datapath: Fix comment style.

[mirror_ovs.git] / datapath / actions.c

/*
 * Copyright (c) 2007-2014 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/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/openvswitch.h>
#include <linux/sctp.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/in6.h>
#include <linux/if_arp.h>
#include <linux/if_vlan.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/checksum.h>
#include <net/dsfield.h>
#include <net/sctp/checksum.h>

#include "datapath.h"
#include "gso.h"
#include "mpls.h"
#include "vlan.h"
#include "vport.h"

static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
                              struct sw_flow_key *key,
                              const struct nlattr *attr, int len);

struct deferred_action {
        struct sk_buff *skb;
        const struct nlattr *actions;

        /* Store pkt_key clone when creating deferred action. */
        struct sw_flow_key pkt_key;
};

#define DEFERRED_ACTION_FIFO_SIZE 10
struct action_fifo {
        int head;
        int tail;
        /* Deferred action fifo queue storage. */
        struct deferred_action fifo[DEFERRED_ACTION_FIFO_SIZE];
};

static struct action_fifo __percpu *action_fifos;
#define EXEC_ACTIONS_LEVEL_LIMIT 4   /* limit used to detect packet
                                      * looping by the network stack
                                      */
static DEFINE_PER_CPU(int, exec_actions_level);

static void action_fifo_init(struct action_fifo *fifo)
{
        fifo->head = 0;
        fifo->tail = 0;
}

static bool action_fifo_is_empty(const struct action_fifo *fifo)
{
        return (fifo->head == fifo->tail);
}

static struct deferred_action *action_fifo_get(struct action_fifo *fifo)
{
        if (action_fifo_is_empty(fifo))
                return NULL;

        return &fifo->fifo[fifo->tail++];
}

static struct deferred_action *action_fifo_put(struct action_fifo *fifo)
{
        if (fifo->head >= DEFERRED_ACTION_FIFO_SIZE - 1)
                return NULL;

        return &fifo->fifo[fifo->head++];
}

/* Return queue entry if fifo is not full */
static struct deferred_action *add_deferred_actions(struct sk_buff *skb,
                                                    const struct sw_flow_key *key,
                                                    const struct nlattr *attr)
{
        struct action_fifo *fifo;
        struct deferred_action *da;

        fifo = this_cpu_ptr(action_fifos);
        da = action_fifo_put(fifo);
        if (da) {
                da->skb = skb;
                da->actions = attr;
                da->pkt_key = *key;
        }

        return da;
}

static void invalidate_flow_key(struct sw_flow_key *key)
{
        key->eth.type = htons(0);
}

static bool is_flow_key_valid(const struct sw_flow_key *key)
{
        return !!key->eth.type;
}

static int make_writable(struct sk_buff *skb, int write_len)
{
        if (!pskb_may_pull(skb, write_len))
                return -ENOMEM;

        if (!skb_cloned(skb) || skb_clone_writable(skb, write_len))
                return 0;

        return pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
}

/* The end of the mac header.
 *
 * For non-MPLS skbs this will correspond to the network header.
 * For MPLS skbs it will be before the network_header as the MPLS
 * label stack lies between the end of the mac header and the network
 * header. That is, for MPLS skbs the end of the mac header
 * is the top of the MPLS label stack.
 */
static unsigned char *mac_header_end(const struct sk_buff *skb)
{
        return skb_mac_header(skb) + skb->mac_len;
}

static int push_mpls(struct sk_buff *skb, struct sw_flow_key *key,
                     const struct ovs_action_push_mpls *mpls)
{
        __be32 *new_mpls_lse;
        struct ethhdr *hdr;

        if (skb_cow_head(skb, MPLS_HLEN) < 0)
                return -ENOMEM;

        skb_push(skb, MPLS_HLEN);
        memmove(skb_mac_header(skb) - MPLS_HLEN, skb_mac_header(skb),
                skb->mac_len);
        skb_reset_mac_header(skb);

