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>
Link: https://lore.kernel.org/r/20210809111407.596077-3-leo.yan@linaro.org
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
*/
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