[PATCH tip/core/rcu 17/18] rcu/nocb: Use build-time no-CBs check in rcu_pending()
From: Paul E. McKenney
Date: Thu Aug 01 2019 - 19:09:35 EST
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@xxxxxxxxxxxxx>
---
kernel/rcu/tree.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 14939273d120..fb6b80aa34f6 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -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;
--
2.17.1