reservation: add reservation_object_get_excl_rcu()
In the atomic modesetting path, each driver simply wants to grab a ref
to the exclusive fence from a reservation object to store in the incoming
drm_plane_state, without doing the whole RCU dance. Since each driver
will need to do this, lets make a helper.
v2: rename to _rcu instead of _unlocked to be more consistent
Signed-off-by: Rob Clark <robdclark@gmail.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
diff --git a/include/linux/reservation.h b/include/linux/reservation.h
index 5a0b64c..49d0576 100644
--- a/include/linux/reservation.h
+++ b/include/linux/reservation.h
@@ -120,6 +120,24 @@
reservation_object_held(obj));
}
+static inline struct fence *
+reservation_object_get_excl_rcu(struct reservation_object *obj)
+{
+ struct fence *fence;
+ unsigned seq;
+retry:
+ seq = read_seqcount_begin(&obj->seq);
+ rcu_read_lock();
+ fence = rcu_dereference(obj->fence_excl);
+ if (read_seqcount_retry(&obj->seq, seq)) {
+ rcu_read_unlock();
+ goto retry;
+ }
+ fence = fence_get(fence);
+ rcu_read_unlock();
+ return fence;
+}
+
int reservation_object_reserve_shared(struct reservation_object *obj);
void reservation_object_add_shared_fence(struct reservation_object *obj,
struct fence *fence);