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

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Message-ID: <560A48D5.7010901@intel.com>
Date:	Tue, 29 Sep 2015 11:16:21 +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 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.

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

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