Re: [RFC][PATCH] ftracetest: Fix hist unsupported result in hist selftests

[Namhyung Kim <namhyung@kernel.org>]

On Mon, May 23, 2016 at 09:50:45PM -0400, Steven Rostedt wrote:
> On Tue, 24 May 2016 08:54:38 +0900
> Namhyung Kim <namhyung@kernel.org> wrote:
> 
> > Hi Steve,
> > 
> > On Mon, May 23, 2016 at 03:15:38PM -0400, Steven Rostedt wrote:
> > > 
> > > [ Folks, is this a proper work around? ]
> > > 
> > > When histograms are not configured in the kernel, the ftracetest histogram
> > > selftests should return "unsupported" and not "Failed". To detect this, the
> > > test scripts have:
> > > 
> > >  FEATURE=`grep hist events/sched/sched_process_fork/trigger`
> > >  if [ -z "$FEATURE" ]; then
> > >      echo "hist trigger is not supported"
> > >      exit_unsupported
> > >  fi
> > > 
> > > The problem is that '-e' is in effect and any error will cause the program
> > > to terminate. The grep for 'hist' fails, because it is not compiled it (thus
> > > unsupported), but because grep has an error code for failing to find the
> > > string, it causes the program to terminate, and is marked as a failed test.  
> > 
> > We have a feature check before doing grep, doesn't it detect such
> > case?
> > 
> >   if [ ! -f events/sched/sched_process_fork/trigger ]; then
> >       echo "event trigger is not supported"
> >       exit_unsupported
> >   fi
> > 
> 
> Triggers exist, but the "hist" trigger does not, and that's what is
> being checked.

Why not checking "hist" file then?

Thanks,
Namhyung