// SPDX-License-Identifier: GPL-2.0-only
// Copyright (c) 2020 Facebook Inc.

#include <linux/ethtool_netlink.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include <net/udp_tunnel.h>
#include <net/vxlan.h>

enum udp_tunnel_nic_table_entry_flags {
        UDP_TUNNEL_NIC_ENTRY_ADD        = BIT(0),
        UDP_TUNNEL_NIC_ENTRY_DEL        = BIT(1),
        UDP_TUNNEL_NIC_ENTRY_OP_FAIL    = BIT(2),
        UDP_TUNNEL_NIC_ENTRY_FROZEN     = BIT(3),
};

struct udp_tunnel_nic_table_entry {
        __be16 port;
        u8 type;
        u8 flags;
        u16 use_cnt;
#define UDP_TUNNEL_NIC_USE_CNT_MAX      U16_MAX
        u8 hw_priv;
};

/**
 * struct udp_tunnel_nic - UDP tunnel port offload state
 * @work:       async work for talking to hardware from process context
 * @dev:        netdev pointer
 * @need_sync:  at least one port start changed
 * @need_replay: space was freed, we need a replay of all ports
 * @work_pending: @work is currently scheduled
 * @n_tables:   number of tables under @entries
 * @missed:     bitmap of tables which overflown
 * @entries:    table of tables of ports currently offloaded
 */
struct udp_tunnel_nic {
        struct work_struct work;

        struct net_device *dev;

        u8 need_sync:1;
        u8 need_replay:1;
        u8 work_pending:1;

        unsigned int n_tables;
        unsigned long missed;
        struct udp_tunnel_nic_table_entry **entries;
};

/* We ensure all work structs are done using driver state, but not the code.
 * We need a workqueue we can flush before module gets removed.
 */
static struct workqueue_struct *udp_tunnel_nic_workqueue;

static const char *udp_tunnel_nic_tunnel_type_name(unsigned int type)
{
        switch (type) {
        case UDP_TUNNEL_TYPE_VXLAN:
                return "vxlan";
        case UDP_TUNNEL_TYPE_GENEVE:
                return "geneve";
        case UDP_TUNNEL_TYPE_VXLAN_GPE:
                return "vxlan-gpe";
        default:
                return "unknown";
        }
}

static bool
udp_tunnel_nic_entry_is_free(struct udp_tunnel_nic_table_entry *entry)
{
        return entry->use_cnt == 0 && !entry->flags;
}

static bool
udp_tunnel_nic_entry_is_present(struct udp_tunnel_nic_table_entry *entry)
{
        return entry->use_cnt && !(entry->flags & ~UDP_TUNNEL_NIC_ENTRY_FROZEN);
}

static bool
udp_tunnel_nic_entry_is_frozen(struct udp_tunnel_nic_table_entry *entry)
{
        return entry->flags & UDP_TUNNEL_NIC_ENTRY_FROZEN;
}

static void
udp_tunnel_nic_entry_freeze_used(struct udp_tunnel_nic_table_entry *entry)
{
        if (!udp_tunnel_nic_entry_is_free(entry))
                entry->flags |= UDP_TUNNEL_NIC_ENTRY_FROZEN;
}

static void
udp_tunnel_nic_entry_unfreeze(struct udp_tunnel_nic_table_entry *entry)
{
        entry->flags &= ~UDP_TUNNEL_NIC_ENTRY_FROZEN;
}

static bool
udp_tunnel_nic_entry_is_queued(struct udp_tunnel_nic_table_entry *entry)
{
        return entry->flags & (UDP_TUNNEL_NIC_ENTRY_ADD |
                               UDP_TUNNEL_NIC_ENTRY_DEL);
}

static void
udp_tunnel_nic_entry_queue(struct udp_tunnel_nic *utn,
                           struct udp_tunnel_nic_table_entry *entry,
                           unsigned int flag)
{
        entry->flags |= flag;
        utn->need_sync = 1;
}

