linux-kernel - Re: [PATCH] ftrace: Consistently restore trace function on sysctl enabling

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Date:	Tue, 26 Mar 2013 15:10:14 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jan Kiszka <jan.kiszka@...mens.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH] ftrace: Consistently restore trace function on sysctl
 enabling

On Tue, 2013-03-26 at 17:53 +0100, Jan Kiszka wrote:
> If we reenable ftrace via syctl, we currently set ftrace_trace_function
> based on the previous simplistic algorithm. This is inconsistent with
> what update_ftrace_function does. So better call that helper instead.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
> ---
>  kernel/trace/ftrace.c |    8 ++------
>  1 files changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 62b71f6..b9b90f0 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -4538,12 +4538,8 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
>  		ftrace_startup_sysctl();
>  
>  		/* we are starting ftrace again */
> -		if (ftrace_ops_list != &ftrace_list_end) {
> -			if (ftrace_ops_list->next == &ftrace_list_end)
> -				ftrace_trace_function = ftrace_ops_list->func;
> -			else
> -				ftrace_trace_function = ftrace_ops_list_func;
> -		}

I remember there was a reason why I didn't update this, but I can't
remember why. Looking at it now, it doesn't look like there is a reason.

I'll have to think about this one more. Another score for not
commenting :-p

Thanks,

-- Steve

> +		if (ftrace_ops_list != &ftrace_list_end)
> +			update_ftrace_function();
>  
>  	} else {
>  		/* stopping ftrace calls (just send to ftrace_stub) */


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