text: /*
   * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014 Nicira, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at:
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include <config.h>
  #include "netdev.h"
  
  #include <errno.h>
  #include <inttypes.h>
  #include <netinet/in.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include "coverage.h"
  #include "dpif.h"
  #include "dp-packet.h"
  #include "dynamic-string.h"
  #include "fatal-signal.h"
  #include "hash.h"
  #include "list.h"
  #include "netdev-dpdk.h"
  #include "netdev-provider.h"
  #include "netdev-vport.h"
  #include "openflow/openflow.h"
  #include "packets.h"
  #include "poll-loop.h"
  #include "seq.h"
  #include "shash.h"
  #include "smap.h"
  #include "sset.h"
  #include "svec.h"
  #include "openvswitch/vlog.h"
  
  VLOG_DEFINE_THIS_MODULE(netdev);
  
  COVERAGE_DEFINE(netdev_received);
  COVERAGE_DEFINE(netdev_sent);
  COVERAGE_DEFINE(netdev_add_router);
  COVERAGE_DEFINE(netdev_get_stats);
  
  struct netdev_saved_flags {
      struct netdev *netdev;
      struct ovs_list node;           /* In struct netdev's saved_flags_list. */
      enum netdev_flags saved_flags;
      enum netdev_flags saved_values;
  };
  
  /* Protects 'netdev_shash' and the mutable members of struct netdev. */
  static struct ovs_mutex netdev_mutex = OVS_MUTEX_INITIALIZER;
  
  /* All created network devices. */
  static struct shash netdev_shash OVS_GUARDED_BY(netdev_mutex)
      = SHASH_INITIALIZER(&netdev_shash);
  
  /* Protects 'netdev_classes' against insertions or deletions.
   *
   * This is a recursive mutex to allow recursive acquisition when calling into
   * providers.  For example, netdev_run() calls into provider 'run' functions,
   * which might reasonably want to call one of the netdev functions that takes
   * netdev_class_mutex. */
  static struct ovs_mutex netdev_class_mutex OVS_ACQ_BEFORE(netdev_mutex);
  
  /* Contains 'struct netdev_registered_class'es. */
  static struct hmap netdev_classes OVS_GUARDED_BY(netdev_class_mutex)
      = HMAP_INITIALIZER(&netdev_classes);
  
  struct netdev_registered_class {
      /* In 'netdev_classes', by class->type. */
      struct hmap_node hmap_node OVS_GUARDED_BY(netdev_class_mutex);
      const struct netdev_class *class OVS_GUARDED_BY(netdev_class_mutex);
      /* Number of 'struct netdev's of this class. */
      int ref_cnt OVS_GUARDED_BY(netdev_class_mutex);
  };
  
  /* This is set pretty low because we probably won't learn anything from the
   * additional log messages. */
  static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
  
  static void restore_all_flags(void *aux OVS_UNUSED);
  void update_device_args(struct netdev *, const struct shash *args);
  
  int
  netdev_n_txq(const struct netdev *netdev)
  {
      return netdev->n_txq;
  }
  
  int
  netdev_n_rxq(const struct netdev *netdev)
  {
      return netdev->n_rxq;
  }
  
  bool
  netdev_is_pmd(const struct netdev *netdev)
  {
      return (!strcmp(netdev->netdev_class->type, "dpdk") ||
              !strcmp(netdev->netdev_class->type, "dpdkr"));
  }
  
  static void
  netdev_class_mutex_initialize(void)
      OVS_EXCLUDED(netdev_class_mutex, netdev_mutex)
  {
      static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
  
      if (ovsthread_once_start(&once)) {
          ovs_mutex_init_recursive(&netdev_class_mutex);
          ovsthread_once_done(&once);
      }
  }
  
  static void
  netdev_initialize(void)
      OVS_EXCLUDED(netdev_class_mutex, netdev_mutex)
  {
      static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
  
      if (ovsthread_once_start(&once)) {
          netdev_class_mutex_initialize();
  
          fatal_signal_add_hook(restore_all_flags, NULL, NULL, true);
          netdev_vport_patch_register();
  
  #ifdef __linux__
          netdev_register_provider(&netdev_linux_class);
          netdev_register_provider(&netdev_internal_class);
          netdev_register_provider(&netdev_tap_class);
          netdev_vport_tunnel_register();
  #endif
  #if defined(__FreeBSD__) || defined(__NetBSD__)
          netdev_register_provider(&netdev_tap_class);
          netdev_register_provider(&netdev_bsd_class);
  #endif
  #ifdef _WIN32
          netdev_register_provider(&netdev_windows_class);
          netdev_register_provider(&netdev_internal_class);
          netdev_vport_tunnel_register();
  #endif
          netdev_dpdk_register();
  
          ovsthread_once_done(&once);
      }
  }
  
  /* Performs periodic work needed by all the various kinds of netdevs.
   *
   * If your program opens any netdevs, it must call this function within its
   * main poll loop. */
  void
  netdev_run(void)
      OVS_EXCLUDED(netdev_class_mutex, netdev_mutex)
  {
      struct netdev_registered_class *rc;
  
      netdev_initialize();
      ovs_mutex_lock(&netdev_class_mutex);
      HMAP_FOR_EACH (rc, hmap_node, &netdev_classes) {
          if (rc->class->run) {
              rc->class->run();
          }
      }
      ovs_mutex_unlock(&netdev_class_mutex);
  }
  
  /* Arranges for poll_block() to wake up when netdev_run() needs to be called.
   *
   * If your program opens any netdevs, it must call this function within its
   * main poll loop. */
  void
  netdev_wait(void)
      OVS_EXCLUDED(netdev_class_mutex, netdev_mutex)
  {
      struct netdev_registered_class *rc;
  
      ovs_mutex_lock(&netdev_class_mutex);
      HMAP_FOR_EACH (rc, hmap_node, &netdev_classes) {
          if (rc->class->wait) {
              rc->class->wait();
          }
      }
      ovs_mutex_unlock(&netdev_class_mutex);
  }
  
  static struct netdev_registered_class *
  netdev_lookup_class(const char *type)
      OVS_REQ_RDLOCK(netdev_class_mutex)
  {
      struct netdev_registered_class *rc;
  
      HMAP_FOR_EACH_WITH_HASH (rc, hmap_node, hash_string(type, 0),
                               &netdev_classes) {
          if (!strcmp(type, rc->class->type)) {
              return rc;
          }
      }
      return NULL;
  }
  
  /* Initializes and registers a new netdev provider.  After successful
   * registration, new netdevs of that type can be opened using netdev_open(). */
  int
  netdev_register_provider(const struct netdev_class *new_class)
      OVS_EXCLUDED(netdev_class_mutex, netdev_mutex)
  {
      int error;
  
      netdev_class_mutex_initialize();
      ovs_mutex_lock(&netdev_class_mutex);
      if (netdev_lookup_class(new_class->type)) {
          VLOG_WARN("attempted to register duplicate netdev provider: %s",
                     new_class->type);
          error = EEXIST;
      } else {
          error = new_class->init ? new_class->init() : 0;
          if (!error) {
              struct netdev_registered_class *rc;
  
              rc = xmalloc(sizeof *rc);
              hmap_insert(&netdev_classes, &rc->hmap_node,
                          hash_string(new_class->type, 0));
              rc->class = new_class;
              rc->ref_cnt = 0;
          } else {
              VLOG_ERR("failed to initialize %s network device class: %s",
                       new_class->type, ovs_strerror(error));
          }
      }
      ovs_mutex_unlock(&netdev_class_mutex);
  
