text: /*
   * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016 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 "dpif-provider.h"
  
  #include <ctype.h>
  #include <errno.h>
  #include <inttypes.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "coverage.h"
  #include "dpctl.h"
  #include "dp-packet.h"
  #include "dpif-netdev.h"
  #include "openvswitch/dynamic-string.h"
  #include "flow.h"
  #include "netdev.h"
  #include "netlink.h"
  #include "odp-execute.h"
  #include "odp-util.h"
  #include "openvswitch/ofp-print.h"
  #include "openvswitch/ofpbuf.h"
  #include "packets.h"
  #include "openvswitch/poll-loop.h"
  #include "route-table.h"
  #include "seq.h"
  #include "openvswitch/shash.h"
  #include "sset.h"
  #include "timeval.h"
  #include "tnl-neigh-cache.h"
  #include "tnl-ports.h"
  #include "util.h"
  #include "uuid.h"
  #include "valgrind.h"
  #include "openvswitch/ofp-errors.h"
  #include "openvswitch/vlog.h"
  #include "lib/netdev-provider.h"
  
  VLOG_DEFINE_THIS_MODULE(dpif);
  
  COVERAGE_DEFINE(dpif_destroy);
  COVERAGE_DEFINE(dpif_port_add);
  COVERAGE_DEFINE(dpif_port_del);
  COVERAGE_DEFINE(dpif_flow_flush);
  COVERAGE_DEFINE(dpif_flow_get);
  COVERAGE_DEFINE(dpif_flow_put);
  COVERAGE_DEFINE(dpif_flow_del);
  COVERAGE_DEFINE(dpif_execute);
  COVERAGE_DEFINE(dpif_purge);
  COVERAGE_DEFINE(dpif_execute_with_help);
  COVERAGE_DEFINE(dpif_meter_set);
  COVERAGE_DEFINE(dpif_meter_get);
  COVERAGE_DEFINE(dpif_meter_del);
  
  static const struct dpif_class *base_dpif_classes[] = {
  #if defined(__linux__) || defined(_WIN32)
      &dpif_netlink_class,
  #endif
      &dpif_netdev_class,
  };
  
  struct registered_dpif_class {
      const struct dpif_class *dpif_class;
      int refcount;
  };
  static struct shash dpif_classes = SHASH_INITIALIZER(&dpif_classes);
  static struct sset dpif_disallowed = SSET_INITIALIZER(&dpif_disallowed);
  
  /* Protects 'dpif_classes', including the refcount, and 'dpif_disallowed'. */
  static struct ovs_mutex dpif_mutex = OVS_MUTEX_INITIALIZER;
  
  /* Rate limit for individual messages going to or from the datapath, output at
   * DBG level.  This is very high because, if these are enabled, it is because
   * we really need to see them. */
  static struct vlog_rate_limit dpmsg_rl = VLOG_RATE_LIMIT_INIT(600, 600);
  
  /* Not really much point in logging many dpif errors. */
  static struct vlog_rate_limit error_rl = VLOG_RATE_LIMIT_INIT(60, 5);
  
  static void log_operation(const struct dpif *, const char *operation,
                            int error);
  static bool should_log_flow_message(const struct vlog_module *module,
                                      int error);
  
  /* Incremented whenever tnl route, arp, etc changes. */
  struct seq *tnl_conf_seq;
  
  static bool
  dpif_is_tap_port(const char *type)
  {
      return !strcmp(type, "tap");
  }
  
  static void
  dp_initialize(void)
  {
      static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
  
      if (ovsthread_once_start(&once)) {
          int i;
  
          tnl_conf_seq = seq_create();
          dpctl_unixctl_register();
          tnl_port_map_init();
          tnl_neigh_cache_init();
          route_table_init();
  
          for (i = 0; i < ARRAY_SIZE(base_dpif_classes); i++) {
              dp_register_provider(base_dpif_classes[i]);
          }
  
          ovsthread_once_done(&once);
      }
  }
  
  static int
  dp_register_provider__(const struct dpif_class *new_class)
  {
      struct registered_dpif_class *registered_class;
      int error;
  
      if (sset_contains(&dpif_disallowed, new_class->type)) {
          VLOG_DBG("attempted to register disallowed provider: %s",
                   new_class->type);
          return EINVAL;
      }
  
      if (shash_find(&dpif_classes, new_class->type)) {
          VLOG_WARN("attempted to register duplicate datapath provider: %s",
                    new_class->type);
          return EEXIST;
      }
  
      error = new_class->init ? new_class->init() : 0;
      if (error) {
          VLOG_WARN("failed to initialize %s datapath class: %s",
                    new_class->type, ovs_strerror(error));
          return error;
      }
  
      registered_class = xmalloc(sizeof *registered_class);
      registered_class->dpif_class = new_class;
      registered_class->refcount = 0;
  
      shash_add(&dpif_classes, new_class->type, registered_class);
  
      return 0;
  }
  
  /* Registers a new datapath provider.  After successful registration, new
   * datapaths of that type can be opened using dpif_open(). */
  int
  dp_register_provider(const struct dpif_class *new_class)
  {
      int error;
  
      ovs_mutex_lock(&dpif_mutex);
      error = dp_register_provider__(new_class);
      ovs_mutex_unlock(&dpif_mutex);
  
      return error;
  }
  
  /* Unregisters a datapath provider.  'type' must have been previously
   * registered and not currently be in use by any dpifs.  After unregistration
   * new datapaths of that type cannot be opened using dpif_open(). */
  static int
  dp_unregister_provider__(const char *type)
  {
      struct shash_node *node;
      struct registered_dpif_class *registered_class;
  
      node = shash_find(&dpif_classes, type);
      if (!node) {
          return EAFNOSUPPORT;
      }
  
      registered_class = node->data;
      if (registered_class->refcount) {
          VLOG_WARN("attempted to unregister in use datapath provider: %s", type);
          return EBUSY;
      }
  
      shash_delete(&dpif_classes, node);
      free(registered_class);
  
      return 0;
  }
  
  /* Unregisters a datapath provider.  'type' must have been previously
   * registered and not currently be in use by any dpifs.  After unregistration
   * new datapaths of that type cannot be opened using dpif_open(). */
  int
  dp_unregister_provider(const char *type)
  {
      int error;
  
      dp_initialize();
  
      ovs_mutex_lock(&dpif_mutex);
      error = dp_unregister_provider__(type);
      ovs_mutex_unlock(&dpif_mutex);
  
      return error;
  }
  
  /* Disallows a provider.  Causes future calls of dp_register_provider() with
   * a dpif_class which implements 'type' to fail. */
  void
  dp_disallow_provider(const char *type)
  {
      ovs_mutex_lock(&dpif_mutex);
      sset_add(&dpif_disallowed, type);
      ovs_mutex_unlock(&dpif_mutex);
  }
  
  /* Adds the types of all currently registered datapath providers to 'types'.
   * The caller must first initialize the sset. */
  void
  dp_enumerate_types(struct sset *types)
  {
      struct shash_node *node;
  
      dp_initialize();
  
      ovs_mutex_lock(&dpif_mutex);
      SHASH_FOR_EACH(node, &dpif_classes) {
          const struct registered_dpif_class *registered_class = node->data;
          sset_add(types, registered_class->dpif_class->type);
      }
      ovs_mutex_unlock(&dpif_mutex);
  }
  
  static void
  dp_class_unref(struct registered_dpif_class *rc)
  {
      ovs_mutex_lock(&dpif_mutex);
      ovs_assert(rc->refcount);
      rc->refcount--;
      ovs_mutex_unlock(&dpif_mutex);
  }
  
  static struct registered_dpif_class *
  dp_class_lookup(const char *type)
  {
      struct registered_dpif_class *rc;
  
      ovs_mutex_lock(&dpif_mutex);
      rc = shash_find_data(&dpif_classes, type);
      if (rc) {
          rc->refcount++;
      }
      ovs_mutex_unlock(&dpif_mutex);
  
      return rc;
  }
  
  /* Clears 'names' and enumerates the names of all known created datapaths with
   * the given 'type'.  The caller must first initialize the sset.  Returns 0 if
   * successful, otherwise a positive errno value.
   *
   * Some kinds of datapaths might not be practically enumerable.  This is not
   * considered an error. */
  int
  dp_enumerate_names(const char *type, struct sset *names)
  {
      struct registered_dpif_class *registered_class;
      const struct dpif_class *dpif_class;
      int error;
  
      dp_initialize();
      sset_clear(names);
  
      registered_class = dp_class_lookup(type);
      if (!registered_class) {
          VLOG_WARN("could not enumerate unknown type: %s", type);
          return EAFNOSUPPORT;
      }
  
      dpif_class = registered_class->dpif_class;
      error = (dpif_class->enumerate
               ? dpif_class->enumerate(names, dpif_class)
               : 0);
      if (error) {
          VLOG_WARN("failed to enumerate %s datapaths: %s", dpif_class->type,
                     ovs_strerror(error));
      }
      dp_class_unref(registered_class);
  