static void
udp_tunnel_nic_ti_from_entry(struct udp_tunnel_nic_table_entry *entry,
                             struct udp_tunnel_info *ti)
{
        memset(ti, 0, sizeof(*ti));
        ti->port = entry->port;
        ti->type = entry->type;
        ti->hw_priv = entry->hw_priv;
}

static bool
udp_tunnel_nic_is_empty(struct net_device *dev, struct udp_tunnel_nic *utn)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        unsigned int i, j;

        for (i = 0; i < utn->n_tables; i++)
                for (j = 0; j < info->tables[i].n_entries; j++)
                        if (!udp_tunnel_nic_entry_is_free(&utn->entries[i][j]))
                                return false;
        return true;
}

static bool
udp_tunnel_nic_should_replay(struct net_device *dev, struct udp_tunnel_nic *utn)
{
        const struct udp_tunnel_nic_table_info *table;
        unsigned int i, j;

        if (!utn->missed)
                return false;

        for (i = 0; i < utn->n_tables; i++) {
                table = &dev->udp_tunnel_nic_info->tables[i];
                if (!test_bit(i, &utn->missed))
                        continue;

                for (j = 0; j < table->n_entries; j++)
                        if (udp_tunnel_nic_entry_is_free(&utn->entries[i][j]))
                                return true;
        }

        return false;
}

static void
__udp_tunnel_nic_get_port(struct net_device *dev, unsigned int table,
                          unsigned int idx, struct udp_tunnel_info *ti)
{
        struct udp_tunnel_nic_table_entry *entry;
        struct udp_tunnel_nic *utn;

        utn = dev->udp_tunnel_nic;
        entry = &utn->entries[table][idx];

        if (entry->use_cnt)
                udp_tunnel_nic_ti_from_entry(entry, ti);
}

static void
__udp_tunnel_nic_set_port_priv(struct net_device *dev, unsigned int table,
                               unsigned int idx, u8 priv)
{
        dev->udp_tunnel_nic->entries[table][idx].hw_priv = priv;
}

static void
udp_tunnel_nic_entry_update_done(struct udp_tunnel_nic_table_entry *entry,
                                 int err)
{
        bool dodgy = entry->flags & UDP_TUNNEL_NIC_ENTRY_OP_FAIL;

        WARN_ON_ONCE(entry->flags & UDP_TUNNEL_NIC_ENTRY_ADD &&
                     entry->flags & UDP_TUNNEL_NIC_ENTRY_DEL);

        if (entry->flags & UDP_TUNNEL_NIC_ENTRY_ADD &&
            (!err || (err == -EEXIST && dodgy)))
                entry->flags &= ~UDP_TUNNEL_NIC_ENTRY_ADD;

        if (entry->flags & UDP_TUNNEL_NIC_ENTRY_DEL &&
            (!err || (err == -ENOENT && dodgy)))
                entry->flags &= ~UDP_TUNNEL_NIC_ENTRY_DEL;

        if (!err)
                entry->flags &= ~UDP_TUNNEL_NIC_ENTRY_OP_FAIL;
        else
                entry->flags |= UDP_TUNNEL_NIC_ENTRY_OP_FAIL;
}

static void
udp_tunnel_nic_device_sync_one(struct net_device *dev,
                               struct udp_tunnel_nic *utn,
                               unsigned int table, unsigned int idx)
{
        struct udp_tunnel_nic_table_entry *entry;
        struct udp_tunnel_info ti;
        int err;

        entry = &utn->entries[table][idx];
        if (!udp_tunnel_nic_entry_is_queued(entry))
                return;

        udp_tunnel_nic_ti_from_entry(entry, &ti);
        if (entry->flags & UDP_TUNNEL_NIC_ENTRY_ADD)
                err = dev->udp_tunnel_nic_info->set_port(dev, table, idx, &ti);
        else
                err = dev->udp_tunnel_nic_info->unset_port(dev, table, idx,
                                                           &ti);
        udp_tunnel_nic_entry_update_done(entry, err);

        if (err)
                netdev_warn(dev,
                            "UDP tunnel port sync failed port %d type %s: %d\n",
                            be16_to_cpu(entry->port),
                            udp_tunnel_nic_tunnel_type_name(entry->type),
                            err);
}

