FW_LOADER_USER_HELPER

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Message-ID: <20190205024150.4ntyl5gccvk7soux@xps.therub.org>
Date:   Mon, 4 Feb 2019 20:41:50 -0600
From:   Dan Rue <dan.rue@...aro.org>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     Shuah Khan <shuah@...nel.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kees Cook <keescook@...omium.org>,
        linux-kselftest@...r.kernel.org,
        Brendan Higgins <brendanhiggins@...gle.com>
Subject: Re: [PATCH 2/2] selftests: firmware: add
 CONFIG_FW_LOADER_USER_HELPER_FALLBACK to config

On Mon, Feb 04, 2019 at 05:39:57PM -0600, Luis Chamberlain wrote:
> On Thu, Nov 29, 2018 at 8:31 PM Luis Chamberlain <mcgrof@...nel.org> wrote:
> >
> > On Mon, Nov 26, 2018 at 09:12:16PM -0600, Dan Rue wrote:
> > > CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y is required for fw_fallback.sh.
> > > Without it, fw_fallback.sh fails with 'usermode helper disabled so
> > > ignoring test'. Enable the config in selftest so that it gets built by
> > > default.
> > >
> > > Signed-off-by: Dan Rue <dan.rue@...aro.org>
> > > ---
> > >  tools/testing/selftests/firmware/config | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/tools/testing/selftests/firmware/config b/tools/testing/selftests/firmware/config
> > > index bf634dda0720..913a25a4a32b 100644
> > > --- a/tools/testing/selftests/firmware/config
> > > +++ b/tools/testing/selftests/firmware/config
> > > @@ -1,5 +1,6 @@
> > >  CONFIG_TEST_FIRMWARE=y
> > >  CONFIG_FW_LOADER=y
> > >  CONFIG_FW_LOADER_USER_HELPER=y
> > > +CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
> > >  CONFIG_IKCONFIG=y
> > >  CONFIG_IKCONFIG_PROC=y
> >
> > NACK -- the point of the changes was to *allow* us to mimic such
> > configuration through a proc sysctl knob.
> >
> > You aren forcing CONFIG_FW_LOADER_USER_HELPER_FALLBACK but just having
> > CONFIG_FW_LOADER_USER_HELPER suffices to emulate the_FALLBACK
> > functionality.
> 
> Dan, again, you broke the whole point to the amount of work that went
> into emulating testing. As such anyone testing their changes would
> yield incorrect results.
> 
> > The issue here seems to be that *all* tests fail once a configuration is
> > found which is not suitable a tests. With the shiny new proc sysctls we
> > can test all 3 kernel configurations in one shot. Since we test 3
> > different kernel configurations naturally some of these won't have the
> > features needed, so that failure should be treated as non-fatal to allow
> > the chain of other tests to continue.
> >
> > This issue was a regression due to commit a6a9be9270c87 ("selftests:
> > firmware: return Kselftest Skip code for skipped tests") by Shuah for
> > the verify_reqs(). We need to treat this as a non-fatal / don't skip
> > return value.
> >
> > The following would fix this chaining issue:
> >
> > diff --git a/tools/testing/selftests/firmware/fw_lib.sh b/tools/testing/selftests/firmware/fw_lib.sh
> > index 6c5f1b2ffb74..1cbb12e284a6 100755
> > --- a/tools/testing/selftests/firmware/fw_lib.sh
> > +++ b/tools/testing/selftests/firmware/fw_lib.sh
> > @@ -91,7 +91,7 @@ verify_reqs()
> >         if [ "$TEST_REQS_FW_SYSFS_FALLBACK" = "yes" ]; then
> >                 if [ ! "$HAS_FW_LOADER_USER_HELPER" = "yes" ]; then
> >                         echo "usermode helper disabled so ignoring test"
> > -                       exit $ksft_skip
> > +                       exit 0
> >                 fi
> >         fi
> >  }
> >
> > However its not clear to me if instead we want some new special return
> > value for selftests so that the framework can detect an that an error
> > is non-fatal, and can continue. This is a tricky situation given the
> > script, existing upstream kernel module, are aware of such emulation
> > hacks via sysctl, but knowledge of this is not obvious to selftests.
> >
> > Shuah, how do you suggest we handle this corner case? If you are OK
> > with the above hunk for now I can send a fix for it. In either case
> > this commit was added on v4.18, so the fix would be a stable fix.
> 
> In lieu of any suggestion I'm going to request we revert this commit
> and send the above fix.

Sorry, I didn't realize this was waiting on me. I agree with all of your
feedback. Please revert 7492902e8d22 ("selftests: firmware: add
CONFIG_FW_LOADER_USER_HELPER_FALLBACK to config") and add my Acked-by to
the proposed fix above.

Shuah, do I need to send a patch for that revert?

It would be nice if there were a way (maybe there is?) to let each of
the individual tests be exposed and run by run_kselftest.sh so that each
test gets its own proper pass/skip/fail. It could be done in this case
by making fw_run_tests.sh look more like run_kselftest.sh (running each
test in a subshell and capturing its exit code), but that starts to get
a bit fragile and ugly, too.

Dan

> 
>  Luis