rcu/nocb: Remove halfway (de-)offloading handling from rcu_core()'s QS reporting

RCU core can't be running anymore while in the middle of (de-)offloading
since this sort of transition now only applies to offline CPUs.

The locked callback acceleration handling during the transition can
therefore be removed.

Signed-off-by: Frederic Weisbecker <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Paul E. McKenney <[email protected]>
Signed-off-by: Neeraj Upadhyay <[email protected]>

Author: Frederic Weisbecker

kernel/rcu/tree.c

@@ -2386,7 +2386,6 @@ rcu_report_qs_rdp(struct rcu_data *rdp)
 {
 	unsigned long flags;
 	unsigned long mask;
-	bool needacc = false;
 	struct rcu_node *rnp;
 
 	WARN_ON_ONCE(rdp->cpu != smp_processor_id());
@@ -2423,23 +2422,11 @@ rcu_report_qs_rdp(struct rcu_data *rdp)
 			 * to return true.  So complain, but don't awaken.
 			 */
 			WARN_ON_ONCE(rcu_accelerate_cbs(rnp, rdp));
-		} else if (!rcu_segcblist_completely_offloaded(&rdp->cblist)) {
-			/*
-			 * ...but NOCB kthreads may miss or delay callbacks acceleration
-			 * if in the middle of a (de-)offloading process.
-			 */
-			needacc = true;
 		}
 
 		rcu_disable_urgency_upon_qs(rdp);
 		rcu_report_qs_rnp(mask, rnp, rnp->gp_seq, flags);
 		/* ^^^ Released rnp->lock */
-
-		if (needacc) {
-			rcu_nocb_lock_irqsave(rdp, flags);
-			rcu_accelerate_cbs_unlocked(rnp, rdp);
-			rcu_nocb_unlock_irqrestore(rdp, flags);
-		}
 	}
 }