Historically, we used the value -1. Just treat 0 as the special
case now. Clarify a comment (which was wrong, when we come via
device_online() the first time, the online_type would have been 0 /
MEM_ONLINE). The default is now always MMOP_OFFLINE. This removes the
last user of the manual "-1", which didn't use the enum value.

This is a preparation to use the online_type as an array index.

Reviewed-by: Wei Yang <redacted>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Wei Yang <redacted>
Signed-off-by: David Hildenbrand <redacted>
---
 drivers/base/memory.c          | 11 ++++-------
 include/linux/memory_hotplug.h |  2 +-
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 8c5ce42c0fc3..e7e77cafef80 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c

@@ -211,17 +211,14 @@ static int memory_subsys_online(struct device *dev)
                return 0;

        /*
-        * If we are called from state_store(), online_type will be
-        * set >= 0 Otherwise we were called from the device online
-        * attribute and need to set the online_type.
+        * When called via device_online() without configuring the online_type,
+        * we want to default to MMOP_ONLINE.
         */
-       if (mem->online_type < 0)
+       if (mem->online_type == MMOP_OFFLINE)
                mem->online_type = MMOP_ONLINE;

        ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
-
-       /* clear online_type */
-       mem->online_type = -1;
+       mem->online_type = MMOP_OFFLINE;

        return ret;
 }

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 3aaf00db224c..76f3c617a8ab 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h

@@ -48,7 +48,7 @@ enum {
 /* Types for control the zone type of onlined and offlined memory */
 enum {
        /* Offline the memory. */
-       MMOP_OFFLINE = -1,
+       MMOP_OFFLINE = 0,
        /* Online the memory. Zone depends, see default_zone_for_pfn(). */
        MMOP_ONLINE,
        /* Online the memory to ZONE_NORMAL. */
--

2.24.1