Commit 921bb5fa authored May 21, 2019 by Paul E. McKenney

rcu/nocb: Use build-time no-CBs check in rcu_pending()

Currently, rcu_pending() invokes rcu_segcblist_is_offloaded() even
in CONFIG_RCU_NOCB_CPU=n kernels, which cannot possibly be offloaded.
Given that rcu_pending() is on a fastpath, it makes sense to check for
CONFIG_RCU_NOCB_CPU=y before invoking rcu_segcblist_is_offloaded().
This commit therefore makes this change.

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

parent c1ab99d6

kernel/rcu/tree.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -2773,7 +2773,8 @@ static int rcu_pending(void)
		/* Has RCU gone idle with this CPU needing another grace period? */
		if (!rcu_gp_in_progress() &&
		rcu_segcblist_is_enabled(&rdp->cblist) &&
		!rcu_segcblist_is_offloaded(&rdp->cblist) &&
		(!IS_ENABLED(CONFIG_RCU_NOCB_CPU) \|\|
		!rcu_segcblist_is_offloaded(&rdp->cblist)) &&
		!rcu_segcblist_restempty(&rdp->cblist, RCU_NEXT_READY_TAIL))
		return 1;

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