rcu: Move _rcu_barrier()'s rcu_head structures to rcu_data structures

In order for multiple flavors of RCU to each concurrently run one
rcu_barrier(), each flavor needs its own per-CPU set of rcu_head
structures.  This commit therefore moves _rcu_barrier()'s set of
per-CPU rcu_head structures from per-CPU variables to the existing
per-CPU and per-RCU-flavor rcu_data structures.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 049896a835d9..586d93c978f2 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -314,6 +314,9 @@ struct rcu_data {
         unsigned long n_rp_need_fqs;
         unsigned long n_rp_need_nothing;
 
+        /* 6) _rcu_barrier() callback. */
+        struct rcu_head barrier_head;
+
         int cpu;
         struct rcu_state *rsp;
 };