Re: [PATCH v8 02/12] drm/i915: Add i915 perf infrastructure

On Fri, Oct 28, 2016 at 3:27 PM, Matthew Auld < matthew.william.auld@gmail.com> wrote:

...

+/* Note we copy the properties from userspace outside of the i915 perf

• • mutex to avoid an awkward lockdep with mmap_sem.
• • Note this function only validates properties in isolation it doesn't
• • validate that the combination of properties makes sense or that all
• • properties necessary for a particular kind of stream have been set.
• */

+static int read_properties_unlocked(struct drm_i915_private *dev_priv,

•                               u64 __user *uprops,
  

•                               u32 n_props,
  

•                               struct perf_open_properties *props)
  

+{

•   u64 __user *uprop = uprops;
  

•   int i;
  

•   memset(props, 0, sizeof(struct perf_open_properties));
  

•   if (!n_props) {
  

•           DRM_ERROR("No i915 perf properties given");
  

•           return -EINVAL;
  

•   }
  

•   if (n_props > DRM_I915_PERF_PROP_MAX) {
  

Ah but DRM_I915_PERF_PROP_MAX is not a property itself.

I'm not sure I follow what your implied concern is?

This is just a sanity check for the number properties given by userspace, based on the assumption that there's currently no reason for multiple values with a particular property id.