static void
udp_tunnel_nic_device_sync_by_port(struct net_device *dev,
                                   struct udp_tunnel_nic *utn)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        unsigned int i, j;

        for (i = 0; i < utn->n_tables; i++)
                for (j = 0; j < info->tables[i].n_entries; j++)
                        udp_tunnel_nic_device_sync_one(dev, utn, i, j);
}

static void
udp_tunnel_nic_device_sync_by_table(struct net_device *dev,
                                    struct udp_tunnel_nic *utn)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        unsigned int i, j;
        int err;

        for (i = 0; i < utn->n_tables; i++) {
                /* Find something that needs sync in this table */
                for (j = 0; j < info->tables[i].n_entries; j++)
                        if (udp_tunnel_nic_entry_is_queued(&utn->entries[i][j]))
                                break;
                if (j == info->tables[i].n_entries)
                        continue;

                err = info->sync_table(dev, i);
                if (err)
                        netdev_warn(dev, "UDP tunnel port sync failed for table %d: %d\n",
                                    i, err);

                for (j = 0; j < info->tables[i].n_entries; j++) {
                        struct udp_tunnel_nic_table_entry *entry;

                        entry = &utn->entries[i][j];
                        if (udp_tunnel_nic_entry_is_queued(entry))
                                udp_tunnel_nic_entry_update_done(entry, err);
                }
        }
}

static void
__udp_tunnel_nic_device_sync(struct net_device *dev, struct udp_tunnel_nic *utn)
{
        if (!utn->need_sync)
                return;

        if (dev->udp_tunnel_nic_info->sync_table)
                udp_tunnel_nic_device_sync_by_table(dev, utn);
        else
                udp_tunnel_nic_device_sync_by_port(dev, utn);

        utn->need_sync = 0;
        /* Can't replay directly here, in case we come from the tunnel driver's
         * notification - trying to replay may deadlock inside tunnel driver.
         */
        utn->need_replay = udp_tunnel_nic_should_replay(dev, utn);
}

static void
udp_tunnel_nic_device_sync(struct net_device *dev, struct udp_tunnel_nic *utn)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        bool may_sleep;

        if (!utn->need_sync)
                return;

        /* Drivers which sleep in the callback need to update from
         * the workqueue, if we come from the tunnel driver's notification.
         */
        may_sleep = info->flags & UDP_TUNNEL_NIC_INFO_MAY_SLEEP;
        if (!may_sleep)
                __udp_tunnel_nic_device_sync(dev, utn);
        if (may_sleep || utn->need_replay) {
                queue_work(udp_tunnel_nic_workqueue, &utn->work);
                utn->work_pending = 1;
        }
}

static bool
udp_tunnel_nic_table_is_capable(const struct udp_tunnel_nic_table_info *table,
                                struct udp_tunnel_info *ti)
{
        return table->tunnel_types & ti->type;
}

static bool
udp_tunnel_nic_is_capable(struct net_device *dev, struct udp_tunnel_nic *utn,
                          struct udp_tunnel_info *ti)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        unsigned int i;

        /* Special case IPv4-only NICs */
        if (info->flags & UDP_TUNNEL_NIC_INFO_IPV4_ONLY &&
            ti->sa_family != AF_INET)
                return false;

        for (i = 0; i < utn->n_tables; i++)
                if (udp_tunnel_nic_table_is_capable(&info->tables[i], ti))
                        return true;
        return false;
}

static int
udp_tunnel_nic_has_collision(struct net_device *dev, struct udp_tunnel_nic *utn,
                             struct udp_tunnel_info *ti)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        struct udp_tunnel_nic_table_entry *entry;
        unsigned int i, j;

        for (i = 0; i < utn->n_tables; i++)
                for (j = 0; j < info->tables[i].n_entries; j++) {
                        entry = &utn->entries[i][j];