        new_mpls_lse = (__be32 *)mac_header_end(skb);
        *new_mpls_lse = mpls->mpls_lse;

        if (skb->ip_summed == CHECKSUM_COMPLETE)
                skb->csum = csum_add(skb->csum, csum_partial(new_mpls_lse,
                                                             MPLS_HLEN, 0));

        hdr = eth_hdr(skb);
        hdr->h_proto = mpls->mpls_ethertype;
        if (!ovs_skb_get_inner_protocol(skb))
                ovs_skb_set_inner_protocol(skb, skb->protocol);
        skb->protocol = mpls->mpls_ethertype;
        invalidate_flow_key(key);
        return 0;
}

static int pop_mpls(struct sk_buff *skb, struct sw_flow_key *key,
                    const __be16 ethertype)
{
        struct ethhdr *hdr;
        int err;

        err = make_writable(skb, skb->mac_len + MPLS_HLEN);
        if (unlikely(err))
                return err;

        if (skb->ip_summed == CHECKSUM_COMPLETE)
                skb->csum = csum_sub(skb->csum,
                                     csum_partial(mac_header_end(skb),
                                                  MPLS_HLEN, 0));

        memmove(skb_mac_header(skb) + MPLS_HLEN, skb_mac_header(skb),
                skb->mac_len);

        __skb_pull(skb, MPLS_HLEN);
        skb_reset_mac_header(skb);

        /* mac_header_end() is used to locate the ethertype
         * field correctly in the presence of VLAN tags.
         */
        hdr = (struct ethhdr *)(mac_header_end(skb) - ETH_HLEN);
        hdr->h_proto = ethertype;
        if (eth_p_mpls(skb->protocol))
                skb->protocol = ethertype;
        invalidate_flow_key(key);
        return 0;
}

static int set_mpls(struct sk_buff *skb, struct sw_flow_key *key,
                    const __be32 *mpls_lse)
{
        __be32 *stack = (__be32 *)mac_header_end(skb);
        int err;

        err = make_writable(skb, skb->mac_len + MPLS_HLEN);
        if (unlikely(err))
                return err;

        if (skb->ip_summed == CHECKSUM_COMPLETE) {
                __be32 diff[] = { ~(*stack), *mpls_lse };
                skb->csum = ~csum_partial((char *)diff, sizeof(diff),
                                          ~skb->csum);
        }

        *stack = *mpls_lse;
        key->mpls.top_lse = *mpls_lse;
        return 0;
}

/* remove VLAN header from packet and update csum accordingly. */
static int __pop_vlan_tci(struct sk_buff *skb, __be16 *current_tci)
{
        struct vlan_hdr *vhdr;
        int err;

        err = make_writable(skb, VLAN_ETH_HLEN);
        if (unlikely(err))
                return err;

        if (skb->ip_summed == CHECKSUM_COMPLETE)
                skb->csum = csum_sub(skb->csum, csum_partial(skb->data
                                        + (2 * ETH_ALEN), VLAN_HLEN, 0));

        vhdr = (struct vlan_hdr *)(skb->data + ETH_HLEN);
        *current_tci = vhdr->h_vlan_TCI;

        memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN);
        __skb_pull(skb, VLAN_HLEN);

        vlan_set_encap_proto(skb, vhdr);
        skb->mac_header += VLAN_HLEN;
        /* Update mac_len for subsequent MPLS actions */
        skb->mac_len -= VLAN_HLEN;

        return 0;
}

static int pop_vlan(struct sk_buff *skb, struct sw_flow_key *key)
{
        __be16 tci;
        int err;

        if (likely(vlan_tx_tag_present(skb))) {
                vlan_set_tci(skb, 0);
        } else {
                if (unlikely(skb->protocol != htons(ETH_P_8021Q) ||
                             skb->len < VLAN_ETH_HLEN))
                        return 0;

                err = __pop_vlan_tci(skb, &tci);
                if (err)
                        return err;
        }
        /* move next vlan tag to hw accel tag */
        if (likely(skb->protocol != htons(ETH_P_8021Q) ||
                   skb->len < VLAN_ETH_HLEN)) {
                key->eth.tci = 0;
                return 0;
        }

        invalidate_flow_key(key);
        err = __pop_vlan_tci(skb, &tci);
        if (unlikely(err))
                return err;

