linux-kernel - Re: [PATCH 17/25] perf callchain: Allow for max_stack greater than PERF_MAX_STACK

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Date:	Thu, 1 Oct 2015 14:45:01 +0300
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Jiri Olsa <jolsa@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 17/25] perf callchain: Allow for max_stack greater than
 PERF_MAX_STACK_DEPTH

On 29/09/15 11:16, Adrian Hunter wrote:
> On 28/09/15 23:08, Arnaldo Carvalho de Melo wrote:
>> Em Fri, Sep 25, 2015 at 04:15:48PM +0300, Adrian Hunter escreveu:
>>> Adjust the validation to allow for max_stack greater than
>>> PERF_MAX_STACK_DEPTH.
>>>
>>> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
>>> ---
>>>  tools/perf/util/machine.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
>>> index fd1efeafb343..d7bd9a304535 100644
>>> --- a/tools/perf/util/machine.c
>>> +++ b/tools/perf/util/machine.c
>>> @@ -1831,7 +1831,7 @@ static int thread__resolve_callchain_sample(struct thread *thread,
>>>  	}
>>>  
>>>  check_calls:
>>> -	if (chain->nr > PERF_MAX_STACK_DEPTH) {
>>> +	if (chain->nr > PERF_MAX_STACK_DEPTH && (int)chain->nr > max_stack) {
>>
>> Both?
> 
> Yes.
> 
> In the case of a hardware generated callchain, the callchain can be up to
> PERF_MAX_STACK_DEPTH but max_stack can be less than PERF_MAX_STACK_DEPTH to
> limit the number processed.
> 
> In the case of a synthesized callchain, the callchain can be up to max_stack
> which might be more than PERF_MAX_STACK_DEPTH.

Is this ok?

> 
>>
>>>  		pr_warning("corrupted callchain. skipping...\n");
>>>  		return 0;
>>>  	}
>>> -- 
>>> 1.9.1
>>
> 
> 

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