ofproto: Match VLAN PCP and rewrite ToS bits (OpenFlow 0.9)

[ovs.git] / datapath / datapath.c

/*
 * Copyright (c) 2007, 2008, 2009, 2010 Nicira Networks.
 * Distributed under the terms of the GNU GPL version 2.
 *
 * Significant portions of this file may be copied from parts of the Linux
 * kernel, by Linus Torvalds and others.
 */

/* Functions for managing the dp interface/device. */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/if_arp.h>
#include <linux/if_bridge.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/delay.h>
#include <linux/time.h>
#include <linux/etherdevice.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/llc.h>
#include <linux/mutex.h>
#include <linux/percpu.h>
#include <linux/rcupdate.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/version.h>
#include <linux/ethtool.h>
#include <linux/random.h>
#include <linux/wait.h>
#include <asm/system.h>
#include <asm/div64.h>
#include <asm/bug.h>
#include <linux/netfilter_bridge.h>
#include <linux/netfilter_ipv4.h>
#include <linux/inetdevice.h>
#include <linux/list.h>
#include <linux/rculist.h>
#include <linux/workqueue.h>
#include <linux/dmi.h>
#include <net/llc.h>

#include "openvswitch/datapath-protocol.h"
#include "datapath.h"
#include "actions.h"
#include "dp_dev.h"
#include "flow.h"

#include "compat.h"


int (*dp_ioctl_hook)(struct net_device *dev, struct ifreq *rq, int cmd);
EXPORT_SYMBOL(dp_ioctl_hook);

/* Datapaths.  Protected on the read side by rcu_read_lock, on the write side
 * by dp_mutex.
 *
 * dp_mutex nests inside the RTNL lock: if you need both you must take the RTNL
 * lock first.
 *
 * It is safe to access the datapath and net_bridge_port structures with just
 * dp_mutex.
 */
static struct datapath *dps[ODP_MAX];
static DEFINE_MUTEX(dp_mutex);

/* Number of milliseconds between runs of the maintenance thread. */
#define MAINT_SLEEP_MSECS 1000

static int new_nbp(struct datapath *, struct net_device *, int port_no);

/* Must be called with rcu_read_lock or dp_mutex. */
struct datapath *get_dp(int dp_idx)
{
        if (dp_idx < 0 || dp_idx >= ODP_MAX)
                return NULL;
        return rcu_dereference(dps[dp_idx]);
}
EXPORT_SYMBOL_GPL(get_dp);

static struct datapath *get_dp_locked(int dp_idx)
{
        struct datapath *dp;

        mutex_lock(&dp_mutex);
        dp = get_dp(dp_idx);
        if (dp)
                mutex_lock(&dp->mutex);
        mutex_unlock(&dp_mutex);
        return dp;
}

static inline size_t br_nlmsg_size(void)
{
        return NLMSG_ALIGN(sizeof(struct ifinfomsg))
               + nla_total_size(IFNAMSIZ) /* IFLA_IFNAME */
               + nla_total_size(MAX_ADDR_LEN) /* IFLA_ADDRESS */
               + nla_total_size(4) /* IFLA_MASTER */
               + nla_total_size(4) /* IFLA_MTU */
               + nla_total_size(4) /* IFLA_LINK */
               + nla_total_size(1); /* IFLA_OPERSTATE */
}

static int dp_fill_ifinfo(struct sk_buff *skb,
                          const struct net_bridge_port *port,
                          int event, unsigned int flags)
{
        const struct datapath *dp = port->dp;
        const struct net_device *dev = port->dev;
        struct ifinfomsg *hdr;
        struct nlmsghdr *nlh;

        nlh = nlmsg_put(skb, 0, 0, event, sizeof(*hdr), flags);
        if (nlh == NULL)
                return -EMSGSIZE;

        hdr = nlmsg_data(nlh);
        hdr->ifi_family = AF_BRIDGE;
        hdr->__ifi_pad = 0;
        hdr->ifi_type = dev->type;
        hdr->ifi_index = dev->ifindex;
        hdr->ifi_flags = dev_get_flags(dev);
        hdr->ifi_change = 0;

        NLA_PUT_STRING(skb, IFLA_IFNAME, dev->name);
        NLA_PUT_U32(skb, IFLA_MASTER, dp->ports[ODPP_LOCAL]->dev->ifindex);
        NLA_PUT_U32(skb, IFLA_MTU, dev->mtu);
#ifdef IFLA_OPERSTATE
        NLA_PUT_U8(skb, IFLA_OPERSTATE,
                   netif_running(dev) ? dev->operstate : IF_OPER_DOWN);
#endif

        if (dev->addr_len)
                NLA_PUT(skb, IFLA_ADDRESS, dev->addr_len, dev->dev_addr);

        if (dev->ifindex != dev->iflink)
                NLA_PUT_U32(skb, IFLA_LINK, dev->iflink);

        return nlmsg_end(skb, nlh);

nla_put_failure:
        nlmsg_cancel(skb, nlh);
        return -EMSGSIZE;
}

static void dp_ifinfo_notify(int event, struct net_bridge_port *port)
{
        struct net *net = dev_net(port->dev);
        struct sk_buff *skb;
        int err = -ENOBUFS;

        skb = nlmsg_new(br_nlmsg_size(), GFP_KERNEL);
        if (skb == NULL)
                goto errout;

        err = dp_fill_ifinfo(skb, port, event, 0);
        if (err < 0) {
                /* -EMSGSIZE implies BUG in br_nlmsg_size() */
                WARN_ON(err == -EMSGSIZE);
                kfree_skb(skb);
                goto errout;
        }
        rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_KERNEL);
        return;
errout:
        if (err < 0)
                rtnl_set_sk_err(net, RTNLGRP_LINK, err);
}

static void release_dp(struct kobject *kobj)
{
        struct datapath *dp = container_of(kobj, struct datapath, ifobj);
        kfree(dp);
}

static struct kobj_type dp_ktype = {
        .release = release_dp
};

static int create_dp(int dp_idx, const char __user *devnamep)
{
        struct net_device *dp_dev;
        char devname[IFNAMSIZ];
        struct datapath *dp;
        int err;
        int i;

        if (devnamep) {
                err = -EFAULT;
                if (strncpy_from_user(devname, devnamep, IFNAMSIZ - 1) < 0)
                        goto err;
                devname[IFNAMSIZ - 1] = '\0';
        } else {
                snprintf(devname, sizeof devname, "of%d", dp_idx);
        }

        rtnl_lock();
        mutex_lock(&dp_mutex);
        err = -ENODEV;
        if (!try_module_get(THIS_MODULE))
                goto err_unlock;

        /* Exit early if a datapath with that number already exists.
         * (We don't use -EEXIST because that's ambiguous with 'devname'
         * conflicting with an existing network device name.) */
        err = -EBUSY;
        if (get_dp(dp_idx))
                goto err_put_module;

        err = -ENOMEM;
        dp = kzalloc(sizeof *dp, GFP_KERNEL);
        if (dp == NULL)
                goto err_put_module;
        INIT_LIST_HEAD(&dp->port_list);
        mutex_init(&dp->mutex);
        dp->dp_idx = dp_idx;
        for (i = 0; i < DP_N_QUEUES; i++)
                skb_queue_head_init(&dp->queues[i]);
        init_waitqueue_head(&dp->waitqueue);

