/* Copyright (C) 2013 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#ifndef _IP_SET_HASH_GEN_H
#define _IP_SET_HASH_GEN_H

#include <linux/rcupdate.h>
#include <linux/jhash.h>
#include <linux/types.h>
#include <linux/netfilter/ipset/ip_set_timeout.h>

#define __ipset_dereference_protected(p, c)     rcu_dereference_protected(p, c)
#define ipset_dereference_protected(p, set) \
        __ipset_dereference_protected(p, spin_is_locked(&(set)->lock))

#define rcu_dereference_bh_nfnl(p)      rcu_dereference_bh_check(p, 1)

/* Hashing which uses arrays to resolve clashing. The hash table is resized
 * (doubled) when searching becomes too long.
 * Internally jhash is used with the assumption that the size of the
 * stored data is a multiple of sizeof(u32).
 *
 * Readers and resizing
 *
 * Resizing can be triggered by userspace command only, and those
 * are serialized by the nfnl mutex. During resizing the set is
 * read-locked, so the only possible concurrent operations are
 * the kernel side readers. Those must be protected by proper RCU locking.
 */

/* Number of elements to store in an initial array block */
#define AHASH_INIT_SIZE                 4
/* Max number of elements to store in an array block */
#define AHASH_MAX_SIZE                  (3 * AHASH_INIT_SIZE)
/* Max muber of elements in the array block when tuned */
#define AHASH_MAX_TUNED                 64

/* Max number of elements can be tuned */
#ifdef IP_SET_HASH_WITH_MULTI
#define AHASH_MAX(h)                    ((h)->ahash_max)

static inline u8
tune_ahash_max(u8 curr, u32 multi)
{
        u32 n;

        if (multi < curr)
                return curr;

        n = curr + AHASH_INIT_SIZE;
        /* Currently, at listing one hash bucket must fit into a message.
         * Therefore we have a hard limit here.
         */
        return n > curr && n <= AHASH_MAX_TUNED ? n : curr;
}

#define TUNE_AHASH_MAX(h, multi)        \
        ((h)->ahash_max = tune_ahash_max((h)->ahash_max, multi))
#else
#define AHASH_MAX(h)                    AHASH_MAX_SIZE
#define TUNE_AHASH_MAX(h, multi)
#endif

/* A hash bucket */
struct hbucket {
        struct rcu_head rcu;    /* for call_rcu_bh */
        /* Which positions are used in the array */
        DECLARE_BITMAP(used, AHASH_MAX_TUNED);
        u8 size;                /* size of the array */
        u8 pos;                 /* position of the first free entry */
        unsigned char value[0]  /* the array of the values */
                __aligned(__alignof__(u64));
};

/* The hash table: the table size stored here in order to make resizing easy */
struct htable {
        atomic_t ref;           /* References for resizing */
        atomic_t uref;          /* References for dumping */
        u8 htable_bits;         /* size of hash table == 2^htable_bits */
        struct hbucket __rcu *bucket[0]; /* hashtable buckets */
};

#define hbucket(h, i)           ((h)->bucket[i])
#define ext_size(n, dsize)      \
        (sizeof(struct hbucket) + (n) * (dsize))

#ifndef IPSET_NET_COUNT
#define IPSET_NET_COUNT         1
#endif

/* Book-keeping of the prefixes added to the set */
struct net_prefixes {
        u32 nets[IPSET_NET_COUNT]; /* number of elements for this cidr */
        u8 cidr[IPSET_NET_COUNT];  /* the cidr value */
};

/* Compute the hash table size */
static size_t
htable_size(u8 hbits)
{
        size_t hsize;

        /* We must fit both into u32 in jhash and size_t */
        if (hbits > 31)
                return 0;
        hsize = jhash_size(hbits);
        if ((((size_t)-1) - sizeof(struct htable)) / sizeof(struct hbucket *)
            < hsize)
                return 0;

        return hsize * sizeof(struct hbucket *) + sizeof(struct htable);
}

/* Compute htable_bits from the user input parameter hashsize */
static u8
htable_bits(u32 hashsize)
{
        /* Assume that hashsize == 2^htable_bits */
        u8 bits = fls(hashsize - 1);

        if (jhash_size(bits) != hashsize)
                /* Round up to the first 2^n value */
                bits = fls(hashsize);

        return bits;
}

#ifdef IP_SET_HASH_WITH_NETS
#if IPSET_NET_COUNT > 1
#define __CIDR(cidr, i)         (cidr[i])
#else
#define __CIDR(cidr, i)         (cidr)
#endif

/* cidr + 1 is stored in net_prefixes to support /0 */
#define NCIDR_PUT(cidr)         ((cidr) + 1)
#define NCIDR_GET(cidr)         ((cidr) - 1)

#ifdef IP_SET_HASH_WITH_NETS_PACKED
/* When cidr is packed with nomatch, cidr - 1 is stored in the data entry */
#define DCIDR_PUT(cidr)         ((cidr) - 1)
#define DCIDR_GET(cidr, i)      (__CIDR(cidr, i) + 1)
#else
#define DCIDR_PUT(cidr)         (cidr)
#define DCIDR_GET(cidr, i)      __CIDR(cidr, i)
#endif

#define INIT_CIDR(cidr, host_mask)      \
        DCIDR_PUT(((cidr) ? NCIDR_GET(cidr) : host_mask))

#ifdef IP_SET_HASH_WITH_NET0
/* cidr from 0 to HOST_MASK value and c = cidr + 1 */
#define NLEN                    (HOST_MASK + 1)
#define CIDR_POS(c)             ((c) - 1)
#else
/* cidr from 1 to HOST_MASK value and c = cidr + 1 */
#define NLEN                    HOST_MASK
#define CIDR_POS(c)             ((c) - 2)
#endif

#else
#define NLEN                    0
#endif /* IP_SET_HASH_WITH_NETS */

#endif /* _IP_SET_HASH_GEN_H */

#ifndef MTYPE
#error "MTYPE is not defined!"
#endif

#ifndef HTYPE
#error "HTYPE is not defined!"
#endif

#ifndef HOST_MASK
#error "HOST_MASK is not defined!"
#endif

/* Family dependent templates */

#undef ahash_data
#undef mtype_data_equal
#undef mtype_do_data_match
#undef mtype_data_set_flags
#undef mtype_data_reset_elem
#undef mtype_data_reset_flags
#undef mtype_data_netmask
#undef mtype_data_list
#undef mtype_data_next
#undef mtype_elem

