mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-29 05:44:11 +00:00
Code Issues Releases Wiki Activity

coresight: tmc-etf: Add comment for store ordering

Browse source 
Since the function CS_LOCK() has contained memory barrier mb(), it
ensures the visibility of the AUX trace data before updating the
aux_head, thus it's needless to add any explicit barrier anymore.

Add comment to make clear for the barrier usage for ETF.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Link: https://lore.kernel.org/r/20210809111407.596077-4-leo.yan@linaro.org
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
This commit is contained in:
Leo Yan 2021-08-09 19:14:01 +08:00 committed by Mathieu Poirier
parent 26701ceb4c
commit bd8d06886d
1 changed files with 5 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
drivers/hwtracing/coresight/coresight-tmc-etf.c
View file

@ -553,6 +553,11 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
if (buf->snapshot)
handle->head += to_read;
/*
* CS_LOCK() contains mb() so it can ensure visibility of the AUX trace
* data before the aux_head is updated via perf_aux_output_end(), which
* is expected by the perf ring buffer.
*/
CS_LOCK(drvdata->base);
out:
spin_unlock_irqrestore(&drvdata->spinlock, flags);