Hi Suzuki,
On Mon, Jul 12, 2021 at 11:40:12AM +0100, Suzuki Kuruppassery Poulose wrote:
On 11/07/2021 11:40, 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
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..713205db15a1 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;
- /*
* It requires the ordering between the AUX trace data and aux_head* store, below smp_wmb() ensures the AUX trace data is visible prior* to updating aux_head.*/Please could we reword this a bit, something like :
/* * 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. */
Will refine with this in next spin. Thanks for review!
- smp_wmb();
Reviewed-by: Suzuki K Poulose suzuki.poulose@arm.com