diff options
Diffstat (limited to 'drivers/hwtracing/coresight/coresight-tmc-etf.c')
| -rw-r--r-- | drivers/hwtracing/coresight/coresight-tmc-etf.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c index cd0fb7bfba68..4c4cbd1f7258 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c @@ -546,13 +546,17 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev, /* * In snapshot mode we simply increment the head by the number of byte - * that were written. User space function cs_etm_find_snapshot() will - * figure out how many bytes to get from the AUX buffer based on the - * position of the head. + * that were written. User space will figure out how many bytes to get + * from the AUX buffer based on the position of the head. */ 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); |