coresight: etm4x: Add lock for reading virtual context ID comparator

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@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20220204152403.71775-2-leo.yan@linaro.org

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
index 57e94424a8d65d883548cd3b8b28d0e7553b5cfb..c376f9e230d362f97ba8c06825ab5f2164ce764a 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
@@ -2115,7 +2115,9 @@ 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);
 }