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Date: Wed, 15 Jul 2009 10:28:43 -0400
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] tracing/function: fix the return value of
	ftrace_trace_onoff_callback()
Message-ID: <20090715142814.GA6184@nowhere>
References: <4A5D5B12.2050802@cn.fujitsu.com>
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On Wed, Jul 15, 2009 at 12:29:06PM +0800, Xiao Guangrong wrote:
> ftrace_trace_onoff_callback() will return error even if we do the
> right operation, for example:
> 
> # echo _spin_*:traceon:10 > set_ftrace_filter
> -bash: echo: write error: Invalid argument
> # cat set_ftrace_filter
> #### all functions enabled ####
> _spin_trylock_bh:traceon:count=10
> _spin_unlock_irq:traceon:count=10
> _spin_unlock_bh:traceon:count=10
> _spin_lock_irq:traceon:count=10
> _spin_unlock:traceon:count=10
> _spin_trylock:traceon:count=10
> _spin_unlock_irqrestore:traceon:count=10
> _spin_lock_irqsave:traceon:count=10
> _spin_lock_bh:traceon:count=10
> _spin_lock:traceon:count=10
> 
> We want to set _spin_*:traceon:10 to set_ftrace_filter, it complain
> with "Invalid argument", but the operation is successful.
> So, this patch fix it.
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>


Looks good, thanks.

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


> ---
>  kernel/trace/trace_functions.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
> index 7402144..75ef000 100644
> --- a/kernel/trace/trace_functions.c
> +++ b/kernel/trace/trace_functions.c
> @@ -363,7 +363,7 @@ ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable)
>   out_reg:
>  	ret = register_ftrace_function_probe(glob, ops, count);
>  
> -	return ret;
> +	return ret < 0 ? ret : 0;
>  }
>  
>  static struct ftrace_func_command ftrace_traceon_cmd = {
> -- 
> 1.6.1.2
> 

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