        __vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), ntohs(tci));
        return 0;
}

static int push_vlan(struct sk_buff *skb, struct sw_flow_key *key,
                     const struct ovs_action_push_vlan *vlan)
{
        if (unlikely(vlan_tx_tag_present(skb))) {
                u16 current_tag;

                /* push down current VLAN tag */
                current_tag = vlan_tx_tag_get(skb);

                if (!__vlan_put_tag(skb, skb->vlan_proto, current_tag))
                        return -ENOMEM;

                /* Update mac_len for subsequent MPLS actions */
                skb->mac_len += VLAN_HLEN;

                if (skb->ip_summed == CHECKSUM_COMPLETE)
                        skb->csum = csum_add(skb->csum, csum_partial(skb->data
                                        + (2 * ETH_ALEN), VLAN_HLEN, 0));

                invalidate_flow_key(key);
        } else {
                key->eth.tci = vlan->vlan_tci;
        }
        __vlan_hwaccel_put_tag(skb, vlan->vlan_tpid, ntohs(vlan->vlan_tci) & ~VLAN_TAG_PRESENT);
        return 0;
}

static int set_eth_addr(struct sk_buff *skb, struct sw_flow_key *key,
                        const struct ovs_key_ethernet *eth_key)
{
        int err;
        err = make_writable(skb, ETH_HLEN);
        if (unlikely(err))
                return err;

        skb_postpull_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);

        ether_addr_copy(eth_hdr(skb)->h_source, eth_key->eth_src);
        ether_addr_copy(eth_hdr(skb)->h_dest, eth_key->eth_dst);

        ovs_skb_postpush_rcsum(skb, eth_hdr(skb), ETH_ALEN * 2);

        ether_addr_copy(key->eth.src, eth_key->eth_src);
        ether_addr_copy(key->eth.dst, eth_key->eth_dst);
        return 0;
}

static void set_ip_addr(struct sk_buff *skb, struct iphdr *nh,
                        __be32 *addr, __be32 new_addr)
{
        int transport_len = skb->len - skb_transport_offset(skb);

        if (nh->protocol == IPPROTO_TCP) {
                if (likely(transport_len >= sizeof(struct tcphdr)))
                        inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
                                                 *addr, new_addr, 1);
        } else if (nh->protocol == IPPROTO_UDP) {
                if (likely(transport_len >= sizeof(struct udphdr))) {
                        struct udphdr *uh = udp_hdr(skb);

                        if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
                                inet_proto_csum_replace4(&uh->check, skb,
                                                         *addr, new_addr, 1);
                                if (!uh->check)
                                        uh->check = CSUM_MANGLED_0;
                        }
                }
        }

        csum_replace4(&nh->check, *addr, new_addr);
        skb_clear_hash(skb);
        *addr = new_addr;
}

static void update_ipv6_checksum(struct sk_buff *skb, u8 l4_proto,
                                 __be32 addr[4], const __be32 new_addr[4])
{
        int transport_len = skb->len - skb_transport_offset(skb);

        if (l4_proto == NEXTHDR_TCP) {
                if (likely(transport_len >= sizeof(struct tcphdr)))
                        inet_proto_csum_replace16(&tcp_hdr(skb)->check, skb,
                                                  addr, new_addr, 1);
        } else if (l4_proto == NEXTHDR_UDP) {
                if (likely(transport_len >= sizeof(struct udphdr))) {
                        struct udphdr *uh = udp_hdr(skb);

