linux-kernel - [RFC 09/13] drm/cgroup: Only track clients which are providing drm_cgroup

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Date:   Wed,  9 Nov 2022 16:11:37 +0000
From:   Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>
To:     Intel-gfx@...ts.freedesktop.org
Cc:     cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        Tejun Heo <tj@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Zefan Li <lizefan.x@...edance.com>,
        Dave Airlie <airlied@...hat.com>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Rob Clark <robdclark@...omium.org>,
        Stéphane Marchesin <marcheu@...omium.org>,
        "T . J . Mercier" <tjmercier@...gle.com>, Kenny.Ho@....com,
        Christian König <christian.koenig@....com>,
        Brian Welty <brian.welty@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Subject: [RFC 09/13] drm/cgroup: Only track clients which are providing drm_cgroup_ops

From: Tvrtko Ursulin <tvrtko.ursulin@...el.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@...el.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 e3854741c584..d3050c744e3e 100644
--- a/drivers/gpu/drm/drm_cgroup.c
+++ b/drivers/gpu/drm/drm_cgroup.c
@@ -35,6 +35,9 @@ 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 (WARN_ON_ONCE(!clients))
@@ -66,6 +69,9 @@ 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) {
@@ -101,6 +107,9 @@ 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, new);
 	clients = xa_load(&drm_pid_clients, old);
 
-- 
2.34.1