// SPDX-License-Identifier: GPL-2.0
/*
 * linux/mm/mmzone.c
 *
 * management codes for pgdats, zones and page flags
 */


#include <linux/stddef.h>
#include <linux/mm.h>
#include <linux/mmzone.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)
{
        /*
         * Find the next suitable zone to use for the allocation.
         * Only filter based on nodemask if it's set
         */
        if (unlikely(nodes == NULL))
                while (zonelist_zone_idx(z) > highest_zoneidx)
                        z++;
        else
                while (zonelist_zone_idx(z) > highest_zoneidx ||
                                (zonelist_zone(z) && !zref_in_nodemask(z, nodes)))
                        z++;

        return z;
}

void lruvec_init(struct lruvec *lruvec)
{
        enum lru_list lru;

        memset(lruvec, 0, sizeof(struct lruvec));
        spin_lock_init(&lruvec->lru_lock);
        zswap_lruvec_state_init(lruvec);

        for_each_lru(lru)
                INIT_LIST_HEAD(&lruvec->lists[lru]);
        /*
         * The "Unevictable LRU" is imaginary: though its size is maintained,
         * it is never scanned, and unevictable pages are not threaded on it
         * (so that their lru fields can be reused to hold mlock_count).
         * Poison its list head, so that any operations on it would crash.
         */
        list_del(&lruvec->lists[LRU_UNEVICTABLE]);

        lru_gen_init_lruvec(lruvec);
}

#if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS)
int folio_xchg_last_cpupid(struct folio *folio, int cpupid)
{
        unsigned long old_flags, flags;
        int last_cpupid;

        old_flags = READ_ONCE(folio->flags.f);
        do {
                flags = old_flags;
                last_cpupid = (flags >> LAST_CPUPID_PGSHIFT) & LAST_CPUPID_MASK;

                flags &= ~(LAST_CPUPID_MASK << LAST_CPUPID_PGSHIFT);
                flags |= (cpupid & LAST_CPUPID_MASK) << LAST_CPUPID_PGSHIFT;
        } while (unlikely(!try_cmpxchg(&folio->flags.f, &old_flags, flags)));

        return last_cpupid;
}
#endif