+Initialization
+
+ Each thread that has reader critical sections (that uses
+ rcu_read_lock()/rcu_read_unlock() must first register to the URCU
+ library. This is done by calling rcu_register_thread().
+
+Reading
+
+ Reader critical sections must be protected by locating them between
+ calls to rcu_read_lock() and rcu_read_unlock(). Inside that lock,
+ rcu_dereference() may be called to read an RCU protected pointer.
+
+Writing
+
+ rcu_assign_pointer() and rcu_xchg_pointer() may be called anywhere.
+ After, synchronize_rcu() must be called. When it returns, the old
+ values are not in usage anymore.
+
+Being careful with signals
+
+ The library uses signals internally. The signal handler is
+ registered with the SA_RESTART flag. However, these signals may cause
+ some non-restartable system calls to fail with errno = EINTR. Care
+ should be taken to restart system calls manually if they fail with this
+ error. A list of non-restartable system calls may be found in
+ signal(7).
+
+Usage of DEBUG_FULL_MB
+
+ DEBUG_FULL_MB uses full SMP barriers for readers. This eliminates the
+ need for signals but results in slower reads.
+
+
+Usage of DEBUG_YIELD
+
+ DEBUG_YIELD is used to add random delays in the code for testing
+ purposes.