From e6bde73b07edeb703d4c89c1daabc09c303de11f Mon Sep 17 00:00:00 2001
From: Akinobu Mita <akinobu.mita@gmail.com>
Date: Wed, 26 May 2010 14:43:29 -0700
Subject: [PATCH] cpu-hotplug: return better errno on cpu hotplug failure

Currently, onlining or offlining a CPU failure by one of the cpu notifiers
error always cause -EINVAL error.  (i.e.  writing 0 or 1 to
/sys/devices/system/cpu/cpuX/online gets EINVAL)

To get better error reporting rather than always getting -EINVAL, This
changes cpu_notify() to return -errno value with notifier_to_errno() and
fix the callers.  Now that cpu notifiers can return encapsulate errno
value.

Currently, all cpu hotplug notifiers return NOTIFY_OK, NOTIFY_BAD, or
NOTIFY_DONE.  So cpu_notify() can returns 0 or -EPERM with this change for
now.

(notifier_to_errno(NOTIFY_OK) == 0, notifier_to_errno(NOTIFY_DONE) == 0,
notifier_to_errno(NOTIFY_BAD) == -EPERM)

Forthcoming patches convert several cpu notifiers to return encapsulate
errno value with notifier_from_errno().

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
Reading git-format-patch failed