linux/drivers/net/net_failover.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/* Copyright (c) 2018, Intel Corporation. */
   3
   4/* This provides a net_failover interface for paravirtual drivers to
   5 * provide an alternate datapath by exporting APIs to create and
   6 * destroy a upper 'net_failover' netdev. The upper dev manages the
   7 * original paravirtual interface as a 'standby' netdev and uses the
   8 * generic failover infrastructure to register and manage a direct
   9 * attached VF as a 'primary' netdev. This enables live migration of
  10 * a VM with direct attached VF by failing over to the paravirtual
  11 * datapath when the VF is unplugged.
  12 *
  13 * Some of the netdev management routines are based on bond/team driver as
  14 * this driver provides active-backup functionality similar to those drivers.
  15 */
  16
  17#include <linux/netdevice.h>
  18#include <linux/etherdevice.h>
  19#include <linux/ethtool.h>
  20#include <linux/module.h>
  21#include <linux/slab.h>
  22#include <linux/netpoll.h>
  23#include <linux/rtnetlink.h>
  24#include <linux/if_vlan.h>
  25#include <linux/pci.h>
  26#include <net/sch_generic.h>
  27#include <uapi/linux/if_arp.h>
  28#include <net/net_failover.h>
  29
  30static bool net_failover_xmit_ready(struct net_device *dev)
  31{
  32        return netif_running(dev) && netif_carrier_ok(dev);
  33}
  34
  35static int net_failover_open(struct net_device *dev)
  36{
  37        struct net_failover_info *nfo_info = netdev_priv(dev);
  38        struct net_device *primary_dev, *standby_dev;
  39        int err;
  40
  41        primary_dev = rtnl_dereference(nfo_info->primary_dev);
  42        if (primary_dev) {
  43                err = dev_open(primary_dev, NULL);
  44                if (err)
  45                        goto err_primary_open;
  46        }
  47
  48        standby_dev = rtnl_dereference(nfo_info->standby_dev);
  49        if (standby_dev) {
  50                err = dev_open(standby_dev, NULL);
  51                if (err)
  52                        goto err_standby_open;
  53        }
  54
  55        if ((primary_dev && net_failover_xmit_ready(primary_dev)) ||
  56            (standby_dev && net_failover_xmit_ready(standby_dev))) {
  57                netif_carrier_on(dev);
  58                netif_tx_wake_all_queues(dev);
  59        }
  60
  61        return 0;
  62
  63err_standby_open:
  64        dev_close(primary_dev);
  65err_primary_open:
  66        netif_tx_disable(dev);
  67        return err;
  68}
  69
  70static int net_failover_close(struct net_device *dev)
  71{
  72        struct net_failover_info *nfo_info = netdev_priv(dev);
  73        struct net_device *slave_dev;
  74
  75        netif_tx_disable(dev);
  76
  77        slave_dev = rtnl_dereference(nfo_info->primary_dev);
  78        if (slave_dev)
  79                dev_close(slave_dev);
  80
  81        slave_dev = rtnl_dereference(nfo_info->standby_dev);
  82        if (slave_dev)
  83                dev_close(slave_dev);
  84
  85        return 0;
  86}
  87
  88static netdev_tx_t net_failover_drop_xmit(struct sk_buff *skb,
  89                                          struct net_device *dev)
  90{
  91        atomic_long_inc(&dev->tx_dropped);
  92        dev_kfree_skb_any(skb);
  93        return NETDEV_TX_OK;
  94}
  95
  96static netdev_tx_t net_failover_start_xmit(struct sk_buff *skb,
  97                                           struct net_device *dev)
  98{
  99        struct net_failover_info *nfo_info = netdev_priv(dev);
 100        struct net_device *xmit_dev;
 101
 102        /* Try xmit via primary netdev followed by standby netdev */
 103        xmit_dev = rcu_dereference_bh(nfo_info->primary_dev);
 104        if (!xmit_dev || !net_failover_xmit_ready(xmit_dev)) {
 105                xmit_dev = rcu_dereference_bh(nfo_info->standby_dev);
 106                if (!xmit_dev || !net_failover_xmit_ready(xmit_dev))
 107                        return net_failover_drop_xmit(skb, dev);
 108        }
 109
 110        skb->dev = xmit_dev;
 111        skb->queue_mapping = qdisc_skb_cb(skb)->slave_dev_queue_mapping;
 112