      return error;
  }
  
  /* Parses 'datapath_name_', which is of the form [type@]name into its
   * component pieces.  'name' and 'type' must be freed by the caller.
   *
   * The returned 'type' is normalized, as if by dpif_normalize_type(). */
  void
  dp_parse_name(const char *datapath_name_, char **name, char **type)
  {
      char *datapath_name = xstrdup(datapath_name_);
      char *separator;
  
      separator = strchr(datapath_name, '@');
      if (separator) {
          *separator = '\0';
          *type = datapath_name;
          *name = xstrdup(dpif_normalize_type(separator + 1));
      } else {
          *name = datapath_name;
          *type = xstrdup(dpif_normalize_type(NULL));
      }
  }
  
  static int
  do_open(const char *name, const char *type, bool create, struct dpif **dpifp)
  {
      struct dpif *dpif = NULL;
      int error;
      struct registered_dpif_class *registered_class;
      struct registered_dpif_offload_class *registered_offload_class;
  
      dp_initialize();
  
      type = dpif_normalize_type(type);
      registered_class = dp_class_lookup(type);
      if (!registered_class) {
          VLOG_WARN("could not create datapath %s of unknown type %s", name,
                    type);
          error = EAFNOSUPPORT;
          goto exit;
      }
  
      dp_offload_initialize();
  
      registered_offload_class = dp_offload_class_lookup(type);
      if (!registered_offload_class) {
          VLOG_WARN("Could not create offload datapath %s of unknown type %s",
                    name, type);
          error = EAFNOSUPPORT;
          dp_class_unref(registered_class);
          goto exit;
      }
  
      error = registered_class->dpif_class->open(registered_class->dpif_class,
                                                 name, create, &dpif);
      if (!error) {
          const char *dpif_type_str = dpif_normalize_type(dpif_type(dpif));
          struct dpif_port_dump port_dump;
          struct dpif_port dpif_port;
  
          ovs_assert(dpif->dpif_class == registered_class->dpif_class);
  
          DPIF_PORT_FOR_EACH(&dpif_port, &port_dump, dpif) {
              struct netdev *netdev;
              int err;
  
              if (dpif_is_tap_port(dpif_port.type)) {
                  continue;
              }
  
              err = netdev_open(dpif_port.name, dpif_port.type, &netdev);
  
              if (!err) {
                  netdev_set_dpif_type(netdev, dpif_type_str);
                  netdev_ports_insert(netdev, &dpif_port);
                  netdev_close(netdev);
              } else {
                  VLOG_WARN("could not open netdev %s type %s: %s",
                            dpif_port.name, dpif_port.type, ovs_strerror(err));
              }
          }
      } else {
          dp_offload_class_unref(registered_offload_class);
          dp_class_unref(registered_class);
      }
  
  exit:
      *dpifp = error ? NULL : dpif;
      return error;
  }
  
  /* Tries to open an existing datapath named 'name' and type 'type'.  Will fail
   * if no datapath with 'name' and 'type' exists.  'type' may be either NULL or
   * the empty string to specify the default system type.  Returns 0 if
   * successful, otherwise a positive errno value.  On success stores a pointer
   * to the datapath in '*dpifp', otherwise a null pointer. */
  int
  dpif_open(const char *name, const char *type, struct dpif **dpifp)
  {
      return do_open(name, type, false, dpifp);
  }
  
  /* Tries to create and open a new datapath with the given 'name' and 'type'.
   * 'type' may be either NULL or the empty string to specify the default system
   * type.  Will fail if a datapath with 'name' and 'type' already exists.
   * Returns 0 if successful, otherwise a positive errno value.  On success
   * stores a pointer to the datapath in '*dpifp', otherwise a null pointer. */
  int
  dpif_create(const char *name, const char *type, struct dpif **dpifp)
  {
      return do_open(name, type, true, dpifp);
  }
  
  /* Tries to open a datapath with the given 'name' and 'type', creating it if it
   * does not exist.  'type' may be either NULL or the empty string to specify
   * the default system type.  Returns 0 if successful, otherwise a positive
   * errno value. On success stores a pointer to the datapath in '*dpifp',
   * otherwise a null pointer. */
  int
  dpif_create_and_open(const char *name, const char *type, struct dpif **dpifp)
  {
      int error;
  
      error = dpif_create(name, type, dpifp);
      if (error == EEXIST || error == EBUSY) {
          error = dpif_open(name, type, dpifp);
          if (error) {
              VLOG_WARN("datapath %s already exists but cannot be opened: %s",
                        name, ovs_strerror(error));
          }
      } else if (error) {
          VLOG_WARN("failed to create datapath %s: %s",
                    name, ovs_strerror(error));
      }
      return error;
  }
  
  static void
  dpif_remove_netdev_ports(struct dpif *dpif) {
      const char *dpif_type_str = dpif_normalize_type(dpif_type(dpif));
      struct dpif_port_dump port_dump;
      struct dpif_port dpif_port;
  
      DPIF_PORT_FOR_EACH (&dpif_port, &port_dump, dpif) {
          if (!dpif_is_tap_port(dpif_port.type)) {
              netdev_ports_remove(dpif_port.port_no, dpif_type_str);
          }
      }
  }
  
  /* Closes and frees the connection to 'dpif'.  Does not destroy the datapath
   * itself; call dpif_delete() first, instead, if that is desirable. */
  void
  dpif_close(struct dpif *dpif)
  {
      if (dpif) {
          struct registered_dpif_class *rc;
  
          dpif_offload_close(dpif);
          rc = shash_find_data(&dpif_classes, dpif->dpif_class->type);
  
          if (rc->refcount == 1) {
              dpif_remove_netdev_ports(dpif);
          }
          dpif_uninit(dpif, true);
          dp_class_unref(rc);
      }
  }
  
  /* Performs periodic work needed by 'dpif'. */
  bool
  dpif_run(struct dpif *dpif)
  {
      if (dpif->dpif_class->run) {
          return dpif->dpif_class->run(dpif);
      }
      return false;
  }
  
  /* Arranges for poll_block() to wake up when dp_run() needs to be called for
   * 'dpif'. */
  void
  dpif_wait(struct dpif *dpif)
  {
      if (dpif->dpif_class->wait) {
          dpif->dpif_class->wait(dpif);
      }
  }
  
  /* Returns the name of datapath 'dpif' prefixed with the type
   * (for use in log messages). */
  const char *
  dpif_name(const struct dpif *dpif)
  {
      return dpif->full_name;
  }
  
  /* Returns the name of datapath 'dpif' without the type
   * (for use in device names). */
  const char *
  dpif_base_name(const struct dpif *dpif)
  {
      return dpif->base_name;
  }
  
  /* Returns the type of datapath 'dpif'. */
  const char *
  dpif_type(const struct dpif *dpif)
  {
      return dpif->dpif_class->type;
  }
  
  /* Checks if datapath 'dpif' requires cleanup. */
  bool
  dpif_cleanup_required(const struct dpif *dpif)
  {
      return dpif->dpif_class->cleanup_required;
  }
  
  /* Returns the fully spelled out name for the given datapath 'type'.
   *
   * Normalized type string can be compared with strcmp().  Unnormalized type
   * string might be the same even if they have different spellings. */
  const char *
  dpif_normalize_type(const char *type)
  {
      return type && type[0] ? type : "system";
  }
  
  /* Destroys the datapath that 'dpif' is connected to, first removing all of its
   * ports.  After calling this function, it does not make sense to pass 'dpif'
   * to any functions other than dpif_name() or dpif_close(). */
  int
  dpif_delete(struct dpif *dpif)
  {
      int error;
  
      COVERAGE_INC(dpif_destroy);
  
      error = dpif->dpif_class->destroy(dpif);
      log_operation(dpif, "delete", error);
      return error;
  }
  
  /* Retrieves statistics for 'dpif' into 'stats'.  Returns 0 if successful,
   * otherwise a positive errno value. */
  int
  dpif_get_dp_stats(const struct dpif *dpif, struct dpif_dp_stats *stats)
  {
      int error = dpif->dpif_class->get_stats(dpif, stats);
      if (error) {
          memset(stats, 0, sizeof *stats);
      }
      log_operation(dpif, "get_stats", error);
      return error;
  }
  
  int
  dpif_set_features(struct dpif *dpif, uint32_t new_features)
  {
      int error = dpif->dpif_class->set_features(dpif, new_features);
  
      log_operation(dpif, "set_features", error);
      return error;
  }
  
  const char *
  dpif_port_open_type(const char *datapath_type, const char *port_type)
  {
      struct registered_dpif_class *rc;
  
      datapath_type = dpif_normalize_type(datapath_type);
  
      ovs_mutex_lock(&dpif_mutex);
      rc = shash_find_data(&dpif_classes, datapath_type);
      if (rc && rc->dpif_class->port_open_type) {
          port_type = rc->dpif_class->port_open_type(rc->dpif_class, port_type);
      }
      ovs_mutex_unlock(&dpif_mutex);
  
      return port_type;
  }
  
  /* Attempts to add 'netdev' as a port on 'dpif'.  If 'port_nop' is
   * non-null and its value is not ODPP_NONE, then attempts to use the
   * value as the port number.
   *
   * If successful, returns 0 and sets '*port_nop' to the new port's port
   * number (if 'port_nop' is non-null).  On failure, returns a positive
   * errno value and sets '*port_nop' to ODPP_NONE (if 'port_nop' is
   * non-null). */
  int
  dpif_port_add(struct dpif *dpif, struct netdev *netdev, odp_port_t *port_nop)
  {
      const char *netdev_name = netdev_get_name(netdev);
      odp_port_t port_no = ODPP_NONE;
      int error;
  