                        if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
                                inet_proto_csum_replace16(&uh->check, skb,
                                                          addr, new_addr, 1);
                                if (!uh->check)
                                        uh->check = CSUM_MANGLED_0;
                        }
                }
        } else if (l4_proto == NEXTHDR_ICMP) {
                if (likely(transport_len >= sizeof(struct icmp6hdr)))
                        inet_proto_csum_replace16(&icmp6_hdr(skb)->icmp6_cksum,
                                                  skb, addr, new_addr, 1);
        }
}

static void set_ipv6_addr(struct sk_buff *skb, u8 l4_proto,
                          __be32 addr[4], const __be32 new_addr[4],
                          bool recalculate_csum)
{
        if (likely(recalculate_csum))
                update_ipv6_checksum(skb, l4_proto, addr, new_addr);

        skb_clear_hash(skb);
        memcpy(addr, new_addr, sizeof(__be32[4]));
}

static void set_ipv6_tc(struct ipv6hdr *nh, u8 tc)
{
        nh->priority = tc >> 4;
        nh->flow_lbl[0] = (nh->flow_lbl[0] & 0x0F) | ((tc & 0x0F) << 4);
}

static void set_ipv6_fl(struct ipv6hdr *nh, u32 fl)
{
        nh->flow_lbl[0] = (nh->flow_lbl[0] & 0xF0) | (fl & 0x000F0000) >> 16;
        nh->flow_lbl[1] = (fl & 0x0000FF00) >> 8;
        nh->flow_lbl[2] = fl & 0x000000FF;
}

static void set_ip_ttl(struct sk_buff *skb, struct iphdr *nh, u8 new_ttl)
{
        csum_replace2(&nh->check, htons(nh->ttl << 8), htons(new_ttl << 8));
        nh->ttl = new_ttl;
}

static int set_ipv4(struct sk_buff *skb, struct sw_flow_key *key,
                    const struct ovs_key_ipv4 *ipv4_key)
{
        struct iphdr *nh;
        int err;

        err = make_writable(skb, skb_network_offset(skb) +
                                 sizeof(struct iphdr));
        if (unlikely(err))
                return err;

        nh = ip_hdr(skb);

        if (ipv4_key->ipv4_src != nh->saddr) {
                set_ip_addr(skb, nh, &nh->saddr, ipv4_key->ipv4_src);
                key->ipv4.addr.src = ipv4_key->ipv4_src;
        }

        if (ipv4_key->ipv4_dst != nh->daddr) {
                set_ip_addr(skb, nh, &nh->daddr, ipv4_key->ipv4_dst);
                key->ipv4.addr.dst = ipv4_key->ipv4_dst;
        }

        if (ipv4_key->ipv4_tos != nh->tos) {
                ipv4_change_dsfield(nh, 0, ipv4_key->ipv4_tos);
                key->ip.tos = nh->tos;
        }

        if (ipv4_key->ipv4_ttl != nh->ttl) {
                set_ip_ttl(skb, nh, ipv4_key->ipv4_ttl);
                key->ip.ttl = ipv4_key->ipv4_ttl;
        }

        return 0;
}

static int set_ipv6(struct sk_buff *skb, struct sw_flow_key *key,
                    const struct ovs_key_ipv6 *ipv6_key)
{
        struct ipv6hdr *nh;
        int err;
        __be32 *saddr;
        __be32 *daddr;

        err = make_writable(skb, skb_network_offset(skb) +
                            sizeof(struct ipv6hdr));
        if (unlikely(err))
                return err;

        nh = ipv6_hdr(skb);
        saddr = (__be32 *)&nh->saddr;
        daddr = (__be32 *)&nh->daddr;

        if (memcmp(ipv6_key->ipv6_src, saddr, sizeof(ipv6_key->ipv6_src))) {
                set_ipv6_addr(skb, ipv6_key->ipv6_proto, saddr,
                              ipv6_key->ipv6_src, true);
                memcpy(&key->ipv6.addr.src, ipv6_key->ipv6_src,
                       sizeof(ipv6_key->ipv6_src));
        }

