drivers/net/net_failover.c

   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/netdevice.h>
  23 #include <linux/netpoll.h>
  24 #include <linux/rtnetlink.h>
  25 #include <linux/if_vlan.h>
  26 #include <linux/pci.h>
  27 #include <net/sch_generic.h>
  28 #include <uapi/linux/if_arp.h>
  29 #include <net/net_failover.h>
  30
  31 static bool net_failover_xmit_ready(struct net_device *dev)
  32 {
  33         return netif_running(dev) && netif_carrier_ok(dev);
  34 }
  35
  36 static int net_failover_open(struct net_device *dev)
  37 {
  38         struct net_failover_info *nfo_info = netdev_priv(dev);
  39         struct net_device *primary_dev, *standby_dev;
  40         int err;
  41
  42         primary_dev = rtnl_dereference(nfo_info->primary_dev);
  43         if (primary_dev) {
  44                 err = dev_open(primary_dev);
  45                 if (err)
  46                         goto err_primary_open;
  47         }
  48
  49         standby_dev = rtnl_dereference(nfo_info->standby_dev);
  50         if (standby_dev) {
  51                 err = dev_open(standby_dev);
  52                 if (err)
  53                         goto err_standby_open;
  54         }
  55
  56         if ((primary_dev && net_failover_xmit_ready(primary_dev)) ||
  57             (standby_dev && net_failover_xmit_ready(standby_dev))) {
  58                 netif_carrier_on(dev);
  59                 netif_tx_wake_all_queues(dev);
  60         }
  61
  62         return 0;
  63
  64 err_standby_open:
  65         dev_close(primary_dev);
  66 err_primary_open:
  67         netif_tx_disable(dev);
  68         return err;
  69 }
  70
  71 static 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
  89 static 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
  97 static 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
 117 static u16 net_failover_select_queue(struct net_device *dev,
 118                                      struct sk_buff *skb, void *accel_priv,
 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                                                     accel_priv, fallback);
 132                 else
 133                         txq = fallback(primary_dev, skb);
 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  */
 157 static 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
 183 static 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
 216 static 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 = rcu_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 = rcu_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
 244 static 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
 266 static 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
 291 static 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
 308 static 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
 325 static 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
 332 static 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
 353 static 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  */
 363 static 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
 381 static void net_failover_compute_features(struct net_device *dev)
 382 {
 383         u32 vlan_features = FAILOVER_VLAN_FEATURES & 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
 435 static 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
 462 static 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
 498 static 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);
 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_uc_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
 566 err_vlan_add:
 567         dev_uc_unsync(slave_dev, failover_dev);
 568         dev_mc_unsync(slave_dev, failover_dev);
 569         dev_close(slave_dev);
 570 err_dev_open:
 571         dev_put(slave_dev);
 572         dev_set_mtu(slave_dev, orig_mtu);
 573 done:
 574         return err;
 575 }
 576
 577 static 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
 593 static 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         vlan_vids_del_by_dev(slave_dev, failover_dev);
 605         dev_uc_unsync(slave_dev, failover_dev);
 606         dev_mc_unsync(slave_dev, failover_dev);
 607         dev_close(slave_dev);
 608
 609         nfo_info = netdev_priv(failover_dev);
 610         dev_get_stats(failover_dev, &nfo_info->failover_stats);
