tree 30d7d74e4af8af8c8d8b7cb00cf54b292d12c68e
parent c57afe80db4e169135eb675acc2d241e26cc064e
author Paul E. McKenney <paul.mckenney@linaro.org> 1335200799 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1335455345 -0700

rcu: Add warning for RCU_FAST_NO_HZ timer firing

RCU_FAST_NO_HZ uses a timer to limit the time that a CPU with callbacks
can remain in dyntick-idle mode.  This timer is cancelled when the CPU
exits idle, and therefore should never fire.  However, if the timer
were migrated to some other CPU for whatever reason (1) the timer could
actually fire and (2) firing on some other CPU would fail to wake up the
CPU with callbacks, possibly resulting in sluggishness or a system hang.

This commit therfore adds a WARN_ON_ONCE() to the timer handler in order
to detect this condition.

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