      COVERAGE_INC(dpif_port_add);
  
      if (port_nop) {
          port_no = *port_nop;
      }
  
      error = dpif->dpif_class->port_add(dpif, netdev, &port_no);
      if (!error) {
          VLOG_DBG_RL(&dpmsg_rl, "%s: added %s as port %"PRIu32,
                      dpif_name(dpif), netdev_name, port_no);
  
          if (!dpif_is_tap_port(netdev_get_type(netdev))) {
  
              const char *dpif_type_str = dpif_normalize_type(dpif_type(dpif));
              struct dpif_port dpif_port;
  
              netdev_set_dpif_type(netdev, dpif_type_str);
  
              dpif_port.type = CONST_CAST(char *, netdev_get_type(netdev));
              dpif_port.name = CONST_CAST(char *, netdev_name);
              dpif_port.port_no = port_no;
              netdev_ports_insert(netdev, &dpif_port);
          }
      } else {
          VLOG_WARN_RL(&error_rl, "%s: failed to add %s as port: %s",
                       dpif_name(dpif), netdev_name, ovs_strerror(error));
          port_no = ODPP_NONE;
      }
      if (port_nop) {
          *port_nop = port_no;
      }
      return error;
  }
  
  /* Attempts to remove 'dpif''s port number 'port_no'.  Returns 0 if successful,
   * otherwise a positive errno value. */
  int
  dpif_port_del(struct dpif *dpif, odp_port_t port_no, bool local_delete)
  {
      int error = 0;
  
      COVERAGE_INC(dpif_port_del);
  
      if (!local_delete) {
          error = dpif->dpif_class->port_del(dpif, port_no);
          if (!error) {
              VLOG_DBG_RL(&dpmsg_rl, "%s: port_del(%"PRIu32")",
                          dpif_name(dpif), port_no);
          } else {
              log_operation(dpif, "port_del", error);
          }
      }
  
      netdev_ports_remove(port_no, dpif_normalize_type(dpif_type(dpif)));
      return error;
  }
  
  /* Makes a deep copy of 'src' into 'dst'. */
  void
  dpif_port_clone(struct dpif_port *dst, const struct dpif_port *src)
  {
      dst->name = xstrdup(src->name);
      dst->type = xstrdup(src->type);
      dst->port_no = src->port_no;
  }
  
  /* Frees memory allocated to members of 'dpif_port'.
   *
   * Do not call this function on a dpif_port obtained from
   * dpif_port_dump_next(): that function retains ownership of the data in the
   * dpif_port. */
  void
  dpif_port_destroy(struct dpif_port *dpif_port)
  {
      free(dpif_port->name);
      free(dpif_port->type);
  }
  
  /* Checks if port named 'devname' exists in 'dpif'.  If so, returns
   * true; otherwise, returns false. */
  bool
  dpif_port_exists(const struct dpif *dpif, const char *devname)
  {
      int error = dpif->dpif_class->port_query_by_name(dpif, devname, NULL);
      if (error != 0 && error != ENODEV) {
          VLOG_WARN_RL(&error_rl, "%s: failed to query port %s: %s",
                       dpif_name(dpif), devname, ovs_strerror(error));
      }
  
      return !error;
  }
  
  /* Refreshes configuration of 'dpif's port. */
  int
  dpif_port_set_config(struct dpif *dpif, odp_port_t port_no,
                       const struct smap *cfg)
  {
      int error = 0;
  
      if (dpif->dpif_class->port_set_config) {
          error = dpif->dpif_class->port_set_config(dpif, port_no, cfg);
          if (error) {
              log_operation(dpif, "port_set_config", error);
          }
      }
  
      return error;
  }
  
  /* Looks up port number 'port_no' in 'dpif'.  On success, returns 0 and
   * initializes '*port' appropriately; on failure, returns a positive errno
   * value.
   *
   * Retuns ENODEV if the port doesn't exist.
   *
   * The caller owns the data in 'port' and must free it with
   * dpif_port_destroy() when it is no longer needed. */
  int
  dpif_port_query_by_number(const struct dpif *dpif, odp_port_t port_no,
                            struct dpif_port *port)
  {
      int error = dpif->dpif_class->port_query_by_number(dpif, port_no, port);
      if (!error) {
          VLOG_DBG_RL(&dpmsg_rl, "%s: port %"PRIu32" is device %s",
                      dpif_name(dpif), port_no, port->name);
      } else {
          memset(port, 0, sizeof *port);
          VLOG_WARN_RL(&error_rl, "%s: failed to query port %"PRIu32": %s",
                       dpif_name(dpif), port_no, ovs_strerror(error));
      }
      return error;
  }
  
  /* Looks up port named 'devname' in 'dpif'.  On success, returns 0 and
   * initializes '*port' appropriately; on failure, returns a positive errno
   * value.
   *
   * Retuns ENODEV if the port doesn't exist.
   *
   * The caller owns the data in 'port' and must free it with
   * dpif_port_destroy() when it is no longer needed. */
  int
  dpif_port_query_by_name(const struct dpif *dpif, const char *devname,
                          struct dpif_port *port)
  {
      int error = dpif->dpif_class->port_query_by_name(dpif, devname, port);
      if (!error) {
          VLOG_DBG_RL(&dpmsg_rl, "%s: device %s is on port %"PRIu32,
                      dpif_name(dpif), devname, port->port_no);
      } else {
          memset(port, 0, sizeof *port);
  
          /* For ENODEV we use DBG level because the caller is probably
           * interested in whether 'dpif' actually has a port 'devname', so that
           * it's not an issue worth logging if it doesn't.  Other errors are
           * uncommon and more likely to indicate a real problem. */
          VLOG_RL(&error_rl, error == ENODEV ? VLL_DBG : VLL_WARN,
                  "%s: failed to query port %s: %s",
                  dpif_name(dpif), devname, ovs_strerror(error));
      }
      return error;
  }
  
  /* Returns the Netlink PID value to supply in OVS_ACTION_ATTR_USERSPACE
   * actions as the OVS_USERSPACE_ATTR_PID attribute's value, for use in
   * flows whose packets arrived on port 'port_no'.
   *
   * A 'port_no' of ODPP_NONE is a special case: it returns a reserved PID, not
   * allocated to any port, that the client may use for special purposes.
   *
   * The return value is only meaningful when DPIF_UC_ACTION has been enabled in
   * the 'dpif''s listen mask.  It is allowed to change when DPIF_UC_ACTION is
   * disabled and then re-enabled, so a client that does that must be prepared to
   * update all of the flows that it installed that contain
   * OVS_ACTION_ATTR_USERSPACE actions. */
  uint32_t
  dpif_port_get_pid(const struct dpif *dpif, odp_port_t port_no)
  {
      return (dpif->dpif_class->port_get_pid
              ? (dpif->dpif_class->port_get_pid)(dpif, port_no)
              : 0);
  }
  
  /* Looks up port number 'port_no' in 'dpif'.  On success, returns 0 and copies
   * the port's name into the 'name_size' bytes in 'name', ensuring that the
   * result is null-terminated.  On failure, returns a positive errno value and
   * makes 'name' the empty string. */
  int
  dpif_port_get_name(struct dpif *dpif, odp_port_t port_no,
                     char *name, size_t name_size)
  {
      struct dpif_port port;
      int error;
  
      ovs_assert(name_size > 0);
  
      error = dpif_port_query_by_number(dpif, port_no, &port);
      if (!error) {
          ovs_strlcpy(name, port.name, name_size);
          dpif_port_destroy(&port);
      } else {
          *name = '\0';
      }
      return error;
  }
  
  /* Initializes 'dump' to begin dumping the ports in a dpif.
   *
   * This function provides no status indication.  An error status for the entire
   * dump operation is provided when it is completed by calling
   * dpif_port_dump_done().
   */
  void
  dpif_port_dump_start(struct dpif_port_dump *dump, const struct dpif *dpif)
  {
      dump->dpif = dpif;
      dump->error = dpif->dpif_class->port_dump_start(dpif, &dump->state);
      log_operation(dpif, "port_dump_start", dump->error);
  }
  
  /* Attempts to retrieve another port from 'dump', which must have been
   * initialized with dpif_port_dump_start().  On success, stores a new dpif_port
   * into 'port' and returns true.  On failure, returns false.
   *
   * Failure might indicate an actual error or merely that the last port has been
   * dumped.  An error status for the entire dump operation is provided when it
   * is completed by calling dpif_port_dump_done().
   *
   * The dpif owns the data stored in 'port'.  It will remain valid until at
   * least the next time 'dump' is passed to dpif_port_dump_next() or
   * dpif_port_dump_done(). */
  bool
  dpif_port_dump_next(struct dpif_port_dump *dump, struct dpif_port *port)
  {
      const struct dpif *dpif = dump->dpif;
  
      if (dump->error) {
          return false;
      }
  
      dump->error = dpif->dpif_class->port_dump_next(dpif, dump->state, port);
      if (dump->error == EOF) {
          VLOG_DBG_RL(&dpmsg_rl, "%s: dumped all ports", dpif_name(dpif));
      } else {
          log_operation(dpif, "port_dump_next", dump->error);
      }
  
      if (dump->error) {
          dpif->dpif_class->port_dump_done(dpif, dump->state);
          return false;
      }
      return true;
  }
  