 113        return dev_queue_xmit(skb);
 114}
 115
 116static u16 net_failover_select_queue(struct net_device *dev,
 117                                     struct sk_buff *skb,
 118                                     struct net_device *sb_dev,
 119                                     select_queue_fallback_t fallback)
 120{
 121        struct net_failover_info *nfo_info = netdev_priv(dev);
 122        struct net_device *primary_dev;
 123        u16 txq;
 124
 125        primary_dev = rcu_dereference(nfo_info->primary_dev);
 126        if (primary_dev) {
 127                const struct net_device_ops *ops = primary_dev->netdev_ops;
 128
 129                if (ops->ndo_select_queue)
 130                        txq = ops->ndo_select_queue(primary_dev, skb,
 131                                                    sb_dev, fallback);
 132                else
 133                        txq = fallback(primary_dev, skb, NULL);
 134
 135                qdisc_skb_cb(skb)->slave_dev_queue_mapping = skb->queue_mapping;
 136
 137                return txq;
 138        }
 139
 140        txq = skb_rx_queue_recorded(skb) ? skb_get_rx_queue(skb) : 0;
 141
 142        /* Save the original txq to restore before passing to the driver */
 143        qdisc_skb_cb(skb)->slave_dev_queue_mapping = skb->queue_mapping;
 144
 145        if (unlikely(txq >= dev->real_num_tx_queues)) {
 146                do {
 147                        txq -= dev->real_num_tx_queues;
 148                } while (txq >= dev->real_num_tx_queues);
 149        }
 150
 151        return txq;
 152}
 153
 154/* fold stats, assuming all rtnl_link_stats64 fields are u64, but
 155 * that some drivers can provide 32bit values only.
 156 */
 157static void net_failover_fold_stats(struct rtnl_link_stats64 *_res,
 158                                    const struct rtnl_link_stats64 *_new,
 159                                    const struct rtnl_link_stats64 *_old)
 160{
 161        const u64 *new = (const u64 *)_new;
 162        const u64 *old = (const u64 *)_old;
 163        u64 *res = (u64 *)_res;
 164        int i;
 165
 166        for (i = 0; i < sizeof(*_res) / sizeof(u64); i++) {
 167                u64 nv = new[i];
 168                u64 ov = old[i];
 169                s64 delta = nv - ov;
 170
 171                /* detects if this particular field is 32bit only */
 172                if (((nv | ov) >> 32) == 0)
 173                        delta = (s64)(s32)((u32)nv - (u32)ov);
 174
 175                /* filter anomalies, some drivers reset their stats
 176                 * at down/up events.
 177                 */
 178                if (delta > 0)
 179                        res[i] += delta;
 180        }
 181}
 182
 183static void net_failover_get_stats(struct net_device *dev,
 184                                   struct rtnl_link_stats64 *stats)
 185{
 186        struct net_failover_info *nfo_info = netdev_priv(dev);
 187        const struct rtnl_link_stats64 *new;
 188        struct rtnl_link_stats64 temp;
 189        struct net_device *slave_dev;
 190
 191        spin_lock(&nfo_info->stats_lock);
 192        memcpy(stats, &nfo_info->failover_stats, sizeof(*stats));
 193
 194        rcu_read_lock();
 195
 196        slave_dev = rcu_dereference(nfo_info->primary_dev);
 197        if (slave_dev) {
 198                new = dev_get_stats(slave_dev, &temp);
 199                net_failover_fold_stats(stats, new, &nfo_info->primary_stats);
 200                memcpy(&nfo_info->primary_stats, new, sizeof(*new));
 201        }
 202
 203        slave_dev = rcu_dereference(nfo_info->standby_dev);
 204        if (slave_dev) {
 205                new = dev_get_stats(slave_dev, &temp);
 206                net_failover_fold_stats(stats, new, &nfo_info->standby_stats);
 207                memcpy(&nfo_info->standby_stats, new, sizeof(*new));
 208        }
 209
 210        rcu_read_unlock();
 211
 212        memcpy(&nfo_info->failover_stats, stats, sizeof(*stats));
 213        spin_unlock(&nfo_info->stats_lock);
 214}
 215
 216static int net_failover_change_mtu(struct net_device *dev, int new_mtu)
 217{
 218        struct net_failover_info *nfo_info = netdev_priv(dev);