        /* Initialize kobject for bridge.  This will be added as
         * /sys/class/net/<devname>/brif later, if sysfs is enabled. */
        dp->ifobj.kset = NULL;
        kobject_init(&dp->ifobj, &dp_ktype);

        /* Allocate table. */
        err = -ENOMEM;
        rcu_assign_pointer(dp->table, dp_table_create(DP_L1_SIZE));
        if (!dp->table)
                goto err_free_dp;

        /* Set up our datapath device. */
        dp_dev = dp_dev_create(dp, devname, ODPP_LOCAL);
        err = PTR_ERR(dp_dev);
        if (IS_ERR(dp_dev))
                goto err_destroy_table;

        err = new_nbp(dp, dp_dev, ODPP_LOCAL);
        if (err) {
                dp_dev_destroy(dp_dev);
                goto err_destroy_table;
        }

        dp->drop_frags = 0;
        dp->stats_percpu = alloc_percpu(struct dp_stats_percpu);
        if (!dp->stats_percpu)
                goto err_destroy_local_port;

        rcu_assign_pointer(dps[dp_idx], dp);
        mutex_unlock(&dp_mutex);
        rtnl_unlock();

        dp_sysfs_add_dp(dp);

        return 0;

err_destroy_local_port:
        dp_del_port(dp->ports[ODPP_LOCAL]);
err_destroy_table:
        dp_table_destroy(dp->table, 0);
err_free_dp:
        kfree(dp);
err_put_module:
        module_put(THIS_MODULE);
err_unlock:
        mutex_unlock(&dp_mutex);
        rtnl_unlock();
err:
        return err;
}

static void do_destroy_dp(struct datapath *dp)
{
        struct net_bridge_port *p, *n;
        int i;

        list_for_each_entry_safe (p, n, &dp->port_list, node)
                if (p->port_no != ODPP_LOCAL)
                        dp_del_port(p);

        dp_sysfs_del_dp(dp);

        rcu_assign_pointer(dps[dp->dp_idx], NULL);

        dp_del_port(dp->ports[ODPP_LOCAL]);

        dp_table_destroy(dp->table, 1);

        for (i = 0; i < DP_N_QUEUES; i++)
                skb_queue_purge(&dp->queues[i]);
        for (i = 0; i < DP_MAX_GROUPS; i++)
                kfree(dp->groups[i]);
        free_percpu(dp->stats_percpu);
        kobject_put(&dp->ifobj);
        module_put(THIS_MODULE);
}

static int destroy_dp(int dp_idx)
{
        struct datapath *dp;
        int err;

        rtnl_lock();
        mutex_lock(&dp_mutex);
        dp = get_dp(dp_idx);
        err = -ENODEV;
        if (!dp)
                goto err_unlock;

        do_destroy_dp(dp);
        err = 0;

err_unlock:
        mutex_unlock(&dp_mutex);
        rtnl_unlock();
        return err;
}

static void release_nbp(struct kobject *kobj)
{
        struct net_bridge_port *p = container_of(kobj, struct net_bridge_port, kobj);
        kfree(p);
}

static struct kobj_type brport_ktype = {
#ifdef CONFIG_SYSFS
        .sysfs_ops = &brport_sysfs_ops,
#endif
        .release = release_nbp
};

/* Called with RTNL lock and dp_mutex. */
static int new_nbp(struct datapath *dp, struct net_device *dev, int port_no)
{
        struct net_bridge_port *p;

        if (dev->br_port != NULL)
                return -EBUSY;

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

        dev_set_promiscuity(dev, 1);
        dev_hold(dev);
        p->port_no = port_no;
        p->dp = dp;
        p->dev = dev;
        atomic_set(&p->sflow_pool, 0);
        if (!is_dp_dev(dev))
                rcu_assign_pointer(dev->br_port, p);
        else {
                /* It would make sense to assign dev->br_port here too, but
                 * that causes packets received on internal ports to get caught
                 * in dp_frame_hook().  In turn dp_frame_hook() can reject them
                 * back to network stack, but that's a waste of time. */
        }
        rcu_assign_pointer(dp->ports[port_no], p);
        list_add_rcu(&p->node, &dp->port_list);
        dp->n_ports++;

        /* Initialize kobject for bridge.  This will be added as
         * /sys/class/net/<devname>/brport later, if sysfs is enabled. */
        p->kobj.kset = NULL;
        kobject_init(&p->kobj, &brport_ktype);

        dp_ifinfo_notify(RTM_NEWLINK, p);

        return 0;
}

static int add_port(int dp_idx, struct odp_port __user *portp)
{
        struct net_device *dev;
        struct datapath *dp;
        struct odp_port port;
        int port_no;
        int err;

        err = -EFAULT;
        if (copy_from_user(&port, portp, sizeof port))
                goto out;
        port.devname[IFNAMSIZ - 1] = '\0';

        rtnl_lock();
        dp = get_dp_locked(dp_idx);
        err = -ENODEV;
        if (!dp)
                goto out_unlock_rtnl;

        for (port_no = 1; port_no < DP_MAX_PORTS; port_no++)
                if (!dp->ports[port_no])
                        goto got_port_no;
        err = -EFBIG;
        goto out_unlock_dp;

got_port_no:
        if (!(port.flags & ODP_PORT_INTERNAL)) {
                err = -ENODEV;
                dev = dev_get_by_name(&init_net, port.devname);
                if (!dev)
                        goto out_unlock_dp;

                err = -EINVAL;
                if (dev->flags & IFF_LOOPBACK || dev->type != ARPHRD_ETHER ||
                    is_dp_dev(dev))
                        goto out_put;
        } else {
                dev = dp_dev_create(dp, port.devname, port_no);
                err = PTR_ERR(dev);
                if (IS_ERR(dev))
                        goto out_unlock_dp;
                dev_hold(dev);
        }

        err = new_nbp(dp, dev, port_no);
        if (err)
                goto out_put;

        set_dp_devs_mtu(dp, dev);
        dp_sysfs_add_if(dp->ports[port_no]);

        err = __put_user(port_no, &portp->port);

out_put:
        dev_put(dev);
out_unlock_dp:
        mutex_unlock(&dp->mutex);
out_unlock_rtnl:
        rtnl_unlock();
out:
        return err;
}

int dp_del_port(struct net_bridge_port *p)
{
        ASSERT_RTNL();

        if (p->port_no != ODPP_LOCAL)
                dp_sysfs_del_if(p);
        dp_ifinfo_notify(RTM_DELLINK, p);

        p->dp->n_ports--;

        if (is_dp_dev(p->dev)) {
                /* Make sure that no packets arrive from now on, since
                 * dp_dev_xmit() will try to find itself through
                 * p->dp->ports[], and we're about to set that to null. */
                netif_tx_disable(p->dev);
        }

