linux-kernel - Re: [PATCH v8 4/5] perf config: Use zfree() instead of free() at perf_config_set_

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Date:	Fri, 10 Jun 2016 20:03:05 +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>,
	Wang Nan <wangnan0@...wei.com>, Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH v8 4/5] perf config: Use zfree() instead of free() at
 perf_config_set__delete()



On 06/09/2016 10:37 PM, Arnaldo Carvalho de Melo wrote:
> Em Wed, Jun 08, 2016 at 09:36:52PM +0900, Taeung Song escreveu:
>> perf_config_set__delete() delete allocated the config set
>> but the global variable 'config_set' is used all around.
>
>> So purge and zfree by an address of the global variable
>> , i.e. 'struct perf_config_set **' type
>> instead of using local variable 'set' of which type
>> is 'struct perf_config_set *'.
>
>> -void perf_config_set__delete(struct perf_config_set *set)
>> +void perf_config_set__delete(struct perf_config_set **set)
>>   {
>> -	if (set == NULL)
>> +	if (*set == NULL)
>>   		return;
>>
>> -	perf_config_set__purge(set);
>> -	free(set);
>> +	perf_config_set__purge(*set);
>> +	zfree(set);
>>   }
>
> Nope, don't change conventions like taht, a delete method should not
> receive a pointer to the pointer to be deleted, no odd cases, please.
>
> If you really think this is interesting, please introduce zdelete(),
> i.e.:
>
> void perf_config_set__zdelete(struct perf_config_set **set)
> {
> 	if (!set)
> 		return;
>
> 	perf_config_set__delete(*set);
> 	*set = NULL;
> }
>

I understood!

If we don't use the config set as a global variable,
it seems that we wouldn't need to change perf_config_set__delete() to 
perf_config_set__zdelete() as this patch.

Thanks,
Taeung