#undef mtype_ahash_destroy
#undef mtype_ext_cleanup
#undef mtype_add_cidr
#undef mtype_del_cidr
#undef mtype_ahash_memsize
#undef mtype_flush
#undef mtype_destroy
#undef mtype_same_set
#undef mtype_kadt
#undef mtype_uadt

#undef mtype_add
#undef mtype_del
#undef mtype_test_cidrs
#undef mtype_test
#undef mtype_uref
#undef mtype_expire
#undef mtype_resize
#undef mtype_head
#undef mtype_list
#undef mtype_gc
#undef mtype_gc_init
#undef mtype_variant
#undef mtype_data_match

#undef htype
#undef HKEY

#define mtype_data_equal        IPSET_TOKEN(MTYPE, _data_equal)
#ifdef IP_SET_HASH_WITH_NETS
#define mtype_do_data_match     IPSET_TOKEN(MTYPE, _do_data_match)
#else
#define mtype_do_data_match(d)  1
#endif
#define mtype_data_set_flags    IPSET_TOKEN(MTYPE, _data_set_flags)
#define mtype_data_reset_elem   IPSET_TOKEN(MTYPE, _data_reset_elem)
#define mtype_data_reset_flags  IPSET_TOKEN(MTYPE, _data_reset_flags)
#define mtype_data_netmask      IPSET_TOKEN(MTYPE, _data_netmask)
#define mtype_data_list         IPSET_TOKEN(MTYPE, _data_list)
#define mtype_data_next         IPSET_TOKEN(MTYPE, _data_next)
#define mtype_elem              IPSET_TOKEN(MTYPE, _elem)

#define mtype_ahash_destroy     IPSET_TOKEN(MTYPE, _ahash_destroy)
#define mtype_ext_cleanup       IPSET_TOKEN(MTYPE, _ext_cleanup)
#define mtype_add_cidr          IPSET_TOKEN(MTYPE, _add_cidr)
#define mtype_del_cidr          IPSET_TOKEN(MTYPE, _del_cidr)
#define mtype_ahash_memsize     IPSET_TOKEN(MTYPE, _ahash_memsize)
#define mtype_flush             IPSET_TOKEN(MTYPE, _flush)
#define mtype_destroy           IPSET_TOKEN(MTYPE, _destroy)
#define mtype_same_set          IPSET_TOKEN(MTYPE, _same_set)
#define mtype_kadt              IPSET_TOKEN(MTYPE, _kadt)
#define mtype_uadt              IPSET_TOKEN(MTYPE, _uadt)

#define mtype_add               IPSET_TOKEN(MTYPE, _add)
#define mtype_del               IPSET_TOKEN(MTYPE, _del)
#define mtype_test_cidrs        IPSET_TOKEN(MTYPE, _test_cidrs)
#define mtype_test              IPSET_TOKEN(MTYPE, _test)
#define mtype_uref              IPSET_TOKEN(MTYPE, _uref)
#define mtype_expire            IPSET_TOKEN(MTYPE, _expire)
#define mtype_resize            IPSET_TOKEN(MTYPE, _resize)
#define mtype_head              IPSET_TOKEN(MTYPE, _head)
#define mtype_list              IPSET_TOKEN(MTYPE, _list)
#define mtype_gc                IPSET_TOKEN(MTYPE, _gc)
#define mtype_gc_init           IPSET_TOKEN(MTYPE, _gc_init)
#define mtype_variant           IPSET_TOKEN(MTYPE, _variant)
#define mtype_data_match        IPSET_TOKEN(MTYPE, _data_match)

#ifndef HKEY_DATALEN
#define HKEY_DATALEN            sizeof(struct mtype_elem)
#endif

#define htype                   MTYPE

#define HKEY(data, initval, htable_bits)                        \
({                                                              \
        const u32 *__k = (const u32 *)data;                     \
        u32 __l = HKEY_DATALEN / sizeof(u32);                   \
                                                                \
        BUILD_BUG_ON(HKEY_DATALEN % sizeof(u32) != 0);          \
                                                                \
        jhash2(__k, __l, initval) & jhash_mask(htable_bits);    \
})

/* The generic hash structure */
struct htype {
        struct htable __rcu *table; /* the hash table */
        struct timer_list gc;   /* garbage collection when timeout enabled */
        struct ip_set *set;     /* attached to this ip_set */
        u32 maxelem;            /* max elements in the hash */
        u32 initval;            /* random jhash init value */
#ifdef IP_SET_HASH_WITH_MARKMASK
        u32 markmask;           /* markmask value for mark mask to store */
#endif
#ifdef IP_SET_HASH_WITH_MULTI
        u8 ahash_max;           /* max elements in an array block */
#endif
#ifdef IP_SET_HASH_WITH_NETMASK
        u8 netmask;             /* netmask value for subnets to store */
#endif
        struct mtype_elem next; /* temporary storage for uadd */
#ifdef IP_SET_HASH_WITH_NETS
        struct net_prefixes nets[NLEN]; /* book-keeping of prefixes */
#endif
};

#ifdef IP_SET_HASH_WITH_NETS
/* Network cidr size book keeping when the hash stores different
 * sized networks. cidr == real cidr + 1 to support /0.
 */
static void
mtype_add_cidr(struct htype *h, u8 cidr, u8 n)
{
        int i, j;