                        if (!udp_tunnel_nic_entry_is_free(entry) &&
                            entry->port == ti->port &&
                            entry->type != ti->type) {
                                __set_bit(i, &utn->missed);
                                return true;
                        }
                }
        return false;
}

static void
udp_tunnel_nic_entry_adj(struct udp_tunnel_nic *utn,
                         unsigned int table, unsigned int idx, int use_cnt_adj)
{
        struct udp_tunnel_nic_table_entry *entry =  &utn->entries[table][idx];
        bool dodgy = entry->flags & UDP_TUNNEL_NIC_ENTRY_OP_FAIL;
        unsigned int from, to;

        WARN_ON(entry->use_cnt + (u32)use_cnt_adj > U16_MAX);

        /* If not going from used to unused or vice versa - all done.
         * For dodgy entries make sure we try to sync again (queue the entry).
         */
        entry->use_cnt += use_cnt_adj;
        if (!dodgy && !entry->use_cnt == !(entry->use_cnt - use_cnt_adj))
                return;

        /* Cancel the op before it was sent to the device, if possible,
         * otherwise we'd need to take special care to issue commands
         * in the same order the ports arrived.
         */
        if (use_cnt_adj < 0) {
                from = UDP_TUNNEL_NIC_ENTRY_ADD;
                to = UDP_TUNNEL_NIC_ENTRY_DEL;
        } else {
                from = UDP_TUNNEL_NIC_ENTRY_DEL;
                to = UDP_TUNNEL_NIC_ENTRY_ADD;
        }

        if (entry->flags & from) {
                entry->flags &= ~from;
                if (!dodgy)
                        return;
        }

        udp_tunnel_nic_entry_queue(utn, entry, to);
}

static bool
udp_tunnel_nic_entry_try_adj(struct udp_tunnel_nic *utn,
                             unsigned int table, unsigned int idx,
                             struct udp_tunnel_info *ti, int use_cnt_adj)
{
        struct udp_tunnel_nic_table_entry *entry =  &utn->entries[table][idx];

        if (udp_tunnel_nic_entry_is_free(entry) ||
            entry->port != ti->port ||
            entry->type != ti->type)
                return false;

        if (udp_tunnel_nic_entry_is_frozen(entry))
                return true;

        udp_tunnel_nic_entry_adj(utn, table, idx, use_cnt_adj);
        return true;
}

/* Try to find existing matching entry and adjust its use count, instead of
 * adding a new one. Returns true if entry was found. In case of delete the
 * entry may have gotten removed in the process, in which case it will be
 * queued for removal.
 */
static bool
udp_tunnel_nic_try_existing(struct net_device *dev, struct udp_tunnel_nic *utn,
                            struct udp_tunnel_info *ti, int use_cnt_adj)
{
        const struct udp_tunnel_nic_table_info *table;
        unsigned int i, j;

        for (i = 0; i < utn->n_tables; i++) {
                table = &dev->udp_tunnel_nic_info->tables[i];
                if (!udp_tunnel_nic_table_is_capable(table, ti))
                        continue;

                for (j = 0; j < table->n_entries; j++)
                        if (udp_tunnel_nic_entry_try_adj(utn, i, j, ti,
                                                         use_cnt_adj))
                                return true;
        }

        return false;
}

static bool
udp_tunnel_nic_add_existing(struct net_device *dev, struct udp_tunnel_nic *utn,
                            struct udp_tunnel_info *ti)
{
        return udp_tunnel_nic_try_existing(dev, utn, ti, +1);
}

static bool
udp_tunnel_nic_del_existing(struct net_device *dev, struct udp_tunnel_nic *utn,
                            struct udp_tunnel_info *ti)
{
        return udp_tunnel_nic_try_existing(dev, utn, ti, -1);
}

static bool
udp_tunnel_nic_add_new(struct net_device *dev, struct udp_tunnel_nic *utn,
                       struct udp_tunnel_info *ti)
{
        const struct udp_tunnel_nic_table_info *table;
        unsigned int i, j;

        for (i = 0; i < utn->n_tables; i++) {
                table = &dev->udp_tunnel_nic_info->tables[i];
                if (!udp_tunnel_nic_table_is_capable(table, ti))
                        continue;

                for (j = 0; j < table->n_entries; j++) {
                        struct udp_tunnel_nic_table_entry *entry;