        /* First drop references to device. */
        dev_set_promiscuity(p->dev, -1);
        list_del_rcu(&p->node);
        rcu_assign_pointer(p->dp->ports[p->port_no], NULL);
        rcu_assign_pointer(p->dev->br_port, NULL);

        /* Then wait until no one is still using it, and destroy it. */
        synchronize_rcu();

        if (is_dp_dev(p->dev))
                dp_dev_destroy(p->dev);
        dev_put(p->dev);
        kobject_put(&p->kobj);

        return 0;
}

static int del_port(int dp_idx, int port_no)
{
        struct net_bridge_port *p;
        struct datapath *dp;
        LIST_HEAD(dp_devs);
        int err;

        err = -EINVAL;
        if (port_no < 0 || port_no >= DP_MAX_PORTS || port_no == ODPP_LOCAL)
                goto out;

        rtnl_lock();
        dp = get_dp_locked(dp_idx);
        err = -ENODEV;
        if (!dp)
                goto out_unlock_rtnl;

        p = dp->ports[port_no];
        err = -ENOENT;
        if (!p)
                goto out_unlock_dp;

        err = dp_del_port(p);

out_unlock_dp:
        mutex_unlock(&dp->mutex);
out_unlock_rtnl:
        rtnl_unlock();
out:
        return err;
}

/* Must be called with rcu_read_lock. */
static void
do_port_input(struct net_bridge_port *p, struct sk_buff *skb) 
{
        /* 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).
         * (No one comes after us, since we tell handle_bridge() that we took
         * the packet.) */
        skb = skb_share_check(skb, GFP_ATOMIC);
        if (!skb)
                return;

        /* Push the Ethernet header back on. */
        skb_push(skb, ETH_HLEN);
        skb_reset_mac_header(skb);
        dp_process_received_packet(skb, p);
}

/* Must be called with rcu_read_lock and with bottom-halves disabled. */
void dp_process_received_packet(struct sk_buff *skb, struct net_bridge_port *p)
{
        struct datapath *dp = p->dp;
        struct dp_stats_percpu *stats;
        struct odp_flow_key key;
        struct sw_flow *flow;

        WARN_ON_ONCE(skb_shared(skb));

        /* BHs are off so we don't have to use get_cpu()/put_cpu() here. */
        stats = percpu_ptr(dp->stats_percpu, smp_processor_id());

        if (flow_extract(skb, p ? p->port_no : ODPP_NONE, &key)) {
                if (dp->drop_frags) {
                        kfree_skb(skb);
                        stats->n_frags++;
                        return;
                }
        }

        flow = dp_table_lookup(rcu_dereference(dp->table), &key);
        if (flow) {
                struct sw_flow_actions *acts = rcu_dereference(flow->sf_acts);
                flow_used(flow, skb);
                execute_actions(dp, skb, &key, acts->actions, acts->n_actions,
                                GFP_ATOMIC);
                stats->n_hit++;
        } else {
                stats->n_missed++;
                dp_output_control(dp, skb, _ODPL_MISS_NR, 0);
        }
}

/*
 * Used as br_handle_frame_hook.  (Cannot run bridge at the same time, even on
 * different set of devices!)
 */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
/* Called with rcu_read_lock and bottom-halves disabled. */
static struct sk_buff *dp_frame_hook(struct net_bridge_port *p,
                                         struct sk_buff *skb)
{
        do_port_input(p, skb);
        return NULL;
}
#elif LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
/* Called with rcu_read_lock and bottom-halves disabled. */
static int dp_frame_hook(struct net_bridge_port *p, struct sk_buff **pskb)
{
        do_port_input(p, *pskb);
        return 1;
}
#else
#error
#endif

#if defined(CONFIG_XEN) && defined(HAVE_PROTO_DATA_VALID)
/* This code is based on a skb_checksum_setup from net/dev/core.c from a
 * combination of Lenny's 2.6.26 Xen kernel and Xen's
 * linux-2.6.18-92.1.10.el5.xs5.0.0.394.644.  We can't call this function
 * directly because it isn't exported in all versions. */
static int skb_pull_up_to(struct sk_buff *skb, void *ptr)
{
        if (ptr < (void *)skb->tail)
                return 1;
        if (__pskb_pull_tail(skb,
                             ptr - (void *)skb->data - skb_headlen(skb))) {
                return 1;
        } else {
                return 0;
        }
}

int vswitch_skb_checksum_setup(struct sk_buff *skb)
{
        struct iphdr *iph;
        unsigned char *th;
        int err = -EPROTO;
        __u16 csum_start, csum_offset;

        if (!skb->proto_csum_blank)
                return 0;

        if (skb->protocol != htons(ETH_P_IP))
                goto out;

        if (!skb_pull_up_to(skb, skb_network_header(skb) + 1))
                goto out;

        iph = ip_hdr(skb);
        th = skb_network_header(skb) + 4 * iph->ihl;

        csum_start = th - skb->head;
        switch (iph->protocol) {
        case IPPROTO_TCP:
                csum_offset = offsetof(struct tcphdr, check);
                break;
        case IPPROTO_UDP:
                csum_offset = offsetof(struct udphdr, check);
                break;
        default:
                if (net_ratelimit())
                        printk(KERN_ERR "Attempting to checksum a non-"
                               "TCP/UDP packet, dropping a protocol"
                               " %d packet", iph->protocol);
                goto out;
        }

        if (!skb_pull_up_to(skb, th + csum_offset + 2))
                goto out;

        skb->ip_summed = CHECKSUM_PARTIAL;
        skb->proto_csum_blank = 0;

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
        skb->csum_start = csum_start;
        skb->csum_offset = csum_offset;
#else
        skb_set_transport_header(skb, csum_start - skb_headroom(skb));
        skb->csum = csum_offset;
#endif

        err = 0;

