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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>
This commit is contained in:
Paul E. McKenney 2019-05-21 13:53:28 -07:00
parent c1ab99d66e
commit 921bb5fad1
1 changed files with 2 additions and 1 deletions
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3
kernel/rcu/tree.c
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@ -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;