[PATCH] cpu hotplug: fix hotplug cpu documentation for proper usage

Update hotplug cpu documentation to clearly state when to use
register_cpu_notifier() and register_hotcpu_notifier.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt
index 1bcf699..bc107cb 100644 (file)
--- a/Documentation/cpu-hotplug.txt
+++ b/Documentation/cpu-hotplug.txt
@@ -251,16 +251,24 @@ A: This is what you would need in your kernel code to receive notifications.
                return NOTIFY_OK;
        }
 
-       static struct notifier_block foobar_cpu_notifer =
+       static struct notifier_block __cpuinitdata foobar_cpu_notifer =
        {
           .notifier_call = foobar_cpu_callback,
        };
 
+You need to call register_cpu_notifier() from your init function.
+Init functions could be of two types:
+1. early init (init function called when only the boot processor is online).
+2. late init (init function called _after_ all the CPUs are online).
 
-In your init function,
+For the first case, you should add the following to your init function
 
        register_cpu_notifier(&foobar_cpu_notifier);
 
+For the second case, you should add the following to your init function
+
+       register_hotcpu_notifier(&foobar_cpu_notifier);
+
 You can fail PREPARE notifiers if something doesn't work to prepare resources.
 This will stop the activity and send a following CANCELED event back.