out:
        return err;
}
#endif /* CONFIG_XEN && HAVE_PROTO_DATA_VALID */

 /* Types of checksums that we can receive (these all refer to L4 checksums):
 * 1. CHECKSUM_NONE: Device that did not compute checksum, contains full
 *      (though not verified) checksum in packet but not in skb->csum.  Packets
 *      from the bridge local port will also have this type.
 * 2. CHECKSUM_COMPLETE (CHECKSUM_HW): Good device that computes checksums,
 *      also the GRE module.  This is the same as CHECKSUM_NONE, except it has
 *      a valid skb->csum.  Importantly, both contain a full checksum (not
 *      verified) in the packet itself.  The only difference is that if the
 *      packet gets to L4 processing on this machine (not in DomU) we won't
 *      have to recompute the checksum to verify.  Most hardware devices do not
 *      produce packets with this type, even if they support receive checksum
 *      offloading (they produce type #5).
 * 3. CHECKSUM_PARTIAL (CHECKSUM_HW): Packet without full checksum and needs to
 *      be computed if it is sent off box.  Unfortunately on earlier kernels,
 *      this case is impossible to distinguish from #2, despite having opposite
 *      meanings.  Xen adds an extra field on earlier kernels (see #4) in order
 *      to distinguish the different states.  The only real user of this type
 *      with bridging is Xen (on later kernels).
 * 4. CHECKSUM_UNNECESSARY (with proto_csum_blank true): This packet was
 *      generated locally by a Xen DomU and has a partial checksum.  If it is
 *      handled on this machine (Dom0 or DomU), then the checksum will not be
 *      computed.  If it goes off box, the checksum in the packet needs to be
 *      completed.  Calling skb_checksum_setup converts this to CHECKSUM_HW
 *      (CHECKSUM_PARTIAL) so that the checksum can be completed.  In later
 *      kernels, this combination is replaced with CHECKSUM_PARTIAL.
 * 5. CHECKSUM_UNNECESSARY (with proto_csum_blank false): Packet with a correct
 *      full checksum or using a protocol without a checksum.  skb->csum is
 *      undefined.  This is common from devices with receive checksum
 *      offloading.  This is somewhat similar to CHECKSUM_NONE, except that
 *      nobody will try to verify the checksum with CHECKSUM_UNNECESSARY.
 *
 * Note that on earlier kernels, CHECKSUM_COMPLETE and CHECKSUM_PARTIAL are
 * both defined as CHECKSUM_HW.  Normally the meaning of CHECKSUM_HW is clear
 * based on whether it is on the transmit or receive path.  After the datapath
 * it will be intepreted as CHECKSUM_PARTIAL.  If the packet already has a
 * checksum, we will panic.  Since we can receive packets with checksums, we
 * assume that all CHECKSUM_HW packets have checksums and map them to
 * CHECKSUM_NONE, which has a similar meaning (the it is only different if the
 * packet is processed by the local IP stack, in which case it will need to
 * be reverified).  If we receive a packet with CHECKSUM_HW that really means
 * CHECKSUM_PARTIAL, it will be sent with the wrong checksum.  However, there
 * shouldn't be any devices that do this with bridging.
 *
 * The bridge has similar behavior and this function closely resembles
 * skb_forward_csum().  It is slightly different because we are only concerned
 * with bridging and not other types of forwarding and can get away with
 * slightly more optimal behavior.*/
void
forward_ip_summed(struct sk_buff *skb)
{
#ifdef CHECKSUM_HW
        if (skb->ip_summed == CHECKSUM_HW)
                skb->ip_summed = CHECKSUM_NONE;
#endif
}

/* Append each packet in 'skb' list to 'queue'.  There will be only one packet
 * unless we broke up a GSO packet. */
static int
queue_control_packets(struct sk_buff *skb, struct sk_buff_head *queue,
                      int queue_no, u32 arg)
{
        struct sk_buff *nskb;
        int port_no;
        int err;

        port_no = ODPP_LOCAL;
        if (skb->dev) {
                if (skb->dev->br_port)
                        port_no = skb->dev->br_port->port_no;
                else if (is_dp_dev(skb->dev))
                        port_no = dp_dev_priv(skb->dev)->port_no;
        }

        do {
                struct odp_msg *header;

                nskb = skb->next;
                skb->next = NULL;

                /* If a checksum-deferred packet is forwarded to the
                 * controller, correct the pointers and checksum.  This happens
                 * on a regular basis only on Xen, on which VMs can pass up
                 * packets that do not have their checksum computed.
                 */
                err = vswitch_skb_checksum_setup(skb);
                if (err)
                        goto err_kfree_skbs;
#ifndef CHECKSUM_HW
                if (skb->ip_summed == CHECKSUM_PARTIAL) {
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22)
                        /* Until 2.6.22, the start of the transport header was
                         * also the start of data to be checksummed.  Linux
                         * 2.6.22 introduced the csum_start field for this
                         * purpose, but we should point the transport header to
                         * it anyway for backward compatibility, as
                         * dev_queue_xmit() does even in 2.6.28. */
                        skb_set_transport_header(skb, skb->csum_start -
                                                 skb_headroom(skb));
#endif
                        err = skb_checksum_help(skb);
                        if (err)
                                goto err_kfree_skbs;
                }
#else
                if (skb->ip_summed == CHECKSUM_HW) {
                        err = skb_checksum_help(skb, 0);
                        if (err)
                                goto err_kfree_skbs;
                }
#endif

                err = skb_cow(skb, sizeof *header);
                if (err)
                        goto err_kfree_skbs;

                header = (struct odp_msg*)__skb_push(skb, sizeof *header);
                header->type = queue_no;
                header->length = skb->len;
                header->port = port_no;
                header->reserved = 0;
                header->arg = arg;
                skb_queue_tail(queue, skb);

                skb = nskb;
        } while (skb);
        return 0;

err_kfree_skbs:
        kfree_skb(skb);
        while ((skb = nskb) != NULL) {
                nskb = skb->next;
                kfree_skb(skb);
        }
        return err;
}

int
dp_output_control(struct datapath *dp, struct sk_buff *skb, int queue_no,
                  u32 arg)
{
        struct dp_stats_percpu *stats;
        struct sk_buff_head *queue;
        int err;

        WARN_ON_ONCE(skb_shared(skb));
        BUG_ON(queue_no != _ODPL_MISS_NR && queue_no != _ODPL_ACTION_NR && queue_no != _ODPL_SFLOW_NR);
        queue = &dp->queues[queue_no];
        err = -ENOBUFS;
        if (skb_queue_len(queue) >= DP_MAX_QUEUE_LEN)
                goto err_kfree_skb;

        forward_ip_summed(skb);

        /* Break apart GSO packets into their component pieces.  Otherwise
         * userspace may try to stuff a 64kB packet into a 1500-byte MTU. */
        if (skb_is_gso(skb)) {
                struct sk_buff *nskb = skb_gso_segment(skb, 0);
                if (nskb) {
                        kfree_skb(skb);
                        skb = nskb;
                        if (unlikely(IS_ERR(skb))) {
                                err = PTR_ERR(skb);
                                goto err;
                        }
                } else {
                        /* XXX This case might not be possible.  It's hard to
                         * tell from the skb_gso_segment() code and comment. */
                }
        }

        err = queue_control_packets(skb, queue, queue_no, arg);
        wake_up_interruptible(&dp->waitqueue);
        return err;

err_kfree_skb:
        kfree_skb(skb);
err:
        stats = percpu_ptr(dp->stats_percpu, get_cpu());
        stats->n_lost++;
        put_cpu();

        return err;
}

static int flush_flows(struct datapath *dp)
{
        dp->n_flows = 0;
        return dp_table_flush(dp);
}

static int validate_actions(const struct sw_flow_actions *actions)
{
        unsigned int i;

        for (i = 0; i < actions->n_actions; i++) {
                const union odp_action *a = &actions->actions[i];
                switch (a->type) {
                case ODPAT_OUTPUT:
                        if (a->output.port >= DP_MAX_PORTS)
                                return -EINVAL;
                        break;

                case ODPAT_OUTPUT_GROUP:
                        if (a->output_group.group >= DP_MAX_GROUPS)
                                return -EINVAL;
                        break;

                case ODPAT_SET_VLAN_VID:
                        if (a->vlan_vid.vlan_vid & htons(~VLAN_VID_MASK))
                                return -EINVAL;
                        break;