 611
 612         slave_is_standby = slave_dev->dev.parent == failover_dev->dev.parent;
 613         if (slave_is_standby) {
 614                 RCU_INIT_POINTER(nfo_info->standby_dev, NULL);
 615         } else {
 616                 RCU_INIT_POINTER(nfo_info->primary_dev, NULL);
 617                 if (standby_dev) {
 618                         failover_dev->min_mtu = standby_dev->min_mtu;
 619                         failover_dev->max_mtu = standby_dev->max_mtu;
 620                 }
 621         }
 622
 623         dev_put(slave_dev);
 624
 625         net_failover_compute_features(failover_dev);
 626
 627         netdev_info(failover_dev, "failover %s slave:%s unregistered\n",
 628                     slave_is_standby ? "standby" : "primary", slave_dev->name);
 629
 630         return 0;
 631 }
 632
 633 static int net_failover_slave_link_change(struct net_device *slave_dev,
 634                                           struct net_device *failover_dev)
 635 {
 636         struct net_device *primary_dev, *standby_dev;
 637         struct net_failover_info *nfo_info;
 638
 639         nfo_info = netdev_priv(failover_dev);
 640
 641         primary_dev = rtnl_dereference(nfo_info->primary_dev);
 642         standby_dev = rtnl_dereference(nfo_info->standby_dev);
 643
 644         if (slave_dev != primary_dev && slave_dev != standby_dev)
 645                 return -ENODEV;
 646
 647         if ((primary_dev && net_failover_xmit_ready(primary_dev)) ||
 648             (standby_dev && net_failover_xmit_ready(standby_dev))) {
 649                 netif_carrier_on(failover_dev);
 650                 netif_tx_wake_all_queues(failover_dev);
 651         } else {
 652                 dev_get_stats(failover_dev, &nfo_info->failover_stats);
 653                 netif_carrier_off(failover_dev);
 654                 netif_tx_stop_all_queues(failover_dev);
 655         }
 656
 657         net_failover_lower_state_changed(slave_dev, primary_dev, standby_dev);
 658
 659         return 0;
 660 }
 661
 662 static int net_failover_slave_name_change(struct net_device *slave_dev,
 663                                           struct net_device *failover_dev)
 664 {
 665         struct net_device *primary_dev, *standby_dev;
 666         struct net_failover_info *nfo_info;
 667
 668         nfo_info = netdev_priv(failover_dev);
 669
 670         primary_dev = rtnl_dereference(nfo_info->primary_dev);
 671         standby_dev = rtnl_dereference(nfo_info->standby_dev);
 672
 673         if (slave_dev != primary_dev && slave_dev != standby_dev)
 674                 return -ENODEV;
 675
 676         /* We need to bring up the slave after the rename by udev in case
 677          * open failed with EBUSY when it was registered.
 678          */
 679         dev_open(slave_dev);
 680
 681         return 0;
 682 }
 683
 684 static struct failover_ops net_failover_ops = {
 685         .slave_pre_register     = net_failover_slave_pre_register,
 686         .slave_register         = net_failover_slave_register,
 687         .slave_pre_unregister   = net_failover_slave_pre_unregister,
 688         .slave_unregister       = net_failover_slave_unregister,
 689         .slave_link_change      = net_failover_slave_link_change,
 690         .slave_name_change      = net_failover_slave_name_change,
 691         .slave_handle_frame     = net_failover_handle_frame,
 692 };
 693
 694 /**
 695  * net_failover_create - Create and register a failover instance
 696  *
 697  * @dev: standby netdev
 698  *
 699  * Creates a failover netdev and registers a failover instance for a standby
 700  * netdev. Used by paravirtual drivers that use 3-netdev model.
 701  * The failover netdev acts as a master device and controls 2 slave devices -
 702  * the original standby netdev and a VF netdev with the same MAC gets
 703  * registered as primary netdev.
 704  *
 705  * Return: pointer to failover instance
 706  */
 707 struct failover *net_failover_create(struct net_device *standby_dev)
 708 {
 709         struct device *dev = standby_dev->dev.parent;
 710         struct net_device *failover_dev;
 711         struct failover *failover;
 712         int err;
 713
 714         /* Alloc at least 2 queues, for now we are going with 16 assuming
 715          * that VF devices being enslaved won't have too many queues.