  /* Completes port table dump operation 'dump', which must have been initialized
   * with dpif_port_dump_start().  Returns 0 if the dump operation was
   * error-free, otherwise a positive errno value describing the problem. */
  int
  dpif_port_dump_done(struct dpif_port_dump *dump)
  {
      const struct dpif *dpif = dump->dpif;
      if (!dump->error) {
          dump->error = dpif->dpif_class->port_dump_done(dpif, dump->state);
          log_operation(dpif, "port_dump_done", dump->error);
      }
      return dump->error == EOF ? 0 : dump->error;
  }
  
  /* Polls for changes in the set of ports in 'dpif'.  If the set of ports in
   * 'dpif' has changed, this function does one of the following:
   *
   * - Stores the name of the device that was added to or deleted from 'dpif' in
   *   '*devnamep' and returns 0.  The caller is responsible for freeing
   *   '*devnamep' (with free()) when it no longer needs it.
   *
   * - Returns ENOBUFS and sets '*devnamep' to NULL.
   *
   * This function may also return 'false positives', where it returns 0 and
   * '*devnamep' names a device that was not actually added or deleted or it
   * returns ENOBUFS without any change.
   *
   * Returns EAGAIN if the set of ports in 'dpif' has not changed.  May also
   * return other positive errno values to indicate that something has gone
   * wrong. */
  int
  dpif_port_poll(const struct dpif *dpif, char **devnamep)
  {
      int error = dpif->dpif_class->port_poll(dpif, devnamep);
      if (error) {
          *devnamep = NULL;
      }
      return error;
  }
  
  /* Arranges for the poll loop to wake up when port_poll(dpif) will return a
   * value other than EAGAIN. */
  void
  dpif_port_poll_wait(const struct dpif *dpif)
  {
      dpif->dpif_class->port_poll_wait(dpif);
  }
  
  /* Extracts the flow stats for a packet.  The 'flow' and 'packet'
   * arguments must have been initialized through a call to flow_extract().
   * 'used' is stored into stats->used. */
  void
  dpif_flow_stats_extract(const struct flow *flow, const struct dp_packet *packet,
                          long long int used, struct dpif_flow_stats *stats)
  {
      stats->tcp_flags = ntohs(flow->tcp_flags);
      stats->n_bytes = dp_packet_size(packet);
      stats->n_packets = 1;
      stats->used = used;
  }
  
  /* Appends a human-readable representation of 'stats' to 's'. */
  void
  dpif_flow_stats_format(const struct dpif_flow_stats *stats, struct ds *s)
  {
      ds_put_format(s, "packets:%"PRIu64", bytes:%"PRIu64", used:",
                    stats->n_packets, stats->n_bytes);
      if (stats->used) {
          ds_put_format(s, "%.3fs", (time_msec() - stats->used) / 1000.0);
      } else {
          ds_put_format(s, "never");
      }
      if (stats->tcp_flags) {
          ds_put_cstr(s, ", flags:");
          packet_format_tcp_flags(s, stats->tcp_flags);
      }
  }
  
  /* Deletes all flows from 'dpif'.  Returns 0 if successful, otherwise a
   * positive errno value.  */
  int
  dpif_flow_flush(struct dpif *dpif)
  {
      int error;
  
      COVERAGE_INC(dpif_flow_flush);
  
      error = dpif->dpif_class->flow_flush(dpif);
      log_operation(dpif, "flow_flush", error);
      return error;
  }
  
  /* Attempts to install 'key' into the datapath, fetches it, then deletes it.
   * Returns true if the datapath supported installing 'flow', false otherwise.
   */
  bool
  dpif_probe_feature(struct dpif *dpif, const char *name,
                     const struct ofpbuf *key, const struct ofpbuf *actions,
                     const ovs_u128 *ufid)
  {
      struct dpif_flow flow;
      struct ofpbuf reply;
      uint64_t stub[DPIF_FLOW_BUFSIZE / 8];
      bool enable_feature = false;
      int error;
      const struct nlattr *nl_actions = actions ? actions->data : NULL;
      const size_t nl_actions_size = actions ? actions->size : 0;
  
      /* Use DPIF_FP_MODIFY to cover the case where ovs-vswitchd is killed (and
       * restarted) at just the right time such that feature probes from the
       * previous run are still present in the datapath. */
      error = dpif_flow_put(dpif, DPIF_FP_CREATE | DPIF_FP_MODIFY | DPIF_FP_PROBE,
                            key->data, key->size, NULL, 0,
                            nl_actions, nl_actions_size,
                            ufid, NON_PMD_CORE_ID, NULL);
      if (error) {
          if (error != EINVAL && error != EOVERFLOW) {
              VLOG_WARN("%s: %s flow probe failed (%s)",
                        dpif_name(dpif), name, ovs_strerror(error));
          }
          return false;
      }
  
      ofpbuf_use_stack(&reply, &stub, sizeof stub);
      error = dpif_flow_get(dpif, key->data, key->size, ufid,
                            NON_PMD_CORE_ID, &reply, &flow);
      if (!error
          && (!ufid || (flow.ufid_present
                        && ovs_u128_equals(*ufid, flow.ufid)))) {
          enable_feature = true;
      }
  
      error = dpif_flow_del(dpif, key->data, key->size, ufid,
                            NON_PMD_CORE_ID, NULL);
      if (error) {
          VLOG_WARN("%s: failed to delete %s feature probe flow",
                    dpif_name(dpif), name);
      }
  
      return enable_feature;
  }
  
  /* A dpif_operate() wrapper for performing a single DPIF_OP_FLOW_GET. */
  int
  dpif_flow_get(struct dpif *dpif,
                const struct nlattr *key, size_t key_len, const ovs_u128 *ufid,
                const unsigned pmd_id, struct ofpbuf *buf, struct dpif_flow *flow)
  {
      struct dpif_op *opp;
      struct dpif_op op;
  
      op.type = DPIF_OP_FLOW_GET;
      op.flow_get.key = key;
      op.flow_get.key_len = key_len;
      op.flow_get.ufid = ufid;
      op.flow_get.pmd_id = pmd_id;
      op.flow_get.buffer = buf;
  
      memset(flow, 0, sizeof *flow);
      op.flow_get.flow = flow;
      op.flow_get.flow->key = key;
      op.flow_get.flow->key_len = key_len;
  
      opp = &op;
      dpif_operate(dpif, &opp, 1, DPIF_OFFLOAD_AUTO);
  
      return op.error;
  }
  
  /* A dpif_operate() wrapper for performing a single DPIF_OP_FLOW_PUT. */
  int
  dpif_flow_put(struct dpif *dpif, enum dpif_flow_put_flags flags,
                const struct nlattr *key, size_t key_len,
                const struct nlattr *mask, size_t mask_len,
                const struct nlattr *actions, size_t actions_len,
                const ovs_u128 *ufid, const unsigned pmd_id,
                struct dpif_flow_stats *stats)
  {
      struct dpif_op *opp;
      struct dpif_op op;
  
      op.type = DPIF_OP_FLOW_PUT;
      op.flow_put.flags = flags;
      op.flow_put.key = key;
      op.flow_put.key_len = key_len;
      op.flow_put.mask = mask;
      op.flow_put.mask_len = mask_len;
      op.flow_put.actions = actions;
      op.flow_put.actions_len = actions_len;
      op.flow_put.ufid = ufid;
      op.flow_put.pmd_id = pmd_id;
      op.flow_put.stats = stats;
  
      opp = &op;
      dpif_operate(dpif, &opp, 1, DPIF_OFFLOAD_AUTO);
  
      return op.error;
  }
  
  /* A dpif_operate() wrapper for performing a single DPIF_OP_FLOW_DEL. */
  int
  dpif_flow_del(struct dpif *dpif,
                const struct nlattr *key, size_t key_len, const ovs_u128 *ufid,
                const unsigned pmd_id, struct dpif_flow_stats *stats)
  {
      struct dpif_op *opp;
      struct dpif_op op;
  
      op.type = DPIF_OP_FLOW_DEL;
      op.flow_del.key = key;
      op.flow_del.key_len = key_len;
      op.flow_del.ufid = ufid;
      op.flow_del.pmd_id = pmd_id;
      op.flow_del.stats = stats;
      op.flow_del.terse = false;
  
      opp = &op;
      dpif_operate(dpif, &opp, 1, DPIF_OFFLOAD_AUTO);
  
      return op.error;
  }
  
  /* Creates and returns a new 'struct dpif_flow_dump' for iterating through the
   * flows in 'dpif'. If 'terse' is true, then only UFID and statistics will
   * be returned in the dump. Otherwise, all fields will be returned.
   *
   * This function always successfully returns a dpif_flow_dump.  Error
   * reporting is deferred to dpif_flow_dump_destroy(). */
  struct dpif_flow_dump *
  dpif_flow_dump_create(const struct dpif *dpif, bool terse,
                        struct dpif_flow_dump_types *types)
  {
      return dpif->dpif_class->flow_dump_create(dpif, terse, types);
  }
  
