[PATCH] mm: Convert memory block states (MEM_*) macros to enum

[Israel Batista <linux@israelbatista.dev.br>]

The MEM_* constants indicating the state of the memory block are
currently defined as macros, meaning their definitions will be omitted
from the debuginfo on most kernel builds. This makes it harder for
debuggers to correctly map the block state at runtime, which can be
quite useful when analysing errors related to memory hot plugging and
unplugging with tools such as drgn and eBPF.

Converting the constants to an enum will ensure the correct information
is emitted by the compiler and available for the debugger, without needing
to hard-code them into the debugger and track their changes.

Signed-off-by: Israel Batista <linux@israelbatista.dev.br>
---
 include/linux/memory.h | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/include/linux/memory.h b/include/linux/memory.h
index ba1515160894..8feba3bfcd18 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -89,13 +89,15 @@ int arch_get_memory_phys_device(unsigned long start_pfn);
 unsigned long memory_block_size_bytes(void);
 int set_memory_block_size_order(unsigned int order);
 
-/* These states are exposed to userspace as text strings in sysfs */
-#define	MEM_ONLINE		(1<<0) /* exposed to userspace */
-#define	MEM_GOING_OFFLINE	(1<<1) /* exposed to userspace */
-#define	MEM_OFFLINE		(1<<2) /* exposed to userspace */
-#define	MEM_GOING_ONLINE	(1<<3)
-#define	MEM_CANCEL_ONLINE	(1<<4)
-#define	MEM_CANCEL_OFFLINE	(1<<5)
+enum mem_states {
+	/* These states are exposed to userspace as text strings in sysfs */
+	MEM_ONLINE		 = (1<<0), /* exposed to userspace */
+	MEM_GOING_OFFLINE	 = (1<<1), /* exposed to userspace */
+	MEM_OFFLINE		 = (1<<2), /* exposed to userspace */
+	MEM_GOING_ONLINE	 = (1<<3),
+	MEM_CANCEL_ONLINE	 = (1<<4),
+	MEM_CANCEL_OFFLINE	 = (1<<5),
+};
 
 struct memory_notify {
 	unsigned long start_pfn;
-- 
2.51.0