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