  /* Destroys 'dump', which must have been created with dpif_flow_dump_create().
   * All dpif_flow_dump_thread structures previously created for 'dump' must
   * previously have been destroyed.
   *
   * Returns 0 if the dump operation was error-free, otherwise a positive errno
   * value describing the problem. */
  int
  dpif_flow_dump_destroy(struct dpif_flow_dump *dump)
  {
      const struct dpif *dpif = dump->dpif;
      int error = dpif->dpif_class->flow_dump_destroy(dump);
      log_operation(dpif, "flow_dump_destroy", error);
      return error == EOF ? 0 : error;
  }
  
  /* Returns new thread-local state for use with dpif_flow_dump_next(). */
  struct dpif_flow_dump_thread *
  dpif_flow_dump_thread_create(struct dpif_flow_dump *dump)
  {
      return dump->dpif->dpif_class->flow_dump_thread_create(dump);
  }
  
  /* Releases 'thread'. */
  void
  dpif_flow_dump_thread_destroy(struct dpif_flow_dump_thread *thread)
  {
      thread->dpif->dpif_class->flow_dump_thread_destroy(thread);
  }
  
  /* Attempts to retrieve up to 'max_flows' more flows from 'thread'.  Returns 0
   * if and only if no flows remained to be retrieved, otherwise a positive
   * number reflecting the number of elements in 'flows[]' that were updated.
   * The number of flows returned might be less than 'max_flows' because
   * fewer than 'max_flows' remained, because this particular datapath does not
   * benefit from batching, or because an error occurred partway through
   * retrieval.  Thus, the caller should continue calling until a 0 return value,
   * even if intermediate return values are less than 'max_flows'.
   *
   * No error status is immediately provided.  An error status for the entire
   * dump operation is provided when it is completed by calling
   * dpif_flow_dump_destroy().
   *
   * All of the data stored into 'flows' is owned by the datapath, not by the
   * caller, and the caller must not modify or free it.  The datapath guarantees
   * that it remains accessible and unchanged until the first of:
   *  - The next call to dpif_flow_dump_next() for 'thread', or
   *  - The next rcu quiescent period. */
  int
  dpif_flow_dump_next(struct dpif_flow_dump_thread *thread,
                      struct dpif_flow *flows, int max_flows)
  {
      struct dpif *dpif = thread->dpif;
      int n;
  
      ovs_assert(max_flows > 0);
      n = dpif->dpif_class->flow_dump_next(thread, flows, max_flows);
      if (n > 0) {
          struct dpif_flow *f;
  
          for (f = flows; f < &flows[n]
               && should_log_flow_message(&this_module, 0); f++) {
              log_flow_message(dpif, 0, &this_module, "flow_dump",
                               f->key, f->key_len, f->mask, f->mask_len,
                               &f->ufid, &f->stats, f->actions, f->actions_len);
          }
      } else {
          VLOG_DBG_RL(&dpmsg_rl, "%s: dumped all flows", dpif_name(dpif));
      }
      return n;
  }
  
  struct dpif_execute_helper_aux {
      struct dpif *dpif;
      const struct flow *flow;
      int error;
      const struct nlattr *meter_action; /* Non-NULL, if have a meter action. */
  };
  
  /* This is called for actions that need the context of the datapath to be
   * meaningful. */
  static void
  dpif_execute_helper_cb(void *aux_, struct dp_packet_batch *packets_,
                         const struct nlattr *action, bool should_steal)
  {
      struct dpif_execute_helper_aux *aux = aux_;
      int type = nl_attr_type(action);
      struct dp_packet *packet = packets_->packets[0];
  
      ovs_assert(dp_packet_batch_size(packets_) == 1);
  
      switch ((enum ovs_action_attr)type) {
      case OVS_ACTION_ATTR_METER:
          /* Maintain a pointer to the first meter action seen. */
          if (!aux->meter_action) {
              aux->meter_action = action;
          }
          break;
  
      case OVS_ACTION_ATTR_CT:
      case OVS_ACTION_ATTR_OUTPUT:
      case OVS_ACTION_ATTR_LB_OUTPUT:
      case OVS_ACTION_ATTR_TUNNEL_PUSH:
      case OVS_ACTION_ATTR_TUNNEL_POP:
      case OVS_ACTION_ATTR_USERSPACE:
      case OVS_ACTION_ATTR_RECIRC: {
          struct dpif_execute execute;
          struct ofpbuf execute_actions;
          uint64_t stub[256 / 8];
          struct pkt_metadata *md = &packet->md;
  
          if (flow_tnl_dst_is_set(&md->tunnel) || aux->meter_action) {
              ofpbuf_use_stub(&execute_actions, stub, sizeof stub);
  
              if (aux->meter_action) {
                  const struct nlattr *a = aux->meter_action;
  
                  /* XXX: This code collects meter actions since the last action
                   * execution via the datapath to be executed right before the
                   * current action that needs to be executed by the datapath.
                   * This is only an approximation, but better than nothing.
                   * Fundamentally, we should have a mechanism by which the
                   * datapath could return the result of the meter action so that
                   * we could execute them at the right order. */
                  do {
                      ofpbuf_put(&execute_actions, a, NLA_ALIGN(a->nla_len));
                      /* Find next meter action before 'action', if any. */
                      do {
                          a = nl_attr_next(a);
                      } while (a != action &&
                               nl_attr_type(a) != OVS_ACTION_ATTR_METER);
                  } while (a != action);
              }
  
              /* The Linux kernel datapath throws away the tunnel information
               * that we supply as metadata.  We have to use a "set" action to
               * supply it. */
              if (md->tunnel.ip_dst) {
                  odp_put_tunnel_action(&md->tunnel, &execute_actions, NULL);
              }
              ofpbuf_put(&execute_actions, action, NLA_ALIGN(action->nla_len));
  
              execute.actions = execute_actions.data;
              execute.actions_len = execute_actions.size;
          } else {
              execute.actions = action;
              execute.actions_len = NLA_ALIGN(action->nla_len);
          }
  
          struct dp_packet *clone = NULL;
          uint32_t cutlen = dp_packet_get_cutlen(packet);
          if (cutlen && (type == OVS_ACTION_ATTR_OUTPUT
                          || type == OVS_ACTION_ATTR_LB_OUTPUT
                          || type == OVS_ACTION_ATTR_TUNNEL_PUSH
                          || type == OVS_ACTION_ATTR_TUNNEL_POP
                          || type == OVS_ACTION_ATTR_USERSPACE)) {
              dp_packet_reset_cutlen(packet);
              if (!should_steal) {
                  packet = clone = dp_packet_clone(packet);
              }
              dp_packet_set_size(packet, dp_packet_size(packet) - cutlen);
          }
  
          execute.packet = packet;
          execute.flow = aux->flow;
          execute.needs_help = false;
          execute.probe = false;
          execute.mtu = 0;
          execute.hash = 0;
          aux->error = dpif_execute(aux->dpif, &execute);
          log_execute_message(aux->dpif, &this_module, &execute,
                              true, aux->error);
  
          dp_packet_delete(clone);
  
          if (flow_tnl_dst_is_set(&md->tunnel) || aux->meter_action) {
              ofpbuf_uninit(&execute_actions);
  
              /* Do not re-use the same meters for later output actions. */
              aux->meter_action = NULL;
          }
          break;
      }
  
      case OVS_ACTION_ATTR_HASH:
      case OVS_ACTION_ATTR_PUSH_VLAN:
      case OVS_ACTION_ATTR_POP_VLAN:
      case OVS_ACTION_ATTR_PUSH_MPLS:
      case OVS_ACTION_ATTR_POP_MPLS:
      case OVS_ACTION_ATTR_SET:
      case OVS_ACTION_ATTR_SET_MASKED:
      case OVS_ACTION_ATTR_SAMPLE:
      case OVS_ACTION_ATTR_TRUNC:
      case OVS_ACTION_ATTR_PUSH_ETH:
      case OVS_ACTION_ATTR_POP_ETH:
      case OVS_ACTION_ATTR_CLONE:
      case OVS_ACTION_ATTR_PUSH_NSH:
      case OVS_ACTION_ATTR_POP_NSH:
      case OVS_ACTION_ATTR_CT_CLEAR:
      case OVS_ACTION_ATTR_UNSPEC:
      case OVS_ACTION_ATTR_CHECK_PKT_LEN:
      case OVS_ACTION_ATTR_DROP:
      case __OVS_ACTION_ATTR_MAX:
          OVS_NOT_REACHED();
      }
      dp_packet_delete_batch(packets_, should_steal);
  }
  
  /* Executes 'execute' by performing most of the actions in userspace and
   * passing the fully constructed packets to 'dpif' for output and userspace
   * actions.
   *
   * This helps with actions that a given 'dpif' doesn't implement directly. */
  static int
  dpif_execute_with_help(struct dpif *dpif, struct dpif_execute *execute)
  {
      struct dpif_execute_helper_aux aux = {dpif, execute->flow, 0, NULL};
      struct dp_packet_batch pb;
  
