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

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Date:   Tue, 5 Feb 2019 11:14:17 -0800
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Dan Rue <dan.rue@...aro.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 08:41:50PM -0600, Dan Rue wrote:
> 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?

I can send the revert and the subsequent fix.

  Luis