root/mm/mmzone.c

DEFINITIONS

1. first_online_pgdat
2. next_online_pgdat
3. next_zone
4. zref_in_nodemask
5. next_zones_zonelist

/*
 * linux/mm/mmzone.c
 *
 * management codes for pgdats and zones.
 */


#include <linux/stddef.h>
#include <linux/mmzone.h>
#include <linux/module.h>

struct pglist_data *first_online_pgdat(void)
{
        return NODE_DATA(first_online_node);
}

struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
{
        int nid = next_online_node(pgdat->node_id);

        if (nid == MAX_NUMNODES)
                return NULL;
        return NODE_DATA(nid);
}

/*
 * next_zone - helper magic for for_each_zone()
 */
struct zone *next_zone(struct zone *zone)
{
        pg_data_t *pgdat = zone->zone_pgdat;

        if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
                zone++;
        else {
                pgdat = next_online_pgdat(pgdat);
                if (pgdat)
                        zone = pgdat->node_zones;
                else
                        zone = NULL;
        }
        return zone;
}

static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
{
#ifdef CONFIG_NUMA
        return node_isset(zonelist_node_idx(zref), *nodes);
#else
        return 1;
#endif /* CONFIG_NUMA */
}

/* Returns the next zone at or below highest_zoneidx in a zonelist */
struct zoneref *next_zones_zonelist(struct zoneref *z,
                                        enum zone_type highest_zoneidx,
                                        nodemask_t *nodes,
                                        struct zone **zone)
{
        /*
         * Find the next suitable zone to use for the allocation.
         * Only filter based on nodemask if it's set
         */
        if (likely(nodes == NULL))
                while (zonelist_zone_idx(z) > highest_zoneidx)
                        z++;
        else
                while (zonelist_zone_idx(z) > highest_zoneidx ||
                                (z->zone && !zref_in_nodemask(z, nodes)))
                        z++;

        *zone = zonelist_zone(z);
        return z;
}