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

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Date:   Wed, 9 Feb 2022 17:33:04 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Suzuki K Poulose <suzuki.poulose@....com>
Cc:     Mathieu Poirier <mathieu.poirier@...aro.org>,
        Mike Leach <mike.leach@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 RESEND 1/4] coresight: etm4x: Add lock for reading
 virtual context ID comparator

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@...aro.org>
> > Reviewed-by: Suzuki K Poulose <suzuki.poulose@....com>
> > ---
> >   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.

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

BTW, I think you could pick another two refactoring patches:
https://lore.kernel.org/lkml/20220204135051.60639-2-leo.yan@linaro.org/
https://lore.kernel.org/lkml/20220204135051.60639-3-leo.yan@linaro.org/

Thanks,
Leo