 219        struct net_device *primary_dev, *standby_dev;
 220        int ret = 0;
 221
 222        primary_dev = rtnl_dereference(nfo_info->primary_dev);
 223        if (primary_dev) {
 224                ret = dev_set_mtu(primary_dev, new_mtu);
 225                if (ret)
 226                        return ret;
 227        }
 228
 229        standby_dev = rtnl_dereference(nfo_info->standby_dev);
 230        if (standby_dev) {
 231                ret = dev_set_mtu(standby_dev, new_mtu);
 232                if (ret) {
 233                        if (primary_dev)
 234                                dev_set_mtu(primary_dev, dev->mtu);
 235                        return ret;
 236                }
 237        }
 238
 239        dev->mtu = new_mtu;
 240
 241        return 0;
 242}
 243
 244static void net_failover_set_rx_mode(struct net_device *dev)
 245{
 246        struct net_failover_info *nfo_info = netdev_priv(dev);
 247        struct net_device *slave_dev;
 248
 249        rcu_read_lock();
 250
 251        slave_dev = rcu_dereference(nfo_info->primary_dev);
 252        if (slave_dev) {
 253                dev_uc_sync_multiple(slave_dev, dev);
 254                dev_mc_sync_multiple(slave_dev, dev);
 255        }
 256
 257        slave_dev = rcu_dereference(nfo_info->standby_dev);
 258        if (slave_dev) {
 259                dev_uc_sync_multiple(slave_dev, dev);
 260                dev_mc_sync_multiple(slave_dev, dev);
 261        }
 262
 263        rcu_read_unlock();
 264}
 265
 266static int net_failover_vlan_rx_add_vid(struct net_device *dev, __be16 proto,
 267                                        u16 vid)
 268{
 269        struct net_failover_info *nfo_info = netdev_priv(dev);
 270        struct net_device *primary_dev, *standby_dev;
 271        int ret = 0;
 272
 273        primary_dev = rcu_dereference(nfo_info->primary_dev);
 274        if (primary_dev) {
 275                ret = vlan_vid_add(primary_dev, proto, vid);
 276                if (ret)
 277                        return ret;
 278        }
 279
 280        standby_dev = rcu_dereference(nfo_info->standby_dev);
 281        if (standby_dev) {
 282                ret = vlan_vid_add(standby_dev, proto, vid);
 283                if (ret)
 284                        if (primary_dev)
 285                                vlan_vid_del(primary_dev, proto, vid);
 286        }
 287
 288        return ret;
 289}
 290
 291static int net_failover_vlan_rx_kill_vid(struct net_device *dev, __be16 proto,
 292                                         u16 vid)
 293{
 294        struct net_failover_info *nfo_info = netdev_priv(dev);
 295        struct net_device *slave_dev;
 296
 297        slave_dev = rcu_dereference(nfo_info->primary_dev);
 298        if (slave_dev)
 299                vlan_vid_del(slave_dev, proto, vid);
 300
 301        slave_dev = rcu_dereference(nfo_info->standby_dev);
 302        if (slave_dev)
 303                vlan_vid_del(slave_dev, proto, vid);
 304
 305        return 0;
 306}
 307
 308static const struct net_device_ops failover_dev_ops = {
 309        .ndo_open               = net_failover_open,
 310        .ndo_stop               = net_failover_close,
 311        .ndo_start_xmit         = net_failover_start_xmit,
 312        .ndo_select_queue       = net_failover_select_queue,
 313        .ndo_get_stats64        = net_failover_get_stats,
 314        .ndo_change_mtu         = net_failover_change_mtu,
 315        .ndo_set_rx_mode        = net_failover_set_rx_mode,
 316        .ndo_vlan_rx_add_vid    = net_failover_vlan_rx_add_vid,
 317        .ndo_vlan_rx_kill_vid   = net_failover_vlan_rx_kill_vid,
 318        .ndo_validate_addr      = eth_validate_addr,
 319        .ndo_features_check     = passthru_features_check,
 320};
 321
 322#define FAILOVER_NAME "net_failover"
 323#define FAILOVER_VERSION "0.1"
 324
 325static void nfo_ethtool_get_drvinfo(struct net_device *dev,
 326                                    struct ethtool_drvinfo *drvinfo)
 327{
 328        strlcpy(drvinfo->driver, FAILOVER_NAME, sizeof(drvinfo->driver));
 329        strlcpy(drvinfo->version, FAILOVER_VERSION, sizeof(drvinfo->version));
