call_rcu — Queue an RCU callback for invocation after a grace period.
structure to be used for queueing the RCU updates.
actual update function to be invoked after the grace period
The update function will be invoked some time after a full grace period elapses, in other words after all currently executing RCU read-side critical sections have completed. RCU read-side critical sections are delimited by rcu_read_lock and rcu_read_unlock, and may be nested.