                case ODPAT_SET_VLAN_PCP:
                        if (a->vlan_pcp.vlan_pcp
                            & ~(VLAN_PCP_MASK >> VLAN_PCP_SHIFT))
                                return -EINVAL;
                        break;

                default:
                        if (a->type >= ODPAT_N_ACTIONS)
                                return -EOPNOTSUPP;
                        break;
                }
        }

        return 0;
}

static struct sw_flow_actions *get_actions(const struct odp_flow *flow)
{
        struct sw_flow_actions *actions;
        int error;

        actions = flow_actions_alloc(flow->n_actions);
        error = PTR_ERR(actions);
        if (IS_ERR(actions))
                goto error;

        error = -EFAULT;
        if (copy_from_user(actions->actions, flow->actions,
                           flow->n_actions * sizeof(union odp_action)))
                goto error_free_actions;
        error = validate_actions(actions);
        if (error)
                goto error_free_actions;

        return actions;

error_free_actions:
        kfree(actions);
error:
        return ERR_PTR(error);
}

static void get_stats(struct sw_flow *flow, struct odp_flow_stats *stats)
{
        if (flow->used.tv_sec) {
                stats->used_sec = flow->used.tv_sec;
                stats->used_nsec = flow->used.tv_nsec;
        } else {
                stats->used_sec = 0;
                stats->used_nsec = 0;
        }
        stats->n_packets = flow->packet_count;
        stats->n_bytes = flow->byte_count;
        stats->ip_tos = flow->ip_tos;
        stats->tcp_flags = flow->tcp_flags;
        stats->error = 0;
}

static void clear_stats(struct sw_flow *flow)
{
        flow->used.tv_sec = flow->used.tv_nsec = 0;
        flow->tcp_flags = 0;
        flow->ip_tos = 0;
        flow->packet_count = 0;
        flow->byte_count = 0;
}

static int put_flow(struct datapath *dp, struct odp_flow_put __user *ufp)
{
        struct odp_flow_put uf;
        struct sw_flow *flow;
        struct dp_table *table;
        struct odp_flow_stats stats;
        int error;

        error = -EFAULT;
        if (copy_from_user(&uf, ufp, sizeof(struct odp_flow_put)))
                goto error;

        table = rcu_dereference(dp->table);
        flow = dp_table_lookup(table, &uf.flow.key);
        if (!flow) {
                /* No such flow. */
                struct sw_flow_actions *acts;

                error = -ENOENT;
                if (!(uf.flags & ODPPF_CREATE))
                        goto error;

                /* Expand table, if necessary, to make room. */
                if (dp->n_flows >= table->n_buckets) {
                        error = -ENOSPC;
                        if (table->n_buckets >= DP_MAX_BUCKETS)
                                goto error;

                        error = dp_table_expand(dp);
                        if (error)
                                goto error;
                        table = rcu_dereference(dp->table);
                }

                /* Allocate flow. */
                error = -ENOMEM;
                flow = kmem_cache_alloc(flow_cache, GFP_KERNEL);
                if (flow == NULL)
                        goto error;
                flow->key = uf.flow.key;
                spin_lock_init(&flow->lock);
                clear_stats(flow);

                /* Obtain actions. */
                acts = get_actions(&uf.flow);
                error = PTR_ERR(acts);
                if (IS_ERR(acts))
                        goto error_free_flow;
                rcu_assign_pointer(flow->sf_acts, acts);

                /* Put flow in bucket. */
                error = dp_table_insert(table, flow);
                if (error)
                        goto error_free_flow_acts;
                dp->n_flows++;
                memset(&stats, 0, sizeof(struct odp_flow_stats));
        } else {
                /* We found a matching flow. */
                struct sw_flow_actions *old_acts, *new_acts;
                unsigned long int flags;

                /* Bail out if we're not allowed to modify an existing flow. */
                error = -EEXIST;
                if (!(uf.flags & ODPPF_MODIFY))
                        goto error;

                /* Swap actions. */
                new_acts = get_actions(&uf.flow);
                error = PTR_ERR(new_acts);
                if (IS_ERR(new_acts))
                        goto error;
                old_acts = rcu_dereference(flow->sf_acts);
                if (old_acts->n_actions != new_acts->n_actions ||
                    memcmp(old_acts->actions, new_acts->actions,
                           sizeof(union odp_action) * old_acts->n_actions)) {
                        rcu_assign_pointer(flow->sf_acts, new_acts);
                        flow_deferred_free_acts(old_acts);
                } else {
                        kfree(new_acts);
                }

                /* Fetch stats, then clear them if necessary. */
                spin_lock_irqsave(&flow->lock, flags);
                get_stats(flow, &stats);
                if (uf.flags & ODPPF_ZERO_STATS)
                        clear_stats(flow);
                spin_unlock_irqrestore(&flow->lock, flags);
        }

        /* Copy stats to userspace. */
        if (__copy_to_user(&ufp->flow.stats, &stats,
                           sizeof(struct odp_flow_stats)))
                return -EFAULT;
        return 0;

error_free_flow_acts:
        kfree(flow->sf_acts);
error_free_flow:
        kmem_cache_free(flow_cache, flow);
error:
        return error;
}

static int put_actions(const struct sw_flow *flow, struct odp_flow __user *ufp)
{
        union odp_action __user *actions;
        struct sw_flow_actions *sf_acts;
        u32 n_actions;

        if (__get_user(actions, &ufp->actions) ||
            __get_user(n_actions, &ufp->n_actions))
                return -EFAULT;

        if (!n_actions)
                return 0;

        sf_acts = rcu_dereference(flow->sf_acts);
        if (__put_user(sf_acts->n_actions, &ufp->n_actions) ||
            (actions && copy_to_user(actions, sf_acts->actions,
                                     sizeof(union odp_action) *
                                     min(sf_acts->n_actions, n_actions))))
                return -EFAULT;

        return 0;
}

static int answer_query(struct sw_flow *flow, u32 query_flags,
                        struct odp_flow __user *ufp)
{
        struct odp_flow_stats stats;
        unsigned long int flags;

        spin_lock_irqsave(&flow->lock, flags);
        get_stats(flow, &stats);

        if (query_flags & ODPFF_ZERO_TCP_FLAGS) {
                flow->tcp_flags = 0;
        }
        spin_unlock_irqrestore(&flow->lock, flags);

        if (__copy_to_user(&ufp->stats, &stats, sizeof(struct odp_flow_stats)))
                return -EFAULT;
        return put_actions(flow, ufp);
}

static int del_flow(struct datapath *dp, struct odp_flow __user *ufp)
{
        struct dp_table *table = rcu_dereference(dp->table);
        struct odp_flow uf;
        struct sw_flow *flow;
        int error;

        error = -EFAULT;
        if (copy_from_user(&uf, ufp, sizeof uf))
                goto error;

        flow = dp_table_lookup(table, &uf.key);
        error = -ENOENT;
        if (!flow)
                goto error;

        /* XXX redundant lookup */
        error = dp_table_delete(table, flow);
        if (error)
                goto error;