                        entry = &utn->entries[i][j];
                        if (!udp_tunnel_nic_entry_is_free(entry))
                                continue;

                        entry->port = ti->port;
                        entry->type = ti->type;
                        entry->use_cnt = 1;
                        udp_tunnel_nic_entry_queue(utn, entry,
                                                   UDP_TUNNEL_NIC_ENTRY_ADD);
                        return true;
                }

                /* The different table may still fit this port in, but there
                 * are no devices currently which have multiple tables accepting
                 * the same tunnel type, and false positives are okay.
                 */
                __set_bit(i, &utn->missed);
        }

        return false;
}

static void
__udp_tunnel_nic_add_port(struct net_device *dev, struct udp_tunnel_info *ti)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        struct udp_tunnel_nic *utn;

        utn = dev->udp_tunnel_nic;
        if (!utn)
                return;
        if (!netif_running(dev) && info->flags & UDP_TUNNEL_NIC_INFO_OPEN_ONLY)
                return;
        if (info->flags & UDP_TUNNEL_NIC_INFO_STATIC_IANA_VXLAN &&
            ti->port == htons(IANA_VXLAN_UDP_PORT)) {
                if (ti->type != UDP_TUNNEL_TYPE_VXLAN)
                        netdev_warn(dev, "device assumes port 4789 will be used by vxlan tunnels\n");
                return;
        }

        if (!udp_tunnel_nic_is_capable(dev, utn, ti))
                return;

        /* It may happen that a tunnel of one type is removed and different
         * tunnel type tries to reuse its port before the device was informed.
         * Rely on utn->missed to re-add this port later.
         */
        if (udp_tunnel_nic_has_collision(dev, utn, ti))
                return;

        if (!udp_tunnel_nic_add_existing(dev, utn, ti))
                udp_tunnel_nic_add_new(dev, utn, ti);

        udp_tunnel_nic_device_sync(dev, utn);
}

static void
__udp_tunnel_nic_del_port(struct net_device *dev, struct udp_tunnel_info *ti)
{
        struct udp_tunnel_nic *utn;

        utn = dev->udp_tunnel_nic;
        if (!utn)
                return;

        if (!udp_tunnel_nic_is_capable(dev, utn, ti))
                return;

        udp_tunnel_nic_del_existing(dev, utn, ti);

        udp_tunnel_nic_device_sync(dev, utn);
}

static void __udp_tunnel_nic_reset_ntf(struct net_device *dev)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        struct udp_tunnel_nic *utn;
        unsigned int i, j;

        ASSERT_RTNL();

        utn = dev->udp_tunnel_nic;
        if (!utn)
                return;

        utn->need_sync = false;
        for (i = 0; i < utn->n_tables; i++)
                for (j = 0; j < info->tables[i].n_entries; j++) {
                        struct udp_tunnel_nic_table_entry *entry;

                        entry = &utn->entries[i][j];

                        entry->flags &= ~(UDP_TUNNEL_NIC_ENTRY_DEL |
                                          UDP_TUNNEL_NIC_ENTRY_OP_FAIL);
                        /* We don't release rtnl across ops */
                        WARN_ON(entry->flags & UDP_TUNNEL_NIC_ENTRY_FROZEN);
                        if (!entry->use_cnt)
                                continue;

                        udp_tunnel_nic_entry_queue(utn, entry,
                                                   UDP_TUNNEL_NIC_ENTRY_ADD);
                }

