tree 162c63edcc463e18d50fb5b5be479785f02222c4
parent 10f39bb1b2c1923ca73e70cb13aeee0e9b822d8f
author Peter Zijlstra <a.p.zijlstra@chello.nl> 1311113245 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1311184211 -0700

sched: Add irq_{enter,exit}() to scheduler_ipi()

Ensure scheduler_ipi() calls irq_{enter,exit} when it does some actual
work. Traditionally we never did any actual work from the resched IPI
and all magic happened in the return from interrupt path.

Now that we do do some work, we need to ensure irq_{enter,exit} are
called so that we don't confuse things.

This affects things like timekeeping, NO_HZ and RCU, basically
everything with a hook in irq_enter/exit.

Explicit examples of things going wrong are:

  sched_clock_cpu() -- has a callback when leaving NO_HZ state to take
                    a new reading from GTOD and TSC. Without this
                    callback, time is stuck in the past.

  RCU -- needs in_irq() to work in order to avoid some nasty deadlocks

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>