On Thu, 10 Oct 2019 10:50:35 +0200
Petr Mladek [off-list ref] wrote:

It will make the flag unusable for other ftrace users. But it
will be already be the case when it can't be disabled.

Honestly, I hate that flag. Most people don't even know about it. It
was added in the beginning of ftrace as a way to stop function tracing
in the latency tracer. But that use case has been obsoleted by
328df4759c03e ("tracing: Add function-trace option to disable function
tracing of latency tracers"). I may just remove the damn thing and only
add it back if somebody complains about it.

-- Steve