linux-phytec-fsl

rcu: Use RCU's online-CPU state for expedited IPI retry

This commit improves the accuracy of the interaction between CPU hotplug
operations and RCU's expedited grace periods by using RCU's online-CPU
state to determine when failed IPIs should be retried.

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