lib/netdev-provider.h

   1 /*
   2  * Copyright (c) 2009, 2010 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef NETDEV_PROVIDER_H
  18 #define NETDEV_PROVIDER_H 1
  19
  20 /* Generic interface to network devices. */
  21
  22 #include <assert.h>
  23
  24 #include "netdev.h"
  25 #include "list.h"
  26 #include "shash.h"
  27
  28 #ifdef  __cplusplus
  29 extern "C" {
  30 #endif
  31
  32 struct arg {
  33     char *key;
  34     char *value;
  35 };
  36
  37 /* A network device (e.g. an Ethernet device).
  38  *
  39  * This structure should be treated as opaque by network device
  40  * implementations. */
  41 struct netdev_dev {
  42     char *name;                         /* Name of network device. */
  43     const struct netdev_class *netdev_class; /* Functions to control
  44                                                 this device. */
  45     int ref_cnt;                        /* Times this devices was opened. */
  46     struct shash_node *node;            /* Pointer to element in global map. */
  47     struct arg *args;                   /* Argument list from last config. */
  48     int n_args;                         /* Number of arguments in 'args'. */
  49 };
  50
  51 void netdev_dev_init(struct netdev_dev *, const char *name,
  52                      const struct netdev_class *);
  53 void netdev_dev_uninit(struct netdev_dev *, bool destroy);
  54 const char *netdev_dev_get_type(const struct netdev_dev *);
  55 const struct netdev_class *netdev_dev_get_class(const struct netdev_dev *);
  56 const char *netdev_dev_get_name(const struct netdev_dev *);
  57 struct netdev_dev *netdev_dev_from_name(const char *name);
  58 void netdev_dev_get_devices(const struct netdev_class *,
  59                             struct shash *device_list);
  60
  61 static inline void netdev_dev_assert_class(const struct netdev_dev *netdev_dev,
  62                                            const struct netdev_class *class_)
  63 {
  64     assert(netdev_dev->netdev_class == class_);
  65 }
  66
  67 /* A instance of an open network device.
  68  *
  69  * This structure should be treated as opaque by network device
  70  * implementations. */
  71 struct netdev {
  72     struct netdev_dev *netdev_dev;   /* Parent netdev_dev. */
  73     struct list node;                /* Element in global list. */
  74
  75     enum netdev_flags save_flags;    /* Initial device flags. */
  76     enum netdev_flags changed_flags; /* Flags that we changed. */
  77 };
  78
  79 void netdev_init(struct netdev *, struct netdev_dev *);
  80 void netdev_uninit(struct netdev *, bool close);
  81 struct netdev_dev *netdev_get_dev(const struct netdev *);
  82
  83 static inline void netdev_assert_class(const struct netdev *netdev,
  84                                        const struct netdev_class *netdev_class)
  85 {
  86     netdev_dev_assert_class(netdev_get_dev(netdev), netdev_class);
  87 }
  88
  89 /* A network device notifier.
  90  *
  91  * Network device implementations should use netdev_notifier_init() to
  92  * initialize this structure, but they may freely read its members after
  93  * initialization. */
  94 struct netdev_notifier {
  95     struct netdev *netdev;
  96     void (*cb)(struct netdev_notifier *);
  97     void *aux;
  98 };
  99 void netdev_notifier_init(struct netdev_notifier *, struct netdev *,
 100                           void (*cb)(struct netdev_notifier *), void *aux);
 101
 102 /* Network device class structure, to be defined by each implementation of a
 103  * network device.
 104  *
 105  * These functions return 0 if successful or a positive errno value on failure,
 106  * except where otherwise noted. */
 107 struct netdev_class {
 108     /* Type of netdevs in this class, e.g. "system", "tap", "gre", etc.
 109      *
 110      * One of the providers should supply a "system" type, since this is
 111      * the type assumed if no type is specified when opening a netdev.
 112      * The "system" type corresponds to an existing network device on
 113      * the system. */
 114     const char *type;
 115
 116     /* Called when the netdev provider is registered, typically at program
 117      * startup.  Returning an error from this function will prevent any network
 118      * device in this class from being opened.