        /* XXX These statistics might lose a few packets, since other CPUs can
         * be using this flow.  We used to synchronize_rcu() to make sure that
         * we get completely accurate stats, but that blows our performance,
         * badly. */
        dp->n_flows--;
        error = answer_query(flow, 0, ufp);
        flow_deferred_free(flow);

error:
        return error;
}

static int query_flows(struct datapath *dp, const struct odp_flowvec *flowvec)
{
        struct dp_table *table = rcu_dereference(dp->table);
        int i;
        for (i = 0; i < flowvec->n_flows; i++) {
                struct __user odp_flow *ufp = &flowvec->flows[i];
                struct odp_flow uf;
                struct sw_flow *flow;
                int error;

                if (__copy_from_user(&uf, ufp, sizeof uf))
                        return -EFAULT;

                flow = dp_table_lookup(table, &uf.key);
                if (!flow)
                        error = __put_user(ENOENT, &ufp->stats.error);
                else
                        error = answer_query(flow, uf.flags, ufp);
                if (error)
                        return -EFAULT;
        }
        return flowvec->n_flows;
}

struct list_flows_cbdata {
        struct odp_flow __user *uflows;
        int n_flows;
        int listed_flows;
};

static int list_flow(struct sw_flow *flow, void *cbdata_)
{
        struct list_flows_cbdata *cbdata = cbdata_;
        struct odp_flow __user *ufp = &cbdata->uflows[cbdata->listed_flows++];
        int error;

        if (__copy_to_user(&ufp->key, &flow->key, sizeof flow->key))
                return -EFAULT;
        error = answer_query(flow, 0, ufp);
        if (error)
                return error;

        if (cbdata->listed_flows >= cbdata->n_flows)
                return cbdata->listed_flows;
        return 0;
}

static int list_flows(struct datapath *dp, const struct odp_flowvec *flowvec)
{
        struct list_flows_cbdata cbdata;
        int error;

        if (!flowvec->n_flows)
                return 0;

        cbdata.uflows = flowvec->flows;
        cbdata.n_flows = flowvec->n_flows;
        cbdata.listed_flows = 0;
        error = dp_table_foreach(rcu_dereference(dp->table),
                                 list_flow, &cbdata);
        return error ? error : cbdata.listed_flows;
}

static int do_flowvec_ioctl(struct datapath *dp, unsigned long argp,
                            int (*function)(struct datapath *,
                                            const struct odp_flowvec *))
{
        struct odp_flowvec __user *uflowvec;
        struct odp_flowvec flowvec;
        int retval;

        uflowvec = (struct odp_flowvec __user *)argp;
        if (!access_ok(VERIFY_WRITE, uflowvec, sizeof *uflowvec) ||
            copy_from_user(&flowvec, uflowvec, sizeof flowvec))
                return -EFAULT;

        if (flowvec.n_flows > INT_MAX / sizeof(struct odp_flow))
                return -EINVAL;

        if (!access_ok(VERIFY_WRITE, flowvec.flows,
                       flowvec.n_flows * sizeof(struct odp_flow)))
                return -EFAULT;

        retval = function(dp, &flowvec);
        return (retval < 0 ? retval
                : retval == flowvec.n_flows ? 0
                : __put_user(retval, &uflowvec->n_flows));
}

static int do_execute(struct datapath *dp, const struct odp_execute *executep)
{
        struct odp_execute execute;
        struct odp_flow_key key;
        struct sk_buff *skb;
        struct sw_flow_actions *actions;
        struct ethhdr *eth;
        int err;

        err = -EFAULT;
        if (copy_from_user(&execute, executep, sizeof execute))
                goto error;

        err = -EINVAL;
        if (execute.length < ETH_HLEN || execute.length > 65535)
                goto error;

        err = -ENOMEM;
        actions = flow_actions_alloc(execute.n_actions);
        if (!actions)
                goto error;

        err = -EFAULT;
        if (copy_from_user(actions->actions, execute.actions,
                           execute.n_actions * sizeof *execute.actions))
                goto error_free_actions;

        err = validate_actions(actions);
        if (err)
                goto error_free_actions;

        err = -ENOMEM;
        skb = alloc_skb(execute.length, GFP_KERNEL);
        if (!skb)
                goto error_free_actions;
        if (execute.in_port < DP_MAX_PORTS) {
                struct net_bridge_port *p = dp->ports[execute.in_port];
                if (p)
                        skb->dev = p->dev;
        }

        err = -EFAULT;
        if (copy_from_user(skb_put(skb, execute.length), execute.data,
                           execute.length))
                goto error_free_skb;

        skb_reset_mac_header(skb);
        eth = eth_hdr(skb);

        /* Normally, setting the skb 'protocol' field would be handled by a
         * call to eth_type_trans(), but it assumes there's a sending
         * device, which we may not have. */
        if (ntohs(eth->h_proto) >= 1536)
                skb->protocol = eth->h_proto;
        else
                skb->protocol = htons(ETH_P_802_2);

        flow_extract(skb, execute.in_port, &key);
        err = execute_actions(dp, skb, &key, actions->actions,
                              actions->n_actions, GFP_KERNEL);
        kfree(actions);
        return err;

error_free_skb:
        kfree_skb(skb);
error_free_actions:
        kfree(actions);
error:
        return err;
}

static int get_dp_stats(struct datapath *dp, struct odp_stats __user *statsp)
{
        struct odp_stats stats;
        int i;

        stats.n_flows = dp->n_flows;
        stats.cur_capacity = rcu_dereference(dp->table)->n_buckets;
        stats.max_capacity = DP_MAX_BUCKETS;
        stats.n_ports = dp->n_ports;
        stats.max_ports = DP_MAX_PORTS;
        stats.max_groups = DP_MAX_GROUPS;
        stats.n_frags = stats.n_hit = stats.n_missed = stats.n_lost = 0;
        for_each_possible_cpu(i) {
                const struct dp_stats_percpu *s;
                s = percpu_ptr(dp->stats_percpu, i);
                stats.n_frags += s->n_frags;
                stats.n_hit += s->n_hit;
                stats.n_missed += s->n_missed;
                stats.n_lost += s->n_lost;
        }
        stats.max_miss_queue = DP_MAX_QUEUE_LEN;
        stats.max_action_queue = DP_MAX_QUEUE_LEN;
        return copy_to_user(statsp, &stats, sizeof stats) ? -EFAULT : 0;
}

/* MTU of the dp pseudo-device: ETH_DATA_LEN or the minimum of the ports */
int dp_min_mtu(const struct datapath *dp)
{
        struct net_bridge_port *p;
        int mtu = 0;

        ASSERT_RTNL();

        list_for_each_entry_rcu (p, &dp->port_list, node) {
                struct net_device *dev = p->dev;

                /* Skip any internal ports, since that's what we're trying to
                 * set. */
                if (is_dp_dev(dev))
                        continue;

                if (!mtu || dev->mtu < mtu)
                        mtu = dev->mtu;
        }

        return mtu ? mtu : ETH_DATA_LEN;
}

/* Sets the MTU of all datapath devices to the minimum of the ports. 'dev'
 * is the device whose MTU may have changed.  Must be called with RTNL lock
 * and dp_mutex. */
void set_dp_devs_mtu(const struct datapath *dp, struct net_device *dev)
{
        struct net_bridge_port *p;
        int mtu;