 330}
 331
 332static int nfo_ethtool_get_link_ksettings(struct net_device *dev,
 333                                          struct ethtool_link_ksettings *cmd)
 334{
 335        struct net_failover_info *nfo_info = netdev_priv(dev);
 336        struct net_device *slave_dev;
 337
 338        slave_dev = rtnl_dereference(nfo_info->primary_dev);
 339        if (!slave_dev || !net_failover_xmit_ready(slave_dev)) {
 340                slave_dev = rtnl_dereference(nfo_info->standby_dev);
 341                if (!slave_dev || !net_failover_xmit_ready(slave_dev)) {
 342                        cmd->base.duplex = DUPLEX_UNKNOWN;
 343                        cmd->base.port = PORT_OTHER;
 344                        cmd->base.speed = SPEED_UNKNOWN;
 345
 346                        return 0;
 347                }
 348        }
 349
 350        return __ethtool_get_link_ksettings(slave_dev, cmd);
 351}
 352
 353static const struct ethtool_ops failover_ethtool_ops = {
 354        .get_drvinfo            = nfo_ethtool_get_drvinfo,
 355        .get_link               = ethtool_op_get_link,
 356        .get_link_ksettings     = nfo_ethtool_get_link_ksettings,
 357};
 358
 359/* Called when slave dev is injecting data into network stack.
 360 * Change the associated network device from lower dev to failover dev.
 361 * note: already called with rcu_read_lock
 362 */
 363static rx_handler_result_t net_failover_handle_frame(struct sk_buff **pskb)
 364{
 365        struct sk_buff *skb = *pskb;
 366        struct net_device *dev = rcu_dereference(skb->dev->rx_handler_data);
 367        struct net_failover_info *nfo_info = netdev_priv(dev);
 368        struct net_device *primary_dev, *standby_dev;
 369
 370        primary_dev = rcu_dereference(nfo_info->primary_dev);
 371        standby_dev = rcu_dereference(nfo_info->standby_dev);
 372
 373        if (primary_dev && skb->dev == standby_dev)
 374                return RX_HANDLER_EXACT;
 375
 376        skb->dev = dev;
 377
 378        return RX_HANDLER_ANOTHER;
 379}
 380
 381static void net_failover_compute_features(struct net_device *dev)
 382{
 383        netdev_features_t vlan_features = FAILOVER_VLAN_FEATURES &
 384                                          NETIF_F_ALL_FOR_ALL;
 385        netdev_features_t enc_features  = FAILOVER_ENC_FEATURES;
 386        unsigned short max_hard_header_len = ETH_HLEN;
 387        unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE |
 388                                        IFF_XMIT_DST_RELEASE_PERM;
 389        struct net_failover_info *nfo_info = netdev_priv(dev);
 390        struct net_device *primary_dev, *standby_dev;
 391
 392        primary_dev = rcu_dereference(nfo_info->primary_dev);
 393        if (primary_dev) {
 394                vlan_features =
 395                        netdev_increment_features(vlan_features,
 396                                                  primary_dev->vlan_features,
 397                                                  FAILOVER_VLAN_FEATURES);
 398                enc_features =
 399                        netdev_increment_features(enc_features,
 400                                                  primary_dev->hw_enc_features,
 401                                                  FAILOVER_ENC_FEATURES);
 402
 403                dst_release_flag &= primary_dev->priv_flags;
 404                if (primary_dev->hard_header_len > max_hard_header_len)
 405                        max_hard_header_len = primary_dev->hard_header_len;
 406        }
 407
 408        standby_dev = rcu_dereference(nfo_info->standby_dev);
 409        if (standby_dev) {
 410                vlan_features =
 411                        netdev_increment_features(vlan_features,
 412                                                  standby_dev->vlan_features,
 413                                                  FAILOVER_VLAN_FEATURES);
 414                enc_features =
 415                        netdev_increment_features(enc_features,
 416                                                  standby_dev->hw_enc_features,
 417                                                  FAILOVER_ENC_FEATURES);
 418
