Re: [PATCH 2/2] ftrace/selftest: Test if set_event/ftrace_pid exists before writing

[Steven Rostedt]

On Wed, 03 Jul 2019 15:50:01 -0400
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> From: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx>
> 
> While testing on a very old kernel (3.5), the tests failed because the write
> to set_event_pid in the setup code, did not exist. The tests themselves
> could pass, but the setup failed causing an error.
> 
> Other files test for existance before writing to them. Do the same for
> set_event_pid and set_ftrace_pid.
> 
> Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
> ---
>  tools/testing/selftests/ftrace/test.d/functions | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
> index 779ec11f61bd..a7b06291e32c 100644
> --- a/tools/testing/selftests/ftrace/test.d/functions
> +++ b/tools/testing/selftests/ftrace/test.d/functions
> @@ -91,8 +91,8 @@ initialize_ftrace() { # Reset ftrace to initial-state
>      reset_events_filter
>      reset_ftrace_filter
>      disable_events
> -    echo > set_event_pid	# event tracer is always on
> -    echo > set_ftrace_pid
> +    [ -f set_event_pid ] && echo > set_event_pid  # event tracer is always on

I probably should remove that comment, because I believe that was why
it wasn't tested :-/

-- Steve


> +    [ -f set_ftrace_pid ] && echo > set_ftrace_pid
>      [ -f set_ftrace_filter ] && echo | tee set_ftrace_*
>      [ -f set_graph_function ] && echo | tee set_graph_*
>      [ -f stack_trace_filter ] && echo > stack_trace_filter