Re: [RFA][PATCH 06/27] microblaze: ftrace: Add call to ftrace_graph_is_dead() in function graph code

[Steven Rostedt <rostedt@goodmis.org>]

Michal,

Can you ack this please?

-- Steve


On Thu, 26 Jun 2014 12:52:27 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
> 
> ftrace_stop() is going away as it disables parts of function tracing
> that affects users that should not be affected. But ftrace_graph_stop()
> is built on ftrace_stop(). Here's another example of killing all of
> function tracing because something went wrong with function graph
> tracing.
> 
> Instead of disabling all users of function tracing on function graph
> error, disable only function graph tracing. To do this, the arch code
> must call ftrace_graph_is_dead() before it implements function graph.
> 
> Cc: Michal Simek <monstr@monstr.eu>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
>  arch/microblaze/kernel/ftrace.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/microblaze/kernel/ftrace.c b/arch/microblaze/kernel/ftrace.c
> index bbcd2533766c..fc7b48a52cd5 100644
> --- a/arch/microblaze/kernel/ftrace.c
> +++ b/arch/microblaze/kernel/ftrace.c
> @@ -27,6 +27,9 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
>  	unsigned long return_hooker = (unsigned long)
>  				&return_to_handler;
>  
> +	if (unlikely(ftrace_graph_is_dead()))
> +		return;
> +
>  	if (unlikely(atomic_read(&current->tracing_graph_pause)))
>  		return;
>