Re: [RFA][PATCH 07/27] MIPS: ftrace: Add call to ftrace_graph_is_dead() in function graph code

[Steven Rostedt <rostedt@xxxxxxxxxxx>]

Adding linux-mips@xxxxxxxxxxxxxx.

-- Steve


On Thu, 26 Jun 2014 12:52:28 -0400
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>
> 
> 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: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
> ---
>  arch/mips/kernel/ftrace.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
> index 60e7e5e45af1..8b6538750fe1 100644
> --- a/arch/mips/kernel/ftrace.c
> +++ b/arch/mips/kernel/ftrace.c
> @@ -302,6 +302,9 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
>  	    &return_to_handler;
>  	int faulted, insns;
>  
> +	if (unlikely(ftrace_graph_is_dead()))
> +		return;
> +
>  	if (unlikely(atomic_read(&current->tracing_graph_pause)))
>  		return;
>