rcu: Open-code the rcu_cblist_n_lazy_cbs() function

Because the rcu_cblist_n_lazy_cbs() just samples the ->len_lazy counter,
and because the rcu_cblist structure is quite straightforward, it makes
sense to open-code rcu_cblist_n_lazy_cbs(p) as p->len_lazy, cutting out
a level of indirection.  This commit makes this change.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>

kernel/rcu/rcu_segcblist.h

@@ -22,12 +22,6 @@
 
 #include <linux/rcu_segcblist.h>
 
-/* Return number of lazy callbacks in simple callback list. */
-static inline long rcu_cblist_n_lazy_cbs(struct rcu_cblist *rclp)
-{
-	return rclp->len_lazy;
-}
-
 /*
  * Account for the fact that a previously dequeued callback turned out
  * to be marked as lazy.

kernel/rcu/tree.c

@@ -2634,7 +2634,7 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp, unsigned long flags)
 
 	/* Do the accounting first. */
 	rdp->n_cbs_adopted += rsp->orphan_done.len;
-	if (rcu_cblist_n_lazy_cbs(&rsp->orphan_done) != rsp->orphan_done.len)
+	if (rsp->orphan_done.len_lazy != rsp->orphan_done.len)
 		rcu_idle_count_callbacks_posted();
 	rcu_segcblist_insert_count(&rdp->cblist, &rsp->orphan_done);
 

kernel/rcu/tree_plugin.h

@@ -1935,7 +1935,7 @@ static bool __maybe_unused rcu_nocb_adopt_orphan_cbs(struct rcu_state *rsp,
 						     unsigned long flags)
 {
 	long ql = rsp->orphan_done.len;
-	long qll = rcu_cblist_n_lazy_cbs(&rsp->orphan_done);
+	long qll = rsp->orphan_done.len_lazy;
 
 	/* If this is not a no-CBs CPU, tell the caller to do it the old way. */
 	if (!rcu_is_nocb_cpu(smp_processor_id()))

kernel/rcu/tree_trace.c

@@ -277,7 +277,7 @@ static void print_one_rcu_state(struct seq_file *m, struct rcu_state *rsp)
 		   rsp->n_force_qs, rsp->n_force_qs_ngp,
 		   rsp->n_force_qs - rsp->n_force_qs_ngp,
 		   READ_ONCE(rsp->n_force_qs_lh),
-		   rcu_cblist_n_lazy_cbs(&rsp->orphan_done),
+		   rsp->orphan_done.len_lazy,
 		   rsp->orphan_done.len);
 	for (rnp = &rsp->node[0]; rnp - &rsp->node[0] < rcu_num_nodes; rnp++) {
 		if (rnp->level != level) {