From 824815c4cd13e384ef5a4be725ec4b06e4ad2c2a Mon Sep 17 00:00:00 2001 From: Rob Clark Date: Thu, 31 Mar 2016 16:23:51 -0400 Subject: [PATCH] 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 Acked-by: Sumit Semwal --- include/linux/reservation.h | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/include/linux/reservation.h b/include/linux/reservation.h index 5a0b64cf68b4..49d057655d62 100644 --- a/include/linux/reservation.h +++ b/include/linux/reservation.h @@ -120,6 +120,24 @@ reservation_object_get_excl(struct reservation_object *obj) 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); -- 2.20.1