Pull the RCU adaptive-idle feature from Paul E. McKenney:
"This series adds RCU APIs that allow non-idle tasks to
enter RCU idle mode and provides x86 code to make use of them, allowing
RCU to treat user-mode execution as an extended quiescent state when the
new RCU_USER_QS kernel configuration parameter is specified. Work is
in progress to port this to a few other architectures, but is not part
of this series."
Signed-off-by: Ingo Molnar <mingo@kernel.org>