linux-kernel - Re: [BUGFIX][PATCH v6 2/9] perf config: If collect_config() is failed, finally free a config set after it is done

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Date:	Tue, 7 Jun 2016 16:44:50 +0900
From:	Taeung Song <treeze.taeung@...il.com>
To:	Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:	linux-kernel@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>
Subject: Re: [BUGFIX][PATCH v6 2/9] perf config: If collect_config() is
 failed, finally free a config set after it is done



On 06/07/2016 06:37 AM, Taeung Song wrote:
>
>
> On 06/07/2016 05:23 AM, Arnaldo Carvalho de Melo wrote:
>> Em Mon, Jun 06, 2016 at 07:52:53PM +0900, Taeung Song escreveu:
>>> Because of die() at perf_parse_file() a config set was freed
>>> in collect_config(), if failed.
>>> But it is natural to free a config set after collect_config() is done
>>> when some problems happened.
>>>
>>> So, in case of failure, lastly free a config set at
>>> perf_config_set__new()
>>> instead of freeing the config set in collect_config().
>>>
>>> Cc: Namhyung Kim <namhyung@...nel.org>
>>> Cc: Jiri Olsa <jolsa@...hat.com>
>>> Cc: Masami Hiramatsu <mhiramat@...nel.org>
>>> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
>>> Signed-off-by: Taeung Song <treeze.taeung@...il.com>
>>> ---
>>>   tools/perf/util/config.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
>>> index b500737..d013f90 100644
>>> --- a/tools/perf/util/config.c
>>> +++ b/tools/perf/util/config.c
>>> @@ -639,7 +639,6 @@ static int collect_config(const char *var, const
>>> char *value,
>>>
>>>   out_free:
>>>       free(key);
>>> -    perf_config_set__delete(set);
>>>       return -1;
>>>   }
>>>
>>> @@ -649,7 +648,8 @@ struct perf_config_set *perf_config_set__new(void)
>>>
>>>       if (set) {
>>>           INIT_LIST_HEAD(&set->sections);
>>> -        perf_config(collect_config, set);
>>> +        if (perf_config(collect_config, set) < 0)
>>> +            perf_config_set__delete(set);
>>>       }
>>>
>>>       return set;
>>
>> You can't do that, there is something missing, without looking at the
>> code I think you need:
>>
>>       if (set) {
>>           INIT_LIST_HEAD(&set->sections);
>> -        perf_config(collect_config, set);
>> +        if (perf_config(collect_config, set) < 0) {
>> +            perf_config_set__delete(set);
>> +            set = NULL;
>> +        }
>>       }
>>
>>       return set;
>>
>> No?
>>
>
> Granted
> Sorry for missing above..
>
> I modified using 'return NULL;' instead of 'set = NULL;' as below
>
> diff --git a/tools/perf/util/config.c b/tools/perf/util/config.c
> index c73f1c4..cb749d3 100644
> --- a/tools/perf/util/config.c
> +++ b/tools/perf/util/config.c
> @@ -643,7 +643,6 @@ static int collect_config(const char *var, const
> char *value,
>
>   out_free:
>           free(key);
> -        perf_config_set__delete(set);
>           return -1;
>   }
>
> @@ -653,7 +652,10 @@ struct perf_config_set *perf_config_set__new(void)
>
>           if (set) {
>                   INIT_LIST_HEAD(&set->sections);
> -                perf_config(collect_config, set);
> +                if (perf_config(collect_config, set) < 0) {
> +                        perf_config_set__delete(set);
> +                        return NULL;
> +                }
>           }
>
>           return set;
>
> Because in near future, perf_config_set__delete() will use zfree().
>
> will send changed this patch soon !
> Thank you for your review :)
>

Hum.. my answer was stupid.
There isn't difference between 'return NULL;' and 'set = NULL;'
as a result at perf_config_set__new().
And zfree() at perf_config_set__delete() aren't related to this situation..

Anyway.. I'll send v7 with changed this patch as you said!!

Thanks,
Taeung