mm/zonelist: enumerate zonelists array index

Hardcoding index to zonelists array in gfp_zonelist() is not a good
idea, let's enumerate it to improve readability.

No functional change.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix CONFIG_NUMA=n build]
[n-horiguchi@ah.jp.nec.com: fix warning in comparing enumerator]
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 11 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 996384672c73..12c98dfc31b1 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -571,19 +571,17 @@ static inline bool zone_is_empty(struct zone *zone)
 /* Maximum number of zones on a zonelist */
 #define MAX_ZONES_PER_ZONELIST (MAX_NUMNODES * MAX_NR_ZONES)
 
+enum {
+        ZONELIST_FALLBACK,      /* zonelist with fallback */
 #ifdef CONFIG_NUMA
-
-/*
- * The NUMA zonelists are doubled because we need zonelists that restrict the
- * allocations to a single node for __GFP_THISNODE.
- *
- * [0]  : Zonelist with fallback
- * [1]  : No fallback (__GFP_THISNODE)
- */
-#define MAX_ZONELISTS 2
-#else
-#define MAX_ZONELISTS 1
+        /*
+         * The NUMA zonelists are doubled because we need zonelists that
+         * restrict the allocations to a single node for __GFP_THISNODE.
+         */
+        ZONELIST_NOFALLBACK,    /* zonelist without fallback (__GFP_THISNODE) */
 #endif
+        MAX_ZONELISTS
+};
 
 /*
  * This struct contains information about a zone in a zonelist. It is stored