[PATCH] zone gfp_flags generate from ZONE_ constants

Andy Whitcroft
2006-01-17T15:52:27Z

zone gfp_flags generate from ZONE_ constants

Change the allocation of the __GFP_zone style zone modifiers so that
they are generated from the values of the ZONE_zone definitions.
Note that when no zone modifiers are specified select the default
zone, typically ZONE_NORMAL.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
---
gfp.h | 22 ++++++++++++++++------
mmzone.h | 2 ++
2 files changed, 18 insertions(+), 6 deletions(-)
diff -upN reference/include/linux/gfp.h current/include/linux/gfp.h
--- reference/include/linux/gfp.h
+++ current/include/linux/gfp.h
@@ -11,15 +11,25 @@ struct vm_area_struct;
/*
* GFP bitmasks..
*/
-/* Zone modifiers in GFP_ZONEMASK (see linux/mmzone.h - low three bits) */
-#define __GFP_DMA ((__force gfp_t)0x01u)
-#define __GFP_HIGHMEM ((__force gfp_t)0x02u)
+
+/*
+ * Generate the zone modifier bit. Zone ZONE_DEFAULT doesn't require a bit
+ * as the absence of all zone modifiers implies this zone. Renormalise the
+ * zone number such that ZONE_DEFAULT is at the bottom and discard it.
+ * These must fit within the bitmask GFP_ZONEMASK defined in linux/mmzone.h.
+ */
+#define __ZONE_BIT(x) (((x) ^ ZONE_DEFAULT) - 1)
+#define ZONE_MODIFIER(x) ((__force gfp_t)(((x) == ZONE_DEFAULT)? (0) : \
+ 1UL << __ZONE_BIT(x)))
+
+#define __GFP_DMA ZONE_MODIFIER(ZONE_DMA)
+#define __GFP_HIGHMEM ZONE_MODIFIER(ZONE_HIGHMEM)
#ifdef CONFIG_DMA_IS_DMA32
-#define __GFP_DMA32 ((__force gfp_t)0x01) /* ZONE_DMA is ZONE_DMA32 */
+#define __GFP_DMA32 ZONE_MODIFIER(ZONE_DMA) /* ZONE_DMA is ZONE_DMA32 */
#elif BITS_PER_LONG < 64
-#define __GFP_DMA32 ((__force gfp_t)0x00) /* ZONE_NORMAL is ZONE_DMA32 */
+#define __GFP_DMA32 ZONE_MODIFIER(ZONE_NORMAL) /* ZONE_NORMAL is ZONE_DMA32 */
#else
-#define __GFP_DMA32 ((__force gfp_t)0x04) /* Has own ZONE_DMA32 */
+#define __GFP_DMA32 ZONE_MODIFIER(ZONE_DMA32) /* Has own ZONE_DMA32 */
#endif

/*
diff -upN reference/include/linux/mmzone.h current/include/linux/mmzone.h
--- reference/include/linux/mmzone.h
+++ current/include/linux/mmzone.h
@@ -77,6 +77,8 @@ struct per_cpu_pageset {
#define MAX_NR_ZONES 4 /* Sync this with ZONES_SHIFT */
#define ZONES_SHIFT 2 /* ceil(log2(MAX_NR_ZONES)) */

+/* Select the zone to use when no __GFP flags are selected. */
+#define ZONE_DEFAULT ZONE_NORMAL

/*
* When a memory allocation must conform to specific limitations (such

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