      COVERAGE_INC(dpif_execute_with_help);
  
      dp_packet_batch_init_packet(&pb, execute->packet);
      odp_execute_actions(&aux, &pb, false, execute->actions,
                          execute->actions_len, dpif_execute_helper_cb);
      return aux.error;
  }
  
  /* Returns true if the datapath needs help executing 'execute'. */
  static bool
  dpif_execute_needs_help(const struct dpif_execute *execute)
  {
      return execute->needs_help || nl_attr_oversized(execute->actions_len);
  }
  
  /* A dpif_operate() wrapper for performing a single DPIF_OP_EXECUTE. */
  int
  dpif_execute(struct dpif *dpif, struct dpif_execute *execute)
  {
      if (execute->actions_len) {
          struct dpif_op *opp;
          struct dpif_op op;
  
          op.type = DPIF_OP_EXECUTE;
          op.execute = *execute;
  
          opp = &op;
          dpif_operate(dpif, &opp, 1, DPIF_OFFLOAD_AUTO);
  
          return op.error;
      } else {
          return 0;
      }
  }
  
  /* Executes each of the 'n_ops' operations in 'ops' on 'dpif', in the order in
   * which they are specified.  Places each operation's results in the "output"
   * members documented in comments, and 0 in the 'error' member on success or a
   * positive errno on failure.
   */
  void
  dpif_operate(struct dpif *dpif, struct dpif_op **ops, size_t n_ops,
               enum dpif_offload_type offload_type)
  {
      if (offload_type == DPIF_OFFLOAD_ALWAYS && !netdev_is_flow_api_enabled()) {
          size_t i;
          for (i = 0; i < n_ops; i++) {
              struct dpif_op *op = ops[i];
              op->error = EINVAL;
          }
          return;
      }
  
      while (n_ops > 0) {
          size_t chunk;
  
          /* Count 'chunk', the number of ops that can be executed without
           * needing any help.  Ops that need help should be rare, so we
           * expect this to ordinarily be 'n_ops', that is, all the ops. */
          for (chunk = 0; chunk < n_ops; chunk++) {
              struct dpif_op *op = ops[chunk];
  
              if (op->type == DPIF_OP_EXECUTE
                  && dpif_execute_needs_help(&op->execute)) {
                  break;
              }
          }
  
          if (chunk) {
              /* Execute a chunk full of ops that the dpif provider can
               * handle itself, without help. */
              size_t i;
  
              dpif->dpif_class->operate(dpif, ops, chunk, offload_type);
  
              for (i = 0; i < chunk; i++) {
                  struct dpif_op *op = ops[i];
                  int error = op->error;
  
                  switch (op->type) {
                  case DPIF_OP_FLOW_PUT: {
                      struct dpif_flow_put *put = &op->flow_put;
  
                      COVERAGE_INC(dpif_flow_put);
                      log_flow_put_message(dpif, &this_module, put, error);
                      if (error && put->stats) {
                          memset(put->stats, 0, sizeof *put->stats);
                      }
                      break;
                  }
  
                  case DPIF_OP_FLOW_GET: {
                      struct dpif_flow_get *get = &op->flow_get;
  
                      COVERAGE_INC(dpif_flow_get);
                      if (error) {
                          memset(get->flow, 0, sizeof *get->flow);
                      }
                      log_flow_get_message(dpif, &this_module, get, error);
  
                      break;
                  }
  
                  case DPIF_OP_FLOW_DEL: {
                      struct dpif_flow_del *del = &op->flow_del;
  
                      COVERAGE_INC(dpif_flow_del);
                      log_flow_del_message(dpif, &this_module, del, error);
                      if (error && del->stats) {
                          memset(del->stats, 0, sizeof *del->stats);
                      }
                      break;
                  }
  
                  case DPIF_OP_EXECUTE:
                      COVERAGE_INC(dpif_execute);
                      log_execute_message(dpif, &this_module, &op->execute,
                                          false, error);
                      break;
                  }
              }
  
              ops += chunk;
              n_ops -= chunk;
          } else {
              /* Help the dpif provider to execute one op. */
              struct dpif_op *op = ops[0];
  
              COVERAGE_INC(dpif_execute);
              op->error = dpif_execute_with_help(dpif, &op->execute);
              ops++;
              n_ops--;
          }
      }
  }
  
  /* Returns a string that represents 'type', for use in log messages. */
  const char *
  dpif_upcall_type_to_string(enum dpif_upcall_type type)
  {
      switch (type) {
      case DPIF_UC_MISS: return "miss";
      case DPIF_UC_ACTION: return "action";
      case DPIF_N_UC_TYPES: default: return "<unknown>";
      }
  }
  
  /* Enables or disables receiving packets with dpif_recv() on 'dpif'.  Returns 0
   * if successful, otherwise a positive errno value.
   *
   * Turning packet receive off and then back on may change the Netlink PID
   * assignments returned by dpif_port_get_pid().  If the client does this, it
   * must update all of the flows that have OVS_ACTION_ATTR_USERSPACE actions
   * using the new PID assignment. */
  int
  dpif_recv_set(struct dpif *dpif, bool enable)
  {
      int error = 0;
  
      if (dpif->dpif_class->recv_set) {
          error = dpif->dpif_class->recv_set(dpif, enable);
          log_operation(dpif, "recv_set", error);
      }
      return error;
  }
  
  /* Refreshes the poll loops and Netlink sockets associated to each port,
   * when the number of upcall handlers (upcall receiving thread) is changed
   * to 'n_handlers' and receiving packets for 'dpif' is enabled by
   * recv_set().
   *
   * Since multiple upcall handlers can read upcalls simultaneously from
   * 'dpif', each port can have multiple Netlink sockets, one per upcall
   * handler.  So, handlers_set() is responsible for the following tasks:
   *
   *    When receiving upcall is enabled, extends or creates the
   *    configuration to support:
   *
   *        - 'n_handlers' Netlink sockets for each port.
   *
   *        - 'n_handlers' poll loops, one for each upcall handler.
   *
   *        - registering the Netlink sockets for the same upcall handler to
   *          the corresponding poll loop.
   *
   * Returns 0 if successful, otherwise a positive errno value. */
  int
  dpif_handlers_set(struct dpif *dpif, uint32_t n_handlers)
  {
      int error = 0;
  
      if (dpif->dpif_class->handlers_set) {
          error = dpif->dpif_class->handlers_set(dpif, n_handlers);
          log_operation(dpif, "handlers_set", error);
      }
      return error;
  }
  
  /* Checks if a certain number of handlers are required.
   *
   * If a certain number of handlers are required, returns 'true' and sets
   * 'n_handlers' to that number of handler threads.
   *
   * If not, returns 'false'
   */
  bool
  dpif_number_handlers_required(struct dpif *dpif, uint32_t *n_handlers)
  {
      if (dpif->dpif_class->number_handlers_required) {
          return dpif->dpif_class->number_handlers_required(dpif, n_handlers);
      }
      return false;
  }
  
  void
  dpif_register_dp_purge_cb(struct dpif *dpif, dp_purge_callback *cb, void *aux)
  {
      if (dpif->dpif_class->register_dp_purge_cb) {
          dpif->dpif_class->register_dp_purge_cb(dpif, cb, aux);
      }
  }
  
  void
  dpif_register_upcall_cb(struct dpif *dpif, upcall_callback *cb, void *aux)
  {
      if (dpif->dpif_class->register_upcall_cb) {
          dpif->dpif_class->register_upcall_cb(dpif, cb, aux);
      }
  }
  
  void
  dpif_enable_upcall(struct dpif *dpif)
  {
      if (dpif->dpif_class->enable_upcall) {
          dpif->dpif_class->enable_upcall(dpif);
      }
  }
  
  void
  dpif_disable_upcall(struct dpif *dpif)
  {
      if (dpif->dpif_class->disable_upcall) {
          dpif->dpif_class->disable_upcall(dpif);
      }
  }
  
  void
  dpif_print_packet(struct dpif *dpif, struct dpif_upcall *upcall)
  {
      if (!VLOG_DROP_DBG(&dpmsg_rl)) {
          struct ds flow;
          char *packet;
  
          packet = ofp_dp_packet_to_string(&upcall->packet);
  
          ds_init(&flow);
          odp_flow_key_format(upcall->key, upcall->key_len, &flow);
  