 419                dst_release_flag &= standby_dev->priv_flags;
 420                if (standby_dev->hard_header_len > max_hard_header_len)
 421                        max_hard_header_len = standby_dev->hard_header_len;
 422        }
 423
 424        dev->vlan_features = vlan_features;
 425        dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL;
 426        dev->hard_header_len = max_hard_header_len;
 427
 428        dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
 429        if (dst_release_flag == (IFF_XMIT_DST_RELEASE |
 430                                 IFF_XMIT_DST_RELEASE_PERM))
 431                dev->priv_flags |= IFF_XMIT_DST_RELEASE;
 432
 433        netdev_change_features(dev);
 434}
 435
 436static void net_failover_lower_state_changed(struct net_device *slave_dev,
 437                                             struct net_device *primary_dev,
 438                                             struct net_device *standby_dev)
 439{
 440        struct netdev_lag_lower_state_info info;
 441
 442        if (netif_carrier_ok(slave_dev))
 443                info.link_up = true;
 444        else
 445                info.link_up = false;
 446
 447        if (slave_dev == primary_dev) {
 448                if (netif_running(primary_dev))
 449                        info.tx_enabled = true;
 450                else
 451                        info.tx_enabled = false;
 452        } else {
 453                if ((primary_dev && netif_running(primary_dev)) ||
 454                    (!netif_running(standby_dev)))
 455                        info.tx_enabled = false;
 456                else
 457                        info.tx_enabled = true;
 458        }
 459
 460        netdev_lower_state_changed(slave_dev, &info);
 461}
 462
 463static int net_failover_slave_pre_register(struct net_device *slave_dev,
 464                                           struct net_device *failover_dev)
 465{
 466        struct net_device *standby_dev, *primary_dev;
 467        struct net_failover_info *nfo_info;
 468        bool slave_is_standby;
 469
 470        nfo_info = netdev_priv(failover_dev);
 471        standby_dev = rtnl_dereference(nfo_info->standby_dev);
 472        primary_dev = rtnl_dereference(nfo_info->primary_dev);
 473        slave_is_standby = slave_dev->dev.parent == failover_dev->dev.parent;
 474        if (slave_is_standby ? standby_dev : primary_dev) {
 475                netdev_err(failover_dev, "%s attempting to register as slave dev when %s already present\n",
 476                           slave_dev->name,
 477                           slave_is_standby ? "standby" : "primary");
 478                return -EINVAL;
 479        }
 480
 481        /* We want to allow only a direct attached VF device as a primary
 482         * netdev. As there is no easy way to check for a VF device, restrict
 483         * this to a pci device.
 484         */
 485        if (!slave_is_standby && (!slave_dev->dev.parent ||
 486                                  !dev_is_pci(slave_dev->dev.parent)))
 487                return -EINVAL;
 488
 489        if (failover_dev->features & NETIF_F_VLAN_CHALLENGED &&
 490            vlan_uses_dev(failover_dev)) {
 491                netdev_err(failover_dev, "Device %s is VLAN challenged and failover device has VLAN set up\n",
 492                           failover_dev->name);
 493                return -EINVAL;
 494        }
 495
 496        return 0;
 497}
 498
 499static int net_failover_slave_register(struct net_device *slave_dev,
 500                                       struct net_device *failover_dev)
 501{
 502        struct net_device *standby_dev, *primary_dev;
 503        struct net_failover_info *nfo_info;
 504        bool slave_is_standby;
 505        u32 orig_mtu;
 506        int err;
 507
 508        /* Align MTU of slave with failover dev */
 509        orig_mtu = slave_dev->mtu;
 510        err = dev_set_mtu(slave_dev, failover_dev->mtu);
 511        if (err) {
 512                netdev_err(failover_dev, "unable to change mtu of %s to %u register failed\n",
 513                           slave_dev->name, failover_dev->mtu);
 514                goto done;