      return error;
  }
  
  /* Unregisters a netdev provider.  'type' must have been previously
   * registered and not currently be in use by any netdevs.  After unregistration
   * new netdevs of that type cannot be opened using netdev_open(). */
  int
  netdev_unregister_provider(const char *type)
      OVS_EXCLUDED(netdev_class_mutex, netdev_mutex)
  {
      struct netdev_registered_class *rc;
      int error;
  
      ovs_mutex_lock(&netdev_class_mutex);
      rc = netdev_lookup_class(type);
      if (!rc) {
          VLOG_WARN("attempted to unregister a netdev provider that is not "
                    "registered: %s", type);
          error = EAFNOSUPPORT;
      } else {
          if (!rc->ref_cnt) {
              hmap_remove(&netdev_classes, &rc->hmap_node);
              free(rc);
              error = 0;
          } else {
              VLOG_WARN("attempted to unregister in use netdev provider: %s",
                        type);
              error = EBUSY;
          }
      }
      ovs_mutex_unlock(&netdev_class_mutex);
  
      return error;
  }
  
  /* Clears 'types' and enumerates the types of all currently registered netdev
   * providers into it.  The caller must first initialize the sset. */
  void
  netdev_enumerate_types(struct sset *types)
      OVS_EXCLUDED(netdev_mutex)
  {
      struct netdev_registered_class *rc;
  
      netdev_initialize();
      sset_clear(types);
  
      ovs_mutex_lock(&netdev_class_mutex);
      HMAP_FOR_EACH (rc, hmap_node, &netdev_classes) {
          sset_add(types, rc->class->type);
      }
      ovs_mutex_unlock(&netdev_class_mutex);
  }
  
  /* Check that the network device name is not the same as any of the registered
   * vport providers' dpif_port name (dpif_port is NULL if the vport provider
   * does not define it) or the datapath internal port name (e.g. ovs-system).
   *
   * Returns true if there is a name conflict, false otherwise. */
  bool
  netdev_is_reserved_name(const char *name)
      OVS_EXCLUDED(netdev_mutex)
  {
      struct netdev_registered_class *rc;
  
      netdev_initialize();
  
      ovs_mutex_lock(&netdev_class_mutex);
      HMAP_FOR_EACH (rc, hmap_node, &netdev_classes) {
          const char *dpif_port = netdev_vport_class_get_dpif_port(rc->class);
          if (dpif_port && !strncmp(name, dpif_port, strlen(dpif_port))) {
              ovs_mutex_unlock(&netdev_class_mutex);
              return true;
          }
      }
      ovs_mutex_unlock(&netdev_class_mutex);
  
      if (!strncmp(name, "ovs-", 4)) {
          struct sset types;
          const char *type;
  
          sset_init(&types);
          dp_enumerate_types(&types);
          SSET_FOR_EACH (type, &types) {
              if (!strcmp(name+4, type)) {
                  sset_destroy(&types);
                  return true;
              }
          }
          sset_destroy(&types);
      }
  
      return false;
  }
  
  /* Opens the network device named 'name' (e.g. "eth0") of the specified 'type'
   * (e.g. "system") and returns zero if successful, otherwise a positive errno
   * value.  On success, sets '*netdevp' to the new network device, otherwise to
   * null.
   *
   * Some network devices may need to be configured (with netdev_set_config())
   * before they can be used. */
  int
  netdev_open(const char *name, const char *type, struct netdev **netdevp)
      OVS_EXCLUDED(netdev_mutex)
  {
      struct netdev *netdev;
      int error;
  
      netdev_initialize();
  
      ovs_mutex_lock(&netdev_class_mutex);
      ovs_mutex_lock(&netdev_mutex);
      netdev = shash_find_data(&netdev_shash, name);
      if (!netdev) {
          struct netdev_registered_class *rc;
  
          rc = netdev_lookup_class(type && type[0] ? type : "system");
          if (rc) {
              netdev = rc->class->alloc();
              if (netdev) {
                  memset(netdev, 0, sizeof *netdev);
                  netdev->netdev_class = rc->class;
                  netdev->name = xstrdup(name);
                  netdev->change_seq = 1;
                  netdev->node = shash_add(&netdev_shash, name, netdev);
  
                  /* By default enable one tx and rx queue per netdev. */
                  netdev->n_txq = netdev->netdev_class->send ? 1 : 0;
                  netdev->n_rxq = netdev->netdev_class->rxq_alloc ? 1 : 0;
  
                  list_init(&netdev->saved_flags_list);
  
                  error = rc->class->construct(netdev);
                  if (!error) {
                      rc->ref_cnt++;
                      netdev_change_seq_changed(netdev);
                  } else {
                      free(netdev->name);
                      ovs_assert(list_is_empty(&netdev->saved_flags_list));
                      shash_delete(&netdev_shash, netdev->node);
                      rc->class->dealloc(netdev);
                  }
              } else {
                  error = ENOMEM;
              }
          } else {
              VLOG_WARN("could not create netdev %s of unknown type %s",
                        name, type);
              error = EAFNOSUPPORT;
          }
      } else {
          error = 0;
      }
  
      if (!error) {
          netdev->ref_cnt++;
          *netdevp = netdev;
      } else {
          *netdevp = NULL;
      }
      ovs_mutex_unlock(&netdev_mutex);
      ovs_mutex_unlock(&netdev_class_mutex);
  
      return error;
  }
  
  /* Returns a reference to 'netdev_' for the caller to own. Returns null if
   * 'netdev_' is null. */
  struct netdev *
  netdev_ref(const struct netdev *netdev_)
      OVS_EXCLUDED(netdev_mutex)
  {
      struct netdev *netdev = CONST_CAST(struct netdev *, netdev_);
  
      if (netdev) {
          ovs_mutex_lock(&netdev_mutex);
          ovs_assert(netdev->ref_cnt > 0);
          netdev->ref_cnt++;
          ovs_mutex_unlock(&netdev_mutex);
      }
      return netdev;
  }
  
  /* Reconfigures the device 'netdev' with 'args'.  'args' may be empty
   * or NULL if none are needed. */
  int
  netdev_set_config(struct netdev *netdev, const struct smap *args, char **errp)
      OVS_EXCLUDED(netdev_mutex)
  {
      if (netdev->netdev_class->set_config) {
          const struct smap no_args = SMAP_INITIALIZER(&no_args);
          int error;
  
          error = netdev->netdev_class->set_config(netdev,
                                                   args ? args : &no_args);
          if (error) {
              VLOG_WARN_BUF(errp, "%s: could not set configuration (%s)",
                            netdev_get_name(netdev), ovs_strerror(error));
          }
          return error;
      } else if (args && !smap_is_empty(args)) {
          VLOG_WARN_BUF(errp, "%s: arguments provided to device that is not configurable",
                        netdev_get_name(netdev));
      }
      return 0;
  }
  
  /* Returns the current configuration for 'netdev' in 'args'.  The caller must
   * have already initialized 'args' with smap_init().  Returns 0 on success, in
   * which case 'args' will be filled with 'netdev''s configuration.  On failure
   * returns a positive errno value, in which case 'args' will be empty.
   *
   * The caller owns 'args' and its contents and must eventually free them with
   * smap_destroy(). */
  int
  netdev_get_config(const struct netdev *netdev, struct smap *args)
      OVS_EXCLUDED(netdev_mutex)
  {
      int error;
  
      smap_clear(args);
      if (netdev->netdev_class->get_config) {
          error = netdev->netdev_class->get_config(netdev, args);
          if (error) {
              smap_clear(args);
          }
      } else {
          error = 0;
      }
  
      return error;
  }
  
  const struct netdev_tunnel_config *
  netdev_get_tunnel_config(const struct netdev *netdev)
      OVS_EXCLUDED(netdev_mutex)
  {
      if (netdev->netdev_class->get_tunnel_config) {
          return netdev->netdev_class->get_tunnel_config(netdev);
      } else {
          return NULL;
      }
  }
  