        if (memcmp(ipv6_key->ipv6_dst, daddr, sizeof(ipv6_key->ipv6_dst))) {
                unsigned int offset = 0;
                int flags = OVS_IP6T_FH_F_SKIP_RH;
                bool recalc_csum = true;

                if (ipv6_ext_hdr(nh->nexthdr))
                        recalc_csum = ipv6_find_hdr(skb, &offset,
                                                    NEXTHDR_ROUTING, NULL,
                                                    &flags) != NEXTHDR_ROUTING;

                set_ipv6_addr(skb, ipv6_key->ipv6_proto, daddr,
                              ipv6_key->ipv6_dst, recalc_csum);
                memcpy(&key->ipv6.addr.dst, ipv6_key->ipv6_dst,
                       sizeof(ipv6_key->ipv6_dst));
        }

        set_ipv6_tc(nh, ipv6_key->ipv6_tclass);
        key->ip.tos = ipv6_get_dsfield(nh);

        set_ipv6_fl(nh, ntohl(ipv6_key->ipv6_label));
        key->ipv6.label = *(__be32 *)nh & htonl(IPV6_FLOWINFO_FLOWLABEL);

        nh->hop_limit = ipv6_key->ipv6_hlimit;
        key->ip.ttl = ipv6_key->ipv6_hlimit;
        return 0;
}

/* Must follow make_writable() since that can move the skb data. */
static void set_tp_port(struct sk_buff *skb, __be16 *port,
                         __be16 new_port, __sum16 *check)
{
        inet_proto_csum_replace2(check, skb, *port, new_port, 0);
        *port = new_port;
        skb_clear_hash(skb);
}

static void set_udp_port(struct sk_buff *skb, __be16 *port, __be16 new_port)
{
        struct udphdr *uh = udp_hdr(skb);

        if (uh->check && skb->ip_summed != CHECKSUM_PARTIAL) {
                set_tp_port(skb, port, new_port, &uh->check);

                if (!uh->check)
                        uh->check = CSUM_MANGLED_0;
        } else {
                *port = new_port;
                skb_clear_hash(skb);
        }
}

static int set_udp(struct sk_buff *skb, struct sw_flow_key *key,
                   const struct ovs_key_udp *udp_port_key)
{
        struct udphdr *uh;
        int err;

        err = make_writable(skb, skb_transport_offset(skb) +
                                 sizeof(struct udphdr));
        if (unlikely(err))
                return err;

        uh = udp_hdr(skb);
        if (udp_port_key->udp_src != uh->source) {
                set_udp_port(skb, &uh->source, udp_port_key->udp_src);
                key->tp.src = udp_port_key->udp_src;
        }

        if (udp_port_key->udp_dst != uh->dest) {
                set_udp_port(skb, &uh->dest, udp_port_key->udp_dst);
                key->tp.dst = udp_port_key->udp_dst;
        }

        return 0;
}

static int set_tcp(struct sk_buff *skb, struct sw_flow_key *key,
                   const struct ovs_key_tcp *tcp_port_key)
{
        struct tcphdr *th;
        int err;

        err = make_writable(skb, skb_transport_offset(skb) +
                                 sizeof(struct tcphdr));
        if (unlikely(err))
                return err;

        th = tcp_hdr(skb);
        if (tcp_port_key->tcp_src != th->source) {
                set_tp_port(skb, &th->source, tcp_port_key->tcp_src, &th->check);
                key->tp.src = tcp_port_key->tcp_src;
        }

        if (tcp_port_key->tcp_dst != th->dest) {
                set_tp_port(skb, &th->dest, tcp_port_key->tcp_dst, &th->check);
                key->tp.dst = tcp_port_key->tcp_dst;
        }

        return 0;
}

static int set_sctp(struct sk_buff *skb, struct sw_flow_key *key,
                    const struct ovs_key_sctp *sctp_port_key)
{
        struct sctphdr *sh;
        int err;
        unsigned int sctphoff = skb_transport_offset(skb);