        /* Add in increasing prefix order, so larger cidr first */
        for (i = 0, j = -1; i < NLEN && h->nets[i].cidr[n]; i++) {
                if (j != -1) {
                        continue;
                } else if (h->nets[i].cidr[n] < cidr) {
                        j = i;
                } else if (h->nets[i].cidr[n] == cidr) {
                        h->nets[CIDR_POS(cidr)].nets[n]++;
                        return;
                }
        }
        if (j != -1) {
                for (; i > j; i--)
                        h->nets[i].cidr[n] = h->nets[i - 1].cidr[n];
        }
        h->nets[i].cidr[n] = cidr;
        h->nets[CIDR_POS(cidr)].nets[n] = 1;
}

static void
mtype_del_cidr(struct htype *h, u8 cidr, u8 n)
{
        u8 i, j, net_end = NLEN - 1;

        for (i = 0; i < NLEN; i++) {
                if (h->nets[i].cidr[n] != cidr)
                        continue;
                h->nets[CIDR_POS(cidr)].nets[n]--;
                if (h->nets[CIDR_POS(cidr)].nets[n] > 0)
                        return;
                for (j = i; j < net_end && h->nets[j].cidr[n]; j++)
                        h->nets[j].cidr[n] = h->nets[j + 1].cidr[n];
                h->nets[j].cidr[n] = 0;
                return;
        }
}
#endif

/* Calculate the actual memory size of the set data */
static size_t
mtype_ahash_memsize(const struct htype *h, const struct htable *t)
{
        return sizeof(*h) + sizeof(*t);
}

/* Get the ith element from the array block n */
#define ahash_data(n, i, dsize) \
        ((struct mtype_elem *)((n)->value + ((i) * (dsize))))

static void
mtype_ext_cleanup(struct ip_set *set, struct hbucket *n)
{
        int i;

        for (i = 0; i < n->pos; i++)
                if (test_bit(i, n->used))
                        ip_set_ext_destroy(set, ahash_data(n, i, set->dsize));
}

/* Flush a hash type of set: destroy all elements */
static void
mtype_flush(struct ip_set *set)
{
        struct htype *h = set->data;
        struct htable *t;
        struct hbucket *n;
        u32 i;

        t = ipset_dereference_protected(h->table, set);
        for (i = 0; i < jhash_size(t->htable_bits); i++) {
                n = __ipset_dereference_protected(hbucket(t, i), 1);
                if (!n)
                        continue;
                if (set->extensions & IPSET_EXT_DESTROY)
                        mtype_ext_cleanup(set, n);
                /* FIXME: use slab cache */
                rcu_assign_pointer(hbucket(t, i), NULL);
                kfree_rcu(n, rcu);
        }
#ifdef IP_SET_HASH_WITH_NETS
        memset(h->nets, 0, sizeof(h->nets));
#endif
        set->elements = 0;
        set->ext_size = 0;
}

/* Destroy the hashtable part of the set */
static void
mtype_ahash_destroy(struct ip_set *set, struct htable *t, bool ext_destroy)
{
        struct hbucket *n;
        u32 i;

        for (i = 0; i < jhash_size(t->htable_bits); i++) {
                n = __ipset_dereference_protected(hbucket(t, i), 1);
                if (!n)
                        continue;
                if (set->extensions & IPSET_EXT_DESTROY && ext_destroy)
                        mtype_ext_cleanup(set, n);
                /* FIXME: use slab cache */
                kfree(n);
        }

        ip_set_free(t);
}

/* Destroy a hash type of set */
static void
mtype_destroy(struct ip_set *set)
{
        struct htype *h = set->data;

        if (SET_WITH_TIMEOUT(set))
                del_timer_sync(&h->gc);

        mtype_ahash_destroy(set,
                            __ipset_dereference_protected(h->table, 1), true);
        kfree(h);

        set->data = NULL;
}

static void
mtype_gc_init(struct ip_set *set, void (*gc)(struct timer_list *t))
{
        struct htype *h = set->data;

        timer_setup(&h->gc, gc, 0);
        mod_timer(&h->gc, jiffies + IPSET_GC_PERIOD(set->timeout) * HZ);
        pr_debug("gc initialized, run in every %u\n",
                 IPSET_GC_PERIOD(set->timeout));
}

static bool
mtype_same_set(const struct ip_set *a, const struct ip_set *b)
{
        const struct htype *x = a->data;
        const struct htype *y = b->data;

        /* Resizing changes htable_bits, so we ignore it */
        return x->maxelem == y->maxelem &&
               a->timeout == b->timeout &&
#ifdef IP_SET_HASH_WITH_NETMASK
               x->netmask == y->netmask &&
#endif
#ifdef IP_SET_HASH_WITH_MARKMASK
               x->markmask == y->markmask &&
#endif
               a->extensions == b->extensions;
}

/* Delete expired elements from the hashtable */
static void
mtype_expire(struct ip_set *set, struct htype *h)
{
        struct htable *t;
        struct hbucket *n, *tmp;
        struct mtype_elem *data;
        u32 i, j, d;
        size_t dsize = set->dsize;
#ifdef IP_SET_HASH_WITH_NETS
        u8 k;
#endif

        t = ipset_dereference_protected(h->table, set);
        for (i = 0; i < jhash_size(t->htable_bits); i++) {
                n = __ipset_dereference_protected(hbucket(t, i), 1);
                if (!n)
                        continue;
                for (j = 0, d = 0; j < n->pos; j++) {
                        if (!test_bit(j, n->used)) {
                                d++;
                                continue;
                        }
                        data = ahash_data(n, j, dsize);
                        if (!ip_set_timeout_expired(ext_timeout(data, set)))
                                continue;
                        pr_debug("expired %u/%u\n", i, j);
                        clear_bit(j, n->used);
                        smp_mb__after_atomic();
#ifdef IP_SET_HASH_WITH_NETS
                        for (k = 0; k < IPSET_NET_COUNT; k++)
                                mtype_del_cidr(h,
                                        NCIDR_PUT(DCIDR_GET(data->cidr, k)),
                                        k);
#endif
                        ip_set_ext_destroy(set, data);
                        set->elements--;
                        d++;
                }
                if (d >= AHASH_INIT_SIZE) {
                        if (d >= n->size) {
                                rcu_assign_pointer(hbucket(t, i), NULL);
                                kfree_rcu(n, rcu);
                                continue;
                        }
                        tmp = kzalloc(sizeof(*tmp) +
                                      (n->size - AHASH_INIT_SIZE) * dsize,
                                      GFP_ATOMIC);
                        if (!tmp)
                                /* Still try to delete expired elements */
                                continue;
                        tmp->size = n->size - AHASH_INIT_SIZE;
                        for (j = 0, d = 0; j < n->pos; j++) {
                                if (!test_bit(j, n->used))
                                        continue;
                                data = ahash_data(n, j, dsize);
                                memcpy(tmp->value + d * dsize, data, dsize);
                                set_bit(d, tmp->used);
                                d++;
                        }
                        tmp->pos = d;
                        set->ext_size -= ext_size(AHASH_INIT_SIZE, dsize);
                        rcu_assign_pointer(hbucket(t, i), tmp);
                        kfree_rcu(n, rcu);
                }
        }
}

static void
mtype_gc(struct timer_list *t)
{
        struct htype *h = from_timer(h, t, gc);
        struct ip_set *set = h->set;

        pr_debug("called\n");
        spin_lock_bh(&set->lock);
        mtype_expire(set, h);
        spin_unlock_bh(&set->lock);

        h->gc.expires = jiffies + IPSET_GC_PERIOD(set->timeout) * HZ;
        add_timer(&h->gc);
}