  /* Returns the id of the numa node the 'netdev' is on.  If the function
   * is not implemented, returns NETDEV_NUMA_UNSPEC. */
  int
  netdev_get_numa_id(const struct netdev *netdev)
  {
      if (netdev->netdev_class->get_numa_id) {
          return netdev->netdev_class->get_numa_id(netdev);
      } else {
          return NETDEV_NUMA_UNSPEC;
      }
  }
  
  static void
  netdev_unref(struct netdev *dev)
      OVS_RELEASES(netdev_mutex)
  {
      ovs_assert(dev->ref_cnt);
      if (!--dev->ref_cnt) {
          const struct netdev_class *class = dev->netdev_class;
          struct netdev_registered_class *rc;
  
          dev->netdev_class->destruct(dev);
  
          if (dev->node) {
              shash_delete(&netdev_shash, dev->node);
          }
          free(dev->name);
          dev->netdev_class->dealloc(dev);
          ovs_mutex_unlock(&netdev_mutex);
  
          ovs_mutex_lock(&netdev_class_mutex);
          rc = netdev_lookup_class(class->type);
          ovs_assert(rc->ref_cnt > 0);
          rc->ref_cnt--;
          ovs_mutex_unlock(&netdev_class_mutex);
      } else {
          ovs_mutex_unlock(&netdev_mutex);
      }
  }
  
  /* Closes and destroys 'netdev'. */
  void
  netdev_close(struct netdev *netdev)
      OVS_EXCLUDED(netdev_mutex)
  {
      if (netdev) {
          ovs_mutex_lock(&netdev_mutex);
          netdev_unref(netdev);
      }
  }
  
  /* Removes 'netdev' from the global shash and unrefs 'netdev'.
   *
   * This allows handler and revalidator threads to still retain references
   * to this netdev while the main thread changes interface configuration.
   *
   * This function should only be called by the main thread when closing
   * netdevs during user configuration changes. Otherwise, netdev_close should be
   * used to close netdevs. */
  void
  netdev_remove(struct netdev *netdev)
  {
      if (netdev) {
          ovs_mutex_lock(&netdev_mutex);
          if (netdev->node) {
              shash_delete(&netdev_shash, netdev->node);
              netdev->node = NULL;
              netdev_change_seq_changed(netdev);
          }
          netdev_unref(netdev);
      }
  }
  
  /* Parses 'netdev_name_', which is of the form [type@]name into its component
   * pieces.  'name' and 'type' must be freed by the caller. */
  void
  netdev_parse_name(const char *netdev_name_, char **name, char **type)
  {
      char *netdev_name = xstrdup(netdev_name_);
      char *separator;
  
      separator = strchr(netdev_name, '@');
      if (separator) {
          *separator = '\0';
          *type = netdev_name;
          *name = xstrdup(separator + 1);
      } else {
          *name = netdev_name;
          *type = xstrdup("system");
      }
  }
  
  /* Attempts to open a netdev_rxq handle for obtaining packets received on
   * 'netdev'.  On success, returns 0 and stores a nonnull 'netdev_rxq *' into
   * '*rxp'.  On failure, returns a positive errno value and stores NULL into
   * '*rxp'.
   *
   * Some kinds of network devices might not support receiving packets.  This
   * function returns EOPNOTSUPP in that case.*/
  int
  netdev_rxq_open(struct netdev *netdev, struct netdev_rxq **rxp, int id)
      OVS_EXCLUDED(netdev_mutex)
  {
      int error;
  
      if (netdev->netdev_class->rxq_alloc && id < netdev->n_rxq) {
          struct netdev_rxq *rx = netdev->netdev_class->rxq_alloc();
          if (rx) {
              rx->netdev = netdev;
              rx->queue_id = id;
              error = netdev->netdev_class->rxq_construct(rx);
              if (!error) {
                  netdev_ref(netdev);
                  *rxp = rx;
                  return 0;
              }
              netdev->netdev_class->rxq_dealloc(rx);
          } else {
              error = ENOMEM;
          }
      } else {
          error = EOPNOTSUPP;
      }
  
      *rxp = NULL;
      return error;
  }
  
  /* Closes 'rx'. */
  void
  netdev_rxq_close(struct netdev_rxq *rx)
      OVS_EXCLUDED(netdev_mutex)
  {
      if (rx) {
          struct netdev *netdev = rx->netdev;
          netdev->netdev_class->rxq_destruct(rx);
          netdev->netdev_class->rxq_dealloc(rx);
          netdev_close(netdev);
      }
  }
  
  /* Attempts to receive batch of packets from 'rx'.
   *
   * Returns EAGAIN immediately if no packet is ready to be received.
   *
   * Returns EMSGSIZE, and discards the packet, if the received packet is longer
   * than 'dp_packet_tailroom(buffer)'.
   *
   * It is advised that the tailroom of 'buffer' should be
   * VLAN_HEADER_LEN bytes longer than the MTU to allow space for an
   * out-of-band VLAN header to be added to the packet.  At the very least,
   * 'buffer' must have at least ETH_TOTAL_MIN bytes of tailroom.
   *
   * This function may be set to null if it would always return EOPNOTSUPP
   * anyhow. */
  int
  netdev_rxq_recv(struct netdev_rxq *rx, struct dp_packet **buffers, int *cnt)
  {
      int retval;
  
      retval = rx->netdev->netdev_class->rxq_recv(rx, buffers, cnt);
      if (!retval) {
          COVERAGE_INC(netdev_received);
      }
      return retval;
  }
  
  /* Arranges for poll_block() to wake up when a packet is ready to be received
   * on 'rx'. */
  void
  netdev_rxq_wait(struct netdev_rxq *rx)
  {
      rx->netdev->netdev_class->rxq_wait(rx);
  }
  
  /* Discards any packets ready to be received on 'rx'. */
  int
  netdev_rxq_drain(struct netdev_rxq *rx)
  {
      return (rx->netdev->netdev_class->rxq_drain
              ? rx->netdev->netdev_class->rxq_drain(rx)
              : 0);
  }
  
  /* Configures the number of tx queues and rx queues of 'netdev'.
   * Return 0 if successful, otherwise a positive errno value.
   *
   * On error, the tx queue and rx queue configuration is indeterminant.
   * Caller should make decision on whether to restore the previous or
   * the default configuration.  Also, caller must make sure there is no
   * other thread accessing the queues at the same time. */
  int
  netdev_set_multiq(struct netdev *netdev, unsigned int n_txq,
                    unsigned int n_rxq)
  {
      int error;
  
      error = (netdev->netdev_class->set_multiq
               ? netdev->netdev_class->set_multiq(netdev,
                                                  MAX(n_txq, 1),
                                                  MAX(n_rxq, 1))
               : EOPNOTSUPP);
  
      if (error && error != EOPNOTSUPP) {
          VLOG_DBG_RL(&rl, "failed to set tx/rx queue for network device %s:"
                      "%s", netdev_get_name(netdev), ovs_strerror(error));
      }
  
      return error;
  }
  
  /* Sends 'buffers' on 'netdev'.  Returns 0 if successful (for every packet),
   * otherwise a positive errno value.  Returns EAGAIN without blocking if
   * at least one the packets cannot be queued immediately.  Returns EMSGSIZE
   * if a partial packet was transmitted or if a packet is too big or too small
   * to transmit on the device.
   *
   * If the function returns a non-zero value, some of the packets might have
   * been sent anyway.
   *
   * To retain ownership of 'buffer' caller can set may_steal to false.
   *
   * The network device is expected to maintain one or more packet
   * transmission queues, so that the caller does not ordinarily have to
   * do additional queuing of packets.  'qid' specifies the queue to use
   * and can be ignored if the implementation does not support multiple
   * queues.
   *
   * Some network devices may not implement support for this function.  In such
   * cases this function will always return EOPNOTSUPP. */
  int
  netdev_send(struct netdev *netdev, int qid, struct dp_packet **buffers,
              int cnt, bool may_steal)
  {
      int error;
  
