linux-kernel - Re: [PATCH] selftests/ftrace: treat module requirement unmet situation as unsupported

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Date:   Mon, 4 May 2020 16:45:13 +0800
From:   Po-Hsu Lin <po-hsu.lin@...onical.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     linux-kselftest@...r.kernel.org,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>, mingo@...hat.com,
        shuah <shuah@...nel.org>, Colin King <colin.king@...onical.com>,
        Xiao Yang <yangx.jy@...fujitsu.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftests/ftrace: treat module requirement unmet
 situation as unsupported

On Fri, May 1, 2020 at 9:59 AM Masami Hiramatsu <mhiramat@...nel.org> wrote:
>
> Hi,
>
> On Wed, 29 Apr 2020 17:50:44 +0800
> Po-Hsu Lin <po-hsu.lin@...onical.com> wrote:
>
> > When the required module for the test does not exist, use
> > exit_unsupported instead of exit_unresolved to indicate this test is
> > not supported.
>
> Hmm, this doesn't mean "the function is not supported" but
> "we can not resolve this because of the environmental issue".
> For example, if you forgot to install the modules, but the
> function itself is enabled, that can not be tested, but the
> system supports that feature.
>
> >
> > By doing this we can make test behaviour in sync with the
> > irqsoff_tracer.tc test in preemptirq, which is also treating module
> > existence in this way. Moreover, the test won't exit with a non-zero
> > return value if the module does not exist.
>
> It is OK to return zero even if the result is "unresolved", but
> I don't want to change the result of each test cases, because
> it clarify that you must install modules correctly, instead of
> enabling the feature.

Hello Masami,

With Alan Maguire's recent commit b730d668138c ("ftrace/selftest: make
unresolved cases cause failure if --fail-unresolved set") landed on
the tree.
I think this unresolved return value issue is all good here.

It is indeed a good question to brainstorm with about how to
distinguish a not enabled / enabled but not working feature.
I will fix the irqsoff_tracer.tc test here to make them consistent first.

Thank you for your feedback.
Po-Hsu

>
> And OK, I found irqsoff_tracer.tc IS incorrect. It should be fixed to
> return UNRESOLVED if there is no test module.
>
> If you still think UNRESOLVED is unneeded, please propose the patch
> which removes all UNRESOLVED related code. That can start another
> discussion.
>
> Thank you,
>
>
> >
> > Fixes: 646f01ccdd59 ("ftrace/selftest: Add tests to test register_ftrace_direct()")
> > Fixes: 4d23e9b4fd2e ("selftests/ftrace: Add trace_printk sample module test")
> > Fixes: 7bc026d6c032 ("selftests/ftrace: Add function filter on module testcase")
> > Fixes: af2a0750f374 ("selftests/ftrace: Improve kprobe on module testcase to load/unload module")
> > Signed-off-by: Po-Hsu Lin <po-hsu.lin@...onical.com>
> > ---
> >  tools/testing/selftests/ftrace/test.d/direct/ftrace-direct.tc  | 2 +-
> >  tools/testing/selftests/ftrace/test.d/direct/kprobe-direct.tc  | 2 +-
> >  tools/testing/selftests/ftrace/test.d/event/trace_printk.tc    | 2 +-
> >  tools/testing/selftests/ftrace/test.d/ftrace/func_mod_trace.tc | 2 +-
> >  tools/testing/selftests/ftrace/test.d/kprobe/kprobe_module.tc  | 2 +-
> >  5 files changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/testing/selftests/ftrace/test.d/direct/ftrace-direct.tc b/tools/testing/selftests/ftrace/test.d/direct/ftrace-direct.tc
> > index d75a869..3d6189e 100644
> > --- a/tools/testing/selftests/ftrace/test.d/direct/ftrace-direct.tc
> > +++ b/tools/testing/selftests/ftrace/test.d/direct/ftrace-direct.tc
> > @@ -5,7 +5,7 @@
> >  rmmod ftrace-direct ||:
> >  if ! modprobe ftrace-direct ; then
> >    echo "No ftrace-direct sample module - please make CONFIG_SAMPLE_FTRACE_DIRECT=m"
> > -  exit_unresolved;
> > +  exit_unsupported;
> >  fi
> >
> >  echo "Let the module run a little"
> > diff --git a/tools/testing/selftests/ftrace/test.d/direct/kprobe-direct.tc b/tools/testing/selftests/ftrace/test.d/direct/kprobe-direct.tc
> > index 801ecb6..3d0e3ca 100644
> > --- a/tools/testing/selftests/ftrace/test.d/direct/kprobe-direct.tc
> > +++ b/tools/testing/selftests/ftrace/test.d/direct/kprobe-direct.tc
> > @@ -5,7 +5,7 @@
> >  rmmod ftrace-direct ||:
> >  if ! modprobe ftrace-direct ; then
> >    echo "No ftrace-direct sample module - please build with CONFIG_SAMPLE_FTRACE_DIRECT=m"
> > -  exit_unresolved;
> > +  exit_unsupported;
> >  fi
> >
> >  if [ ! -f kprobe_events ]; then
> > diff --git a/tools/testing/selftests/ftrace/test.d/event/trace_printk.tc b/tools/testing/selftests/ftrace/test.d/event/trace_printk.tc
> > index b02550b..dd8b10d 100644
> > --- a/tools/testing/selftests/ftrace/test.d/event/trace_printk.tc
> > +++ b/tools/testing/selftests/ftrace/test.d/event/trace_printk.tc
> > @@ -5,7 +5,7 @@
> >  rmmod trace-printk ||:
> >  if ! modprobe trace-printk ; then
> >    echo "No trace-printk sample module - please make CONFIG_SAMPLE_TRACE_PRINTK=m"
> > -  exit_unresolved;
> > +  exit_unsupported;
> >  fi
> >
> >  echo "Waiting for irq work"
> > diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func_mod_trace.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func_mod_trace.tc
> > index 1a4b4a4..26dc06a 100644
> > --- a/tools/testing/selftests/ftrace/test.d/ftrace/func_mod_trace.tc
> > +++ b/tools/testing/selftests/ftrace/test.d/ftrace/func_mod_trace.tc
> > @@ -13,7 +13,7 @@ echo '*:mod:trace_printk' > set_ftrace_filter
> >  if ! modprobe trace-printk ; then
> >    echo "No trace-printk sample module - please make CONFIG_SAMPLE_TRACE_PRINTK=
> >  m"
> > -  exit_unresolved;
> > +  exit_unsupported;
> >  fi
> >
> >  : "Wildcard should be resolved after loading module"
> > diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_module.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_module.tc
> > index d861bd7..4e07c69 100644
> > --- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_module.tc
> > +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_module.tc
> > @@ -8,7 +8,7 @@ rmmod trace-printk ||:
> >  if ! modprobe trace-printk ; then
> >    echo "No trace-printk sample module - please make CONFIG_SAMPLE_TRACE_PRINTK=
> >  m"
> > -  exit_unresolved;
> > +  exit_unsupported;
> >  fi
> >
> >  MOD=trace_printk
> > --
> > 2.7.4
> >
>
>
> --
> Masami Hiramatsu <mhiramat@...nel.org>