 515        }
 516
 517        dev_hold(slave_dev);
 518
 519        if (netif_running(failover_dev)) {
 520                err = dev_open(slave_dev, NULL);
 521                if (err && (err != -EBUSY)) {
 522                        netdev_err(failover_dev, "Opening slave %s failed err:%d\n",
 523                                   slave_dev->name, err);
 524                        goto err_dev_open;
 525                }
 526        }
 527
 528        netif_addr_lock_bh(failover_dev);
 529        dev_uc_sync_multiple(slave_dev, failover_dev);
 530        dev_mc_sync_multiple(slave_dev, failover_dev);
 531        netif_addr_unlock_bh(failover_dev);
 532
 533        err = vlan_vids_add_by_dev(slave_dev, failover_dev);
 534        if (err) {
 535                netdev_err(failover_dev, "Failed to add vlan ids to device %s err:%d\n",
 536                           slave_dev->name, err);
 537                goto err_vlan_add;
 538        }
 539
 540        nfo_info = netdev_priv(failover_dev);
 541        standby_dev = rtnl_dereference(nfo_info->standby_dev);
 542        primary_dev = rtnl_dereference(nfo_info->primary_dev);
 543        slave_is_standby = slave_dev->dev.parent == failover_dev->dev.parent;
 544
 545        if (slave_is_standby) {
 546                rcu_assign_pointer(nfo_info->standby_dev, slave_dev);
 547                standby_dev = slave_dev;
 548                dev_get_stats(standby_dev, &nfo_info->standby_stats);
 549        } else {
 550                rcu_assign_pointer(nfo_info->primary_dev, slave_dev);
 551                primary_dev = slave_dev;
 552                dev_get_stats(primary_dev, &nfo_info->primary_stats);
 553                failover_dev->min_mtu = slave_dev->min_mtu;
 554                failover_dev->max_mtu = slave_dev->max_mtu;
 555        }
 556
 557        net_failover_lower_state_changed(slave_dev, primary_dev, standby_dev);
 558        net_failover_compute_features(failover_dev);
 559
 560        call_netdevice_notifiers(NETDEV_JOIN, slave_dev);
 561
 562        netdev_info(failover_dev, "failover %s slave:%s registered\n",
 563                    slave_is_standby ? "standby" : "primary", slave_dev->name);
 564
 565        return 0;
 566
 567err_vlan_add:
 568        dev_uc_unsync(slave_dev, failover_dev);
 569        dev_mc_unsync(slave_dev, failover_dev);
 570        dev_close(slave_dev);
 571err_dev_open:
 572        dev_put(slave_dev);
 573        dev_set_mtu(slave_dev, orig_mtu);
 574done:
 575        return err;
 576}
 577
 578static int net_failover_slave_pre_unregister(struct net_device *slave_dev,
 579                                             struct net_device *failover_dev)
 580{
 581        struct net_device *standby_dev, *primary_dev;
 582        struct net_failover_info *nfo_info;
 583
 584        nfo_info = netdev_priv(failover_dev);
 585        primary_dev = rtnl_dereference(nfo_info->primary_dev);
 586        standby_dev = rtnl_dereference(nfo_info->standby_dev);
 587
 588        if (slave_dev != primary_dev && slave_dev != standby_dev)
 589                return -ENODEV;
 590
 591        return 0;
 592}
 593
 594static int net_failover_slave_unregister(struct net_device *slave_dev,
 595                                         struct net_device *failover_dev)
 596{
 597        struct net_device *standby_dev, *primary_dev;
 598        struct net_failover_info *nfo_info;
 599        bool slave_is_standby;
 600
 601        nfo_info = netdev_priv(failover_dev);
 602        primary_dev = rtnl_dereference(nfo_info->primary_dev);
 603        standby_dev = rtnl_dereference(nfo_info->standby_dev);
 604
 605        if (WARN_ON_ONCE(slave_dev != primary_dev && slave_dev != standby_dev))
 606                return -ENODEV;
 607
 608        vlan_vids_del_by_dev(slave_dev, failover_dev);
 609        dev_uc_unsync(slave_dev, failover_dev);
 610        dev_mc_unsync(slave_dev, failover_dev);
 611        dev_close(slave_dev);
 612
 613        nfo_info = netdev_priv(failover_dev);
 614        dev_get_stats(failover_dev, &nfo_info->failover_stats);
 615
 616        slave_is_standby = slave_dev->dev.parent == failover_dev->dev.parent;
