[RFC 4/8] drm/cgroup: Add over budget signalling callback

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Add a new callback via which the drm cgroup controller is notifying the
drm core that a certain process is above its allotted GPU time.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 include/drm/drm_drv.h |  8 ++++++++
 kernel/cgroup/drm.c   | 16 ++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index d1cee5899cde..c518f03b9f0f 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -173,6 +173,14 @@ struct drm_cgroup_ops {
 	 * Used by the DRM core when queried by the DRM cgroup controller.
 	 */
 	u64 (*active_time_us) (struct drm_file *);
+
+	/**
+	 * @signal_budget:
+	 *
+	 * Optional callback used by the DRM core to forward over/under GPU time
+	 * messages sent by the DRM cgroup controller.
+	 */
+	int (*signal_budget) (struct drm_file *, u64 used, u64 budget);
 };
 
 /**
diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
index acdb76635b60..68f31797c4f0 100644
--- a/kernel/cgroup/drm.c
+++ b/kernel/cgroup/drm.c
@@ -51,6 +51,22 @@ static u64 drmcs_get_active_time_us(struct drm_cgroup_state *drmcs)
 	return total;
 }
 
+static void
+drmcs_signal_budget(struct drm_cgroup_state *drmcs, u64 usage, u64 budget)
+{
+	struct drm_file *fpriv;
+
+	lockdep_assert_held(&drmcg_mutex);
+
+	list_for_each_entry(fpriv, &drmcs->clients, clink) {
+		const struct drm_cgroup_ops *cg_ops =
+			fpriv->minor->dev->driver->cg_ops;
+
+		if (cg_ops && cg_ops->signal_budget)
+			cg_ops->signal_budget(fpriv, usage, budget);
+	}
+}
+
 static void drmcs_free(struct cgroup_subsys_state *css)
 {
 	struct drm_cgroup_state *drmcs = css_to_drmcs(css);
-- 
2.39.2