tree 596d9ed379ef7e2c5d8cf1cc0ba56ade084548ec
parent a10d206ef1a83121ab7430cb196e0376a7145b22
author Paul E. McKenney <paul.mckenney@linaro.org> 1343954630 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1348411435 -0700

rcu: Remove _rcu_barrier() dependency on __stop_machine()

Currently, _rcu_barrier() relies on preempt_disable() to prevent
any CPU from going offline, which in turn depends on CPU hotplug's
use of __stop_machine().

This patch therefore makes _rcu_barrier() use get_online_cpus() to
block CPU-hotplug operations.  This has the added benefit of removing
the need for _rcu_barrier() to adopt callbacks:  Because CPU-hotplug
operations are excluded, there can be no callbacks to adopt.  This
commit simplifies the code accordingly.

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