        err = make_writable(skb, sctphoff + sizeof(struct sctphdr));
        if (unlikely(err))
                return err;

        sh = sctp_hdr(skb);
        if (sctp_port_key->sctp_src != sh->source ||
            sctp_port_key->sctp_dst != sh->dest) {
                __le32 old_correct_csum, new_csum, old_csum;

                old_csum = sh->checksum;
                old_correct_csum = sctp_compute_cksum(skb, sctphoff);

                sh->source = sctp_port_key->sctp_src;
                sh->dest = sctp_port_key->sctp_dst;

                new_csum = sctp_compute_cksum(skb, sctphoff);

                /* Carry any checksum errors through. */
                sh->checksum = old_csum ^ old_correct_csum ^ new_csum;

                skb_clear_hash(skb);
                key->tp.src = sctp_port_key->sctp_src;
                key->tp.dst = sctp_port_key->sctp_dst;
        }

        return 0;
}

static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
{
        struct vport *vport = ovs_vport_rcu(dp, out_port);

        if (likely(vport))
                ovs_vport_send(vport, skb);
        else
                kfree_skb(skb);
}

static int output_userspace(struct datapath *dp, struct sk_buff *skb,
                            struct sw_flow_key *key, const struct nlattr *attr)
{
        struct dp_upcall_info upcall;
        const struct nlattr *a;
        int rem;
        struct ovs_tunnel_info info;

        upcall.cmd = OVS_PACKET_CMD_ACTION;
        upcall.userdata = NULL;
        upcall.portid = 0;
        upcall.egress_tun_info = NULL;

        for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
                 a = nla_next(a, &rem)) {
                switch (nla_type(a)) {
                case OVS_USERSPACE_ATTR_USERDATA:
                        upcall.userdata = a;
                        break;

                case OVS_USERSPACE_ATTR_PID:
                        upcall.portid = nla_get_u32(a);
                        break;

                case OVS_USERSPACE_ATTR_EGRESS_TUN_PORT: {
                        /* Get out tunnel info. */
                        struct vport *vport;

                        vport = ovs_vport_rcu(dp, nla_get_u32(a));
                        if (vport) {
                                int err;

                                err = ovs_vport_get_egress_tun_info(vport, skb,
                                                                    &info);
                                if (!err)
                                        upcall.egress_tun_info = &info;
                        }
                        break;
                }

                } /* End of switch. */
        }

        return ovs_dp_upcall(dp, skb, key, &upcall);
}

static bool last_action(const struct nlattr *a, int rem)
{
        return a->nla_len == rem;
}

static int sample(struct datapath *dp, struct sk_buff *skb,
                  struct sw_flow_key *key, const struct nlattr *attr)
{
        const struct nlattr *acts_list = NULL;
        const struct nlattr *a;
        int rem;

        for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
                 a = nla_next(a, &rem)) {
                switch (nla_type(a)) {
                case OVS_SAMPLE_ATTR_PROBABILITY:
                        if (prandom_u32() >= nla_get_u32(a))
                                return 0;
                        break;

                case OVS_SAMPLE_ATTR_ACTIONS:
                        acts_list = a;
                        break;
                }
        }

        rem = nla_len(acts_list);
        a = nla_data(acts_list);

        /* Actions list is empty, do nothing */
        if (unlikely(!rem))
                return 0;

        /* The only known usage of sample action is having a single user-space
         * action. Treat this usage as a special case.
         * The output_userspace() should clone the skb to be sent to the
         * user space. This skb will be consumed by its caller.
         */
        if (likely(nla_type(a) == OVS_ACTION_ATTR_USERSPACE &&
                   last_action(a, rem)))
                return output_userspace(dp, skb, key, a);

        skb = skb_clone(skb, GFP_ATOMIC);
        if (!skb)
                /* Skip the sample action when out of memory. */
                return 0;

        if (!add_deferred_actions(skb, key, a)) {
                if (net_ratelimit())
                        pr_warn("%s: deferred actions limit reached, dropping sample action\n",
                                ovs_dp_name(dp));

                kfree_skb(skb);
        }
        return 0;
}

static void execute_hash(struct sk_buff *skb, struct sw_flow_key *key,
                         const struct nlattr *attr)
{
        struct ovs_action_hash *hash_act = nla_data(attr);
        u32 hash = 0;

