diff mbox series

[RFC,04/17] drm/cgroup: Allow safe external access to file_priv

Message ID 20221019173254.3361334-5-tvrtko.ursulin@linux.intel.com (mailing list archive)
State New, archived
Headers show
Series DRM scheduling cgroup controller | expand

Commit Message

Tvrtko Ursulin Oct. 19, 2022, 5:32 p.m. UTC 
From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Entry points from the cgroup subsystem into the drm cgroup controller will
need to walk the file_priv structures associated with registered clients
and since those are not RCU protected lets add a hack for now to make this
safe.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/drm_cgroup.c | 7 +++++++
 1 file changed, 7 insertions(+)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/drm_cgroup.c b/drivers/gpu/drm/drm_cgroup.c
index a31ff1d593ab..9e9caeb0aa87 100644
--- a/drivers/gpu/drm/drm_cgroup.c
+++ b/drivers/gpu/drm/drm_cgroup.c
@@ -21,6 +21,13 @@  void drm_clients_close(struct drm_file *file_priv)
 	if (atomic_dec_and_test(&clients->num)) {
 		xa_erase(&drm_pid_clients, pid);
 		kfree_rcu(clients, rcu);
+
+		/*
+		 * FIXME: file_priv is not RCU protected so we add this hack
+		 * to avoid any races with code which walks clients->file_list
+		 * and accesses file_priv.
+		 */
+		synchronize_rcu();
 	}
 }