cpu-hotplug: refcount based cpu hotplug

This patch implements a Refcount + Waitqueue based model for
cpu-hotplug.

Now, a thread which wants to prevent cpu-hotplug, will bump up a global
refcount and the thread which wants to perform a cpu-hotplug operation
will block till the global refcount goes to zero.

The readers, if any, during an ongoing cpu-hotplug operation are blocked
until the cpu-hotplug operation is over.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Paul Jackson <pj@sgi.com> [For !CONFIG_HOTPLUG_CPU ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 0 deletions

diff --git a/init/main.c b/init/main.c
index 80b04b6c5157..f287ca5862b9 100644
--- a/init/main.c
+++ b/init/main.c
@@ -607,6 +607,7 @@ asmlinkage void __init start_kernel(void)
         vfs_caches_init_early();
         cpuset_init_early();
         mem_init();
+        cpu_hotplug_init();
         kmem_cache_init();
         setup_per_cpu_pageset();
         numa_policy_init();