      error = (netdev->netdev_class->send
               ? netdev->netdev_class->send(netdev, qid, buffers, cnt, may_steal)
               : EOPNOTSUPP);
      if (!error) {
          COVERAGE_INC(netdev_sent);
      }
      return error;
  }
  
  int
  netdev_pop_header(struct netdev *netdev, struct dp_packet **buffers, int cnt)
  {
      return (netdev->netdev_class->pop_header
               ? netdev->netdev_class->pop_header(netdev, buffers, cnt)
               : EOPNOTSUPP);
  }
  
  int
  netdev_build_header(const struct netdev *netdev, struct ovs_action_push_tnl *data)
  {
      if (netdev->netdev_class->build_header) {
          return netdev->netdev_class->build_header(netdev, data);
      }
      return EOPNOTSUPP;
  }
  
  int
  netdev_push_header(const struct netdev *netdev,
                     struct dp_packet **buffers, int cnt,
                     const struct ovs_action_push_tnl *data)
  {
      if (netdev->netdev_class->push_header) {
          return netdev->netdev_class->push_header(netdev, buffers, cnt, data);
      } else {
          return -EINVAL;
      }
  }
  
  /* Registers with the poll loop to wake up from the next call to poll_block()
   * when the packet transmission queue has sufficient room to transmit a packet
   * with netdev_send().
   *
   * The network device is expected to maintain one or more packet
   * transmission queues, so that the caller does not ordinarily have to
   * do additional queuing of packets.  'qid' specifies the queue to use
   * and can be ignored if the implementation does not support multiple
   * queues. */
  void
  netdev_send_wait(struct netdev *netdev, int qid)
  {
      if (netdev->netdev_class->send_wait) {
          netdev->netdev_class->send_wait(netdev, qid);
      }
  }
  
  /* Attempts to set 'netdev''s MAC address to 'mac'.  Returns 0 if successful,
   * otherwise a positive errno value. */
  int
  netdev_set_etheraddr(struct netdev *netdev, const uint8_t mac[ETH_ADDR_LEN])
  {
      return netdev->netdev_class->set_etheraddr(netdev, mac);
  }
  
  /* Retrieves 'netdev''s MAC address.  If successful, returns 0 and copies the
   * the MAC address into 'mac'.  On failure, returns a positive errno value and
   * clears 'mac' to all-zeros. */
  int
  netdev_get_etheraddr(const struct netdev *netdev, uint8_t mac[ETH_ADDR_LEN])
  {
      return netdev->netdev_class->get_etheraddr(netdev, mac);
  }
  
  /* Returns the name of the network device that 'netdev' represents,
   * e.g. "eth0".  The caller must not modify or free the returned string. */
  const char *
  netdev_get_name(const struct netdev *netdev)
  {
      return netdev->name;
  }
  
  /* Retrieves the MTU of 'netdev'.  The MTU is the maximum size of transmitted
   * (and received) packets, in bytes, not including the hardware header; thus,
   * this is typically 1500 bytes for Ethernet devices.
   *
   * If successful, returns 0 and stores the MTU size in '*mtup'.  Returns
   * EOPNOTSUPP if 'netdev' does not have an MTU (as e.g. some tunnels do not).
   * On other failure, returns a positive errno value.  On failure, sets '*mtup'
   * to 0. */
  int
  netdev_get_mtu(const struct netdev *netdev, int *mtup)
  {
      const struct netdev_class *class = netdev->netdev_class;
      int error;
  
      error = class->get_mtu ? class->get_mtu(netdev, mtup) : EOPNOTSUPP;
      if (error) {
          *mtup = 0;
          if (error != EOPNOTSUPP) {
              VLOG_DBG_RL(&rl, "failed to retrieve MTU for network device %s: "
                           "%s", netdev_get_name(netdev), ovs_strerror(error));
          }
      }
      return error;
  }
  
  /* Sets the MTU of 'netdev'.  The MTU is the maximum size of transmitted
   * (and received) packets, in bytes.
   *
   * If successful, returns 0.  Returns EOPNOTSUPP if 'netdev' does not have an
   * MTU (as e.g. some tunnels do not).  On other failure, returns a positive
   * errno value. */
  int
  netdev_set_mtu(const struct netdev *netdev, int mtu)
  {
      const struct netdev_class *class = netdev->netdev_class;
      int error;
  
      error = class->set_mtu ? class->set_mtu(netdev, mtu) : EOPNOTSUPP;
      if (error && error != EOPNOTSUPP) {
          VLOG_DBG_RL(&rl, "failed to set MTU for network device %s: %s",
                       netdev_get_name(netdev), ovs_strerror(error));
      }
  
      return error;
  }
  
  /* Returns the ifindex of 'netdev', if successful, as a positive number.  On
   * failure, returns a negative errno value.
   *
   * The desired semantics of the ifindex value are a combination of those
   * specified by POSIX for if_nametoindex() and by SNMP for ifIndex.  An ifindex
   * value should be unique within a host and remain stable at least until
   * reboot.  SNMP says an ifindex "ranges between 1 and the value of ifNumber"
   * but many systems do not follow this rule anyhow.
   *
   * Some network devices may not implement support for this function.  In such
   * cases this function will always return -EOPNOTSUPP.
   */
  int
  netdev_get_ifindex(const struct netdev *netdev)
  {
      int (*get_ifindex)(const struct netdev *);
  
      get_ifindex = netdev->netdev_class->get_ifindex;
  
      return get_ifindex ? get_ifindex(netdev) : -EOPNOTSUPP;
  }
  
  /* Stores the features supported by 'netdev' into each of '*current',
   * '*advertised', '*supported', and '*peer' that are non-null.  Each value is a
   * bitmap of "enum ofp_port_features" bits, in host byte order.  Returns 0 if
   * successful, otherwise a positive errno value.  On failure, all of the
   * passed-in values are set to 0.
   *
   * Some network devices may not implement support for this function.  In such
   * cases this function will always return EOPNOTSUPP. */
  int
  netdev_get_features(const struct netdev *netdev,
                      enum netdev_features *current,
                      enum netdev_features *advertised,
                      enum netdev_features *supported,
                      enum netdev_features *peer)
  {
      int (*get_features)(const struct netdev *netdev,
                          enum netdev_features *current,
                          enum netdev_features *advertised,
                          enum netdev_features *supported,
                          enum netdev_features *peer);
      enum netdev_features dummy[4];
      int error;
  
      if (!current) {
          current = &dummy[0];
      }
      if (!advertised) {
          advertised = &dummy[1];
      }
      if (!supported) {
          supported = &dummy[2];
      }
      if (!peer) {
          peer = &dummy[3];
      }
  
      get_features = netdev->netdev_class->get_features;
      error = get_features
                      ? get_features(netdev, current, advertised, supported,
                                     peer)
                      : EOPNOTSUPP;
      if (error) {
          *current = *advertised = *supported = *peer = 0;
      }
      return error;
  }
  