 617        if (slave_is_standby) {
 618                RCU_INIT_POINTER(nfo_info->standby_dev, NULL);
 619        } else {
 620                RCU_INIT_POINTER(nfo_info->primary_dev, NULL);
 621                if (standby_dev) {
 622                        failover_dev->min_mtu = standby_dev->min_mtu;
 623                        failover_dev->max_mtu = standby_dev->max_mtu;
 624                }
 625        }
 626
 627        dev_put(slave_dev);
 628
 629        net_failover_compute_features(failover_dev);
 630
 631        netdev_info(failover_dev, "failover %s slave:%s unregistered\n",
 632                    slave_is_standby ? "standby" : "primary", slave_dev->name);
 633
 634        return 0;
 635}
 636
 637static int net_failover_slave_link_change(struct net_device *slave_dev,
 638                                          struct net_device *failover_dev)
 639{
 640        struct net_device *primary_dev, *standby_dev;
 641        struct net_failover_info *nfo_info;
 642
 643        nfo_info = netdev_priv(failover_dev);
 644
 645        primary_dev = rtnl_dereference(nfo_info->primary_dev);
 646        standby_dev = rtnl_dereference(nfo_info->standby_dev);
 647
 648        if (slave_dev != primary_dev && slave_dev != standby_dev)
 649                return -ENODEV;
 650
 651        if ((primary_dev && net_failover_xmit_ready(primary_dev)) ||
 652            (standby_dev && net_failover_xmit_ready(standby_dev))) {
 653                netif_carrier_on(failover_dev);
 654                netif_tx_wake_all_queues(failover_dev);
 655        } else {
 656                dev_get_stats(failover_dev, &nfo_info->failover_stats);
 657                netif_carrier_off(failover_dev);
 658                netif_tx_stop_all_queues(failover_dev);
 659        }
 660
 661        net_failover_lower_state_changed(slave_dev, primary_dev, standby_dev);
 662
 663        return 0;
 664}
 665
 666static int net_failover_slave_name_change(struct net_device *slave_dev,
 667                                          struct net_device *failover_dev)
 668{
 669        struct net_device *primary_dev, *standby_dev;
 670        struct net_failover_info *nfo_info;
 671
 672        nfo_info = netdev_priv(failover_dev);
 673
 674        primary_dev = rtnl_dereference(nfo_info->primary_dev);
 675        standby_dev = rtnl_dereference(nfo_info->standby_dev);
 676
 677        if (slave_dev != primary_dev && slave_dev != standby_dev)
 678                return -ENODEV;
 679
 680        /* We need to bring up the slave after the rename by udev in case
 681         * open failed with EBUSY when it was registered.
 682         */
 683        dev_open(slave_dev, NULL);
 684
 685        return 0;
 686}
 687
 688static struct failover_ops net_failover_ops = {
 689        .slave_pre_register     = net_failover_slave_pre_register,
 690        .slave_register         = net_failover_slave_register,
 691        .slave_pre_unregister   = net_failover_slave_pre_unregister,
 692        .slave_unregister       = net_failover_slave_unregister,
 693        .slave_link_change      = net_failover_slave_link_change,
 694        .slave_name_change      = net_failover_slave_name_change,
 695        .slave_handle_frame     = net_failover_handle_frame,
 696};
 697
 698/**
 699 * net_failover_create - Create and register a failover instance
 700 *
 701 * @dev: standby netdev
 702 *
 703 * Creates a failover netdev and registers a failover instance for a standby
 704 * netdev. Used by paravirtual drivers that use 3-netdev model.
 705 * The failover netdev acts as a master device and controls 2 slave devices -
 706 * the original standby netdev and a VF netdev with the same MAC gets
 707 * registered as primary netdev.
 708 *
 709 * Return: pointer to failover instance
 710 */
 711struct failover *net_failover_create(struct net_device *standby_dev)
 712{
 713        struct device *dev = standby_dev->dev.parent;
 714        struct net_device *failover_dev;
 715        struct failover *failover;
 716        int err;
 717
 718        /* Alloc at least 2 queues, for now we are going with 16 assuming
 719         * that VF devices being enslaved won't have too many queues.