        ASSERT_RTNL();

        if (is_dp_dev(dev))
                return;

        mtu = dp_min_mtu(dp);

        list_for_each_entry_rcu (p, &dp->port_list, node) {
                struct net_device *br_dev = p->dev;

                if (is_dp_dev(br_dev))
                        dev_set_mtu(br_dev, mtu);
        }
}

static int
put_port(const struct net_bridge_port *p, struct odp_port __user *uop)
{
        struct odp_port op;
        memset(&op, 0, sizeof op);
        strncpy(op.devname, p->dev->name, sizeof op.devname);
        op.port = p->port_no;
        op.flags = is_dp_dev(p->dev) ? ODP_PORT_INTERNAL : 0;
        return copy_to_user(uop, &op, sizeof op) ? -EFAULT : 0;
}

static int
query_port(struct datapath *dp, struct odp_port __user *uport)
{
        struct odp_port port;

        if (copy_from_user(&port, uport, sizeof port))
                return -EFAULT;
        if (port.devname[0]) {
                struct net_bridge_port *p;
                struct net_device *dev;
                int err;

                port.devname[IFNAMSIZ - 1] = '\0';

                dev = dev_get_by_name(&init_net, port.devname);
                if (!dev)
                        return -ENODEV;

                p = dev->br_port;
                if (!p && is_dp_dev(dev)) {
                        struct dp_dev *dp_dev = dp_dev_priv(dev);
                        if (dp_dev->dp == dp)
                                p = dp->ports[dp_dev->port_no];
                }
                err = p && p->dp == dp ? put_port(p, uport) : -ENOENT;
                dev_put(dev);

                return err;
        } else {
                if (port.port >= DP_MAX_PORTS)
                        return -EINVAL;
                if (!dp->ports[port.port])
                        return -ENOENT;
                return put_port(dp->ports[port.port], uport);
        }
}

static int
list_ports(struct datapath *dp, struct odp_portvec __user *pvp)
{
        struct odp_portvec pv;
        struct net_bridge_port *p;
        int idx;

        if (copy_from_user(&pv, pvp, sizeof pv))
                return -EFAULT;

        idx = 0;
        if (pv.n_ports) {
                list_for_each_entry_rcu (p, &dp->port_list, node) {
                        if (put_port(p, &pv.ports[idx]))
                                return -EFAULT;
                        if (idx++ >= pv.n_ports)
                                break;
                }
        }
        return put_user(dp->n_ports, &pvp->n_ports);
}

/* RCU callback for freeing a dp_port_group */
static void free_port_group(struct rcu_head *rcu)
{
        struct dp_port_group *g = container_of(rcu, struct dp_port_group, rcu);
        kfree(g);
}

static int
set_port_group(struct datapath *dp, const struct odp_port_group __user *upg)
{
        struct odp_port_group pg;
        struct dp_port_group *new_group, *old_group;
        int error;

        error = -EFAULT;
        if (copy_from_user(&pg, upg, sizeof pg))
                goto error;

        error = -EINVAL;
        if (pg.n_ports > DP_MAX_PORTS || pg.group >= DP_MAX_GROUPS)
                goto error;

        error = -ENOMEM;
        new_group = kmalloc(sizeof *new_group + sizeof(u16) * pg.n_ports,
                            GFP_KERNEL);
        if (!new_group)
                goto error;

        new_group->n_ports = pg.n_ports;
        error = -EFAULT;
        if (copy_from_user(new_group->ports, pg.ports,
                           sizeof(u16) * pg.n_ports))
                goto error_free;

        old_group = rcu_dereference(dp->groups[pg.group]);
        rcu_assign_pointer(dp->groups[pg.group], new_group);
        if (old_group)
                call_rcu(&old_group->rcu, free_port_group);
        return 0;

error_free:
        kfree(new_group);
error:
        return error;
}

static int
get_port_group(struct datapath *dp, struct odp_port_group *upg)
{
        struct odp_port_group pg;
        struct dp_port_group *g;
        u16 n_copy;

        if (copy_from_user(&pg, upg, sizeof pg))
                return -EFAULT;

        if (pg.group >= DP_MAX_GROUPS)
                return -EINVAL;

        g = dp->groups[pg.group];
        n_copy = g ? min_t(int, g->n_ports, pg.n_ports) : 0;
        if (n_copy && copy_to_user(pg.ports, g->ports, n_copy * sizeof(u16)))
                return -EFAULT;

        if (put_user(g ? g->n_ports : 0, &upg->n_ports))
                return -EFAULT;

        return 0;
}

static int get_listen_mask(const struct file *f)
{
        return (long)f->private_data;
}

static void set_listen_mask(struct file *f, int listen_mask)
{
        f->private_data = (void*)(long)listen_mask;
}

static long openvswitch_ioctl(struct file *f, unsigned int cmd,
                           unsigned long argp)
{
        int dp_idx = iminor(f->f_dentry->d_inode);
        struct datapath *dp;
        int drop_frags, listeners, port_no;
        unsigned int sflow_probability;
        int err;

        /* Handle commands with special locking requirements up front. */
        switch (cmd) {
        case ODP_DP_CREATE:
                err = create_dp(dp_idx, (char __user *)argp);
                goto exit;

        case ODP_DP_DESTROY:
                err = destroy_dp(dp_idx);
                goto exit;

        case ODP_PORT_ADD:
                err = add_port(dp_idx, (struct odp_port __user *)argp);
                goto exit;

        case ODP_PORT_DEL:
                err = get_user(port_no, (int __user *)argp);
                if (!err)
                        err = del_port(dp_idx, port_no);
                goto exit;
        }

        dp = get_dp_locked(dp_idx);
        err = -ENODEV;
        if (!dp)
                goto exit;

        switch (cmd) {
        case ODP_DP_STATS:
                err = get_dp_stats(dp, (struct odp_stats __user *)argp);
                break;

        case ODP_GET_DROP_FRAGS:
                err = put_user(dp->drop_frags, (int __user *)argp);
                break;

        case ODP_SET_DROP_FRAGS:
                err = get_user(drop_frags, (int __user *)argp);
                if (err)
                        break;
                err = -EINVAL;
                if (drop_frags != 0 && drop_frags != 1)
                        break;
                dp->drop_frags = drop_frags;
                err = 0;
                break;

        case ODP_GET_LISTEN_MASK:
                err = put_user(get_listen_mask(f), (int __user *)argp);
                break;

        case ODP_SET_LISTEN_MASK:
                err = get_user(listeners, (int __user *)argp);
                if (err)
                        break;
                err = -EINVAL;
                if (listeners & ~ODPL_ALL)
                        break;
                err = 0;
                set_listen_mask(f, listeners);
                break;

        case ODP_GET_SFLOW_PROBABILITY:
                err = put_user(dp->sflow_probability, (unsigned int __user *)argp);
                break;

        case ODP_SET_SFLOW_PROBABILITY:
                err = get_user(sflow_probability, (unsigned int __user *)argp);
                if (!err)
                        dp->sflow_probability = sflow_probability;
                break;