  /* Returns the maximum speed of a network connection that has the NETDEV_F_*
   * bits in 'features', in bits per second.  If no bits that indicate a speed
   * are set in 'features', returns 'default_bps'. */
  uint64_t
  netdev_features_to_bps(enum netdev_features features,
                         uint64_t default_bps)
  {
      enum {
          F_1000000MB = NETDEV_F_1TB_FD,
          F_100000MB = NETDEV_F_100GB_FD,
          F_40000MB = NETDEV_F_40GB_FD,
          F_10000MB = NETDEV_F_10GB_FD,
          F_1000MB = NETDEV_F_1GB_HD | NETDEV_F_1GB_FD,
          F_100MB = NETDEV_F_100MB_HD | NETDEV_F_100MB_FD,
          F_10MB = NETDEV_F_10MB_HD | NETDEV_F_10MB_FD
      };
  
      return (  features & F_1000000MB ? UINT64_C(1000000000000)
              : features & F_100000MB  ? UINT64_C(100000000000)
              : features & F_40000MB   ? UINT64_C(40000000000)
              : features & F_10000MB   ? UINT64_C(10000000000)
              : features & F_1000MB    ? UINT64_C(1000000000)
              : features & F_100MB     ? UINT64_C(100000000)
              : features & F_10MB      ? UINT64_C(10000000)
                                       : default_bps);
  }
  
  /* Returns true if any of the NETDEV_F_* bits that indicate a full-duplex link
   * are set in 'features', otherwise false. */
  bool
  netdev_features_is_full_duplex(enum netdev_features features)
  {
      return (features & (NETDEV_F_10MB_FD | NETDEV_F_100MB_FD | NETDEV_F_1GB_FD
                          | NETDEV_F_10GB_FD | NETDEV_F_40GB_FD
                          | NETDEV_F_100GB_FD | NETDEV_F_1TB_FD)) != 0;
  }
  
  /* Set the features advertised by 'netdev' to 'advertise'.  Returns 0 if
   * successful, otherwise a positive errno value. */
  int
  netdev_set_advertisements(struct netdev *netdev,
                            enum netdev_features advertise)
  {
      return (netdev->netdev_class->set_advertisements
              ? netdev->netdev_class->set_advertisements(
                      netdev, advertise)
              : EOPNOTSUPP);
  }
  
  /* If 'netdev' has an assigned IPv4 address, sets '*address' to that address
   * and '*netmask' to its netmask and returns 0.  Otherwise, returns a positive
   * errno value and sets '*address' to 0 (INADDR_ANY).
   *
   * The following error values have well-defined meanings:
   *
   *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
   *
   *   - EOPNOTSUPP: No IPv4 network stack attached to 'netdev'.
   *
   * 'address' or 'netmask' or both may be null, in which case the address or
   * netmask is not reported. */
  int
  netdev_get_in4(const struct netdev *netdev,
                 struct in_addr *address_, struct in_addr *netmask_)
  {
      struct in_addr address;
      struct in_addr netmask;
      int error;
  
      error = (netdev->netdev_class->get_in4
               ? netdev->netdev_class->get_in4(netdev,
                      &address, &netmask)
               : EOPNOTSUPP);
      if (address_) {
          address_->s_addr = error ? 0 : address.s_addr;
      }
      if (netmask_) {
          netmask_->s_addr = error ? 0 : netmask.s_addr;
      }
      return error;
  }
  
  /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask.  If
   * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.  Returns a
   * positive errno value. */
  int
  netdev_set_in4(struct netdev *netdev, struct in_addr addr, struct in_addr mask)
  {
      return (netdev->netdev_class->set_in4
              ? netdev->netdev_class->set_in4(netdev, addr, mask)
              : EOPNOTSUPP);
  }
  
  /* Obtains ad IPv4 address from device name and save the address in
   * in4.  Returns 0 if successful, otherwise a positive errno value.
   */
  int
  netdev_get_in4_by_name(const char *device_name, struct in_addr *in4)
  {
      struct netdev *netdev;
      int error;
  
      error = netdev_open(device_name, "system", &netdev);
      if (error) {
          in4->s_addr = htonl(0);
          return error;
      }
  
      error = netdev_get_in4(netdev, in4, NULL);
      netdev_close(netdev);
      return error;
  }
  
  /* Adds 'router' as a default IP gateway for the TCP/IP stack that corresponds
   * to 'netdev'. */
  int
  netdev_add_router(struct netdev *netdev, struct in_addr router)
  {
      COVERAGE_INC(netdev_add_router);
      return (netdev->netdev_class->add_router
              ? netdev->netdev_class->add_router(netdev, router)
              : EOPNOTSUPP);
  }
  
  /* Looks up the next hop for 'host' for the TCP/IP stack that corresponds to
   * 'netdev'.  If a route cannot not be determined, sets '*next_hop' to 0,
   * '*netdev_name' to null, and returns a positive errno value.  Otherwise, if a
   * next hop is found, stores the next hop gateway's address (0 if 'host' is on
   * a directly connected network) in '*next_hop' and a copy of the name of the
   * device to reach 'host' in '*netdev_name', and returns 0.  The caller is
   * responsible for freeing '*netdev_name' (by calling free()). */
  int
  netdev_get_next_hop(const struct netdev *netdev,
                      const struct in_addr *host, struct in_addr *next_hop,
                      char **netdev_name)
  {
      int error = (netdev->netdev_class->get_next_hop
                   ? netdev->netdev_class->get_next_hop(
                          host, next_hop, netdev_name)
                   : EOPNOTSUPP);
      if (error) {
          next_hop->s_addr = 0;
          *netdev_name = NULL;
      }
      return error;
  }
  
  /* Populates 'smap' with status information.
   *
   * Populates 'smap' with 'netdev' specific status information.  This
   * information may be used to populate the status column of the Interface table
   * as defined in ovs-vswitchd.conf.db(5). */
  int
  netdev_get_status(const struct netdev *netdev, struct smap *smap)
  {
      return (netdev->netdev_class->get_status
              ? netdev->netdev_class->get_status(netdev, smap)
              : EOPNOTSUPP);
  }
  
  /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address and
   * returns 0.  Otherwise, returns a positive errno value and sets '*in6' to
   * all-zero-bits (in6addr_any).
   *
   * The following error values have well-defined meanings:
   *
   *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
   *
   *   - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
   *
   * 'in6' may be null, in which case the address itself is not reported. */
  int
  netdev_get_in6(const struct netdev *netdev, struct in6_addr *in6)
  {
      struct in6_addr dummy;
      int error;
  
      error = (netdev->netdev_class->get_in6
               ? netdev->netdev_class->get_in6(netdev,
                      in6 ? in6 : &dummy)
               : EOPNOTSUPP);
      if (error && in6) {
          memset(in6, 0, sizeof *in6);
      }
      return error;
  }
  
  /* On 'netdev', turns off the flags in 'off' and then turns on the flags in
   * 'on'.  Returns 0 if successful, otherwise a positive errno value. */
  static int
  do_update_flags(struct netdev *netdev, enum netdev_flags off,
                  enum netdev_flags on, enum netdev_flags *old_flagsp,
                  struct netdev_saved_flags **sfp)
      OVS_EXCLUDED(netdev_mutex)
  {
      struct netdev_saved_flags *sf = NULL;
      enum netdev_flags old_flags;
      int error;
  
      error = netdev->netdev_class->update_flags(netdev, off & ~on, on,
                                                 &old_flags);
      if (error) {
          VLOG_WARN_RL(&rl, "failed to %s flags for network device %s: %s",
                       off || on ? "set" : "get", netdev_get_name(netdev),
                       ovs_strerror(error));
          old_flags = 0;
      } else if ((off || on) && sfp) {
          enum netdev_flags new_flags = (old_flags & ~off) | on;
          enum netdev_flags changed_flags = old_flags ^ new_flags;
          if (changed_flags) {
              ovs_mutex_lock(&netdev_mutex);
              *sfp = sf = xmalloc(sizeof *sf);
              sf->netdev = netdev;
              list_push_front(&netdev->saved_flags_list, &sf->node);
              sf->saved_flags = changed_flags;
              sf->saved_values = changed_flags & new_flags;
  
              netdev->ref_cnt++;
              ovs_mutex_unlock(&netdev_mutex);
          }
      }
  
      if (old_flagsp) {
          *old_flagsp = old_flags;
      }
      if (sfp) {
          *sfp = sf;
      }
  
      return error;
  }
  
  /* Obtains the current flags for 'netdev' and stores them into '*flagsp'.
   * Returns 0 if successful, otherwise a positive errno value.  On failure,
   * stores 0 into '*flagsp'. */
  int
  netdev_get_flags(const struct netdev *netdev_, enum netdev_flags *flagsp)
  {
      struct netdev *netdev = CONST_CAST(struct netdev *, netdev_);
      return do_update_flags(netdev, 0, 0, flagsp, NULL);
  }
  
