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>
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 92f2029..a40247e 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -83,6 +83,9 @@
#endif /* CONFIG_SMP */
extern struct sysdev_class cpu_sysdev_class;
+extern void cpu_hotplug_init(void);
+extern void cpu_maps_update_begin(void);
+extern void cpu_maps_update_done(void);
#ifdef CONFIG_HOTPLUG_CPU
/* Stop CPUs going up and down. */