[RFC} memory unplug patchset prep [1/16] zone ids cleanup

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

OThis patch defines ZONE_DMA,DMA32,HIGHMEM on *any* config.
MAX_NR_ZONES is unchanged and not-configured zones's id is greater than it.
Now, you can check zone is configured or not by (zone_id < MAX_NR_ZONES).

Good bye #ifdefs. Compiler will do enough work, I think.

Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
 include/linux/mmzone.h |   33 ++++++++++++------------
 mm/page_alloc.c        |   65 ++++++++++++++++++++++++++-----------------------
 2 files changed, 51 insertions(+), 47 deletions(-)

Index: devel-tree-2.6.20-mm2/include/linux/mmzone.h
===================================================================
--- devel-tree-2.6.20-mm2.orig/include/linux/mmzone.h
+++ devel-tree-2.6.20-mm2/include/linux/mmzone.h
@@ -142,9 +142,24 @@ enum zone_type {
 	 */
 	ZONE_HIGHMEM,
 #endif
-	MAX_NR_ZONES
+	MAX_NR_ZONES,
+#ifndef CONFIG_ZONE_DMA
+	ZONE_DMA,
+#endif
+#ifndef CONFIG_ZONE_DMA32
+	ZONE_DMA32,
+#endif
+#ifndef CONFIG_HIGHMEM
+	ZONE_HIGHMEM,
+#endif
+	MAX_POSSIBLE_ZONES
 };
 
+static inline int is_configured_zone(enum zone_type type)
+{
+	return (type < MAX_NR_ZONES);
+}
+
 /*
  * When a memory allocation must conform to specific limitations (such
  * as being suitable for DMA) the caller will pass in hints to the
@@ -500,11 +515,7 @@ static inline int populated_zone(struct 
 
 static inline int is_highmem_idx(enum zone_type idx)
 {
-#ifdef CONFIG_HIGHMEM
 	return (idx == ZONE_HIGHMEM);
-#else
-	return 0;
-#endif
 }
 
 static inline int is_normal_idx(enum zone_type idx)
@@ -520,11 +531,7 @@ static inline int is_normal_idx(enum zon
  */
 static inline int is_highmem(struct zone *zone)
 {
-#ifdef CONFIG_HIGHMEM
 	return zone == zone->zone_pgdat->node_zones + ZONE_HIGHMEM;
-#else
-	return 0;
-#endif
 }
 
 static inline int is_normal(struct zone *zone)
@@ -534,20 +541,12 @@ static inline int is_normal(struct zone 
 
 static inline int is_dma32(struct zone *zone)
 {
-#ifdef CONFIG_ZONE_DMA32
 	return zone == zone->zone_pgdat->node_zones + ZONE_DMA32;
-#else
-	return 0;
-#endif
 }
 
 static inline int is_dma(struct zone *zone)
 {
-#ifdef CONFIG_ZONE_DMA
 	return zone == zone->zone_pgdat->node_zones + ZONE_DMA;
-#else
-	return 0;
-#endif
 }
 
 /* These two functions are used to setup the per zone pages min values */
Index: devel-tree-2.6.20-mm2/mm/page_alloc.c
===================================================================
--- devel-tree-2.6.20-mm2.orig/mm/page_alloc.c
+++ devel-tree-2.6.20-mm2/mm/page_alloc.c
@@ -72,32 +72,34 @@ static void __free_pages_ok(struct page 
  * TBD: should special case ZONE_DMA32 machines here - in those we normally
  * don't need any ZONE_NORMAL reservation
  */
-int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
-#ifdef CONFIG_ZONE_DMA
-	 256,
-#endif
-#ifdef CONFIG_ZONE_DMA32
-	 256,
-#endif
-#ifdef CONFIG_HIGHMEM
-	 32
-#endif
-};
+int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
 
 EXPORT_SYMBOL(totalram_pages);
 
-static char * const zone_names[MAX_NR_ZONES] = {
-#ifdef CONFIG_ZONE_DMA
-	 "DMA",
-#endif
-#ifdef CONFIG_ZONE_DMA32
-	 "DMA32",
-#endif
-	 "Normal",
-#ifdef CONFIG_HIGHMEM
-	 "HighMem"
-#endif
-};
+static char *zone_names[MAX_POSSIBLE_ZONES];
+
+static char name_dma[] = "DMA";
+static char name_dma32[] = "DMA32";
+static char name_normal[] = "Normal";
+static char name_highmem[] = "Highmem";
+
+static inline void __meminit zone_variables_init(void)
+{
+	if (zone_names[0] != NULL)
+		return;
+	zone_names[ZONE_DMA] = name_dma;
+	zone_names[ZONE_DMA32] = name_dma32;
+	zone_names[ZONE_NORMAL] = name_normal;
+	zone_names[ZONE_HIGHMEM] = name_highmem;
+
+	/* ZONE below NORAML has ratio 256 */
+	if (is_configured_zone(ZONE_DMA))
+		sysctl_lowmem_reserve_ratio[ZONE_DMA] = 256;
+	if (is_configured_zone(ZONE_DMA32))
+		sysctl_lowmem_reserve_ratio[ZONE_DMA32] = 256;
+	if (is_configured_zone(ZONE_HIGHMEM))
+		sysctl_lowmem_reserve_ratio[ZONE_HIGHMEM] = 32;
+}
 
 int min_free_kbytes = 1024;
 
@@ -1638,14 +1640,16 @@ void si_meminfo_node(struct sysinfo *val
 
 	val->totalram = pgdat->node_present_pages;
 	val->freeram = node_page_state(nid, NR_FREE_PAGES);
-#ifdef CONFIG_HIGHMEM
-	val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].present_pages;
-	val->freehigh = zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
+	if (is_configured_zone(ZONE_HIGHMEM)) {
+		val->totalhigh =
+			pgdat->node_zones[ZONE_HIGHMEM].present_pages;
+		val->freehigh =
+			zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
 			NR_FREE_PAGES);
-#else
-	val->totalhigh = 0;
-	val->freehigh = 0;
-#endif
+	} else {
+		val->totalhigh = 0;
+		val->freehigh = 0;
+	}
 	val->mem_unit = PAGE_SIZE;
 }
 #endif
@@ -3048,7 +3052,8 @@ void __init free_area_init_nodes(unsigne
 {
 	unsigned long nid;
 	enum zone_type i;
-
+	/* Parameter Setup */
+	zone_variables_init();
 	/* Sort early_node_map as initialisation assumes it is sorted */
 	sort_node_map();
 
@@ -3119,6 +3124,7 @@ EXPORT_SYMBOL(contig_page_data);
 
 void __init free_area_init(unsigned long *zones_size)
 {
+	zone_variables_init();
 	free_area_init_node(0, NODE_DATA(0), zones_size,
 			__pa(PAGE_OFFSET) >> PAGE_SHIFT, NULL);
 }

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