  /* Sets the flags for 'netdev' to 'flags'.
   * Returns 0 if successful, otherwise a positive errno value. */
  int
  netdev_set_flags(struct netdev *netdev, enum netdev_flags flags,
                   struct netdev_saved_flags **sfp)
  {
      return do_update_flags(netdev, -1, flags, NULL, sfp);
  }
  
  /* Turns on the specified 'flags' on 'netdev':
   *
   *    - On success, returns 0.  If 'sfp' is nonnull, sets '*sfp' to a newly
   *      allocated 'struct netdev_saved_flags *' that may be passed to
   *      netdev_restore_flags() to restore the original values of 'flags' on
   *      'netdev' (this will happen automatically at program termination if
   *      netdev_restore_flags() is never called) , or to NULL if no flags were
   *      actually changed.
   *
   *    - On failure, returns a positive errno value.  If 'sfp' is nonnull, sets
   *      '*sfp' to NULL. */
  int
  netdev_turn_flags_on(struct netdev *netdev, enum netdev_flags flags,
                       struct netdev_saved_flags **sfp)
  {
      return do_update_flags(netdev, 0, flags, NULL, sfp);
  }
  
  /* Turns off the specified 'flags' on 'netdev'.  See netdev_turn_flags_on() for
   * details of the interface. */
  int
  netdev_turn_flags_off(struct netdev *netdev, enum netdev_flags flags,
                        struct netdev_saved_flags **sfp)
  {
      return do_update_flags(netdev, flags, 0, NULL, sfp);
  }
  
  /* Restores the flags that were saved in 'sf', and destroys 'sf'.
   * Does nothing if 'sf' is NULL. */
  void
  netdev_restore_flags(struct netdev_saved_flags *sf)
      OVS_EXCLUDED(netdev_mutex)
  {
      if (sf) {
          struct netdev *netdev = sf->netdev;
          enum netdev_flags old_flags;
  
          netdev->netdev_class->update_flags(netdev,
                                             sf->saved_flags & sf->saved_values,
                                             sf->saved_flags & ~sf->saved_values,
                                             &old_flags);
  
          ovs_mutex_lock(&netdev_mutex);
          list_remove(&sf->node);
          free(sf);
          netdev_unref(netdev);
      }
  }
  
  /* Looks up the ARP table entry for 'ip' on 'netdev'.  If one exists and can be
   * successfully retrieved, it stores the corresponding MAC address in 'mac' and
   * returns 0.  Otherwise, it returns a positive errno value; in particular,
   * ENXIO indicates that there is no ARP table entry for 'ip' on 'netdev'. */
  int
  netdev_arp_lookup(const struct netdev *netdev,
                    ovs_be32 ip, uint8_t mac[ETH_ADDR_LEN])
  {
      int error = (netdev->netdev_class->arp_lookup
                   ? netdev->netdev_class->arp_lookup(netdev, ip, mac)
                   : EOPNOTSUPP);
      if (error) {
          memset(mac, 0, ETH_ADDR_LEN);
      }
      return error;
  }
  
  /* Returns true if carrier is active (link light is on) on 'netdev'. */
  bool
  netdev_get_carrier(const struct netdev *netdev)
  {
      int error;
      enum netdev_flags flags;
      bool carrier;
  
      netdev_get_flags(netdev, &flags);
      if (!(flags & NETDEV_UP)) {
          return false;
      }
  
      if (!netdev->netdev_class->get_carrier) {
          return true;
      }
  
      error = netdev->netdev_class->get_carrier(netdev, &carrier);
      if (error) {
          VLOG_DBG("%s: failed to get network device carrier status, assuming "
                   "down: %s", netdev_get_name(netdev), ovs_strerror(error));
          carrier = false;
      }
  
      return carrier;
  }
  
  /* Returns the number of times 'netdev''s carrier has changed. */
  long long int
  netdev_get_carrier_resets(const struct netdev *netdev)
  {
      return (netdev->netdev_class->get_carrier_resets
              ? netdev->netdev_class->get_carrier_resets(netdev)
              : 0);
  }
  
  /* Attempts to force netdev_get_carrier() to poll 'netdev''s MII registers for
   * link status instead of checking 'netdev''s carrier.  'netdev''s MII
   * registers will be polled once ever 'interval' milliseconds.  If 'netdev'
   * does not support MII, another method may be used as a fallback.  If
   * 'interval' is less than or equal to zero, reverts netdev_get_carrier() to
   * its normal behavior.
   *
   * Returns 0 if successful, otherwise a positive errno value. */
  int
  netdev_set_miimon_interval(struct netdev *netdev, long long int interval)
  {
      return (netdev->netdev_class->set_miimon_interval
              ? netdev->netdev_class->set_miimon_interval(netdev, interval)
              : EOPNOTSUPP);
  }
  
  /* Retrieves current device stats for 'netdev'. */
  int
  netdev_get_stats(const struct netdev *netdev, struct netdev_stats *stats)
  {
      int error;
  
      COVERAGE_INC(netdev_get_stats);
      error = (netdev->netdev_class->get_stats
               ? netdev->netdev_class->get_stats(netdev, stats)
               : EOPNOTSUPP);
      if (error) {
          memset(stats, 0xff, sizeof *stats);
      }
      return error;
  }
  
  /* Attempts to set input rate limiting (policing) policy, such that up to
   * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative burst
   * size of 'kbits' kb. */
  int
  netdev_set_policing(struct netdev *netdev, uint32_t kbits_rate,
                      uint32_t kbits_burst)
  {
      return (netdev->netdev_class->set_policing
              ? netdev->netdev_class->set_policing(netdev,
                      kbits_rate, kbits_burst)
              : EOPNOTSUPP);
  }
  
  /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves it
   * empty if 'netdev' does not support QoS.  Any names added to 'types' should
   * be documented as valid for the "type" column in the "QoS" table in
   * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
   *
   * Every network device supports disabling QoS with a type of "", but this type
   * will not be added to 'types'.
   *
   * The caller must initialize 'types' (e.g. with sset_init()) before calling
   * this function.  The caller is responsible for destroying 'types' (e.g. with
   * sset_destroy()) when it is no longer needed.
   *
   * Returns 0 if successful, otherwise a positive errno value. */
  int
  netdev_get_qos_types(const struct netdev *netdev, struct sset *types)
  {
      const struct netdev_class *class = netdev->netdev_class;
      return (class->get_qos_types
              ? class->get_qos_types(netdev, types)
              : 0);
  }
  