 119      *
 120      * This function may be set to null if a network device class needs no
 121      * initialization at registration time. */
 122     int (*init)(void);
 123
 124     /* Performs periodic work needed by netdevs of this class.  May be null if
 125      * no periodic work is necessary. */
 126     void (*run)(void);
 127
 128     /* Arranges for poll_block() to wake up if the "run" member function needs
 129      * to be called.  May be null if nothing is needed here. */
 130     void (*wait)(void);
 131
 132     /* Attempts to create a network device named 'name' with initial 'args' in
 133      * 'netdev_class'.  On success sets 'netdev_devp' to the newly created
 134      * device. */
 135     int (*create)(const struct netdev_class *netdev_class, const char *name,
 136                   const struct shash *args, struct netdev_dev **netdev_devp);
 137
 138     /* Destroys 'netdev_dev'.
 139      *
 140      * Netdev devices maintain a reference count that is incremented on
 141      * netdev_open() and decremented on netdev_close().  If 'netdev_dev'
 142      * has a non-zero reference count, then this function will not be
 143      * called. */
 144     void (*destroy)(struct netdev_dev *netdev_dev);
 145
 146     /* Reconfigures the device 'netdev_dev' with 'args'.
 147      *
 148      * If this netdev class does not support reconfiguring a netdev
 149      * device, this may be a null pointer.
 150      */
 151     int (*reconfigure)(struct netdev_dev *netdev_dev, const struct shash *args);
 152
 153     /* Attempts to open a network device.  On success, sets 'netdevp'
 154      * to the new network device.
 155      *
 156      * 'ethertype' may be a 16-bit Ethernet protocol value in host byte order
 157      * to capture frames of that type received on the device.  It may also be
 158      * one of the 'enum netdev_pseudo_ethertype' values to receive frames in
 159      * one of those categories. */
 160     int (*open)(struct netdev_dev *netdev_dev, int ethertype,
 161                 struct netdev **netdevp);
 162
 163     /* Closes 'netdev'. */
 164     void (*close)(struct netdev *netdev);
 165
 166     /* Enumerates the names of all network devices of this class.
 167      *
 168      * The caller has already initialized 'all_names' and might already have
 169      * added some names to it.  This function should not disturb any existing
 170      * names in 'all_names'.
 171      *
 172      * If this netdev class does not support enumeration, this may be a null
 173      * pointer. */
 174     int (*enumerate)(struct svec *all_names);
 175
 176     /* Attempts to receive a packet from 'netdev' into the 'size' bytes in
 177      * 'buffer'.  If successful, returns the number of bytes in the received
 178      * packet, otherwise a negative errno value.  Returns -EAGAIN immediately
 179      * if no packet is ready to be received.
 180      *
 181      * May return -EOPNOTSUPP if a network device does not implement packet
 182      * reception through this interface.  This function may be set to null if
 183      * it would always return -EOPNOTSUPP anyhow.  (This will disable the OVS
 184      * integrated DHCP client and OpenFlow controller discovery, and prevent
 185      * the network device from being usefully used by the netdev-based
 186      * "userspace datapath".) */
 187     int (*recv)(struct netdev *netdev, void *buffer, size_t size);
 188
 189     /* Registers with the poll loop to wake up from the next call to
 190      * poll_block() when a packet is ready to be received with netdev_recv() on
 191      * 'netdev'.
 192      *
 193      * May be null if not needed, such as for a network device that does not
 194      * implement packet reception through the 'recv' member function. */
 195     void (*recv_wait)(struct netdev *netdev);
 196
 197     /* Discards all packets waiting to be received from 'netdev'.
 198      *
 199      * May be null if not needed, such as for a network device that does not
 200      * implement packet reception through the 'recv' member function. */
 201     int (*drain)(struct netdev *netdev);
 202
 203     /* Sends the 'size'-byte packet in 'buffer' on 'netdev'.  Returns 0 if
 204      * successful, otherwise a positive errno value.  Returns EAGAIN without
 205      * blocking if the packet cannot be queued immediately.  Returns EMSGSIZE
 206      * if a partial packet was transmitted or if the packet is too big or too
 207      * small to transmit on the device.
 208      *
 209      * The caller retains ownership of 'buffer' in all cases.
 210      *
 211      * The network device is expected to maintain a packet transmission queue,
 212      * so that the caller does not ordinarily have to do additional queuing of
 213      * packets.
 214      *
 215      * May return EOPNOTSUPP if a network device does not implement packet
 216      * transmission through this interface.  This function may be set to null
 217      * if it would always return EOPNOTSUPP anyhow.  (This will disable the OVS
 218      * integrated DHCP client and OpenFlow controller discovery, and prevent
 219      * the network device from being usefully used by the netdev-based
 220      * "userspace datapath".) */
 221     int (*send)(struct netdev *netdev, const void *buffer, size_t size);
 222
 223     /* Registers with the poll loop to wake up from the next call to
 224      * poll_block() when the packet transmission queue for 'netdev' has
 225      * sufficient room to transmit a packet with netdev_send().
