Re: [PATCH v5 2/9] coresight: tmc-etr: Add barrier after updating AUX ring buffer

[Suzuki K Poulose]

On 29/08/2021 11:55, Leo Yan wrote:
> Hi Mathieu, Suzuki,
>
> On Mon, Aug 09, 2021 at 07:14:00PM +0800, 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@xxxxxxxxxx>
> > Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
>
> Could you pick up patches 02 and 03 in this series?  Please note,
> patch 02 has the review tag from Suzuki, but I didn't receive the
> review tag for patch 03.
>
> If anything need to follow up, just let me know.  Thanks!

I have picked up both the patches.

Thanks
Suzuki

> > ---
> >   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..13fd1fc730ed 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;
> > +
> > +	/*
> > +	 * 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
> > --
> > 2.25.1