Re: [PATCH v2 RESEND 1/4] coresight: etm4x: Add lock for reading virtual context ID comparator

[Suzuki K Poulose]

Hi Leo

On 09/02/2022 09:33, Leo Yan wrote:
> Hi Suzuki,
>
> On Wed, Feb 09, 2022 at 05:47:24AM +0000, Suzuki Kuruppassery Poulose wrote:
> > Hi Leo
> >
> > On 04/02/2022 15:24, Leo Yan wrote:
> > > Updates to the values and the index are protected via the spinlock.
> > > Ensure we use the same lock to read the value safely.
> > >
> > > Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> > > Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > > ---
> > >    drivers/hwtracing/coresight/coresight-etm4x-sysfs.c | 2 ++
> > >    1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> > > index 10ef2a29006e..2f3b4eef8261 100644
> > > --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> > > +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
> > > @@ -2111,7 +2111,9 @@ static ssize_t vmid_val_show(struct device *dev,
> > >    	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > >    	struct etmv4_config *config = &drvdata->config;
> > > +	spin_lock(&drvdata->spinlock);
> > >    	val = (unsigned long)config->vmid_val[config->vmid_idx];
> > > +	spin_unlock(&drvdata->spinlock);
> > >    	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
> > >    }
> >
> >
> > I have queued this patch.
>
> Thanks!
>
> > For the rest, we would need to wait until the helper lands in the rc.

Sorry, that was not the exact argument, see below.

> The helper function patch has been landed on the mainline kernel,
> it would be safe to merge the rest patches.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d7e4f8545b497b3f5687e592f1c355cbaee64c8c

The coresight queue is based on rc1 and we already created a stable
tag for TRBE erratas, which was pulled into arm64. So, (correct me
if I am wrong), AFAIU, we cannot rebase the queue on to rc2 where
the patch landed. But happy to proceed, if there is a solution.

Mathieu, what do you think ?

Cheers
Suzuki