[RFC 08/12] drm/cgroup: Only track clients which are providing drm_cgroup_ops

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

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

To reduce the number of tracking going on, especially with drivers which
will not support any sort of control from the drm cgroup controller side,
lets express the funcionality as opt-in and use the presence of
drm_cgroup_ops as activation criteria.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/drm_cgroup.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/drm_cgroup.c b/drivers/gpu/drm/drm_cgroup.c
index ef951421bba6..09249f795af3 100644
--- a/drivers/gpu/drm/drm_cgroup.c
+++ b/drivers/gpu/drm/drm_cgroup.c
@@ -36,6 +36,9 @@ void drm_clients_close(struct drm_file *file_priv)
 
 	lockdep_assert_held(&dev->filelist_mutex);
 
+	if (!dev->driver->cg_ops)
+		return;
+
 	pid = rcu_access_pointer(file_priv->pid);
 	clients = xa_load(&drm_pid_clients, (unsigned long)pid);
 	if (drm_WARN_ON_ONCE(dev, !clients))
@@ -67,6 +70,9 @@ int drm_clients_open(struct drm_file *file_priv)
 
 	lockdep_assert_held(&dev->filelist_mutex);
 
+	if (!dev->driver->cg_ops)
+		return 0;
+
 	pid = (unsigned long)rcu_access_pointer(file_priv->pid);
 	clients = xa_load(&drm_pid_clients, pid);
 	if (!clients) {
@@ -102,6 +108,9 @@ drm_clients_migrate(struct drm_file *file_priv,
 
 	lockdep_assert_held(&dev->filelist_mutex);
 
+	if (!dev->driver->cg_ops)
+		return;
+
 	existing_clients = xa_load(&drm_pid_clients, (unsigned long)new);
 	clients = xa_load(&drm_pid_clients, (unsigned long)old);
 
-- 
2.34.1