/* Resize a hash: create a new hash table with doubling the hashsize
 * and inserting the elements to it. Repeat until we succeed or
 * fail due to memory pressures.
 */
static int
mtype_resize(struct ip_set *set, bool retried)
{
        struct htype *h = set->data;
        struct htable *t, *orig;
        u8 htable_bits;
        size_t extsize, dsize = set->dsize;
#ifdef IP_SET_HASH_WITH_NETS
        u8 flags;
        struct mtype_elem *tmp;
#endif
        struct mtype_elem *data;
        struct mtype_elem *d;
        struct hbucket *n, *m;
        u32 i, j, key;
        int ret;

#ifdef IP_SET_HASH_WITH_NETS
        tmp = kmalloc(dsize, GFP_KERNEL);
        if (!tmp)
                return -ENOMEM;
#endif
        rcu_read_lock_bh();
        orig = rcu_dereference_bh_nfnl(h->table);
        htable_bits = orig->htable_bits;
        rcu_read_unlock_bh();

retry:
        ret = 0;
        htable_bits++;
        if (!htable_bits) {
                /* In case we have plenty of memory :-) */
                pr_warn("Cannot increase the hashsize of set %s further\n",
                        set->name);
                ret = -IPSET_ERR_HASH_FULL;
                goto out;
        }
        t = ip_set_alloc(htable_size(htable_bits));
        if (!t) {
                ret = -ENOMEM;
                goto out;
        }
        t->htable_bits = htable_bits;

        spin_lock_bh(&set->lock);
        orig = __ipset_dereference_protected(h->table, 1);
        /* There can't be another parallel resizing, but dumping is possible */
        atomic_set(&orig->ref, 1);
        atomic_inc(&orig->uref);
        extsize = 0;
        pr_debug("attempt to resize set %s from %u to %u, t %p\n",
                 set->name, orig->htable_bits, htable_bits, orig);
        for (i = 0; i < jhash_size(orig->htable_bits); i++) {
                n = __ipset_dereference_protected(hbucket(orig, i), 1);
                if (!n)
                        continue;
                for (j = 0; j < n->pos; j++) {
                        if (!test_bit(j, n->used))
                                continue;
                        data = ahash_data(n, j, dsize);
#ifdef IP_SET_HASH_WITH_NETS
                        /* We have readers running parallel with us,
                         * so the live data cannot be modified.
                         */
                        flags = 0;
                        memcpy(tmp, data, dsize);
                        data = tmp;
                        mtype_data_reset_flags(data, &flags);
#endif
                        key = HKEY(data, h->initval, htable_bits);
                        m = __ipset_dereference_protected(hbucket(t, key), 1);
                        if (!m) {
                                m = kzalloc(sizeof(*m) +
                                            AHASH_INIT_SIZE * dsize,
                                            GFP_ATOMIC);
                                if (!m) {
                                        ret = -ENOMEM;
                                        goto cleanup;
                                }
                                m->size = AHASH_INIT_SIZE;
                                extsize = ext_size(AHASH_INIT_SIZE, dsize);
                                RCU_INIT_POINTER(hbucket(t, key), m);
                        } else if (m->pos >= m->size) {
                                struct hbucket *ht;

                                if (m->size >= AHASH_MAX(h)) {
                                        ret = -EAGAIN;
                                } else {
                                        ht = kzalloc(sizeof(*ht) +
                                                (m->size + AHASH_INIT_SIZE)
                                                * dsize,
                                                GFP_ATOMIC);
                                        if (!ht)
                                                ret = -ENOMEM;
                                }
                                if (ret < 0)
                                        goto cleanup;
                                memcpy(ht, m, sizeof(struct hbucket) +
                                              m->size * dsize);
                                ht->size = m->size + AHASH_INIT_SIZE;
                                extsize += ext_size(AHASH_INIT_SIZE, dsize);
                                kfree(m);
                                m = ht;
                                RCU_INIT_POINTER(hbucket(t, key), ht);
                        }
                        d = ahash_data(m, m->pos, dsize);
                        memcpy(d, data, dsize);
                        set_bit(m->pos++, m->used);
#ifdef IP_SET_HASH_WITH_NETS
                        mtype_data_reset_flags(d, &flags);
#endif
                }
        }
        rcu_assign_pointer(h->table, t);
        set->ext_size = extsize;

        spin_unlock_bh(&set->lock);

        /* Give time to other readers of the set */
        synchronize_rcu_bh();

        pr_debug("set %s resized from %u (%p) to %u (%p)\n", set->name,
                 orig->htable_bits, orig, t->htable_bits, t);
        /* If there's nobody else dumping the table, destroy it */
        if (atomic_dec_and_test(&orig->uref)) {
                pr_debug("Table destroy by resize %p\n", orig);
                mtype_ahash_destroy(set, orig, false);
        }

out:
#ifdef IP_SET_HASH_WITH_NETS
        kfree(tmp);
#endif
        return ret;

cleanup:
        atomic_set(&orig->ref, 0);
        atomic_dec(&orig->uref);
        spin_unlock_bh(&set->lock);
        mtype_ahash_destroy(set, t, false);
        if (ret == -EAGAIN)
                goto retry;
        goto out;
}

