rcu: Place pointer to call_rcu() in rcu_data structure

This is a preparatory commit for increasing rcu_barrier()'s concurrency.
It adds a pointer in the rcu_data structure to the corresponding call_rcu()
function.  This allows a pointer to the rcu_data structure to imply the
function pointer, which allows _rcu_barrier() state to be placed in the
rcu_state structure.

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, 2 insertions, 0 deletions

diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 780a0195d35a..049896a835d9 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -364,6 +364,8 @@ struct rcu_state {
         u32 levelcnt[MAX_RCU_LVLS + 1];         /* # nodes in each level. */
         u8 levelspread[RCU_NUM_LVLS];           /* kids/node in each level. */
         struct rcu_data __percpu *rda;          /* pointer of percu rcu_data. */
+        void (*call)(struct rcu_head *head,     /* call_rcu() flavor. */
+                     void (*func)(struct rcu_head *head));
 
         /* The following fields are guarded by the root rcu_node's lock. */