[PATCH] mm: name the anonymous MMOP enum as enum mmop

[Gregory Price <gourry@gourry.net>]

Give the MMOP enum (MMOP_OFFLINE, MMOP_ONLINE, etc) a proper type
name so the compiler can help catch invalid values being assigned to
variables of this type.

Leave the existing functions returning int alone to allow for
value-or-error pattern to remain unchanged without churn.

mmop_default_online_type is left as int because it uses the -1
sentinal value to signal it hasn't been initialized yet.

Keep the uint8_t buffer in offline_and_remove_memory() as-is for
space efficiency, with an explicit cast when we consume the value.

Move the enum definition before the CONFIG_MEMORY_HOTPLUG guard so
it is unconditionally available for struct memory_block in memory.h.

No functional change.

Link: https://lore.kernel.org/linux-mm/3424eba7-523b-4351-abd0-3a888a3e5e61@kernel.org/
Suggested-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Suggested-by: "David Hildenbrand (arm)" <david@kernel.org>
Signed-off-by: Gregory Price <gourry@gourry.net>
---
 drivers/base/memory.c          |  2 +-
 include/linux/memory.h         |  3 ++-
 include/linux/memory_hotplug.h | 16 ++++++++--------
 mm/memory_hotplug.c            | 10 +++++-----
 4 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 751f248ca4a8..3753ca80069d 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -452,7 +452,7 @@ static ssize_t phys_device_show(struct device *dev,
 static int print_allowed_zone(char *buf, int len, int nid,
 			      struct memory_group *group,
 			      unsigned long start_pfn, unsigned long nr_pages,
-			      int online_type, struct zone *default_zone)
+			      enum mmop online_type, struct zone *default_zone)
 {
 	struct zone *zone;
 
diff --git a/include/linux/memory.h b/include/linux/memory.h
index faeaa921e55b..5bb5599c6b2b 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -19,6 +19,7 @@
 #include <linux/node.h>
 #include <linux/compiler.h>
 #include <linux/mutex.h>
+#include <linux/memory_hotplug.h>
 
 #define MIN_MEMORY_BLOCK_SIZE     (1UL << SECTION_SIZE_BITS)
 
@@ -77,7 +78,7 @@ enum memory_block_state {
 struct memory_block {
 	unsigned long start_section_nr;
 	enum memory_block_state state;	/* serialized by the dev->lock */
-	int online_type;		/* for passing data to online routine */
+	enum mmop online_type;	/* for passing data to online routine */
 	int nid;			/* NID for this memory block */
 	/*
 	 * The single zone of this memory block if all PFNs of this memory block
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index f2f16cdd73ee..e77ef3d7ff73 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -16,11 +16,8 @@ struct resource;
 struct vmem_altmap;
 struct dev_pagemap;
 
-#ifdef CONFIG_MEMORY_HOTPLUG
-struct page *pfn_to_online_page(unsigned long pfn);
-
 /* Types for control the zone type of onlined and offlined memory */
-enum {
+enum mmop {
 	/* Offline the memory. */
 	MMOP_OFFLINE = 0,
 	/* Online the memory. Zone depends, see default_zone_for_pfn(). */
@@ -31,6 +28,9 @@ enum {
 	MMOP_ONLINE_MOVABLE,
 };
 
+#ifdef CONFIG_MEMORY_HOTPLUG
+struct page *pfn_to_online_page(unsigned long pfn);
+
 /* Flags for add_memory() and friends to specify memory hotplug details. */
 typedef int __bitwise mhp_t;
 
@@ -286,8 +286,8 @@ static inline void __remove_memory(u64 start, u64 size) {}
 
 #ifdef CONFIG_MEMORY_HOTPLUG
 /* Default online_type (MMOP_*) when new memory blocks are added. */
-extern int mhp_get_default_online_type(void);
-extern void mhp_set_default_online_type(int online_type);
+extern enum mmop mhp_get_default_online_type(void);
+extern void mhp_set_default_online_type(enum mmop online_type);
 extern void __ref free_area_init_core_hotplug(struct pglist_data *pgdat);
 extern int __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);
 extern int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags);
@@ -310,8 +310,8 @@ extern void sparse_remove_section(unsigned long pfn, unsigned long nr_pages,
 				  struct vmem_altmap *altmap);
 extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
 					  unsigned long pnum);
-extern struct zone *zone_for_pfn_range(int online_type, int nid,
-		struct memory_group *group, unsigned long start_pfn,
+extern struct zone *zone_for_pfn_range(enum mmop online_type,
+		int nid, struct memory_group *group, unsigned long start_pfn,
 		unsigned long nr_pages);
 extern int arch_create_linear_mapping(int nid, u64 start, u64 size,
 				      struct mhp_params *params);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a63ec679d861..41f48f493b8e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -221,7 +221,7 @@ void put_online_mems(void)
 bool movable_node_enabled = false;
 
 static int mhp_default_online_type = -1;
-int mhp_get_default_online_type(void)
+enum mmop mhp_get_default_online_type(void)
 {
 	if (mhp_default_online_type >= 0)
 		return mhp_default_online_type;
@@ -240,7 +240,7 @@ int mhp_get_default_online_type(void)
 	return mhp_default_online_type;
 }
 
-void mhp_set_default_online_type(int online_type)
+void mhp_set_default_online_type(enum mmop online_type)
 {
 	mhp_default_online_type = online_type;
 }
@@ -1046,7 +1046,7 @@ static inline struct zone *default_zone_for_pfn(int nid, unsigned long start_pfn
 	return movable_node_enabled ? movable_zone : kernel_zone;
 }
 
-struct zone *zone_for_pfn_range(int online_type, int nid,
+struct zone *zone_for_pfn_range(enum mmop online_type, int nid,
 		struct memory_group *group, unsigned long start_pfn,
 		unsigned long nr_pages)
 {
@@ -2305,7 +2305,7 @@ EXPORT_SYMBOL_GPL(remove_memory);
 
 static int try_offline_memory_block(struct memory_block *mem, void *arg)
 {
-	uint8_t online_type = MMOP_ONLINE_KERNEL;
+	enum mmop online_type = MMOP_ONLINE_KERNEL;
 	uint8_t **online_types = arg;
 	struct page *page;
 	int rc;
@@ -2338,7 +2338,7 @@ static int try_reonline_memory_block(struct memory_block *mem, void *arg)
 	int rc;
 
 	if (**online_types != MMOP_OFFLINE) {
-		mem->online_type = **online_types;
+		mem->online_type = (enum mmop)**online_types;
 		rc = device_online(&mem->dev);
 		if (rc < 0)
 			pr_warn("%s: Failed to re-online memory: %d",
-- 
2.47.3