/*
 * Copyright (c) 2007-2012 Nicira, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/if_arp.h>
#include <linux/if_bridge.h>
#include <linux/if_vlan.h>
#include <linux/kernel.h>
#include <linux/llc.h>
#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <linux/openvswitch.h>

#include <net/llc.h>

#include "datapath.h"
#include "vport-internal_dev.h"
#include "vport-netdev.h"

static struct vport_ops ovs_netdev_vport_ops;

/* Must be called with rcu_read_lock. */
static void netdev_port_receive(struct vport *vport, struct sk_buff *skb)
{
        if (unlikely(!vport))
                goto error;

        if (unlikely(skb_warn_if_lro(skb)))
                goto error;

        /* Make our own copy of the packet.  Otherwise we will mangle the
         * packet for anyone who came before us (e.g. tcpdump via AF_PACKET).
         */
        skb = skb_share_check(skb, GFP_ATOMIC);
        if (unlikely(!skb))
                return;

        skb_push(skb, ETH_HLEN);
        ovs_skb_postpush_rcsum(skb, skb->data, ETH_HLEN);

        ovs_vport_receive(vport, skb, NULL);
        return;

error:
        kfree_skb(skb);
}

/* Called with rcu_read_lock and bottom-halves disabled. */
static rx_handler_result_t netdev_frame_hook(struct sk_buff **pskb)
{
        struct sk_buff *skb = *pskb;
        struct vport *vport;

        if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
                return RX_HANDLER_PASS;

        vport = ovs_netdev_get_vport(skb->dev);

        netdev_port_receive(vport, skb);

        return RX_HANDLER_CONSUMED;
}

static struct net_device *get_dpdev(const struct datapath *dp)
{
        struct vport *local;

        local = ovs_vport_ovsl(dp, OVSP_LOCAL);
        BUG_ON(!local);
        return netdev_vport_priv(local)->dev;
}

static struct vport *netdev_create(const struct vport_parms *parms)
{
        struct vport *vport;
        struct netdev_vport *netdev_vport;
        int err;

        vport = ovs_vport_alloc(sizeof(struct netdev_vport),
                                &ovs_netdev_vport_ops, parms);
        if (IS_ERR(vport)) {
                err = PTR_ERR(vport);
                goto error;
        }

        netdev_vport = netdev_vport_priv(vport);

        netdev_vport->dev = dev_get_by_name(ovs_dp_get_net(vport->dp), parms->name);
        if (!netdev_vport->dev) {
                err = -ENODEV;
                goto error_free_vport;
        }

        if (netdev_vport->dev->flags & IFF_LOOPBACK ||
            netdev_vport->dev->type != ARPHRD_ETHER ||
            ovs_is_internal_dev(netdev_vport->dev)) {
                err = -EINVAL;
                goto error_put;
        }

        rtnl_lock();
        err = netdev_master_upper_dev_link(netdev_vport->dev,
                                           get_dpdev(vport->dp));
        if (err)
                goto error_unlock;

        err = netdev_rx_handler_register(netdev_vport->dev, netdev_frame_hook,
                                         vport);
        if (err)
                goto error_master_upper_dev_unlink;

        dev_set_promiscuity(netdev_vport->dev, 1);
        netdev_vport->dev->priv_flags |= IFF_OVS_DATAPATH;
        rtnl_unlock();

        return vport;

error_master_upper_dev_unlink:
        netdev_upper_dev_unlink(netdev_vport->dev, get_dpdev(vport->dp));
error_unlock:
        rtnl_unlock();
error_put:
        dev_put(netdev_vport->dev);
error_free_vport:
        ovs_vport_free(vport);
error:
        return ERR_PTR(err);
}

static void free_port_rcu(struct rcu_head *rcu)
{
        struct netdev_vport *netdev_vport = container_of(rcu,
                                        struct netdev_vport, rcu);

        dev_put(netdev_vport->dev);
        ovs_vport_free(vport_from_priv(netdev_vport));
}

void ovs_netdev_detach_dev(struct vport *vport)
{
        struct netdev_vport *netdev_vport = netdev_vport_priv(vport);

        ASSERT_RTNL();
        netdev_vport->dev->priv_flags &= ~IFF_OVS_DATAPATH;
        netdev_rx_handler_unregister(netdev_vport->dev);
        netdev_upper_dev_unlink(netdev_vport->dev,
                                netdev_master_upper_dev_get(netdev_vport->dev));
        dev_set_promiscuity(netdev_vport->dev, -1);
}

static void netdev_destroy(struct vport *vport)
{
        struct netdev_vport *netdev_vport = netdev_vport_priv(vport);

        rtnl_lock();
        if (netdev_vport->dev->priv_flags & IFF_OVS_DATAPATH)
                ovs_netdev_detach_dev(vport);
        rtnl_unlock();

        call_rcu(&netdev_vport->rcu, free_port_rcu);
}

const char *ovs_netdev_get_name(const struct vport *vport)
{
        const struct netdev_vport *netdev_vport = netdev_vport_priv(vport);
        return netdev_vport->dev->name;
}

static unsigned int packet_length(const struct sk_buff *skb)
{
        unsigned int length = skb->len - ETH_HLEN;

        if (skb->protocol == htons(ETH_P_8021Q))
                length -= VLAN_HLEN;

        return length;
}

static int netdev_send(struct vport *vport, struct sk_buff *skb)
{
        struct netdev_vport *netdev_vport = netdev_vport_priv(vport);
        int mtu = netdev_vport->dev->mtu;
        int len;

        if (unlikely(packet_length(skb) > mtu && !skb_is_gso(skb))) {
                net_warn_ratelimited("%s: dropped over-mtu packet: %d > %d\n",
                                     netdev_vport->dev->name,
                                     packet_length(skb), mtu);
                goto drop;
        }

        skb->dev = netdev_vport->dev;
        len = skb->len;
        dev_queue_xmit(skb);

        return len;

drop:
        kfree_skb(skb);
        return 0;
}

/* Returns null if this device is not attached to a datapath. */
struct vport *ovs_netdev_get_vport(struct net_device *dev)
{
        if (likely(dev->priv_flags & IFF_OVS_DATAPATH))
                return (struct vport *)
                        rcu_dereference_rtnl(dev->rx_handler_data);
        else
                return NULL;
}

static struct vport_ops ovs_netdev_vport_ops = {
        .type           = OVS_VPORT_TYPE_NETDEV,
        .create         = netdev_create,
        .destroy        = netdev_destroy,
        .get_name       = ovs_netdev_get_name,
        .send           = netdev_send,
};

int __init ovs_netdev_init(void)
{
        return ovs_vport_ops_register(&ovs_netdev_vport_ops);
}

void ovs_netdev_exit(void)
{
        ovs_vport_ops_unregister(&ovs_netdev_vport_ops);
}