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

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Date:	Wed, 1 Jun 2016 10:40:39 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	He Kuang <hekuang@...wei.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

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

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