Re: [PATCH -tip v2 2/6] selftests: ftrace: Initialize ftrace before each test

[Steven Rostedt <rostedt@goodmis.org>]

On Sun, 30 Oct 2016 15:54:10 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> Reset ftrace to initial state before running each test.
> This fixes some test cases to enable tracing before starting
> trace test. This can avoid false-positive failure when
> previous testcase fails while disabling tracing.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> Suggested-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  tools/testing/selftests/ftrace/ftracetest       |    2 +-
>  tools/testing/selftests/ftrace/test.d/functions |   25 +++++++++++++++++++++++
>  2 files changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/ftrace/ftracetest b/tools/testing/selftests/ftrace/ftracetest
> index 4c6a0bf..a03d366 100755
> --- a/tools/testing/selftests/ftrace/ftracetest
> +++ b/tools/testing/selftests/ftrace/ftracetest
> @@ -228,7 +228,7 @@ trap 'SIG_RESULT=$XFAIL' $SIG_XFAIL
>  
>  __run_test() { # testfile
>    # setup PID and PPID, $$ is not updated.
> -  (cd $TRACING_DIR; read PID _ < /proc/self/stat ; set -e; set -x; . $1)
> +  (cd $TRACING_DIR; read PID _ < /proc/self/stat; set -e; set -x; initialize_ftrace; . $1)
>    [ $? -ne 0 ] && kill -s $SIG_FAIL $SIG_PID
>  }
>  
> diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
> index c37262f..fbaf565 100644
> --- a/tools/testing/selftests/ftrace/test.d/functions
> +++ b/tools/testing/selftests/ftrace/test.d/functions
> @@ -23,3 +23,28 @@ reset_trigger() { # reset all current setting triggers
>      done
>  }
>  
> +reset_events_filter() { # reset all current setting filters
> +    grep -v ^none events/*/*/filter |
> +    while read line; do
> +	echo 0 > `echo $line | cut -f1 -d:`
> +    done
> +}
> +
> +disable_events() {
> +    echo 0 > events/enable
> +}
> +
> +initialize_ftrace() { # Reset ftrace to initial-state
> +# As the initial state, ftrace will be set to nop tracer,
> +# no events, no triggers, no filters, no function filters,
> +# no probes, and tracing on.
> +    disable_tracing
> +    reset_tracer
> +    reset_trigger
> +    reset_events_filter
> +    disable_events
> +    echo | tee set_ftrace_* set_graph_* stack_trace_filter set_event_pid

I just disabled function graph tracing, and this causes every test to
fail.

   tee: set_graph_*: Permission denied

-- Steve

> +    echo > kprobe_events
> +    echo > uprobe_events
> +    enable_tracing
> +}