 720         */
 721        failover_dev = alloc_etherdev_mq(sizeof(struct net_failover_info), 16);
 722        if (!failover_dev) {
 723                dev_err(dev, "Unable to allocate failover_netdev!\n");
 724                return ERR_PTR(-ENOMEM);
 725        }
 726
 727        dev_net_set(failover_dev, dev_net(standby_dev));
 728        SET_NETDEV_DEV(failover_dev, dev);
 729
 730        failover_dev->netdev_ops = &failover_dev_ops;
 731        failover_dev->ethtool_ops = &failover_ethtool_ops;
 732
 733        /* Initialize the device options */
 734        failover_dev->priv_flags |= IFF_UNICAST_FLT | IFF_NO_QUEUE;
 735        failover_dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE |
 736                                       IFF_TX_SKB_SHARING);
 737
 738        /* don't acquire failover netdev's netif_tx_lock when transmitting */
 739        failover_dev->features |= NETIF_F_LLTX;
 740
 741        /* Don't allow failover devices to change network namespaces. */
 742        failover_dev->features |= NETIF_F_NETNS_LOCAL;
 743
 744        failover_dev->hw_features = FAILOVER_VLAN_FEATURES |
 745                                    NETIF_F_HW_VLAN_CTAG_TX |
 746                                    NETIF_F_HW_VLAN_CTAG_RX |
 747                                    NETIF_F_HW_VLAN_CTAG_FILTER;
 748
 749        failover_dev->hw_features |= NETIF_F_GSO_ENCAP_ALL;
 750        failover_dev->features |= failover_dev->hw_features;
 751
 752        memcpy(failover_dev->dev_addr, standby_dev->dev_addr,
 753               failover_dev->addr_len);
 754
 755        failover_dev->min_mtu = standby_dev->min_mtu;
 756        failover_dev->max_mtu = standby_dev->max_mtu;
 757
 758        err = register_netdev(failover_dev);
 759        if (err) {
 760                dev_err(dev, "Unable to register failover_dev!\n");
 761                goto err_register_netdev;
 762        }
 763
 764        netif_carrier_off(failover_dev);
 765
 766        failover = failover_register(failover_dev, &net_failover_ops);
 767        if (IS_ERR(failover)) {
 768                err = PTR_ERR(failover);
 769                goto err_failover_register;
 770        }
 771
 772        return failover;
 773
 774err_failover_register:
 775        unregister_netdev(failover_dev);
 776err_register_netdev:
 777        free_netdev(failover_dev);
 778
 779        return ERR_PTR(err);
 780}
 781EXPORT_SYMBOL_GPL(net_failover_create);
 782
 783/**
 784 * net_failover_destroy - Destroy a failover instance
 785 *
 786 * @failover: pointer to failover instance
 787 *
 788 * Unregisters any slave netdevs associated with the failover instance by
 789 * calling failover_slave_unregister().
 790 * unregisters the failover instance itself and finally frees the failover
 791 * netdev. Used by paravirtual drivers that use 3-netdev model.
 792 *
 793 */
 794void net_failover_destroy(struct failover *failover)
 795{
 796        struct net_failover_info *nfo_info;
 797        struct net_device *failover_dev;
 798        struct net_device *slave_dev;
 799
 800        if (!failover)
 801                return;
 802
 803        failover_dev = rcu_dereference(failover->failover_dev);
 804        nfo_info = netdev_priv(failover_dev);
 805
 806        netif_device_detach(failover_dev);
 807
 808        rtnl_lock();
 809
 810        slave_dev = rtnl_dereference(nfo_info->primary_dev);
 811        if (slave_dev)
 812                failover_slave_unregister(slave_dev);
 813
 814        slave_dev = rtnl_dereference(nfo_info->standby_dev);
 815        if (slave_dev)
 816                failover_slave_unregister(slave_dev);
 817
 818        failover_unregister(failover);
 819
 820        unregister_netdevice(failover_dev);
 821
 822        rtnl_unlock();
 823
 824        free_netdev(failover_dev);
 825}
 826EXPORT_SYMBOL_GPL(net_failover_destroy);
 827
 828static __init int
 829net_failover_init(void)
 830{
 831        return 0;
 832}
 833module_init(net_failover_init);
 834
 835static __exit
 836void net_failover_exit(void)
 837{
 838}
 839module_exit(net_failover_exit);
 840
 841MODULE_DESCRIPTION("Failover driver for Paravirtual drivers");
 842MODULE_LICENSE("GPL v2");
 843