/* Add an element to a hash and update the internal counters when succeeded,
 * otherwise report the proper error code.
 */
static int
mtype_add(struct ip_set *set, void *value, const struct ip_set_ext *ext,
          struct ip_set_ext *mext, u32 flags)
{
        struct htype *h = set->data;
        struct htable *t;
        const struct mtype_elem *d = value;
        struct mtype_elem *data;
        struct hbucket *n, *old = ERR_PTR(-ENOENT);
        int i, j = -1;
        bool flag_exist = flags & IPSET_FLAG_EXIST;
        bool deleted = false, forceadd = false, reuse = false;
        u32 key, multi = 0;

        if (set->elements >= h->maxelem) {
                if (SET_WITH_TIMEOUT(set))
                        /* FIXME: when set is full, we slow down here */
                        mtype_expire(set, h);
                if (set->elements >= h->maxelem && SET_WITH_FORCEADD(set))
                        forceadd = true;
        }

        t = ipset_dereference_protected(h->table, set);
        key = HKEY(value, h->initval, t->htable_bits);
        n = __ipset_dereference_protected(hbucket(t, key), 1);
        if (!n) {
                if (forceadd || set->elements >= h->maxelem)
                        goto set_full;
                old = NULL;
                n = kzalloc(sizeof(*n) + AHASH_INIT_SIZE * set->dsize,
                            GFP_ATOMIC);
                if (!n)
                        return -ENOMEM;
                n->size = AHASH_INIT_SIZE;
                set->ext_size += ext_size(AHASH_INIT_SIZE, set->dsize);
                goto copy_elem;
        }
        for (i = 0; i < n->pos; i++) {
                if (!test_bit(i, n->used)) {
                        /* Reuse first deleted entry */
                        if (j == -1) {
                                deleted = reuse = true;
                                j = i;
                        }
                        continue;
                }
                data = ahash_data(n, i, set->dsize);
                if (mtype_data_equal(data, d, &multi)) {
                        if (flag_exist ||
                            (SET_WITH_TIMEOUT(set) &&
                             ip_set_timeout_expired(ext_timeout(data, set)))) {
                                /* Just the extensions could be overwritten */
                                j = i;
                                goto overwrite_extensions;
                        }
                        return -IPSET_ERR_EXIST;
                }
                /* Reuse first timed out entry */
                if (SET_WITH_TIMEOUT(set) &&
                    ip_set_timeout_expired(ext_timeout(data, set)) &&
                    j == -1) {
                        j = i;
                        reuse = true;
                }
        }
        if (reuse || forceadd) {
                data = ahash_data(n, j, set->dsize);
                if (!deleted) {
#ifdef IP_SET_HASH_WITH_NETS
                        for (i = 0; i < IPSET_NET_COUNT; i++)
                                mtype_del_cidr(h,
                                        NCIDR_PUT(DCIDR_GET(data->cidr, i)),
                                        i);
#endif
                        ip_set_ext_destroy(set, data);
                        set->elements--;
                }
                goto copy_data;
        }
        if (set->elements >= h->maxelem)
                goto set_full;
        /* Create a new slot */
        if (n->pos >= n->size) {
                TUNE_AHASH_MAX(h, multi);
                if (n->size >= AHASH_MAX(h)) {
                        /* Trigger rehashing */
                        mtype_data_next(&h->next, d);
                        return -EAGAIN;
                }
                old = n;
                n = kzalloc(sizeof(*n) +
                            (old->size + AHASH_INIT_SIZE) * set->dsize,
                            GFP_ATOMIC);
                if (!n)
                        return -ENOMEM;
                memcpy(n, old, sizeof(struct hbucket) +
                       old->size * set->dsize);
                n->size = old->size + AHASH_INIT_SIZE;
                set->ext_size += ext_size(AHASH_INIT_SIZE, set->dsize);
        }

copy_elem:
        j = n->pos++;
        data = ahash_data(n, j, set->dsize);
copy_data:
        set->elements++;
#ifdef IP_SET_HASH_WITH_NETS
        for (i = 0; i < IPSET_NET_COUNT; i++)
                mtype_add_cidr(h, NCIDR_PUT(DCIDR_GET(d->cidr, i)), i);
#endif
        memcpy(data, d, sizeof(struct mtype_elem));
overwrite_extensions:
#ifdef IP_SET_HASH_WITH_NETS
        mtype_data_set_flags(data, flags);
#endif
        if (SET_WITH_COUNTER(set))
                ip_set_init_counter(ext_counter(data, set), ext);
        if (SET_WITH_COMMENT(set))
                ip_set_init_comment(set, ext_comment(data, set), ext);
        if (SET_WITH_SKBINFO(set))
                ip_set_init_skbinfo(ext_skbinfo(data, set), ext);
        /* Must come last for the case when timed out entry is reused */
        if (SET_WITH_TIMEOUT(set))
                ip_set_timeout_set(ext_timeout(data, set), ext->timeout);
        smp_mb__before_atomic();
        set_bit(j, n->used);
        if (old != ERR_PTR(-ENOENT)) {
                rcu_assign_pointer(hbucket(t, key), n);
                if (old)
                        kfree_rcu(old, rcu);
        }

        return 0;
set_full:
        if (net_ratelimit())
                pr_warn("Set %s is full, maxelem %u reached\n",
                        set->name, h->maxelem);
        return -IPSET_ERR_HASH_FULL;
}

/* Delete an element from the hash and free up space if possible.
 */
static int
mtype_del(struct ip_set *set, void *value, const struct ip_set_ext *ext,
          struct ip_set_ext *mext, u32 flags)
{
        struct htype *h = set->data;
        struct htable *t;
        const struct mtype_elem *d = value;
        struct mtype_elem *data;
        struct hbucket *n;
        int i, j, k, ret = -IPSET_ERR_EXIST;
        u32 key, multi = 0;
        size_t dsize = set->dsize;

        t = ipset_dereference_protected(h->table, set);
        key = HKEY(value, h->initval, t->htable_bits);
        n = __ipset_dereference_protected(hbucket(t, key), 1);
        if (!n)
                goto out;
        for (i = 0, k = 0; i < n->pos; i++) {
                if (!test_bit(i, n->used)) {
                        k++;
                        continue;
                }
                data = ahash_data(n, i, dsize);
                if (!mtype_data_equal(data, d, &multi))
                        continue;
                if (SET_WITH_TIMEOUT(set) &&
                    ip_set_timeout_expired(ext_timeout(data, set)))
                        goto out;

