On Thu, Oct 19, 2017 at 06:15:49PM +0100, Suzuki K Poulose wrote:
> We zero out the entire trace buffer used for ETR before it
> is enabled, for helping with debugging. Since we could be
> restoring a session in perf mode, this could destroy the data.
I'm not sure to follow you with "... restoring a session in perf mode ...".
When operating from the perf interface all the memory allocated for a session is
cleanup after, there is no re-using of memory as in sysFS.
> Get rid of this step, if someone wants to debug, they can always
> add it as and when needed.
>
> Cc: Mathieu Poirier <mathieu.poir...@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
> ---
> drivers/hwtracing/coresight/coresight-tmc-etr.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 31353fc34b53..849684f85443 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -971,8 +971,6 @@ static void tmc_etr_enable_hw(struct tmc_drvdata *drvdata,
> return;
>
> drvdata->etr_buf = etr_buf;
> - /* Zero out the memory to help with debug */
> - memset(etr_buf->vaddr, 0, etr_buf->size);
I agree, this can be costly when dealing with large areas of memory.
>
> CS_UNLOCK(drvdata->base);
>
> @@ -1267,9 +1265,8 @@ int tmc_read_unprepare_etr(struct tmc_drvdata *drvdata)
> if (drvdata->mode == CS_MODE_SYSFS) {
> /*
> * The trace run will continue with the same allocated trace
> - * buffer. The trace buffer is cleared in tmc_etr_enable_hw(),
> - * so we don't have to explicitly clear it. Also, since the
> - * tracer is still enabled drvdata::buf can't be NULL.
> + * buffer. Since the tracer is still enabled drvdata::buf can't
> + * be NULL.
> */
> tmc_etr_enable_hw(drvdata, drvdata->sysfs_buf);
> } else {
> --
> 2.13.6
>
