rcu: Optimize rcu_needs_cpu() for RCU_NOCB_CPU_ALL

If CONFIG_RCU_NOCB_CPU_ALL=y, then rcu_needs_cpu() will always
return false, however, the current version nevertheless checks
for RCU callbacks.  This commit therefore creates a static inline
implementation of rcu_needs_cpu() that unconditionally returns false
when CONFIG_RCU_NOCB_CPU_ALL=y.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 72137ee8c603..81198c84e268 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -31,7 +31,9 @@
 #define __LINUX_RCUTREE_H
 
 void rcu_note_context_switch(int cpu);
+#ifndef CONFIG_RCU_NOCB_CPU_ALL
 int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies);
+#endif /* #ifndef CONFIG_RCU_NOCB_CPU_ALL */
 void rcu_cpu_stall_reset(void);
 
 /*