                ret = 0;
                clear_bit(i, n->used);
                smp_mb__after_atomic();
                if (i + 1 == n->pos)
                        n->pos--;
                set->elements--;
#ifdef IP_SET_HASH_WITH_NETS
                for (j = 0; j < IPSET_NET_COUNT; j++)
                        mtype_del_cidr(h, NCIDR_PUT(DCIDR_GET(d->cidr, j)),
                                       j);
#endif
                ip_set_ext_destroy(set, data);

                for (; i < n->pos; i++) {
                        if (!test_bit(i, n->used))
                                k++;
                }
                if (n->pos == 0 && k == 0) {
                        set->ext_size -= ext_size(n->size, dsize);
                        rcu_assign_pointer(hbucket(t, key), NULL);
                        kfree_rcu(n, rcu);
                } else if (k >= AHASH_INIT_SIZE) {
                        struct hbucket *tmp = kzalloc(sizeof(*tmp) +
                                        (n->size - AHASH_INIT_SIZE) * dsize,
                                        GFP_ATOMIC);
                        if (!tmp)
                                goto out;
                        tmp->size = n->size - AHASH_INIT_SIZE;
                        for (j = 0, k = 0; j < n->pos; j++) {
                                if (!test_bit(j, n->used))
                                        continue;
                                data = ahash_data(n, j, dsize);
                                memcpy(tmp->value + k * dsize, data, dsize);
                                set_bit(k, tmp->used);
                                k++;
                        }
                        tmp->pos = k;
                        set->ext_size -= ext_size(AHASH_INIT_SIZE, dsize);
                        rcu_assign_pointer(hbucket(t, key), tmp);
                        kfree_rcu(n, rcu);
                }
                goto out;
        }

out:
        return ret;
}

static inline int
mtype_data_match(struct mtype_elem *data, const struct ip_set_ext *ext,
                 struct ip_set_ext *mext, struct ip_set *set, u32 flags)
{
        if (!ip_set_match_extensions(set, ext, mext, flags, data))
                return 0;
        /* nomatch entries return -ENOTEMPTY */
        return mtype_do_data_match(data);
}

#ifdef IP_SET_HASH_WITH_NETS
/* Special test function which takes into account the different network
 * sizes added to the set
 */
static int
mtype_test_cidrs(struct ip_set *set, struct mtype_elem *d,
                 const struct ip_set_ext *ext,
                 struct ip_set_ext *mext, u32 flags)
{
        struct htype *h = set->data;
        struct htable *t = rcu_dereference_bh(h->table);
        struct hbucket *n;
        struct mtype_elem *data;
#if IPSET_NET_COUNT == 2
        struct mtype_elem orig = *d;
        int ret, i, j = 0, k;
#else
        int ret, i, j = 0;
#endif
        u32 key, multi = 0;

        pr_debug("test by nets\n");
        for (; j < NLEN && h->nets[j].cidr[0] && !multi; j++) {
#if IPSET_NET_COUNT == 2
                mtype_data_reset_elem(d, &orig);
                mtype_data_netmask(d, NCIDR_GET(h->nets[j].cidr[0]), false);
                for (k = 0; k < NLEN && h->nets[k].cidr[1] && !multi;
                     k++) {
                        mtype_data_netmask(d, NCIDR_GET(h->nets[k].cidr[1]),
                                           true);
#else
                mtype_data_netmask(d, NCIDR_GET(h->nets[j].cidr[0]));
#endif
                key = HKEY(d, h->initval, t->htable_bits);
                n =  rcu_dereference_bh(hbucket(t, key));
                if (!n)
                        continue;
                for (i = 0; i < n->pos; i++) {
                        if (!test_bit(i, n->used))
                                continue;
                        data = ahash_data(n, i, set->dsize);
                        if (!mtype_data_equal(data, d, &multi))
                                continue;
                        ret = mtype_data_match(data, ext, mext, set, flags);
                        if (ret != 0)
                                return ret;
#ifdef IP_SET_HASH_WITH_MULTI
                        /* No match, reset multiple match flag */
                        multi = 0;
#endif
                }
#if IPSET_NET_COUNT == 2
                }
#endif
        }
        return 0;
}
#endif

/* Test whether the element is added to the set */
static int
mtype_test(struct ip_set *set, void *value, const struct ip_set_ext *ext,
           struct ip_set_ext *mext, u32 flags)
{
        struct htype *h = set->data;
        struct htable *t;
        struct mtype_elem *d = value;
        struct hbucket *n;
        struct mtype_elem *data;
        int i, ret = 0;
        u32 key, multi = 0;

        t = rcu_dereference_bh(h->table);
#ifdef IP_SET_HASH_WITH_NETS
        /* If we test an IP address and not a network address,

         * try all possible network sizes
         */
        for (i = 0; i < IPSET_NET_COUNT; i++)
                if (DCIDR_GET(d->cidr, i) != HOST_MASK)
                        break;
        if (i == IPSET_NET_COUNT) {
                ret = mtype_test_cidrs(set, d, ext, mext, flags);
                goto out;
        }
#endif

        key = HKEY(d, h->initval, t->htable_bits);
        n = rcu_dereference_bh(hbucket(t, key));
        if (!n) {
                ret = 0;
                goto out;
        }
        for (i = 0; i < n->pos; i++) {
                if (!test_bit(i, n->used))
                        continue;
                data = ahash_data(n, i, set->dsize);
                if (!mtype_data_equal(data, d, &multi))
                        continue;
                ret = mtype_data_match(data, ext, mext, set, flags);
                if (ret != 0)
                        goto out;
        }
out:
        return ret;
}

/* Reply a HEADER request: fill out the header part of the set */
static int
mtype_head(struct ip_set *set, struct sk_buff *skb)
{
        struct htype *h = set->data;
        const struct htable *t;
        struct nlattr *nested;
        size_t memsize;
        u8 htable_bits;