 226      *
 227      * The network device is expected to maintain a packet transmission queue,
 228      * so that the caller does not ordinarily have to do additional queuing of
 229      * packets.  Thus, this function is unlikely to ever be useful.
 230      *
 231      * May be null if not needed, such as for a network device that does not
 232      * implement packet transmission through the 'send' member function. */
 233     void (*send_wait)(struct netdev *netdev);
 234
 235     /* Sets 'netdev''s Ethernet address to 'mac' */
 236     int (*set_etheraddr)(struct netdev *netdev, const uint8_t mac[6]);
 237
 238     /* Retrieves 'netdev''s Ethernet address into 'mac'. */
 239     int (*get_etheraddr)(const struct netdev *netdev, uint8_t mac[6]);
 240
 241     /* Retrieves 'netdev''s MTU into '*mtup'.
 242      *
 243      * The MTU is the maximum size of transmitted (and received) packets, in
 244      * bytes, not including the hardware header; thus, this is typically 1500
 245      * bytes for Ethernet devices.*/
 246     int (*get_mtu)(const struct netdev *netdev, int *mtup);
 247
 248     /* Returns the ifindex of 'netdev', if successful, as a positive number.
 249      * On failure, returns a negative errno value.
 250      *
 251      * The desired semantics of the ifindex value are a combination of those
 252      * specified by POSIX for if_nametoindex() and by SNMP for ifIndex.  An
 253      * ifindex value should be unique within a host and remain stable at least
 254      * until reboot.  SNMP says an ifindex "ranges between 1 and the value of
 255      * ifNumber" but many systems do not follow this rule anyhow.
 256      *
 257      * This function may be set to null if it would always return -EOPNOTSUPP.
 258      */
 259     int (*get_ifindex)(const struct netdev *netdev);
 260
 261     /* Sets 'carrier' to true if carrier is active (link light is on) on
 262      * 'netdev'.
 263      *
 264      * May be null if device does not provide carrier status (will be always
 265      * up as long as device is up).
 266      */
 267     int (*get_carrier)(const struct netdev *netdev, bool *carrier);
 268
 269     /* Retrieves current device stats for 'netdev' into 'stats'.
 270      *
 271      * A network device that supports some statistics but not others, it should
 272      * set the values of the unsupported statistics to all-1-bits
 273      * (UINT64_MAX). */
 274     int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
 275
 276     /* Sets the device stats for 'netdev' to 'stats'.
 277      *
 278      * Most network devices won't support this feature and will set this
 279      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 280      *
 281      * Some network devices might only allow setting their stats to 0. */
 282     int (*set_stats)(struct netdev *netdev, const struct netdev_stats *);
 283
 284     /* Stores the features supported by 'netdev' into each of '*current',
 285      * '*advertised', '*supported', and '*peer'.  Each value is a bitmap of
 286      * "enum ofp_port_features" bits, in host byte order.
 287      *
 288      * This function may be set to null if it would always return EOPNOTSUPP.
 289      */
 290     int (*get_features)(struct netdev *netdev,
 291                         uint32_t *current, uint32_t *advertised,
 292                         uint32_t *supported, uint32_t *peer);
 293
 294     /* Set the features advertised by 'netdev' to 'advertise', which is a
 295      * bitmap of "enum ofp_port_features" bits, in host byte order.
 296      *
 297      * This function may be set to null for a network device that does not
 298      * support configuring advertisements. */
 299     int (*set_advertisements)(struct netdev *netdev, uint32_t advertise);
 300
 301     /* If 'netdev' is a VLAN network device (e.g. one created with vconfig(8)),
 302      * sets '*vlan_vid' to the VLAN VID associated with that device and returns
 303      * 0.
 304      *
 305      * Returns ENOENT if 'netdev' is a network device that is not a
 306      * VLAN device.
 307      *
 308      * This function should be set to null if it doesn't make any sense for
 309      * your network device (it probably doesn't). */
 310     int (*get_vlan_vid)(const struct netdev *netdev, int *vlan_vid);
 311
 312     /* Attempts to set input rate limiting (policing) policy, such that up to
 313      * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative
 314      * burst size of 'kbits' kb.
