[Intel-gfx] [RFC 01/12] drm/i915: Expose list of clients in sysfs

[Chris Wilson]

Quoting Tvrtko Ursulin (2020-03-09 18:31:18)
> +static int
> +__i915_drm_client_register(struct i915_drm_client *client,
> +                          struct task_struct *task)
> +{
> +       struct i915_drm_clients *clients = client->clients;
> +       struct device_attribute *attr;
> +       int ret = -ENOMEM;
> +       char idstr[32];
> +
> +       client->pid = get_task_pid(task, PIDTYPE_PID);
> +
> +       client->name = kstrdup(task->comm, GFP_KERNEL);
> +       if (!client->name)
> +               goto err_name;
> +
> +       if (!clients->root)
> +               return 0; /* intel_fbdev_init registers a client before sysfs */
> +
> +       snprintf(idstr, sizeof(idstr), "%u", client->id);
> +       client->root = kobject_create_and_add(idstr, clients->root);
> +       if (!client->root)
> +               goto err_client;
> +
> +       attr = &client->attr.name;
> +       sysfs_attr_init(&attr->attr);
> +       attr->attr.name = "name";
> +       attr->attr.mode = 0444;
> +       attr->show = show_client_name;
> +
> +       ret = sysfs_create_file(client->root, (struct attribute *)attr);
> +       if (ret)
> +               goto err_attr;
> +
> +       attr = &client->attr.pid;
> +       sysfs_attr_init(&attr->attr);
> +       attr->attr.name = "pid";
> +       attr->attr.mode = 0444;
> +       attr->show = show_client_pid;
> +
> +       ret = sysfs_create_file(client->root, (struct attribute *)attr);
> +       if (ret)
> +               goto err_attr;

How do we think we will extend this (e.g. for client/1/(trace,debug))?

i915_drm_client_add_attr() ?

Or should we put all the attr here and make them known a priori?

I think I prefer i915_drm_client_add_attr, but that will also require a
notification chain? And that smells like overengineering.

At any rate we have 2 other definite users around the corner for the
client sysfs, so we should look at what API suits us.
-Chris