        /* If any members have expired, set->elements will be wrong
         * mytype_expire function will update it with the right count.
         * we do not hold set->lock here, so grab it first.
         * set->elements can still be incorrect in the case of a huge set,
         * because elements might time out during the listing.
         */
        if (SET_WITH_TIMEOUT(set)) {
                spin_lock_bh(&set->lock);
                mtype_expire(set, h);
                spin_unlock_bh(&set->lock);
        }

        rcu_read_lock_bh();
        t = rcu_dereference_bh_nfnl(h->table);
        memsize = mtype_ahash_memsize(h, t) + set->ext_size;
        htable_bits = t->htable_bits;
        rcu_read_unlock_bh();

        nested = ipset_nest_start(skb, IPSET_ATTR_DATA);
        if (!nested)
                goto nla_put_failure;
        if (nla_put_net32(skb, IPSET_ATTR_HASHSIZE,
                          htonl(jhash_size(htable_bits))) ||
            nla_put_net32(skb, IPSET_ATTR_MAXELEM, htonl(h->maxelem)))
                goto nla_put_failure;
#ifdef IP_SET_HASH_WITH_NETMASK
        if (h->netmask != HOST_MASK &&
            nla_put_u8(skb, IPSET_ATTR_NETMASK, h->netmask))
                goto nla_put_failure;
#endif
#ifdef IP_SET_HASH_WITH_MARKMASK
        if (nla_put_u32(skb, IPSET_ATTR_MARKMASK, h->markmask))
                goto nla_put_failure;
#endif
        if (nla_put_net32(skb, IPSET_ATTR_REFERENCES, htonl(set->ref)) ||
            nla_put_net32(skb, IPSET_ATTR_MEMSIZE, htonl(memsize)) ||
            nla_put_net32(skb, IPSET_ATTR_ELEMENTS, htonl(set->elements)))
                goto nla_put_failure;
        if (unlikely(ip_set_put_flags(skb, set)))
                goto nla_put_failure;
        ipset_nest_end(skb, nested);

        return 0;
nla_put_failure:
        return -EMSGSIZE;
}

/* Make possible to run dumping parallel with resizing */
static void
mtype_uref(struct ip_set *set, struct netlink_callback *cb, bool start)
{
        struct htype *h = set->data;
        struct htable *t;

        if (start) {
                rcu_read_lock_bh();
                t = rcu_dereference_bh_nfnl(h->table);
                atomic_inc(&t->uref);
                cb->args[IPSET_CB_PRIVATE] = (unsigned long)t;
                rcu_read_unlock_bh();
        } else if (cb->args[IPSET_CB_PRIVATE]) {
                t = (struct htable *)cb->args[IPSET_CB_PRIVATE];
                if (atomic_dec_and_test(&t->uref) && atomic_read(&t->ref)) {
                        /* Resizing didn't destroy the hash table */
                        pr_debug("Table destroy by dump: %p\n", t);
                        mtype_ahash_destroy(set, t, false);
                }
                cb->args[IPSET_CB_PRIVATE] = 0;
        }
}

/* Reply a LIST/SAVE request: dump the elements of the specified set */
static int
mtype_list(const struct ip_set *set,
           struct sk_buff *skb, struct netlink_callback *cb)
{
        const struct htable *t;
        struct nlattr *atd, *nested;
        const struct hbucket *n;
        const struct mtype_elem *e;
        u32 first = cb->args[IPSET_CB_ARG0];
        /* We assume that one hash bucket fills into one page */
        void *incomplete;
        int i, ret = 0;

        atd = ipset_nest_start(skb, IPSET_ATTR_ADT);
        if (!atd)
                return -EMSGSIZE;

        pr_debug("list hash set %s\n", set->name);
        t = (const struct htable *)cb->args[IPSET_CB_PRIVATE];
        /* Expire may replace a hbucket with another one */
        rcu_read_lock();
        for (; cb->args[IPSET_CB_ARG0] < jhash_size(t->htable_bits);
             cb->args[IPSET_CB_ARG0]++) {
                cond_resched_rcu();
                incomplete = skb_tail_pointer(skb);
                n = rcu_dereference(hbucket(t, cb->args[IPSET_CB_ARG0]));
                pr_debug("cb->arg bucket: %lu, t %p n %p\n",
                         cb->args[IPSET_CB_ARG0], t, n);
                if (!n)
                        continue;
                for (i = 0; i < n->pos; i++) {
                        if (!test_bit(i, n->used))
                                continue;
                        e = ahash_data(n, i, set->dsize);
                        if (SET_WITH_TIMEOUT(set) &&
                            ip_set_timeout_expired(ext_timeout(e, set)))
                                continue;
                        pr_debug("list hash %lu hbucket %p i %u, data %p\n",
                                 cb->args[IPSET_CB_ARG0], n, i, e);
                        nested = ipset_nest_start(skb, IPSET_ATTR_DATA);
                        if (!nested) {
                                if (cb->args[IPSET_CB_ARG0] == first) {
                                        nla_nest_cancel(skb, atd);
                                        ret = -EMSGSIZE;
                                        goto out;
                                }
                                goto nla_put_failure;
                        }
                        if (mtype_data_list(skb, e))
                                goto nla_put_failure;
                        if (ip_set_put_extensions(skb, set, e, true))
                                goto nla_put_failure;
                        ipset_nest_end(skb, nested);
                }
        }
        ipset_nest_end(skb, atd);
        /* Set listing finished */
        cb->args[IPSET_CB_ARG0] = 0;

        goto out;

nla_put_failure:
        nlmsg_trim(skb, incomplete);
        if (unlikely(first == cb->args[IPSET_CB_ARG0])) {
                pr_warn("Can't list set %s: one bucket does not fit into a message. Please report it!\n",
                        set->name);
                cb->args[IPSET_CB_ARG0] = 0;
                ret = -EMSGSIZE;
        } else {
                ipset_nest_end(skb, atd);
        }
out:
        rcu_read_unlock();
        return ret;
}

static int
IPSET_TOKEN(MTYPE, _kadt)(struct ip_set *set, const struct sk_buff *skb,
                          const struct xt_action_param *par,
                          enum ipset_adt adt, struct ip_set_adt_opt *opt);

static int
IPSET_TOKEN(MTYPE, _uadt)(struct ip_set *set, struct nlattr *tb[],
                          enum ipset_adt adt, u32 *lineno, u32 flags,
                          bool retried);

static const struct ip_set_type_variant mtype_variant = {
        .kadt   = mtype_kadt,
        .uadt   = mtype_uadt,
        .adt    = {
                [IPSET_ADD] = mtype_add,
                [IPSET_DEL] = mtype_del,
                [IPSET_TEST] = mtype_test,
        },
        .destroy = mtype_destroy,
        .flush  = mtype_flush,
        .head   = mtype_head,
        .list   = mtype_list,
        .uref   = mtype_uref,
        .resize = mtype_resize,
        .same_set = mtype_same_set,
};