  /* Queries 'netdev' for its capabilities regarding the specified 'type' of QoS,
   * which should be "" or one of the types returned by netdev_get_qos_types()
   * for 'netdev'.  Returns 0 if successful, otherwise a positive errno value.
   * On success, initializes 'caps' with the QoS capabilities; on failure, clears
   * 'caps' to all zeros. */
  int
  netdev_get_qos_capabilities(const struct netdev *netdev, const char *type,
                              struct netdev_qos_capabilities *caps)
  {
      const struct netdev_class *class = netdev->netdev_class;
  
      if (*type) {
          int retval = (class->get_qos_capabilities
                        ? class->get_qos_capabilities(netdev, type, caps)
                        : EOPNOTSUPP);
          if (retval) {
              memset(caps, 0, sizeof *caps);
          }
          return retval;
      } else {
          /* Every netdev supports turning off QoS. */
          memset(caps, 0, sizeof *caps);
          return 0;
      }
  }
  
  /* Obtains the number of queues supported by 'netdev' for the specified 'type'
   * of QoS.  Returns 0 if successful, otherwise a positive errno value.  Stores
   * the number of queues (zero on failure) in '*n_queuesp'.
   *
   * This is just a simple wrapper around netdev_get_qos_capabilities(). */
  int
  netdev_get_n_queues(const struct netdev *netdev,
                      const char *type, unsigned int *n_queuesp)
  {
      struct netdev_qos_capabilities caps;
      int retval;
  
      retval = netdev_get_qos_capabilities(netdev, type, &caps);
      *n_queuesp = caps.n_queues;
      return retval;
  }
  
  /* Queries 'netdev' about its currently configured form of QoS.  If successful,
   * stores the name of the current form of QoS into '*typep', stores any details
   * of configuration as string key-value pairs in 'details', and returns 0.  On
   * failure, sets '*typep' to NULL and returns a positive errno value.
   *
   * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
   *
   * The caller must initialize 'details' as an empty smap (e.g. with
   * smap_init()) before calling this function.  The caller must free 'details'
   * when it is no longer needed (e.g. with smap_destroy()).
   *
   * The caller must not modify or free '*typep'.
   *
   * '*typep' will be one of the types returned by netdev_get_qos_types() for
   * 'netdev'.  The contents of 'details' should be documented as valid for
   * '*typep' in the "other_config" column in the "QoS" table in
   * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)). */
  int
  netdev_get_qos(const struct netdev *netdev,
                 const char **typep, struct smap *details)
  {
      const struct netdev_class *class = netdev->netdev_class;
      int retval;
  
      if (class->get_qos) {
          retval = class->get_qos(netdev, typep, details);
          if (retval) {
              *typep = NULL;
              smap_clear(details);
          }
          return retval;
      } else {
          /* 'netdev' doesn't support QoS, so report that QoS is disabled. */
          *typep = "";
          return 0;
      }
  }
  
  /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to 'type'
   * with details of configuration from 'details'.  Returns 0 if successful,
   * otherwise a positive errno value.  On error, the previous QoS configuration
   * is retained.
   *
   * When this function changes the type of QoS (not just 'details'), this also
   * resets all queue configuration for 'netdev' to their defaults (which depend
   * on the specific type of QoS).  Otherwise, the queue configuration for
   * 'netdev' is unchanged.
   *
   * 'type' should be "" (to disable QoS) or one of the types returned by
   * netdev_get_qos_types() for 'netdev'.  The contents of 'details' should be
   * documented as valid for the given 'type' in the "other_config" column in the
   * "QoS" table in vswitchd/vswitch.xml (which is built as
   * ovs-vswitchd.conf.db(8)).
   *
   * NULL may be specified for 'details' if there are no configuration
   * details. */
  int
  netdev_set_qos(struct netdev *netdev,
                 const char *type, const struct smap *details)
  {
      const struct netdev_class *class = netdev->netdev_class;
  
      if (!type) {
          type = "";
      }
  
      if (class->set_qos) {
          if (!details) {
              static const struct smap empty = SMAP_INITIALIZER(&empty);
              details = &empty;
          }
          return class->set_qos(netdev, type, details);
      } else {
          return *type ? EOPNOTSUPP : 0;
      }
  }
  
  /* Queries 'netdev' for information about the queue numbered 'queue_id'.  If
   * successful, adds that information as string key-value pairs to 'details'.
   * Returns 0 if successful, otherwise a positive errno value.
   *
   * 'queue_id' must be less than the number of queues supported by 'netdev' for
   * the current form of QoS (e.g. as returned by netdev_get_n_queues(netdev)).
   *
   * The returned contents of 'details' should be documented as valid for the
   * given 'type' in the "other_config" column in the "Queue" table in
   * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
   *
   * The caller must initialize 'details' (e.g. with smap_init()) before calling
   * this function.  The caller must free 'details' when it is no longer needed
   * (e.g. with smap_destroy()). */
  int
  netdev_get_queue(const struct netdev *netdev,
                   unsigned int queue_id, struct smap *details)
  {
      const struct netdev_class *class = netdev->netdev_class;
      int retval;
  
      retval = (class->get_queue
                ? class->get_queue(netdev, queue_id, details)
                : EOPNOTSUPP);
      if (retval) {
          smap_clear(details);
      }
      return retval;
  }
  
  /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
   * string pairs in 'details'.  The contents of 'details' should be documented
   * as valid for the given 'type' in the "other_config" column in the "Queue"
   * table in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
   * Returns 0 if successful, otherwise a positive errno value.  On failure, the
   * given queue's configuration should be unmodified.
   *
   * 'queue_id' must be less than the number of queues supported by 'netdev' for
   * the current form of QoS (e.g. as returned by netdev_get_n_queues(netdev)).
   *
   * This function does not modify 'details', and the caller retains ownership of
   * it. */
  int
  netdev_set_queue(struct netdev *netdev,
                   unsigned int queue_id, const struct smap *details)
  {
      const struct netdev_class *class = netdev->netdev_class;
      return (class->set_queue
              ? class->set_queue(netdev, queue_id, details)
              : EOPNOTSUPP);
  }
  
  /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.  Some kinds
   * of QoS may have a fixed set of queues, in which case attempts to delete them
   * will fail with EOPNOTSUPP.
   *
   * Returns 0 if successful, otherwise a positive errno value.  On failure, the
   * given queue will be unmodified.
   *
   * 'queue_id' must be less than the number of queues supported by 'netdev' for
   * the current form of QoS (e.g. as returned by
   * netdev_get_n_queues(netdev)). */
  int
  netdev_delete_queue(struct netdev *netdev, unsigned int queue_id)
  {
      const struct netdev_class *class = netdev->netdev_class;
      return (class->delete_queue
              ? class->delete_queue(netdev, queue_id)
              : EOPNOTSUPP);
  }
  
  /* Obtains statistics about 'queue_id' on 'netdev'.  On success, returns 0 and
   * fills 'stats' with the queue's statistics; individual members of 'stats' may
   * be set to all-1-bits if the statistic is unavailable.  On failure, returns a
   * positive errno value and fills 'stats' with values indicating unsupported
   * statistics. */
  int
  netdev_get_queue_stats(const struct netdev *netdev, unsigned int queue_id,
                         struct netdev_queue_stats *stats)
  {
      const struct netdev_class *class = netdev->netdev_class;
      int retval;
  
      retval = (class->get_queue_stats
                ? class->get_queue_stats(netdev, queue_id, stats)
                : EOPNOTSUPP);
      if (retval) {
          stats->tx_bytes = UINT64_MAX;
          stats->tx_packets = UINT64_MAX;
          stats->tx_errors = UINT64_MAX;
          stats->created = LLONG_MIN;
      }
      return retval;
  }
  
