Re: [PATCH v1 2/4] coresight: etm4x: Don't use virtual contextID for non-root PID namespace

On Thu, Nov 04, 2021 at 03:07:45PM +0000, Suzuki Kuruppassery Poulose wrote:

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@@ -2111,6 +2111,13 @@ static ssize_t vmid_val_show(struct device *dev, struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent); struct etmv4_config *config = &drvdata->config;

• /*

• * Don't use virtual contextID tracing if coming from a PID namespace.
  

• * See comment in ctxid_pid_store().
  

• */
  

• if (task_active_pid_ns(current) != &init_pid_ns)

• return -EINVAL;
  

• spin_lock(&drvdata->spinlock); val = (unsigned long)config->vmid_val[config->vmid_idx]; spin_unlock(&drvdata->spinlock);

@@ -2125,6 +2132,13 @@ static ssize_t vmid_val_store(struct device *dev, struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent); struct etmv4_config *config = &drvdata->config;

• /*

• * Don't use virtual contextID tracing if coming from a PID namespace.
  

• * See comment in ctxid_pid_store().
  

• */
  

• if (task_active_pid_ns(current) != &init_pid_ns)

Please could we add a helper function to make this obvious ?

e.g: task_is_in_root_ns(task) ?

Yeah, I will use a separate patch set to add this helper function and polish relevant codes in the kernel. Thanks for suggestion.

Leo