        case ODP_PORT_QUERY:
                err = query_port(dp, (struct odp_port __user *)argp);
                break;

        case ODP_PORT_LIST:
                err = list_ports(dp, (struct odp_portvec __user *)argp);
                break;

        case ODP_PORT_GROUP_SET:
                err = set_port_group(dp, (struct odp_port_group __user *)argp);
                break;

        case ODP_PORT_GROUP_GET:
                err = get_port_group(dp, (struct odp_port_group __user *)argp);
                break;

        case ODP_FLOW_FLUSH:
                err = flush_flows(dp);
                break;

        case ODP_FLOW_PUT:
                err = put_flow(dp, (struct odp_flow_put __user *)argp);
                break;

        case ODP_FLOW_DEL:
                err = del_flow(dp, (struct odp_flow __user *)argp);
                break;

        case ODP_FLOW_GET:
                err = do_flowvec_ioctl(dp, argp, query_flows);
                break;

        case ODP_FLOW_LIST:
                err = do_flowvec_ioctl(dp, argp, list_flows);
                break;

        case ODP_EXECUTE:
                err = do_execute(dp, (struct odp_execute __user *)argp);
                break;

        default:
                err = -ENOIOCTLCMD;
                break;
        }
        mutex_unlock(&dp->mutex);
exit:
        return err;
}

static int dp_has_packet_of_interest(struct datapath *dp, int listeners)
{
        int i;
        for (i = 0; i < DP_N_QUEUES; i++) {
                if (listeners & (1 << i) && !skb_queue_empty(&dp->queues[i]))
                        return 1;
        }
        return 0;
}

ssize_t openvswitch_read(struct file *f, char __user *buf, size_t nbytes,
                      loff_t *ppos)
{
        /* XXX is there sufficient synchronization here? */
        int listeners = get_listen_mask(f);
        int dp_idx = iminor(f->f_dentry->d_inode);
        struct datapath *dp = get_dp(dp_idx);
        struct sk_buff *skb;
        struct iovec __user iov;
        size_t copy_bytes;
        int retval;

        if (!dp)
                return -ENODEV;

        if (nbytes == 0 || !listeners)
                return 0;

        for (;;) {
                int i;

                for (i = 0; i < DP_N_QUEUES; i++) {
                        if (listeners & (1 << i)) {
                                skb = skb_dequeue(&dp->queues[i]);
                                if (skb)
                                        goto success;
                        }
                }

                if (f->f_flags & O_NONBLOCK) {
                        retval = -EAGAIN;
                        goto error;
                }

                wait_event_interruptible(dp->waitqueue,
                                         dp_has_packet_of_interest(dp,
                                                                   listeners));

                if (signal_pending(current)) {
                        retval = -ERESTARTSYS;
                        goto error;
                }
        }
success:
        copy_bytes = min_t(size_t, skb->len, nbytes);
        iov.iov_base = buf;
        iov.iov_len = copy_bytes;
        retval = skb_copy_datagram_iovec(skb, 0, &iov, iov.iov_len);
        if (!retval)
                retval = copy_bytes;
        kfree_skb(skb);

error:
        return retval;
}

static unsigned int openvswitch_poll(struct file *file, poll_table *wait)
{
        /* XXX is there sufficient synchronization here? */
        int dp_idx = iminor(file->f_dentry->d_inode);
        struct datapath *dp = get_dp(dp_idx);
        unsigned int mask;

        if (dp) {
                mask = 0;
                poll_wait(file, &dp->waitqueue, wait);
                if (dp_has_packet_of_interest(dp, get_listen_mask(file)))
                        mask |= POLLIN | POLLRDNORM;
        } else {
                mask = POLLIN | POLLRDNORM | POLLHUP;
        }
        return mask;
}

struct file_operations openvswitch_fops = {
        /* XXX .aio_read = openvswitch_aio_read, */
        .read  = openvswitch_read,
        .poll  = openvswitch_poll,
        .unlocked_ioctl = openvswitch_ioctl,
        /* XXX .fasync = openvswitch_fasync, */
};

static int major;

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,27)
static struct llc_sap *dp_stp_sap;

static int dp_stp_rcv(struct sk_buff *skb, struct net_device *dev,
                      struct packet_type *pt, struct net_device *orig_dev)
{
        /* We don't really care about STP packets, we just listen for them for
         * mutual exclusion with the bridge module, so this just discards
         * them. */
        kfree_skb(skb);
        return 0;
}

static int dp_avoid_bridge_init(void)
{
        /* Register to receive STP packets because the bridge module also
         * attempts to do so.  Since there can only be a single listener for a
         * given protocol, this provides mutual exclusion against the bridge
         * module, preventing both of them from being loaded at the same
         * time. */
        dp_stp_sap = llc_sap_open(LLC_SAP_BSPAN, dp_stp_rcv);
        if (!dp_stp_sap) {
                printk(KERN_ERR "openvswitch: can't register sap for STP (probably the bridge module is loaded)\n");
                return -EADDRINUSE;
        }
        return 0;
}

static void dp_avoid_bridge_exit(void)
{
        llc_sap_put(dp_stp_sap);
}
#else  /* Linux 2.6.27 or later. */
static int dp_avoid_bridge_init(void)
{
        /* Linux 2.6.27 introduces a way for multiple clients to register for
         * STP packets, which interferes with what we try to do above.
         * Instead, just check whether there's a bridge hook defined.  This is
         * not as safe--the bridge module is willing to load over the top of
         * us--but it provides a little bit of protection. */
        if (br_handle_frame_hook) {
                printk(KERN_ERR "openvswitch: bridge module is loaded, cannot load over it\n");
                return -EADDRINUSE;
        }
        return 0;
}

static void dp_avoid_bridge_exit(void)
{
        /* Nothing to do. */
}
#endif  /* Linux 2.6.27 or later */

static int __init dp_init(void)
{
        int err;

        printk("Open vSwitch %s, built "__DATE__" "__TIME__"\n", VERSION BUILDNR);

        err = dp_avoid_bridge_init();
        if (err)
                return err;

        err = flow_init();
        if (err)
                goto error;

        err = register_netdevice_notifier(&dp_device_notifier);
        if (err)
                goto error_flow_exit;

        major = register_chrdev(0, "openvswitch", &openvswitch_fops);
        if (err < 0)
                goto error_unreg_notifier;

        /* Hook into callback used by the bridge to intercept packets.
         * Parasites we are. */
        br_handle_frame_hook = dp_frame_hook;

        return 0;

error_unreg_notifier:
        unregister_netdevice_notifier(&dp_device_notifier);
error_flow_exit:
        flow_exit();
error:
        return err;
}

static void dp_cleanup(void)
{
        rcu_barrier();
        unregister_chrdev(major, "openvswitch");
        unregister_netdevice_notifier(&dp_device_notifier);
        flow_exit();
        br_handle_frame_hook = NULL;
        dp_avoid_bridge_exit();
}

module_init(dp_init);
module_exit(dp_cleanup);

MODULE_DESCRIPTION("Open vSwitch switching datapath");
MODULE_LICENSE("GPL");