#ifdef IP_SET_EMIT_CREATE
static int
IPSET_TOKEN(HTYPE, _create)(struct net *net, struct ip_set *set,
                            struct nlattr *tb[], u32 flags)
{
        u32 hashsize = IPSET_DEFAULT_HASHSIZE, maxelem = IPSET_DEFAULT_MAXELEM;
#ifdef IP_SET_HASH_WITH_MARKMASK
        u32 markmask;
#endif
        u8 hbits;
#ifdef IP_SET_HASH_WITH_NETMASK
        u8 netmask;
#endif
        size_t hsize;
        struct htype *h;
        struct htable *t;

        pr_debug("Create set %s with family %s\n",
                 set->name, set->family == NFPROTO_IPV4 ? "inet" : "inet6");

#ifdef IP_SET_PROTO_UNDEF
        if (set->family != NFPROTO_UNSPEC)
                return -IPSET_ERR_INVALID_FAMILY;
#else
        if (!(set->family == NFPROTO_IPV4 || set->family == NFPROTO_IPV6))
                return -IPSET_ERR_INVALID_FAMILY;
#endif

        if (unlikely(!ip_set_optattr_netorder(tb, IPSET_ATTR_HASHSIZE) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_MAXELEM) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_TIMEOUT) ||
                     !ip_set_optattr_netorder(tb, IPSET_ATTR_CADT_FLAGS)))
                return -IPSET_ERR_PROTOCOL;

#ifdef IP_SET_HASH_WITH_MARKMASK
        /* Separated condition in order to avoid directive in argument list */
        if (unlikely(!ip_set_optattr_netorder(tb, IPSET_ATTR_MARKMASK)))
                return -IPSET_ERR_PROTOCOL;

        markmask = 0xffffffff;
        if (tb[IPSET_ATTR_MARKMASK]) {
                markmask = ntohl(nla_get_be32(tb[IPSET_ATTR_MARKMASK]));
                if (markmask == 0)
                        return -IPSET_ERR_INVALID_MARKMASK;
        }
#endif

#ifdef IP_SET_HASH_WITH_NETMASK
        netmask = set->family == NFPROTO_IPV4 ? 32 : 128;
        if (tb[IPSET_ATTR_NETMASK]) {
                netmask = nla_get_u8(tb[IPSET_ATTR_NETMASK]);

                if ((set->family == NFPROTO_IPV4 && netmask > 32) ||
                    (set->family == NFPROTO_IPV6 && netmask > 128) ||
                    netmask == 0)
                        return -IPSET_ERR_INVALID_NETMASK;
        }
#endif

        if (tb[IPSET_ATTR_HASHSIZE]) {
                hashsize = ip_set_get_h32(tb[IPSET_ATTR_HASHSIZE]);
                if (hashsize < IPSET_MIMINAL_HASHSIZE)
                        hashsize = IPSET_MIMINAL_HASHSIZE;
        }

        if (tb[IPSET_ATTR_MAXELEM])
                maxelem = ip_set_get_h32(tb[IPSET_ATTR_MAXELEM]);

        hsize = sizeof(*h);
        h = kzalloc(hsize, GFP_KERNEL);
        if (!h)
                return -ENOMEM;

        hbits = htable_bits(hashsize);
        hsize = htable_size(hbits);
        if (hsize == 0) {
                kfree(h);
                return -ENOMEM;
        }
        t = ip_set_alloc(hsize);
        if (!t) {
                kfree(h);
                return -ENOMEM;
        }
        h->maxelem = maxelem;
#ifdef IP_SET_HASH_WITH_NETMASK
        h->netmask = netmask;
#endif
#ifdef IP_SET_HASH_WITH_MARKMASK
        h->markmask = markmask;
#endif
        get_random_bytes(&h->initval, sizeof(h->initval));

        t->htable_bits = hbits;
        RCU_INIT_POINTER(h->table, t);

        h->set = set;
        set->data = h;
#ifndef IP_SET_PROTO_UNDEF
        if (set->family == NFPROTO_IPV4) {
#endif
                set->variant = &IPSET_TOKEN(HTYPE, 4_variant);
                set->dsize = ip_set_elem_len(set, tb,
                        sizeof(struct IPSET_TOKEN(HTYPE, 4_elem)),
                        __alignof__(struct IPSET_TOKEN(HTYPE, 4_elem)));
#ifndef IP_SET_PROTO_UNDEF
        } else {
                set->variant = &IPSET_TOKEN(HTYPE, 6_variant);
                set->dsize = ip_set_elem_len(set, tb,
                        sizeof(struct IPSET_TOKEN(HTYPE, 6_elem)),
                        __alignof__(struct IPSET_TOKEN(HTYPE, 6_elem)));
        }
#endif
        set->timeout = IPSET_NO_TIMEOUT;
        if (tb[IPSET_ATTR_TIMEOUT]) {
                set->timeout = ip_set_timeout_uget(tb[IPSET_ATTR_TIMEOUT]);
#ifndef IP_SET_PROTO_UNDEF
                if (set->family == NFPROTO_IPV4)
#endif
                        IPSET_TOKEN(HTYPE, 4_gc_init)(set,
                                IPSET_TOKEN(HTYPE, 4_gc));
#ifndef IP_SET_PROTO_UNDEF
                else
                        IPSET_TOKEN(HTYPE, 6_gc_init)(set,
                                IPSET_TOKEN(HTYPE, 6_gc));
#endif
        }
        pr_debug("create %s hashsize %u (%u) maxelem %u: %p(%p)\n",
                 set->name, jhash_size(t->htable_bits),
                 t->htable_bits, h->maxelem, set->data, t);

        return 0;
}
#endif /* IP_SET_EMIT_CREATE */

#undef HKEY_DATALEN