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

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Message-ID: <6b91293a-1149-2c77-04a4-421a45d4e1e0@arm.com>
Date:   Wed, 9 Feb 2022 05:47:24 +0000
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     Leo Yan <leo.yan@...aro.org>,
        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 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. For the rest, we would need to wait
until the helper lands in the rc.

Suzuki