linux-kernel - Re: [PATCH 3/3] selftests/ftrace: Use /bin/echo instead of built-in echo

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Date:   Sat, 2 May 2020 12:08:42 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Shuah Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Tom Zanussi <tom.zanussi@...ux.intel.com>,
        Li Philip <philip.li@...el.com>,
        Liu Yiding <yidingx.liu@...el.com>
Subject: Re: [PATCH 3/3] selftests/ftrace: Use /bin/echo instead of built-in
 echo

On Fri, 1 May 2020 10:19:42 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> On Fri,  1 May 2020 22:38:00 +0900
> Masami Hiramatsu <mhiramat@...nel.org> wrote:
> 
> > Since the built-in echo has different behavior in POSIX shell
> > (dash) and bash, we forcibly use /bin/echo -E (not interpret
> > backslash escapes) by default.
> > 
> > This also fixes some test cases which expects built-in
> > echo command.
> > 
> > Reported-by: Liu Yiding <yidingx.liu@...el.com>
> > Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> > ---
> >  tools/testing/selftests/ftrace/test.d/functions    |    3 +++
> >  .../test.d/trigger/trigger-trace-marker-hist.tc    |    2 +-
> >  .../trigger-trace-marker-synthetic-kernel.tc       |    4 ++++
> >  .../trigger/trigger-trace-marker-synthetic.tc      |    4 ++--
> >  4 files changed, 10 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
> > index 5d4550591ff9..ea59b6ea2c3e 100644
> > --- a/tools/testing/selftests/ftrace/test.d/functions
> > +++ b/tools/testing/selftests/ftrace/test.d/functions
> > @@ -1,3 +1,6 @@
> > +# Since the built-in echo has different behavior in POSIX shell (dash) and
> > +# bash, we forcibly use /bin/echo -E (not interpret backslash escapes).
> > +alias echo="/bin/echo -E"
> >  
> >  clear_trace() { # reset trace output
> >      echo > trace
> > diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-hist.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-hist.tc
> > index ab6bedb25736..b3f70f53ee69 100644
> > --- a/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-hist.tc
> > +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-hist.tc
> > @@ -30,7 +30,7 @@ fi
> >  
> >  echo "Test histogram trace_marker tigger"
> >  
> > -echo 'hist:keys=common_pid' > events/ftrace/print/trigger
> > +echo 'hist:keys=ip' > events/ftrace/print/trigger
> 
> This is doing more than just changing the echo being used. It's changing
> the test being done.

Yes, I need Tom's review for this change. As far as I can test, this
fixes the test failure. If this isn't acceptable, we can use "alias echo=echo"
for this test case.

Thank you,

> 
> >  for i in `seq 1 10` ; do echo "hello" > trace_marker; done
> >  grep 'hitcount: *10$' events/ftrace/print/hist > /dev/null || \
> >      fail "hist trigger did not trigger correct times on trace_marker"
> > diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-synthetic-kernel.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-synthetic-kernel.tc
> > index 18b4d1c2807e..c1625d945f4d 100644
> > --- a/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-synthetic-kernel.tc
> > +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-synthetic-kernel.tc
> > @@ -44,6 +44,10 @@ echo 'latency u64 lat' > synthetic_events
> >  echo 'hist:keys=pid:ts0=common_timestamp.usecs' > events/sched/sched_waking/trigger
> >  echo 'hist:keys=common_pid:lat=common_timestamp.usecs-$ts0:onmatch(sched.sched_waking).latency($lat)' > events/ftrace/print/trigger
> >  echo 'hist:keys=common_pid,lat:sort=lat' > events/synthetic/latency/trigger
> > +
> > +# We have to use the built-in echo here because waking up pid must be same
> > +# as echoing pid.
> > +alias echo=echo
> >  sleep 1
> >  echo "hello" > trace_marker
> >  
> > diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-synthetic.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-synthetic.tc
> > index dd262d6d0db6..23e52c8d71de 100644
> > --- a/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-synthetic.tc
> > +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-trace-marker-synthetic.tc
> > @@ -36,8 +36,8 @@ fi
> >  echo "Test histogram trace_marker to trace_marker latency histogram trigger"
> >  
> >  echo 'latency u64 lat' > synthetic_events
> > -echo 'hist:keys=common_pid:ts0=common_timestamp.usecs if buf == "start"' > events/ftrace/print/trigger
> > -echo 'hist:keys=common_pid:lat=common_timestamp.usecs-$ts0:onmatch(ftrace.print).latency($lat) if buf == "end"' >> events/ftrace/print/trigger
> > +echo 'hist:keys=ip:ts0=common_timestamp.usecs if buf == "start"' > events/ftrace/print/trigger
> > +echo 'hist:keys=ip:lat=common_timestamp.usecs-$ts0:onmatch(ftrace.print).latency($lat) if buf == "end"' >> events/ftrace/print/trigger
> 
> This too. And it's not explained in the change log why. In fact, these
> changes look like they belong in a separate patch.
> 
> -- Steve
> 
> >  echo 'hist:keys=common_pid,lat:sort=lat' > events/synthetic/latency/trigger
> >  echo -n "start" > trace_marker
> >  echo -n "end" > trace_marker
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>