  /* Initializes 'dump' to begin dumping the queues in a netdev.
   *
   * This function provides no status indication.  An error status for the entire
   * dump operation is provided when it is completed by calling
   * netdev_queue_dump_done().
   */
  void
  netdev_queue_dump_start(struct netdev_queue_dump *dump,
                          const struct netdev *netdev)
  {
      dump->netdev = netdev_ref(netdev);
      if (netdev->netdev_class->queue_dump_start) {
          dump->error = netdev->netdev_class->queue_dump_start(netdev,
                                                               &dump->state);
      } else {
          dump->error = EOPNOTSUPP;
      }
  }
  
  /* Attempts to retrieve another queue from 'dump', which must have been
   * initialized with netdev_queue_dump_start().  On success, stores a new queue
   * ID into '*queue_id', fills 'details' with configuration details for the
   * queue, and returns true.  On failure, returns false.
   *
   * Queues are not necessarily dumped in increasing order of queue ID (or any
   * other predictable order).
   *
   * Failure might indicate an actual error or merely that the last queue has
   * been dumped.  An error status for the entire dump operation is provided when
   * it is completed by calling netdev_queue_dump_done().
   *
   * The returned contents of 'details' should be documented as valid for the
   * given 'type' in the "other_config" column in the "Queue" table in
   * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
   *
   * The caller must initialize 'details' (e.g. with smap_init()) before calling
   * this function.  This function will clear and replace its contents.  The
   * caller must free 'details' when it is no longer needed (e.g. with
   * smap_destroy()). */
  bool
  netdev_queue_dump_next(struct netdev_queue_dump *dump,
                         unsigned int *queue_id, struct smap *details)
  {
      const struct netdev *netdev = dump->netdev;
  
      if (dump->error) {
          return false;
      }
  
      dump->error = netdev->netdev_class->queue_dump_next(netdev, dump->state,
                                                          queue_id, details);
  
      if (dump->error) {
          netdev->netdev_class->queue_dump_done(netdev, dump->state);
          return false;
      }
      return true;
  }
  
  /* Completes queue table dump operation 'dump', which must have been
   * initialized with netdev_queue_dump_start().  Returns 0 if the dump operation
   * was error-free, otherwise a positive errno value describing the problem. */
  int
  netdev_queue_dump_done(struct netdev_queue_dump *dump)
  {
      const struct netdev *netdev = dump->netdev;
      if (!dump->error && netdev->netdev_class->queue_dump_done) {
          dump->error = netdev->netdev_class->queue_dump_done(netdev,
                                                              dump->state);
      }
      netdev_close(dump->netdev);
      return dump->error == EOF ? 0 : dump->error;
  }
  
  /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's ID,
   * its statistics, and the 'aux' specified by the caller.  The order of
   * iteration is unspecified, but (when successful) each queue is visited
   * exactly once.
   *
   * Calling this function may be more efficient than calling
   * netdev_get_queue_stats() for every queue.
   *
   * 'cb' must not modify or free the statistics passed in.
   *
   * Returns 0 if successful, otherwise a positive errno value.  On error, some
   * configured queues may not have been included in the iteration. */
  int
  netdev_dump_queue_stats(const struct netdev *netdev,
                          netdev_dump_queue_stats_cb *cb, void *aux)
  {
      const struct netdev_class *class = netdev->netdev_class;
      return (class->dump_queue_stats
              ? class->dump_queue_stats(netdev, cb, aux)
              : EOPNOTSUPP);
  }
  
  
  /* Returns the class type of 'netdev'.
   *
   * The caller must not free the returned value. */
  const char *
  netdev_get_type(const struct netdev *netdev)
  {
      return netdev->netdev_class->type;
  }
  
  /* Returns the class associated with 'netdev'. */
  const struct netdev_class *
  netdev_get_class(const struct netdev *netdev)
  {
      return netdev->netdev_class;
  }
  
  /* Returns the netdev with 'name' or NULL if there is none.
   *
   * The caller must free the returned netdev with netdev_close(). */
  struct netdev *
  netdev_from_name(const char *name)
      OVS_EXCLUDED(netdev_mutex)
  {
      struct netdev *netdev;
  
      ovs_mutex_lock(&netdev_mutex);
      netdev = shash_find_data(&netdev_shash, name);
      if (netdev) {
          netdev->ref_cnt++;
      }
      ovs_mutex_unlock(&netdev_mutex);
  
      return netdev;
  }
  
  /* Fills 'device_list' with devices that match 'netdev_class'.
   *
   * The caller is responsible for initializing and destroying 'device_list' and
   * must close each device on the list. */
  void
  netdev_get_devices(const struct netdev_class *netdev_class,
                     struct shash *device_list)
      OVS_EXCLUDED(netdev_mutex)
  {
      struct shash_node *node;
  
      ovs_mutex_lock(&netdev_mutex);
      SHASH_FOR_EACH (node, &netdev_shash) {
          struct netdev *dev = node->data;
  
          if (dev->netdev_class == netdev_class) {
              dev->ref_cnt++;
              shash_add(device_list, node->name, node->data);
          }
      }
      ovs_mutex_unlock(&netdev_mutex);
  }
  
  /* Extracts pointers to all 'netdev-vports' into an array 'vports'
   * and returns it.  Stores the size of the array into '*size'.
   *
   * The caller is responsible for freeing 'vports' and must close
   * each 'netdev-vport' in the list. */
  struct netdev **
  netdev_get_vports(size_t *size)
      OVS_EXCLUDED(netdev_mutex)
  {
      struct netdev **vports;
      struct shash_node *node;
      size_t n = 0;
  
      if (!size) {
          return NULL;
      }
  
      /* Explicitly allocates big enough chunk of memory. */
      vports = xmalloc(shash_count(&netdev_shash) * sizeof *vports);
      ovs_mutex_lock(&netdev_mutex);
      SHASH_FOR_EACH (node, &netdev_shash) {
          struct netdev *dev = node->data;
  
          if (netdev_vport_is_vport_class(dev->netdev_class)) {
              dev->ref_cnt++;
              vports[n] = dev;
              n++;
          }
      }
      ovs_mutex_unlock(&netdev_mutex);
      *size = n;
  
      return vports;
  }
  
  const char *
  netdev_get_type_from_name(const char *name)
  {
      struct netdev *dev = netdev_from_name(name);
      const char *type = dev ? netdev_get_type(dev) : NULL;
      netdev_close(dev);
      return type;
  }
  
  struct netdev *
  netdev_rxq_get_netdev(const struct netdev_rxq *rx)
  {
      ovs_assert(rx->netdev->ref_cnt > 0);
      return rx->netdev;
  }
  
  const char *
  netdev_rxq_get_name(const struct netdev_rxq *rx)
  {
      return netdev_get_name(netdev_rxq_get_netdev(rx));
  }
  
  static void
  restore_all_flags(void *aux OVS_UNUSED)
  {
      struct shash_node *node;
  
      SHASH_FOR_EACH (node, &netdev_shash) {
          struct netdev *netdev = node->data;
          const struct netdev_saved_flags *sf;
          enum netdev_flags saved_values;
          enum netdev_flags saved_flags;
  
          saved_values = saved_flags = 0;
          LIST_FOR_EACH (sf, node, &netdev->saved_flags_list) {
              saved_flags |= sf->saved_flags;
              saved_values &= ~sf->saved_flags;
              saved_values |= sf->saved_flags & sf->saved_values;
          }
          if (saved_flags) {
              enum netdev_flags old_flags;
  
              netdev->netdev_class->update_flags(netdev,
                                                 saved_flags & saved_values,
                                                 saved_flags & ~saved_values,
                                                 &old_flags);
          }
      }
  }
  
  uint64_t
  netdev_get_change_seq(const struct netdev *netdev)
  {
      return netdev->change_seq;
  }
  