 716          */
 717         failover_dev = alloc_etherdev_mq(sizeof(struct net_failover_info), 16);
 718         if (!failover_dev) {
 719                 dev_err(dev, "Unable to allocate failover_netdev!\n");
 720                 return ERR_PTR(-ENOMEM);
 721         }
 722
 723         dev_net_set(failover_dev, dev_net(standby_dev));
 724         SET_NETDEV_DEV(failover_dev, dev);
 725
 726         failover_dev->netdev_ops = &failover_dev_ops;
 727         failover_dev->ethtool_ops = &failover_ethtool_ops;
 728
 729         /* Initialize the device options */
 730         failover_dev->priv_flags |= IFF_UNICAST_FLT | IFF_NO_QUEUE;
 731         failover_dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE |
 732                                        IFF_TX_SKB_SHARING);
 733
 734         /* don't acquire failover netdev's netif_tx_lock when transmitting */
 735         failover_dev->features |= NETIF_F_LLTX;
 736
 737         /* Don't allow failover devices to change network namespaces. */
 738         failover_dev->features |= NETIF_F_NETNS_LOCAL;
 739
 740         failover_dev->hw_features = FAILOVER_VLAN_FEATURES |
 741                                     NETIF_F_HW_VLAN_CTAG_TX |
 742                                     NETIF_F_HW_VLAN_CTAG_RX |
 743                                     NETIF_F_HW_VLAN_CTAG_FILTER;
 744
 745         failover_dev->hw_features |= NETIF_F_GSO_ENCAP_ALL;
 746         failover_dev->features |= failover_dev->hw_features;
 747
 748         memcpy(failover_dev->dev_addr, standby_dev->dev_addr,
 749                failover_dev->addr_len);
 750
 751         failover_dev->min_mtu = standby_dev->min_mtu;
 752         failover_dev->max_mtu = standby_dev->max_mtu;
 753
 754         err = register_netdev(failover_dev);
 755         if (err) {
 756                 dev_err(dev, "Unable to register failover_dev!\n");
 757                 goto err_register_netdev;
 758         }
 759
 760         netif_carrier_off(failover_dev);
 761
 762         failover = failover_register(failover_dev, &net_failover_ops);
 763         if (IS_ERR(failover))
 764                 goto err_failover_register;
 765
 766         return failover;
 767
 768 err_failover_register:
 769         unregister_netdev(failover_dev);
 770 err_register_netdev:
 771         free_netdev(failover_dev);
 772
 773         return ERR_PTR(err);
 774 }
 775 EXPORT_SYMBOL_GPL(net_failover_create);
 776
 777 /**
 778  * net_failover_destroy - Destroy a failover instance
 779  *
 780  * @failover: pointer to failover instance
 781  *
 782  * Unregisters any slave netdevs associated with the failover instance by
 783  * calling failover_slave_unregister().
 784  * unregisters the failover instance itself and finally frees the failover
 785  * netdev. Used by paravirtual drivers that use 3-netdev model.
 786  *
 787  */
 788 void net_failover_destroy(struct failover *failover)
 789 {
 790         struct net_failover_info *nfo_info;
 791         struct net_device *failover_dev;
 792         struct net_device *slave_dev;
 793
 794         if (!failover)
 795                 return;
 796
 797         failover_dev = rcu_dereference(failover->failover_dev);
 798         nfo_info = netdev_priv(failover_dev);
 799
 800         netif_device_detach(failover_dev);
 801
 802         rtnl_lock();
 803
 804         slave_dev = rtnl_dereference(nfo_info->primary_dev);
 805         if (slave_dev)
 806                 failover_slave_unregister(slave_dev);
 807
 808         slave_dev = rtnl_dereference(nfo_info->standby_dev);
 809         if (slave_dev)
 810                 failover_slave_unregister(slave_dev);
 811
 812         failover_unregister(failover);
 813
 814         unregister_netdevice(failover_dev);
 815
 816         rtnl_unlock();
 817
 818         free_netdev(failover_dev);
 819 }
 820 EXPORT_SYMBOL_GPL(net_failover_destroy);
 821
 822 static __init int
 823 net_failover_init(void)
 824 {
 825         return 0;
 826 }
 827 module_init(net_failover_init);
 828
 829 static __exit
 830 void net_failover_exit(void)
 831 {
 832 }
 833 module_exit(net_failover_exit);
 834
 835 MODULE_DESCRIPTION("Failover driver for Paravirtual drivers");
 836 MODULE_LICENSE("GPL v2");