          VLOG_DBG("%s: %s upcall:\n%s\n%s",
                   dpif_name(dpif), dpif_upcall_type_to_string(upcall->type),
                   ds_cstr(&flow), packet);
  
          ds_destroy(&flow);
          free(packet);
      }
  }
  
  /* Pass custom configuration to the datapath implementation.  Some of the
   * changes can be postponed until dpif_run() is called. */
  int
  dpif_set_config(struct dpif *dpif, const struct smap *cfg)
  {
      int error = 0;
  
      if (dpif->dpif_class->set_config) {
          error = dpif->dpif_class->set_config(dpif, cfg);
          if (error) {
              log_operation(dpif, "set_config", error);
          }
      }
  
      return error;
  }
  
  /* Polls for an upcall from 'dpif' for an upcall handler.  Since there can
   * be multiple poll loops, 'handler_id' is needed as index to identify the
   * corresponding poll loop.  If successful, stores the upcall into '*upcall',
   * using 'buf' for storage.  Should only be called if 'recv_set' has been used
   * to enable receiving packets from 'dpif'.
   *
   * 'upcall->key' and 'upcall->userdata' point into data in the caller-provided
   * 'buf', so their memory cannot be freed separately from 'buf'.
   *
   * The caller owns the data of 'upcall->packet' and may modify it.  If
   * packet's headroom is exhausted as it is manipulated, 'upcall->packet'
   * will be reallocated.  This requires the data of 'upcall->packet' to be
   * released with ofpbuf_uninit() before 'upcall' is destroyed.  However,
   * when an error is returned, the 'upcall->packet' may be uninitialized
   * and should not be released.
   *
   * Returns 0 if successful, otherwise a positive errno value.  Returns EAGAIN
   * if no upcall is immediately available. */
  int
  dpif_recv(struct dpif *dpif, uint32_t handler_id, struct dpif_upcall *upcall,
            struct ofpbuf *buf)
  {
      int error = EAGAIN;
  
      if (dpif->dpif_class->recv) {
          error = dpif->dpif_class->recv(dpif, handler_id, upcall, buf);
          if (!error) {
              dpif_print_packet(dpif, upcall);
          } else if (error != EAGAIN) {
              log_operation(dpif, "recv", error);
          }
      }
      return error;
  }
  
  /* Discards all messages that would otherwise be received by dpif_recv() on
   * 'dpif'. */
  void
  dpif_recv_purge(struct dpif *dpif)
  {
      COVERAGE_INC(dpif_purge);
      if (dpif->dpif_class->recv_purge) {
          dpif->dpif_class->recv_purge(dpif);
      }
  }
  
  /* Arranges for the poll loop for an upcall handler to wake up when 'dpif'
   * 'dpif' has a message queued to be received with the recv member
   * function.  Since there can be multiple poll loops, 'handler_id' is
   * needed as index to identify the corresponding poll loop. */
  void
  dpif_recv_wait(struct dpif *dpif, uint32_t handler_id)
  {
      if (dpif->dpif_class->recv_wait) {
          dpif->dpif_class->recv_wait(dpif, handler_id);
      }
  }
  
  /*
   * Return the datapath version. Caller is responsible for freeing
   * the string.
   */
  char *
  dpif_get_dp_version(const struct dpif *dpif)
  {
      char *version = NULL;
  
      if (dpif->dpif_class->get_datapath_version) {
          version = dpif->dpif_class->get_datapath_version();
      }
  
      return version;
  }
  
  /* Obtains the NetFlow engine type and engine ID for 'dpif' into '*engine_type'
   * and '*engine_id', respectively. */
  void
  dpif_get_netflow_ids(const struct dpif *dpif,
                       uint8_t *engine_type, uint8_t *engine_id)
  {
      *engine_type = dpif->netflow_engine_type;
      *engine_id = dpif->netflow_engine_id;
  }
  
  /* Translates OpenFlow queue ID 'queue_id' (in host byte order) into a priority
   * value used for setting packet priority.
   * On success, returns 0 and stores the priority into '*priority'.
   * On failure, returns a positive errno value and stores 0 into '*priority'. */
  int
  dpif_queue_to_priority(const struct dpif *dpif, uint32_t queue_id,
                         uint32_t *priority)
  {
      int error = (dpif->dpif_class->queue_to_priority
                   ? dpif->dpif_class->queue_to_priority(dpif, queue_id,
                                                         priority)
                   : EOPNOTSUPP);
      if (error) {
          *priority = 0;
      }
      log_operation(dpif, "queue_to_priority", error);
      return error;
  }
  
  void
  dpif_init(struct dpif *dpif, const struct dpif_class *dpif_class,
            const struct dpif_offload_class *offload_class, const char *name,
            uint8_t netflow_engine_type, uint8_t netflow_engine_id)
  {
      dpif->dpif_class = dpif_class;
      dpif->offload_class = offload_class;
      dpif->base_name = xstrdup(name);
      dpif->full_name = xasprintf("%s@%s", dpif_class->type, name);
      dpif->netflow_engine_type = netflow_engine_type;
      dpif->netflow_engine_id = netflow_engine_id;
  }
  
  /* Undoes the results of initialization.
   *
   * Normally this function only needs to be called from dpif_close().
   * However, it may be called by providers due to an error on opening
   * that occurs after initialization.  It this case dpif_close() would
   * never be called. */
  void
  dpif_uninit(struct dpif *dpif, bool close)
  {
      char *base_name = dpif->base_name;
      char *full_name = dpif->full_name;
  
      if (close) {
          dpif->dpif_class->close(dpif);
      }
  
      free(base_name);
      free(full_name);
  }
  
  static void
  log_operation(const struct dpif *dpif, const char *operation, int error)
  {
      if (!error) {
          VLOG_DBG_RL(&dpmsg_rl, "%s: %s success", dpif_name(dpif), operation);
      } else if (ofperr_is_valid(error)) {
          VLOG_WARN_RL(&error_rl, "%s: %s failed (%s)",
                       dpif_name(dpif), operation, ofperr_get_name(error));
      } else {
          VLOG_WARN_RL(&error_rl, "%s: %s failed (%s)",
                       dpif_name(dpif), operation, ovs_strerror(error));
      }
  }
  
  static enum vlog_level
  flow_message_log_level(int error)
  {
      /* If flows arrive in a batch, userspace may push down multiple
       * unique flow definitions that overlap when wildcards are applied.
       * Kernels that support flow wildcarding will reject these flows as
       * duplicates (EEXIST), so lower the log level to debug for these
       * types of messages. */
      return (error && error != EEXIST) ? VLL_WARN : VLL_DBG;
  }
  
  static bool
  should_log_flow_message(const struct vlog_module *module, int error)
  {
      return !vlog_should_drop(module, flow_message_log_level(error),
                               error ? &error_rl : &dpmsg_rl);
  }
  
  void
  log_flow_message(const struct dpif *dpif, int error,
                   const struct vlog_module *module,
                   const char *operation,
                   const struct nlattr *key, size_t key_len,
                   const struct nlattr *mask, size_t mask_len,
                   const ovs_u128 *ufid, const struct dpif_flow_stats *stats,
                   const struct nlattr *actions, size_t actions_len)
  {
      struct ds ds = DS_EMPTY_INITIALIZER;
      ds_put_format(&ds, "%s: ", dpif_name(dpif));
      if (error) {
          ds_put_cstr(&ds, "failed to ");
      }
      ds_put_format(&ds, "%s ", operation);
      if (error) {
          ds_put_format(&ds, "(%s) ", ovs_strerror(error));
      }
      if (ufid) {
          odp_format_ufid(ufid, &ds);
          ds_put_cstr(&ds, " ");
      }
      odp_flow_format(key, key_len, mask, mask_len, NULL, &ds, true);
      if (stats) {
          ds_put_cstr(&ds, ", ");
          dpif_flow_stats_format(stats, &ds);
      }
      if (actions || actions_len) {
          ds_put_cstr(&ds, ", actions:");
          format_odp_actions(&ds, actions, actions_len, NULL);
      }
      vlog(module, flow_message_log_level(error), "%s", ds_cstr(&ds));
      ds_destroy(&ds);
  }
  
  void
  log_flow_put_message(const struct dpif *dpif,
                       const struct vlog_module *module,
                       const struct dpif_flow_put *put,
                       int error)
  {
      if (should_log_flow_message(module, error)
          && !(put->flags & DPIF_FP_PROBE)) {
          struct ds s;
  
          ds_init(&s);
          ds_put_cstr(&s, "put");
          if (put->flags & DPIF_FP_CREATE) {
              ds_put_cstr(&s, "[create]");
          }
          if (put->flags & DPIF_FP_MODIFY) {
              ds_put_cstr(&s, "[modify]");
          }
          if (put->flags & DPIF_FP_ZERO_STATS) {
              ds_put_cstr(&s, "[zero]");
          }
          log_flow_message(dpif, error, module, ds_cstr(&s),
                           put->key, put->key_len, put->mask, put->mask_len,
                           put->ufid, put->stats, put->actions,
                           put->actions_len);
          ds_destroy(&s);
      }
  }
  
  void
  log_flow_del_message(const struct dpif *dpif,
                       const struct vlog_module *module,
                       const struct dpif_flow_del *del,
                       int error)
  {
      if (should_log_flow_message(module, error)) {
          log_flow_message(dpif, error, module, "flow_del",
                           del->key, del->key_len,
                           NULL, 0, del->ufid, !error ? del->stats : NULL,
                           NULL, 0);
      }
  }
  
