| Message ID | 20211031144214.237879-2-leo.yan@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | coresight: etm: Correct (virtual) contextID tracing for namespace | expand |
Hi Leo On 31/10/2021 14:42, Leo Yan wrote: > When read the virtual context ID comparator value via sysfs node, the > driver firstly reads out the index, then reads the comparator value > based on index. > > This patch adds the spinlock to protect the atomicity for up two steps. minor nit: This could be : "Updates to the values and the index are protected via the spinlock. Ensure we use the same lock to read the value safely" With that: Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Hi Suzuki, On Mon, Nov 01, 2021 at 09:49:06AM +0000, Suzuki Kuruppassery Poulose wrote: > Hi Leo > > On 31/10/2021 14:42, Leo Yan wrote: > > When read the virtual context ID comparator value via sysfs node, the > > driver firstly reads out the index, then reads the comparator value > > based on index. > > > This patch adds the spinlock to protect the atomicity for up two steps. > > minor nit: This could be : > > "Updates to the values and the index are protected via the > spinlock. Ensure we use the same lock to read the value > safely" Yeah, this is more simple and clear. Will use it. > With that: > > Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Thanks for review. Leo
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c index a0640fa5c55b..e4c8c44d04ef 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); }
When read the virtual context ID comparator value via sysfs node, the driver firstly reads out the index, then reads the comparator value based on index. This patch adds the spinlock to protect the atomicity for up two steps. Signed-off-by: Leo Yan <leo.yan@linaro.org> --- drivers/hwtracing/coresight/coresight-etm4x-sysfs.c | 2 ++ 1 file changed, 2 insertions(+)