        __udp_tunnel_nic_device_sync(dev, utn);
}

static size_t
__udp_tunnel_nic_dump_size(struct net_device *dev, unsigned int table)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        struct udp_tunnel_nic *utn;
        unsigned int j;
        size_t size;

        utn = dev->udp_tunnel_nic;
        if (!utn)
                return 0;

        size = 0;
        for (j = 0; j < info->tables[table].n_entries; j++) {
                if (!udp_tunnel_nic_entry_is_present(&utn->entries[table][j]))
                        continue;

                size += nla_total_size(0) +              /* _TABLE_ENTRY */
                        nla_total_size(sizeof(__be16)) + /* _ENTRY_PORT */
                        nla_total_size(sizeof(u32));     /* _ENTRY_TYPE */
        }

        return size;
}

static int
__udp_tunnel_nic_dump_write(struct net_device *dev, unsigned int table,
                            struct sk_buff *skb)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        struct udp_tunnel_nic *utn;
        struct nlattr *nest;
        unsigned int j;

        utn = dev->udp_tunnel_nic;
        if (!utn)
                return 0;

        for (j = 0; j < info->tables[table].n_entries; j++) {
                if (!udp_tunnel_nic_entry_is_present(&utn->entries[table][j]))
                        continue;

                nest = nla_nest_start(skb, ETHTOOL_A_TUNNEL_UDP_TABLE_ENTRY);

                if (nla_put_be16(skb, ETHTOOL_A_TUNNEL_UDP_ENTRY_PORT,
                                 utn->entries[table][j].port) ||
                    nla_put_u32(skb, ETHTOOL_A_TUNNEL_UDP_ENTRY_TYPE,
                                ilog2(utn->entries[table][j].type)))
                        goto err_cancel;

                nla_nest_end(skb, nest);
        }

        return 0;

err_cancel:
        nla_nest_cancel(skb, nest);
        return -EMSGSIZE;
}

static const struct udp_tunnel_nic_ops __udp_tunnel_nic_ops = {
        .get_port       = __udp_tunnel_nic_get_port,
        .set_port_priv  = __udp_tunnel_nic_set_port_priv,
        .add_port       = __udp_tunnel_nic_add_port,
        .del_port       = __udp_tunnel_nic_del_port,
        .reset_ntf      = __udp_tunnel_nic_reset_ntf,
        .dump_size      = __udp_tunnel_nic_dump_size,
        .dump_write     = __udp_tunnel_nic_dump_write,
};

static void
udp_tunnel_nic_flush(struct net_device *dev, struct udp_tunnel_nic *utn)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        unsigned int i, j;

        for (i = 0; i < utn->n_tables; i++)
                for (j = 0; j < info->tables[i].n_entries; j++) {
                        int adj_cnt = -utn->entries[i][j].use_cnt;

                        if (adj_cnt)
                                udp_tunnel_nic_entry_adj(utn, i, j, adj_cnt);
                }

        __udp_tunnel_nic_device_sync(dev, utn);

        for (i = 0; i < utn->n_tables; i++)
                memset(utn->entries[i], 0, array_size(info->tables[i].n_entries,
                                                      sizeof(**utn->entries)));
        WARN_ON(utn->need_sync);
        utn->need_replay = 0;
}

static void
udp_tunnel_nic_replay(struct net_device *dev, struct udp_tunnel_nic *utn)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        struct udp_tunnel_nic_shared_node *node;
        unsigned int i, j;

        /* Freeze all the ports we are already tracking so that the replay
         * does not double up the refcount.
         */
        for (i = 0; i < utn->n_tables; i++)
                for (j = 0; j < info->tables[i].n_entries; j++)
                        udp_tunnel_nic_entry_freeze_used(&utn->entries[i][j]);
        utn->missed = 0;
        utn->need_replay = 0;

        if (!info->shared) {
                udp_tunnel_get_rx_info(dev);
        } else {
                list_for_each_entry(node, &info->shared->devices, list)
                        udp_tunnel_get_rx_info(node->dev);
        }

        for (i = 0; i < utn->n_tables; i++)
                for (j = 0; j < info->tables[i].n_entries; j++)
                        udp_tunnel_nic_entry_unfreeze(&utn->entries[i][j]);
}

static void udp_tunnel_nic_device_sync_work(struct work_struct *work)
{
        struct udp_tunnel_nic *utn =
                container_of(work, struct udp_tunnel_nic, work);

        rtnl_lock();
        utn->work_pending = 0;
        __udp_tunnel_nic_device_sync(utn->dev, utn);

        if (utn->need_replay)
                udp_tunnel_nic_replay(utn->dev, utn);
        rtnl_unlock();
}

