rcu/nocb: Remove obsolete nocb_head and nocb_tail fields

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

kernel/rcu/tree.h

@@ -194,8 +194,6 @@ struct rcu_data {
 
 	/* 5) Callback offloading. */
 #ifdef CONFIG_RCU_NOCB_CPU
-	struct rcu_head *nocb_head;	/* CBs waiting for kthread. */
-	struct rcu_head **nocb_tail;
 	atomic_long_t nocb_q_count;	/* # CBs waiting for nocb */
 	atomic_long_t nocb_q_count_lazy; /*  invocation (all stages). */
 	struct rcu_head *nocb_cb_head;	/* CBs ready to invoke. */
@@ -211,7 +209,6 @@ struct rcu_data {
 					/* CBs waiting for GP. */
 	struct rcu_head **nocb_gp_tail;
 	bool nocb_gp_sleep;		/* Is the nocb GP thread asleep? */
-	bool nocb_gp_forced;		/* Forced nocb GP thread wakeup? */
 	struct swait_queue_head nocb_gp_wq; /* For nocb kthreads to sleep on. */
 	bool nocb_cb_sleep;		/* Is the nocb CB thread asleep? */
 	struct task_struct *nocb_cb_kthread;

kernel/rcu/tree_plugin.h

@@ -1911,7 +1911,6 @@ void __init rcu_init_nohz(void)
 /* Initialize per-rcu_data variables for no-CBs CPUs. */
 static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
 {
-	rdp->nocb_tail = &rdp->nocb_head;
 	init_swait_queue_head(&rdp->nocb_cb_wq);
 	init_swait_queue_head(&rdp->nocb_gp_wq);
 	rdp->nocb_cb_tail = &rdp->nocb_cb_head;