linux-kernel - Re: Re: [PATCH 2/2] ftrace: Unify effect of writing to trace

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Message-ID: <4A7BF5B3.6060202@cn.fujitsu.com>
Date:	Fri, 07 Aug 2009 17:36:51 +0800
From:	Zhaolei <zhaolei@...fujitsu.com>
To:	Li Zefan <lizf@...fujitsu.com>
CC:	Steven Rostedt <srostedt@...hat.com>, Ingo Molnar <mingo@...e.hu>,
	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Re: [PATCH 2/2] ftrace: Unify effect of writing to trace_options
 and option/*

Li Zefan wrote:
> Zhaolei wrote:
>> "echo noglobal-clock > trace_options" can be used to change trace
>> clock but "echo 0 > options/global-clock" can't.
>>
>> We can fix it by using set_tracer_flags() in trace_options_core_write().
>>
> 
> Nice catch.
> 
>> Signed-off-by: Zhao Lei <zhaolei@...fujitsu.com>
>> ---
>>  kernel/trace/trace.c |    5 ++---
>>  1 files changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
>> index 464b7bb..2fa2bac 100644
>> --- a/kernel/trace/trace.c
>> +++ b/kernel/trace/trace.c
>> @@ -3893,12 +3893,11 @@ trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt,
>>  
>>  	switch (val) {
>>  	case 0:
>> -		trace_flags &= ~(1 << index);
>> +		set_tracer_flags(1 << index, 0);
>>  		break;
>>  	case 1:
>> -		trace_flags |= 1 << index;
>> +		set_tracer_flags(1 << index, 1);
>>  		break;
>> -
>>  	default:
>>  		return -EINVAL;
>>  	}
> 
> The whole switch statement can be simplied:
> 
> 	if (val != 0 || val != 1)
> 		return -EINVAL;
> 	set_tracer_flags(1 << index, val);

Hello, Li

Thanks.
V2 will send.

Thanks
Zhaolei

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