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

[Steven Rostedt]

On Tue, 24 May 2016 08:54:38 +0900
Namhyung Kim <namhyung@xxxxxxxxxx> 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.

-- Steve