linux-kernel - Re: [RFC PATCH] ftrace: Fix depth filtering when func

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Date:   Mon, 22 Jan 2018 18:16:49 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Nikolay Borisov <nborisov@...e.com>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] ftrace: Fix depth filtering when func_stack is
 enabled.

On Mon, 22 Jan 2018 15:50:04 +0200
Nikolay Borisov <nborisov@...e.com> wrote:

> diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
> index 27f7ad12c4b1..b721f1f3f3c0 100644
> --- a/kernel/trace/trace_functions.c
> +++ b/kernel/trace/trace_functions.c
> @@ -181,14 +181,11 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip,
>  		pc = preempt_count();
>  		trace_function(tr, ip, parent_ip, flags, pc);
>  		/*
> -		 * skip over 5 funcs:
> -		 *    __ftrace_trace_stack,
> -		 *    __trace_stack,
> +		 * skip over 2 funcs:
>  		 *    function_stack_trace_call
> -		 *    ftrace_list_func

Thanks, but this breaks when you are not using ORC unwinder.

>  		 *    ftrace_call
>  		 */
> -		__trace_stack(tr, flags, 5, pc);
> +		__trace_stack(tr, flags, 2, pc);
>  	}
>  
>  	atomic_dec(&data->disabled);

There's a bit of ORC unwinder breakage that I'm still dealing with. I
also have patches to handle the differences between ORC and FP, in the
__trace_stack() usages. I'm hoping to have this all fixed by tomorrow,
as I'll be traveling after that.

Thanks!

-- Steve