        /* OVS_HASH_ALG_L4 is the only possible hash algorithm.  */
        hash = skb_get_hash(skb);
        hash = jhash_1word(hash, hash_act->hash_basis);
        if (!hash)
                hash = 0x1;

        key->ovs_flow_hash = hash;
}

static int execute_set_action(struct sk_buff *skb, struct sw_flow_key *key,
                              const struct nlattr *nested_attr)
{
        int err = 0;

        switch (nla_type(nested_attr)) {
        case OVS_KEY_ATTR_PRIORITY:
                skb->priority = nla_get_u32(nested_attr);
                key->phy.priority = skb->priority;
                break;

        case OVS_KEY_ATTR_SKB_MARK:
                skb->mark = nla_get_u32(nested_attr);
                key->phy.skb_mark = skb->mark;
                break;

        case OVS_KEY_ATTR_TUNNEL_INFO:
                OVS_CB(skb)->egress_tun_info = nla_data(nested_attr);
                break;

        case OVS_KEY_ATTR_ETHERNET:
                err = set_eth_addr(skb, key, nla_data(nested_attr));
                break;

        case OVS_KEY_ATTR_IPV4:
                err = set_ipv4(skb, key, nla_data(nested_attr));
                break;

        case OVS_KEY_ATTR_IPV6:
                err = set_ipv6(skb, key, nla_data(nested_attr));
                break;

        case OVS_KEY_ATTR_TCP:
                err = set_tcp(skb, key, nla_data(nested_attr));
                break;

        case OVS_KEY_ATTR_UDP:
                err = set_udp(skb, key, nla_data(nested_attr));
                break;

        case OVS_KEY_ATTR_SCTP:
                err = set_sctp(skb, key, nla_data(nested_attr));
                break;

        case OVS_KEY_ATTR_MPLS:
                err = set_mpls(skb, key, nla_data(nested_attr));
                break;
        }

        return err;
}

static int execute_recirc(struct datapath *dp, struct sk_buff *skb,
                          struct sw_flow_key *key, const struct nlattr *a, int rem)
{
        struct deferred_action *da;

        if (!is_flow_key_valid(key)) {
                int err;

                err = ovs_flow_key_update(skb, key);
                if (err)
                        return err;

        }
        BUG_ON(!is_flow_key_valid(key));

        if (!last_action(a, rem)) {
                /* Recirc action is the not the last action
                 * of the action list, need to clone the skb.
                 */
                skb = skb_clone(skb, GFP_ATOMIC);

                /* Skip the recirc action when out of memory, but
                 * continue on with the rest of the action list.
                 */
                if (!skb)
                        return 0;
        }

        da = add_deferred_actions(skb, key, NULL);
        if (da) {
                da->pkt_key.recirc_id = nla_get_u32(a);
        } else {
                kfree_skb(skb);

                if (net_ratelimit())
                        pr_warn("%s: deferred action limit reached, drop recirc action\n",
                                ovs_dp_name(dp));
        }

        return 0;
}

/* Execute a list of actions against 'skb'. */
static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
                              struct sw_flow_key *key,
                              const struct nlattr *attr, int len)
{
        /* Every output action needs a separate clone of 'skb', but the common
         * case is just a single output action, so that doing a clone and
         * then freeing the original skbuff is wasteful.  So the following code
         * is slightly obscure just to avoid that.
         */
        int prev_port = -1;
        const struct nlattr *a;
        int rem;

        for (a = attr, rem = len; rem > 0;
             a = nla_next(a, &rem)) {
                int err = 0;

                if (unlikely(prev_port != -1)) {
                        struct sk_buff *out_skb = skb_clone(skb, GFP_ATOMIC);

