linux-kernel - Re: ftrace_graph_filter not working correctly since v4.10

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Date:   Thu, 2 Mar 2017 13:05:51 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Todd Brandt <todd.e.brandt@...ux.intel.com>,
        linux-kernel@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>
Subject: Re: ftrace_graph_filter not working correctly since v4.10


Namhyung,

Just an FYI...

-- Steve


On Thu, 2 Mar 2017 12:49:40 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> On Wed, 1 Mar 2017 22:47:30 -0500
> Steven Rostedt <rostedt@...dmis.org> wrote:
> 
> > On Wed, 1 Mar 2017 22:28:43 -0500
> > Steven Rostedt <rostedt@...dmis.org> wrote:  
> > > 
> > > 4.10 is fine. It's what has been merged for 4.11 that's broken. I'm
> > > doing a bisect now to see what broke it. Yes, lots of commits touched
> > > that code recently.    
> > 
> > I found the bad commit. I'll have a patch for you to test tomorrow.
> >   
> 
> Can you test this patch please.
> 
> -- Steve
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 2d554a0..1b33a41 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -4403,10 +4403,9 @@ static void __init set_ftrace_early_graph(char *buf, int enable)
>  	char *func;
>  	struct ftrace_hash *hash;
>  
> -	if (enable)
> -		hash = ftrace_graph_hash;
> -	else
> -		hash = ftrace_graph_notrace_hash;
> +	hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
> +	if (WARN_ON(!hash))
> +		return;
>  
>  	while (buf) {
>  		func = strsep(&buf, ",");
> @@ -4416,6 +4415,11 @@ static void __init set_ftrace_early_graph(char *buf, int enable)
>  			printk(KERN_DEBUG "ftrace: function %s not "
>  					  "traceable\n", func);
>  	}
> +
> +	if (enable)
> +		ftrace_graph_hash = hash;
> +	else
> +		ftrace_graph_notrace_hash = hash;
>  }
>  #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
>