linux-kernel - Re: [PATCH v2 12/17] coresight: trbe: Add a helper to fetch cpudata from perf handle

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Date:   Tue, 5 Oct 2021 23:35:13 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        maz@...nel.org, catalin.marinas@....com, mark.rutland@....com,
        james.morse@....com, anshuman.khandual@....com, leo.yan@...aro.org,
        mike.leach@...aro.org, will@...nel.org, lcherian@...vell.com,
        coresight@...ts.linaro.org
Subject: Re: [PATCH v2 12/17] coresight: trbe: Add a helper to fetch cpudata
 from perf handle

Hi Mathieu

On 04/10/2021 18:42, Mathieu Poirier wrote:
> On Tue, Sep 21, 2021 at 02:41:16PM +0100, Suzuki K Poulose wrote:
>> Add a helper to get the CPU specific data for TRBE instance, from
>> a given perf handle. This also adds extra checks to make sure that
>> the event associated with the handle is "bound" to the CPU and is
>> active on the TRBE.
>>
>> Cc: Anshuman Khandual <anshuman.khandual@....com>
>> Cc: Mike Leach <mike.leach@...aro.org>
>> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
>> Cc: Leo Yan <leo.yan@...aro.org>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
>> ---
>>   drivers/hwtracing/coresight/coresight-trbe.c | 12 ++++++++++--
>>   1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
>> index 983dd5039e52..797d978f9fa7 100644
>> --- a/drivers/hwtracing/coresight/coresight-trbe.c
>> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
>> @@ -268,6 +268,15 @@ static unsigned long trbe_snapshot_offset(struct perf_output_handle *handle)
>>   	return buf->nr_pages * PAGE_SIZE;
>>   }
>>   
>> +static inline struct trbe_cpudata *
>> +trbe_handle_to_cpudata(struct perf_output_handle *handle)
>> +{
>> +	struct trbe_buf *buf = etm_perf_sink_config(handle);
>> +
>> +	BUG_ON(!buf || !buf->cpudata);
>> +	return buf->cpudata;
>> +}
>> +
>>   /*
>>    * TRBE Limit Calculation
>>    *
>> @@ -533,8 +542,7 @@ static enum trbe_fault_action trbe_get_fault_act(struct perf_output_handle *hand
>>   {
>>   	int ec = get_trbe_ec(trbsr);
>>   	int bsc = get_trbe_bsc(trbsr);
>> -	struct trbe_buf *buf = etm_perf_sink_config(handle);
>> -	struct trbe_cpudata *cpudata = buf->cpudata;
>> +	struct trbe_cpudata *cpudata = trbe_handle_to_cpudata(handle);
> 
> There is two other places where this pattern is present:  is_perf_trbe() and
> __trbe_normal_offset().

I skipped them, as they have to get access to the "trbe_buf" anyways.
So the step by step, made sense. But I could replace them too to make it
transparent.

What do you think ?

Suzuki