[PATCH RFC 09/16] rcu: Remove unused expedited_need_qs field from rcu_state

["Paul E. McKenney" <paulmck@kernel.org>]

From: Joel Fernandes <joelagnelf@nvidia.com>

The ->expedited_need_qs counter was part of the old expedited
grace-period machinery that spun waiting for each CPU to check in.
The current implementation instead tracks holdout CPUs via the
rcu_node structures' ->expmask fields and waits on the ->exp_wq[]
wait queues, so nothing reads or writes ->expedited_need_qs any
longer.

Remove the field to avoid wasting space in rcu_state and to keep
readers of the expedited code from searching for nonexistent users.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/tree.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 4069132f9d4446..587bd71396eaa3 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -391,7 +391,6 @@ struct rcu_state {
 	struct mutex exp_mutex;			/* Serialize expedited GP. */
 	struct mutex exp_wake_mutex;		/* Serialize wakeup. */
 	unsigned long expedited_sequence;	/* Take a ticket. */
-	atomic_t expedited_need_qs;		/* # CPUs left to check in. */
 	struct swait_queue_head expedited_wq;	/* Wait for check-ins. */
 	int ncpus_snap;				/* # CPUs seen last time. */
 	u8 cbovld;				/* Callback overload now? */
-- 
2.40.1