rcu: Remove unused rcu_state.boost

Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

Author: Neeraj Upadhyay

kernel/rcu/tree.h

@@ -304,9 +304,8 @@ struct rcu_state {
 
 	/* The following fields are guarded by the root rcu_node's lock. */
 
-	u8	boost ____cacheline_internodealigned_in_smp;
-						/* Subject to priority boost. */
-	unsigned long gp_seq;			/* Grace-period sequence #. */
+	unsigned long gp_seq ____cacheline_internodealigned_in_smp;
+						/* Grace-period sequence #. */
 	unsigned long gp_max;			/* Maximum GP duration in */
 						/*  jiffies. */
 	struct task_struct *gp_kthread;		/* Task for grace periods. */

kernel/rcu/tree_plugin.h

@@ -1175,8 +1175,6 @@ static void rcu_spawn_one_boost_kthread(struct rcu_node *rnp)
 	if (rnp->boost_kthread_task || !rcu_scheduler_fully_active)
 		return;
 
-	rcu_state.boost = 1;
-
 	t = kthread_create(rcu_boost_kthread, (void *)rnp,
 			   "rcub/%d", rnp_index);
 	if (WARN_ON_ONCE(IS_ERR(t)))