  /* Logs that 'execute' was executed on 'dpif' and completed with errno 'error'
   * (0 for success).  'subexecute' should be true if the execution is a result
   * of breaking down a larger execution that needed help, false otherwise.
   *
   *
   * XXX In theory, the log message could be deceptive because this function is
   * called after the dpif_provider's '->execute' function, which is allowed to
   * modify execute->packet and execute->md.  In practice, though:
   *
   *     - dpif-netlink doesn't modify execute->packet or execute->md.
   *
   *     - dpif-netdev does modify them but it is less likely to have problems
   *       because it is built into ovs-vswitchd and cannot have version skew,
   *       etc.
   *
   * It would still be better to avoid the potential problem.  I don't know of a
   * good way to do that, though, that isn't expensive. */
  void
  log_execute_message(const struct dpif *dpif,
                      const struct vlog_module *module,
                      const struct dpif_execute *execute,
                      bool subexecute, int error)
  {
      if (!(error ? VLOG_DROP_WARN(&error_rl) : VLOG_DROP_DBG(&dpmsg_rl))
          && !execute->probe) {
          struct ds ds = DS_EMPTY_INITIALIZER;
          char *packet;
          uint64_t stub[1024 / 8];
          struct ofpbuf md = OFPBUF_STUB_INITIALIZER(stub);
  
          packet = ofp_packet_to_string(dp_packet_data(execute->packet),
                                        dp_packet_size(execute->packet),
                                        execute->packet->packet_type);
          odp_key_from_dp_packet(&md, execute->packet);
          ds_put_format(&ds, "%s: %sexecute ",
                        dpif_name(dpif),
                        (subexecute ? "sub-"
                         : dpif_execute_needs_help(execute) ? "super-"
                         : ""));
          format_odp_actions(&ds, execute->actions, execute->actions_len, NULL);
          if (error) {
              ds_put_format(&ds, " failed (%s)", ovs_strerror(error));
          }
          ds_put_format(&ds, " on packet %s", packet);
          ds_put_format(&ds, " with metadata ");
          odp_flow_format(md.data, md.size, NULL, 0, NULL, &ds, true);
          ds_put_format(&ds, " mtu %d", execute->mtu);
          vlog(module, error ? VLL_WARN : VLL_DBG, "%s", ds_cstr(&ds));
          ds_destroy(&ds);
          free(packet);
          ofpbuf_uninit(&md);
      }
  }
  
  void
  log_flow_get_message(const struct dpif *dpif,
                       const struct vlog_module *module,
                       const struct dpif_flow_get *get,
                       int error)
  {
      if (should_log_flow_message(module, error)) {
          log_flow_message(dpif, error, module, "flow_get",
                           get->key, get->key_len,
                           get->flow->mask, get->flow->mask_len,
                           get->ufid, &get->flow->stats,
                           get->flow->actions, get->flow->actions_len);
      }
  }
  
  bool
  dpif_supports_tnl_push_pop(const struct dpif *dpif)
  {
      return dpif_is_netdev(dpif);
  }
  
  bool
  dpif_supports_explicit_drop_action(const struct dpif *dpif)
  {
      return dpif_is_netdev(dpif);
  }
  
  bool
  dpif_supports_lb_output_action(const struct dpif *dpif)
  {
      /*
       * Balance-tcp optimization is currently supported in netdev
       * datapath only.
       */
      return dpif_is_netdev(dpif);
  }
  
  /* Meters */
  void
  dpif_meter_get_features(const struct dpif *dpif,
                          struct ofputil_meter_features *features)
  {
      memset(features, 0, sizeof *features);
      if (dpif->dpif_class->meter_get_features) {
          dpif->dpif_class->meter_get_features(dpif, features);
      }
  }
  
  /* Adds or modifies the meter in 'dpif' with the given 'meter_id' and
   * the configuration in 'config'.
   *
   * The meter id specified through 'config->meter_id' is ignored. */
  int
  dpif_meter_set(struct dpif *dpif, ofproto_meter_id meter_id,
                 struct ofputil_meter_config *config)
  {
      COVERAGE_INC(dpif_meter_set);
  
      if (!(config->flags & (OFPMF13_KBPS | OFPMF13_PKTPS))) {
          return EBADF; /* Rate unit type not set. */
      }
  
      if ((config->flags & OFPMF13_KBPS) && (config->flags & OFPMF13_PKTPS)) {
          return EBADF; /* Both rate units may not be set. */
      }
  
      if (config->n_bands == 0) {
          return EINVAL;
      }
  
      for (size_t i = 0; i < config->n_bands; i++) {
          if (config->bands[i].rate == 0) {
              return EDOM; /* Rate must be non-zero */
          }
      }
  
      int error = dpif->dpif_class->meter_set(dpif, meter_id, config);
      if (!error) {
          VLOG_DBG_RL(&dpmsg_rl, "%s: DPIF meter %"PRIu32" set",
                      dpif_name(dpif), meter_id.uint32);
      } else {
          VLOG_WARN_RL(&error_rl, "%s: failed to set DPIF meter %"PRIu32": %s",
                       dpif_name(dpif), meter_id.uint32, ovs_strerror(error));
      }
      return error;
  }
  
  int
  dpif_meter_get(const struct dpif *dpif, ofproto_meter_id meter_id,
                 struct ofputil_meter_stats *stats, uint16_t n_bands)
  {
      int error;
  
      COVERAGE_INC(dpif_meter_get);
  
      error = dpif->dpif_class->meter_get(dpif, meter_id, stats, n_bands);
      if (!error) {
          VLOG_DBG_RL(&dpmsg_rl, "%s: DPIF meter %"PRIu32" get stats",
                      dpif_name(dpif), meter_id.uint32);
      } else {
          VLOG_WARN_RL(&error_rl,
                       "%s: failed to get DPIF meter %"PRIu32" stats: %s",
                       dpif_name(dpif), meter_id.uint32, ovs_strerror(error));
          stats->packet_in_count = ~0;
          stats->byte_in_count = ~0;
          stats->n_bands = 0;
      }
      return error;
  }
  
  int
  dpif_meter_del(struct dpif *dpif, ofproto_meter_id meter_id,
                 struct ofputil_meter_stats *stats, uint16_t n_bands)
  {
      int error;
  
      COVERAGE_INC(dpif_meter_del);
  
      error = dpif->dpif_class->meter_del(dpif, meter_id, stats, n_bands);
      if (!error) {
          VLOG_DBG_RL(&dpmsg_rl, "%s: DPIF meter %"PRIu32" deleted",
                      dpif_name(dpif), meter_id.uint32);
      } else {
          VLOG_WARN_RL(&error_rl,
                       "%s: failed to delete DPIF meter %"PRIu32": %s",
                       dpif_name(dpif), meter_id.uint32, ovs_strerror(error));
          if (stats) {
              stats->packet_in_count = ~0;
              stats->byte_in_count = ~0;
              stats->n_bands = 0;
          }
      }
      return error;
  }
  
  int
  dpif_bond_add(struct dpif *dpif, uint32_t bond_id, odp_port_t *member_map)
  {
      return dpif->dpif_class->bond_add
             ? dpif->dpif_class->bond_add(dpif, bond_id, member_map)
             : EOPNOTSUPP;
  }
  
  int
  dpif_bond_del(struct dpif *dpif, uint32_t bond_id)
  {
      return dpif->dpif_class->bond_del
             ? dpif->dpif_class->bond_del(dpif, bond_id)
             : EOPNOTSUPP;
  }
  
  int
  dpif_bond_stats_get(struct dpif *dpif, uint32_t bond_id,
                      uint64_t *n_bytes)
  {
      memset(n_bytes, 0, BOND_BUCKETS * sizeof *n_bytes);
  
      return dpif->dpif_class->bond_stats_get
             ? dpif->dpif_class->bond_stats_get(dpif, bond_id, n_bytes)
             : EOPNOTSUPP;
  }
  
  int
  dpif_get_n_offloaded_flows(struct dpif *dpif, uint64_t *n_flows)
  {
      const char *dpif_type_str = dpif_normalize_type(dpif_type(dpif));
      struct dpif_port_dump port_dump;
      struct dpif_port dpif_port;
      int ret, n_devs = 0;
      uint64_t nflows;
  
      *n_flows = 0;
      DPIF_PORT_FOR_EACH (&dpif_port, &port_dump, dpif) {
          ret = netdev_ports_get_n_flows(dpif_type_str, dpif_port.port_no,
                                         &nflows);
          if (!ret) {
              *n_flows += nflows;
          } else if (ret == EOPNOTSUPP) {
              continue;
          }
          n_devs++;
      }
      return n_devs ? 0 : EOPNOTSUPP;
  }
  
  int
  dpif_cache_get_supported_levels(struct dpif *dpif, uint32_t *levels)
  {
      return dpif->dpif_class->cache_get_supported_levels
             ? dpif->dpif_class->cache_get_supported_levels(dpif, levels)
             : EOPNOTSUPP;
  }
  
  int
  dpif_cache_get_name(struct dpif *dpif, uint32_t level, const char **name)
  {
      return dpif->dpif_class->cache_get_name
             ? dpif->dpif_class->cache_get_name(dpif, level, name)
             : EOPNOTSUPP;
  }
  
  int
  dpif_cache_get_size(struct dpif *dpif, uint32_t level, uint32_t *size)
  {
      return dpif->dpif_class->cache_get_size
             ? dpif->dpif_class->cache_get_size(dpif, level, size)
             : EOPNOTSUPP;
  }
  
  int
  dpif_cache_set_size(struct dpif *dpif, uint32_t level, uint32_t size)
  {
      return dpif->dpif_class->cache_set_size
             ? dpif->dpif_class->cache_set_size(dpif, level, size)
             : EOPNOTSUPP;
  }
  