                        if (out_skb)
                                do_output(dp, out_skb, prev_port);

                        prev_port = -1;
                }

                switch (nla_type(a)) {
                case OVS_ACTION_ATTR_OUTPUT:
                        prev_port = nla_get_u32(a);
                        break;

                case OVS_ACTION_ATTR_USERSPACE:
                        output_userspace(dp, skb, key, a);
                        break;

                case OVS_ACTION_ATTR_HASH:
                        execute_hash(skb, key, a);
                        break;

                case OVS_ACTION_ATTR_PUSH_MPLS:
                        err = push_mpls(skb, key, nla_data(a));
                        break;

                case OVS_ACTION_ATTR_POP_MPLS:
                        err = pop_mpls(skb, key, nla_get_be16(a));
                        break;

                case OVS_ACTION_ATTR_PUSH_VLAN:
                        err = push_vlan(skb, key, nla_data(a));
                        if (unlikely(err)) /* skb already freed. */
                                return err;
                        break;

                case OVS_ACTION_ATTR_POP_VLAN:
                        err = pop_vlan(skb, key);
                        break;

                case OVS_ACTION_ATTR_RECIRC:
                        err = execute_recirc(dp, skb, key, a, rem);
                        if (last_action(a, rem)) {
                                /* If this is the last action, the skb has
                                 * been consumed or freed.
                                 * Return immediately.
                                 */
                                return err;
                        }
                        break;

                case OVS_ACTION_ATTR_SET:
                        err = execute_set_action(skb, key, nla_data(a));
                        break;

                case OVS_ACTION_ATTR_SAMPLE:
                        err = sample(dp, skb, key, a);
                        break;
                }

                if (unlikely(err)) {
                        kfree_skb(skb);
                        return err;
                }
        }

        if (prev_port != -1)
                do_output(dp, skb, prev_port);
        else
                consume_skb(skb);

        return 0;
}

static void process_deferred_actions(struct datapath *dp)
{
        struct action_fifo *fifo = this_cpu_ptr(action_fifos);

        /* Do not touch the FIFO in case there is no deferred actions. */
        if (action_fifo_is_empty(fifo))
                return;

        /* Finishing executing all deferred actions. */
        do {
                struct deferred_action *da = action_fifo_get(fifo);
                struct sk_buff *skb = da->skb;
                const struct nlattr *actions = da->actions;

                if (actions)
                        do_execute_actions(dp, skb, &da->pkt_key, actions,
                                           nla_len(actions));
                else
                        ovs_dp_process_packet(skb, &da->pkt_key);
        } while (!action_fifo_is_empty(fifo));

        /* Reset FIFO for the next packet.  */
        action_fifo_init(fifo);
}

/* Execute a list of actions against 'skb'. */
int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
                        struct sw_flow_key *key,
                        const struct sw_flow_actions *acts)
{
        int level = this_cpu_read(exec_actions_level);
        int err;

        if (unlikely(level >= EXEC_ACTIONS_LEVEL_LIMIT)) {
                if (net_ratelimit())
                        pr_warn("%s: packet loop detected, dropping.\n",
                                ovs_dp_name(dp));

                kfree_skb(skb);
                return -ELOOP;
        }

        this_cpu_inc(exec_actions_level);

        err = do_execute_actions(dp, skb, key, acts->actions, acts->actions_len);

        if (!level)
                process_deferred_actions(dp);

        this_cpu_dec(exec_actions_level);

        /* This return status currently does not reflect the errors
         * encounted during deferred actions execution. Probably needs to
         * be fixed in the future.
         */
        return err;
}

int action_fifos_init(void)
{
        action_fifos = alloc_percpu(struct action_fifo);
        if (!action_fifos)
                return -ENOMEM;

        return 0;
}

void action_fifos_exit(void)
{
        free_percpu(action_fifos);
}