tree 77467d64948328e506f06eaf5a719de7fade4b83
parent 06ae115a1d551cd952d80df06eaf8b5153351875
author Paul E. McKenney <paul.mckenney@linaro.org> 1313542006 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1317271123 -0700

rcu: Permit rt_mutex_unlock() with irqs disabled

Create a separate lockdep class for the rt_mutex used for RCU priority
boosting and enable use of rt_mutex_lock() with irqs disabled.  This
prevents RCU priority boosting from falling prey to deadlocks when
someone begins an RCU read-side critical section in preemptible state,
but releases it with an irq-disabled lock held.

Unfortunately, the scheduler's runqueue and priority-inheritance locks
still must either completely enclose or be completely enclosed by any
overlapping RCU read-side critical section.

This version removes a redundant local_irq_restore() noted by
Yong Zhang.

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