linux-kernel - Re: [PATCH 2/7] ftrace: Add enable/disable ftrace

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Message-ID: <20120130055906.GC22447@somewhere>
Date:	Mon, 30 Jan 2012 06:59:08 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	rostedt@...dmis.org, mingo@...hat.com, paulus@...ba.org,
	acme@...stprotocols.net, a.p.zijlstra@...llo.nl,
	linux-kernel@...r.kernel.org, aarapov@...hat.com
Subject: Re: [PATCH 2/7] ftrace: Add enable/disable ftrace_ops control
 interface

On Sat, Jan 28, 2012 at 07:43:24PM +0100, Jiri Olsa wrote:
> Adding a way to temporarily enable/disable ftrace_ops. The change
> follows the same way as 'global' ftrace_ops are done.
> 
> Introducing 2 global ftrace_ops - control_ops and ftrace_control_list
> which take over all ftrace_ops registered with FTRACE_OPS_FL_CONTROL
> flag. In addition new per cpu flag called 'disabled' is also added to
> ftrace_ops to provide the control information for each cpu.
> 
> When ftrace_ops with FTRACE_OPS_FL_CONTROL is registered, it is
> set as disabled for all cpus.
> 
> The ftrace_control_list contains all the registered 'control' ftrace_ops.
> The control_ops provides function which iterates ftrace_control_list
> and does the check for 'disabled' flag on current cpu.
> 
> Adding 3 inline functions:
>   ftrace_function_local_disable/ftrace_function_local_enable
>   - enable/disable the ftrace_ops on current cpu
>   ftrace_function_local_disabled
>   - get disabled ftrace_ops::disabled value for current cpu
> 
> Signed-off-by: Jiri Olsa <jolsa@...hat.com>
> ---
>  include/linux/ftrace.h |   65 ++++++++++++++++++++++++++++
>  kernel/trace/ftrace.c  |  111 +++++++++++++++++++++++++++++++++++++++++++++---
>  kernel/trace/trace.h   |    2 +
>  3 files changed, 171 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index f33fb3b..5cb3a51 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -31,16 +31,32 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
>  
>  typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip);
>  
> +/*
> + * FTRACE_OPS_FL_* bits denote the state of ftrace_ops struct and are
> + * set in the flags member.
> + *
> + * ENABLED - set/unset when ftrace_ops is registered/unregistered
> + * GLOBAL  - set manualy by ftrace_ops user to denote the ftrace_ops
> + *           is part of the global tracers sharing the same filter
> + *           via set_ftrace_* debugfs files.
> + * DYNAMIC - set when ftrace_ops is registered to denote dynamically
> + *           allocated ftrace_ops which need special care
> + * CONTROL - set manualy by ftrace_ops user to denote the ftrace_ops
> + *           could be controled by following calls:
> + *           ftrace_function_enable, ftrace_function_disable

Should be ftrace_function_local_enable.

Acked-by: Frederic Weisbecker <fweisbec@...il.com>
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