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SubjectRe: [PATCH v5 2/9] coresight: tmc-etr: Add barrier after updating AUX ring buffer
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On 29/08/2021 11:55, Leo Yan wrote:
> Hi Mathieu, Suzuki,
>
> On Mon, Aug 09, 2021 at 07:14:00PM +0800, Leo Yan wrote:
>> Since a memory barrier is required between AUX trace data store and
>> aux_head store, and the AUX trace data is filled with memcpy(), it's
>> sufficient to use smp_wmb() so can ensure the trace data is visible
>> prior to updating aux_head.
>>
>> Signed-off-by: Leo Yan <leo.yan@linaro.org>
>> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>
> Could you pick up patches 02 and 03 in this series? Please note,
> patch 02 has the review tag from Suzuki, but I didn't receive the
> review tag for patch 03.
>
> If anything need to follow up, just let me know. Thanks!

I have picked up both the patches.

Thanks
Suzuki

>
>> ---
>> drivers/hwtracing/coresight/coresight-tmc-etr.c | 8 ++++++++
>> 1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> index acdb59e0e661..13fd1fc730ed 100644
>> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> @@ -1563,6 +1563,14 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
>> */
>> if (etr_perf->snapshot)
>> handle->head += size;
>> +
>> + /*
>> + * Ensure that the AUX trace data is visible before the aux_head
>> + * is updated via perf_aux_output_end(), as expected by the
>> + * perf ring buffer.
>> + */
>> + smp_wmb();
>> +
>> out:
>> /*
>> * Don't set the TRUNCATED flag in snapshot mode because 1) the
>> --
>> 2.25.1
>>

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