 315      *
 316      * This function may be set to null if policing is not supported. */
 317     int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
 318                         unsigned int kbits_burst);
 319
 320     /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves
 321      * it empty if 'netdev' does not support QoS.  Any names added to 'types'
 322      * should be documented as valid for the "type" column in the "QoS" table
 323      * in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 324      *
 325      * Every network device must support disabling QoS with a type of "", but
 326      * this function must not add "" to 'types'.
 327      *
 328      * The caller is responsible for initializing 'types' (e.g. with
 329      * svec_init()) before calling this function.  The caller takes ownership
 330      * of the strings added to 'types'.
 331      *
 332      * May be NULL if 'netdev' does not support QoS at all. */
 333     int (*get_qos_types)(const struct netdev *netdev, struct svec *types);
 334
 335     /* Queries 'netdev' for its capabilities regarding the specified 'type' of
 336      * QoS.  On success, initializes 'caps' with the QoS capabilities.
 337      *
 338      * Should return EOPNOTSUPP if 'netdev' does not support 'type'.  May be
 339      * NULL if 'netdev' does not support QoS at all. */
 340     int (*get_qos_capabilities)(const struct netdev *netdev,
 341                                 const char *type,
 342                                 struct netdev_qos_capabilities *caps);
 343
 344     /* Queries 'netdev' about its currently configured form of QoS.  If
 345      * successful, stores the name of the current form of QoS into '*typep'
 346      * and any details of configuration as string key-value pairs in
 347      * 'details'.
 348      *
 349      * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
 350      *
 351      * The caller initializes 'details' before calling this function.  The
 352      * caller takes ownership of the string key-values pairs added to
 353      * 'details'.
 354      *
 355      * The netdev retains ownership of '*typep'.
 356      *
 357      * '*typep' will be one of the types returned by netdev_get_qos_types() for
 358      * 'netdev'.  The contents of 'details' should be documented as valid for
 359      * '*typep' in the "other_config" column in the "QoS" table in
 360      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 361      *
 362      * May be NULL if 'netdev' does not support QoS at all. */
 363     int (*get_qos)(const struct netdev *netdev,
 364                    const char **typep, struct shash *details);
 365
 366     /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
 367      * 'type' with details of configuration from 'details'.
 368      *
 369      * On error, the previous QoS configuration is retained.
 370      *
 371      * When this function changes the type of QoS (not just 'details'), this
 372      * also resets all queue configuration for 'netdev' to their defaults
 373      * (which depend on the specific type of QoS).  Otherwise, the queue
 374      * configuration for 'netdev' is unchanged.
 375      *
 376      * 'type' should be "" (to disable QoS) or one of the types returned by
 377      * netdev_get_qos_types() for 'netdev'.  The contents of 'details' should
 378      * be documented as valid for the given 'type' in the "other_config" column
 379      * in the "QoS" table in vswitchd/vswitch.xml (which is built as
 380      * ovs-vswitchd.conf.db(8)).
 381      *
 382      * May be NULL if 'netdev' does not support QoS at all. */
 383     int (*set_qos)(struct netdev *netdev,
 384                    const char *type, const struct shash *details);
 385
 386     /* Queries 'netdev' for information about the queue numbered 'queue_id'.
 387      * If successful, adds that information as string key-value pairs to
 388      * 'details'.  Returns 0 if successful, otherwise a positive errno value.
 389      *
 390      * Should return EINVAL if 'queue_id' is greater than or equal to the
 391      * number of supported queues (as reported in the 'n_queues' member of
 392      * struct netdev_qos_capabilities by 'get_qos_capabilities').
 393      *
 394      * The caller initializes 'details' before calling this function.  The
 395      * caller takes ownership of the string key-values pairs added to
 396      * 'details'.
 397      *
 398      * The returned contents of 'details' should be documented as valid for the
 399      * given 'type' in the "other_config" column in the "Queue" table in
 400      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 401      */
 402     int (*get_queue)(const struct netdev *netdev,
 403                      unsigned int queue_id, struct shash *details);
 404
 405     /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
 406      * string pairs in 'details'.  The contents of 'details' should be
 407      * documented as valid for the given 'type' in the "other_config" column in
 408      * the "Queue" table in vswitchd/vswitch.xml (which is built as
 409      * ovs-vswitchd.conf.db(8)).  Returns 0 if successful, otherwise a positive
 410      * errno value.  On failure, the given queue's configuration should be
 411      * unmodified.
