linux-kernel - Re: [PATCH v7 10/14] perf tools: Check the target platform before assigning unwind methods

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Message-ID: <574EB2AA.3060908@huawei.com>
Date:	Wed, 1 Jun 2016 18:02:18 +0800
From:	Hekuang <hekuang@...wei.com>
To:	Jiri Olsa <jolsa@...hat.com>
CC:	<peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
	<alexander.shishkin@...ux.intel.com>, <wangnan0@...wei.com>,
	<jpoimboe@...hat.com>, <ak@...ux.intel.com>, <eranian@...gle.com>,
	<namhyung@...nel.org>, <adrian.hunter@...el.com>,
	<sukadev@...ux.vnet.ibm.com>, <masami.hiramatsu.pt@...achi.com>,
	<tumanova@...ux.vnet.ibm.com>, <kan.liang@...el.com>,
	<penberg@...nel.org>, <dsahern@...il.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 10/14] perf tools: Check the target platform before
 assigning unwind methods



在 2016/6/1 16:40, Jiri Olsa 写道:
> On Tue, May 31, 2016 at 11:19:08AM +0000, He Kuang wrote:
>
> SNIP
>
>> -int unwind__prepare_access(struct thread *thread)
>> +int unwind__prepare_access(struct thread *thread, struct map *map)
>>   {
>> -	unwind__register_ops(thread, local_unwind_libunwind_ops);
>> +	const char *arch;
>> +	enum dso_type dso_type;
>> +	struct unwind_libunwind_ops *ops = local_unwind_libunwind_ops;
>>   
>> -	return thread->unwind_libunwind_ops->prepare_access(thread);
>> +	if (!thread->mg->machine->env)
>> +		return 0;
>> +
>> +	dso_type = dso__type(map->dso, thread->mg->machine);
>> +	if (dso_type == DSO__TYPE_UNKNOWN)
>> +		return 0;
>> +
>> +	if (thread->addr_space)
>> +		pr_debug("unwind: thread map already set, 64bit is %d, dso=%s\n",
>> +			 dso_type == DSO__TYPE_64BIT, map->dso->name);
> should we leave once the address space is set? resseting it over
> again seems like memory leak unless I'm missing something...
>
> also this check should be probably the first thing we do in here

Sure, I must miss the return statement here.
> thanks,
> jirka
>
>> +
>> +	arch = normalize_arch(thread->mg->machine->env->arch);
>> +	pr_debug("unwind: target platform=%s\n", arch);
>> +
>> +	unwind__register_ops(thread, ops);
>> +
>> +	if (thread->unwind_libunwind_ops)
>> +		return thread->unwind_libunwind_ops->prepare_access(thread);
>> +	else
>> +		return 0;
>>   }
> SNIP
>