linux-kernel - Re: Re: Re: [PATCH v3 3/3] perf probe: Show better error message when failed to find variable

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Message-ID: <5551118F.7060101@hitachi.com>
Date:	Tue, 12 May 2015 05:31:11 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
CC:	He Kuang <hekuang@...wei.com>, Ingo Molnar <mingo@...nel.org>,
	a.p.zijlstra@...llo.nl, jolsa@...nel.org, mingo@...hat.com,
	wangnan0@...wei.com, linux-kernel@...r.kernel.org
Subject: Re: Re: Re: [PATCH v3 3/3] perf probe: Show better error message
 when failed to find variable

On 2015/05/11 22:44, Arnaldo Carvalho de Melo wrote:
> Em Mon, May 11, 2015 at 10:35:27AM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Mon, May 11, 2015 at 09:02:47PM +0900, Masami Hiramatsu escreveu:
>>> On 2015/05/11 19:15, He Kuang wrote:
>>>> On 2015/5/11 17:50, Ingo Molnar wrote:
>>>>> * He Kuang <hekuang@...wei.com> wrote:
>>>>>> On 2015/5/11 17:30, Ingo Molnar wrote:
>>>>>>>> After this patch:
>>>>>>>>    $ perf probe --add 'generic_perform_write+118 bytes'
>>>>>>>>    Failed to find the location of bytes at this address.
>>>>>>> What does this sentence mean? I thought 'address' means 'location of
>>>>>>> bytes'. So the address identifies the location and obviously we know
>>>>>>> that. So this message wants to say something else.
>>>>>> 'generic_perform_write' is a function name, while 'bytes' is a local
>>>>>> variable in this function. Maybe the variable I chose make you confused.
>>
>>>>>> This maybe clear:
>>>>>>    Failed to find the location of 'bytes' at this address.
>>>>> Yeah, absolutely! This highlights the importance of putting
>>>>> user-supplied symbols into quotes and such.
>>
>>>>> Maybe even write:
>>
>>>>>      Failed to find the location of the 'bytes' variable at this address.
>>  
>>> OK, He, could you also include this fix?
>>
>> I agree with the change, makes things clearer, will do the change
>> myself. If He has any objection to that, I can fix things up before
>> pushing it to Ingo,

Opps, I missed this...

> 
> So, this is the end result:
> 
> -       if (ret == -ENOENT || ret == -EINVAL)
> -               pr_err("Failed to find the location of %s at this address.\n"
> -                      " Perhaps, it has been optimized out.\n", pf->pvar->var);
> -       else if (ret == -ENOTSUP)
> +       if (ret == -ENOENT || ret == -EINVAL) {
> +               pr_err("Failed to find the location of the '%s' variable at this address.\n"
> +                      " Perhaps it has been optimized out.\n"
> +                      " Use -V with the --range option to show '%s' location range.\n",
> +                      pf->pvar->var, pf->pvar->var);
> +       } else if (ret == -ENOTSUP)

OK, I ack this change.

Thank you,


-- 
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: masami.hiramatsu.pt@...achi.com
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