static struct udp_tunnel_nic *
udp_tunnel_nic_alloc(const struct udp_tunnel_nic_info *info,
                     unsigned int n_tables)
{
        struct udp_tunnel_nic *utn;
        unsigned int i;

        utn = kzalloc(sizeof(*utn), GFP_KERNEL);
        if (!utn)
                return NULL;
        utn->n_tables = n_tables;
        INIT_WORK(&utn->work, udp_tunnel_nic_device_sync_work);

        utn->entries = kmalloc_array(n_tables, sizeof(void *), GFP_KERNEL);
        if (!utn->entries)
                goto err_free_utn;

        for (i = 0; i < n_tables; i++) {
                utn->entries[i] = kcalloc(info->tables[i].n_entries,
                                          sizeof(*utn->entries[i]), GFP_KERNEL);
                if (!utn->entries[i])
                        goto err_free_prev_entries;
        }

        return utn;

err_free_prev_entries:
        while (i--)
                kfree(utn->entries[i]);
        kfree(utn->entries);
err_free_utn:
        kfree(utn);
        return NULL;
}

static void udp_tunnel_nic_free(struct udp_tunnel_nic *utn)
{
        unsigned int i;

        for (i = 0; i < utn->n_tables; i++)
                kfree(utn->entries[i]);
        kfree(utn->entries);
        kfree(utn);
}

static int udp_tunnel_nic_register(struct net_device *dev)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;
        struct udp_tunnel_nic_shared_node *node = NULL;
        struct udp_tunnel_nic *utn;
        unsigned int n_tables, i;

        BUILD_BUG_ON(sizeof(utn->missed) * BITS_PER_BYTE <
                     UDP_TUNNEL_NIC_MAX_TABLES);
        /* Expect use count of at most 2 (IPv4, IPv6) per device */
        BUILD_BUG_ON(UDP_TUNNEL_NIC_USE_CNT_MAX <
                     UDP_TUNNEL_NIC_MAX_SHARING_DEVICES * 2);

        /* Check that the driver info is sane */
        if (WARN_ON(!info->set_port != !info->unset_port) ||
            WARN_ON(!info->set_port == !info->sync_table) ||
            WARN_ON(!info->tables[0].n_entries))
                return -EINVAL;

        if (WARN_ON(info->shared &&
                    info->flags & UDP_TUNNEL_NIC_INFO_OPEN_ONLY))
                return -EINVAL;

        n_tables = 1;
        for (i = 1; i < UDP_TUNNEL_NIC_MAX_TABLES; i++) {
                if (!info->tables[i].n_entries)
                        continue;

                n_tables++;
                if (WARN_ON(!info->tables[i - 1].n_entries))
                        return -EINVAL;
        }

        /* Create UDP tunnel state structures */
        if (info->shared) {
                node = kzalloc(sizeof(*node), GFP_KERNEL);
                if (!node)
                        return -ENOMEM;

                node->dev = dev;
        }

        if (info->shared && info->shared->udp_tunnel_nic_info) {
                utn = info->shared->udp_tunnel_nic_info;
        } else {
                utn = udp_tunnel_nic_alloc(info, n_tables);
                if (!utn) {
                        kfree(node);
                        return -ENOMEM;
                }
        }

        if (info->shared) {
                if (!info->shared->udp_tunnel_nic_info) {
                        INIT_LIST_HEAD(&info->shared->devices);
                        info->shared->udp_tunnel_nic_info = utn;
                }

                list_add_tail(&node->list, &info->shared->devices);
        }

        utn->dev = dev;
        dev_hold(dev);
        dev->udp_tunnel_nic = utn;

        if (!(info->flags & UDP_TUNNEL_NIC_INFO_OPEN_ONLY))
                udp_tunnel_get_rx_info(dev);

        return 0;
}

static void
udp_tunnel_nic_unregister(struct net_device *dev, struct udp_tunnel_nic *utn)
{
        const struct udp_tunnel_nic_info *info = dev->udp_tunnel_nic_info;

