Re: [RFC/PATCH] ftrace: add set_graph_notrace filter

[Heiko Carstens]

On Fri, Oct 11, 2013 at 12:17:17AM -0400, Steven Rostedt wrote:
> Isn't there a way we could pass the state? Hmm, I think we could use
> depth to do that. As depth is a pointer to trace.depth and not used
> before then. We could make it negative and then check that.
> 
> /me looks at other archs.
> 
> Darn it, s390 calls ftrace_push_return_trace() before
> ftrace_graph_entry(). They got fancy, as they must have noticed that
> trace.depth is set by ftrace_push_return_trace() and they just figured
> to let the ftrace_push_return_trace() do the work.
> 
> Hmm, we could add a config to do the check on one side or the other
> depending on how the arch handles it.
> 
> It needs to be well commented though.

I don't remember I why decided to do that more than four years ago, however
on the other hand I really don't think we need a config for this.
So I just committed the patch below... it compiles and doesn't crash
immediately, so must be good.
It will be merged during the next merge window.