        /* For a shared table remove this dev from the list of sharing devices
         * and if there are other devices just detach.
         */
        if (info->shared) {
                struct udp_tunnel_nic_shared_node *node, *first;

                list_for_each_entry(node, &info->shared->devices, list)
                        if (node->dev == dev)
                                break;
                if (node->dev != dev)
                        return;

                list_del(&node->list);
                kfree(node);

                first = list_first_entry_or_null(&info->shared->devices,
                                                 typeof(*first), list);
                if (first) {
                        udp_tunnel_drop_rx_info(dev);
                        utn->dev = first->dev;
                        goto release_dev;
                }

                info->shared->udp_tunnel_nic_info = NULL;
        }

        /* Flush before we check work, so we don't waste time adding entries
         * from the work which we will boot immediately.
         */
        udp_tunnel_nic_flush(dev, utn);

        /* Wait for the work to be done using the state, netdev core will
         * retry unregister until we give up our reference on this device.
         */
        if (utn->work_pending)
                return;

        udp_tunnel_nic_free(utn);
release_dev:
        dev->udp_tunnel_nic = NULL;
        dev_put(dev);
}

static int
udp_tunnel_nic_netdevice_event(struct notifier_block *unused,
                               unsigned long event, void *ptr)
{
        struct net_device *dev = netdev_notifier_info_to_dev(ptr);
        const struct udp_tunnel_nic_info *info;
        struct udp_tunnel_nic *utn;

        info = dev->udp_tunnel_nic_info;
        if (!info)
                return NOTIFY_DONE;

        if (event == NETDEV_REGISTER) {
                int err;

                err = udp_tunnel_nic_register(dev);
                if (err)
                        netdev_WARN(dev, "failed to register for UDP tunnel offloads: %d", err);
                return notifier_from_errno(err);
        }
        /* All other events will need the udp_tunnel_nic state */
        utn = dev->udp_tunnel_nic;
        if (!utn)
                return NOTIFY_DONE;

        if (event == NETDEV_UNREGISTER) {
                udp_tunnel_nic_unregister(dev, utn);
                return NOTIFY_OK;
        }

        /* All other events only matter if NIC has to be programmed open */
        if (!(info->flags & UDP_TUNNEL_NIC_INFO_OPEN_ONLY))
                return NOTIFY_DONE;

        if (event == NETDEV_UP) {
                WARN_ON(!udp_tunnel_nic_is_empty(dev, utn));
                udp_tunnel_get_rx_info(dev);
                return NOTIFY_OK;
        }
        if (event == NETDEV_GOING_DOWN) {
                udp_tunnel_nic_flush(dev, utn);
                return NOTIFY_OK;
        }

        return NOTIFY_DONE;
}

static struct notifier_block udp_tunnel_nic_notifier_block __read_mostly = {
        .notifier_call = udp_tunnel_nic_netdevice_event,
};

static int __init udp_tunnel_nic_init_module(void)
{
        int err;

        udp_tunnel_nic_workqueue = alloc_ordered_workqueue("udp_tunnel_nic", 0);
        if (!udp_tunnel_nic_workqueue)
                return -ENOMEM;

        rtnl_lock();
        udp_tunnel_nic_ops = &__udp_tunnel_nic_ops;
        rtnl_unlock();

        err = register_netdevice_notifier(&udp_tunnel_nic_notifier_block);
        if (err)
                goto err_unset_ops;

        return 0;

err_unset_ops:
        rtnl_lock();
        udp_tunnel_nic_ops = NULL;
        rtnl_unlock();
        destroy_workqueue(udp_tunnel_nic_workqueue);
        return err;
}
late_initcall(udp_tunnel_nic_init_module);

static void __exit udp_tunnel_nic_cleanup_module(void)
{
        unregister_netdevice_notifier(&udp_tunnel_nic_notifier_block);

        rtnl_lock();
        udp_tunnel_nic_ops = NULL;
        rtnl_unlock();

        destroy_workqueue(udp_tunnel_nic_workqueue);
}
module_exit(udp_tunnel_nic_cleanup_module);

MODULE_LICENSE("GPL");