 412      *
 413      * Should return EINVAL if 'queue_id' is greater than or equal to the
 414      * number of supported queues (as reported in the 'n_queues' member of
 415      * struct netdev_qos_capabilities by 'get_qos_capabilities'), or if
 416      * 'details' is invalid for the type of queue.
 417      *
 418      * This function does not modify 'details', and the caller retains
 419      * ownership of it.
 420      *
 421      * May be NULL if 'netdev' does not support QoS at all. */
 422     int (*set_queue)(struct netdev *netdev,
 423                      unsigned int queue_id, const struct shash *details);
 424
 425     /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
 426      *
 427      * Should return EINVAL if 'queue_id' is greater than or equal to the
 428      * number of supported queues (as reported in the 'n_queues' member of
 429      * struct netdev_qos_capabilities by 'get_qos_capabilities').  Should
 430      * return EOPNOTSUPP if 'queue_id' is valid but may not be deleted (e.g. if
 431      * 'netdev' has a fixed set of queues with the current QoS mode).
 432      *
 433      * May be NULL if 'netdev' does not support QoS at all, or if all of its
 434      * QoS modes have fixed sets of queues. */
 435     int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
 436
 437     /* Obtains statistics about 'queue_id' on 'netdev'.  Fills 'stats' with the
 438      * queue's statistics.  May set individual members of 'stats' to all-1-bits
 439      * if the statistic is unavailable.
 440      *
 441      * May be NULL if 'netdev' does not support QoS at all. */
 442     int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
 443                            struct netdev_queue_stats *stats);
 444
 445     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 446      * ID, its configuration, and the 'aux' specified by the caller.  The order
 447      * of iteration is unspecified, but (when successful) each queue is visited
 448      * exactly once.
 449      *
 450      * 'cb' will not modify or free the 'details' argument passed in. */
 451     int (*dump_queues)(const struct netdev *netdev,
 452                        void (*cb)(unsigned int queue_id,
 453                                   const struct shash *details,
 454                                   void *aux),
 455                        void *aux);
 456
 457     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 458      * ID, its statistics, and the 'aux' specified by the caller.  The order of
 459      * iteration is unspecified, but (when successful) each queue must be
 460      * visited exactly once.
 461      *
 462      * 'cb' will not modify or free the statistics passed in. */
 463     int (*dump_queue_stats)(const struct netdev *netdev,
 464                             void (*cb)(unsigned int queue_id,
 465                                        struct netdev_queue_stats *,
 466                                        void *aux),
 467                             void *aux);
 468
 469     /* If 'netdev' has an assigned IPv4 address, sets '*address' to that
 470      * address and '*netmask' to the associated netmask.
 471      *
 472      * The following error values have well-defined meanings:
 473      *
 474      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
 475      *
 476      *   - EOPNOTSUPP: No IPv4 network stack attached to 'netdev'.
 477      *
 478      * This function may be set to null if it would always return EOPNOTSUPP
 479      * anyhow. */
 480     int (*get_in4)(const struct netdev *netdev, struct in_addr *address,
 481                    struct in_addr *netmask);
 482
 483     /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask.  If
 484      * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.
 485      *
 486      * This function may be set to null if it would always return EOPNOTSUPP
 487      * anyhow. */
 488     int (*set_in4)(struct netdev *netdev, struct in_addr addr,
 489                    struct in_addr mask);
 490
 491     /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address.
 492      *
 493      * The following error values have well-defined meanings:
 494      *
 495      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
 496      *
 497      *   - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
 498      *
 499      * This function may be set to null if it would always return EOPNOTSUPP
 500      * anyhow. */
 501     int (*get_in6)(const struct netdev *netdev, struct in6_addr *in6);
 502
 503     /* Adds 'router' as a default IP gateway for the TCP/IP stack that
 504      * corresponds to 'netdev'.
 505      *
 506      * This function may be set to null if it would always return EOPNOTSUPP
 507      * anyhow. */
 508     int (*add_router)(struct netdev *netdev, struct in_addr router);
 509
 510     /* Looks up the next hop for 'host'.  If succesful, stores the next hop
 511      * gateway's address (0 if 'host' is on a directly connected network) in
 512      * '*next_hop' and a copy of the name of the device to reach 'host' in
 513      * '*netdev_name', and returns 0.  The caller is responsible for freeing
 514      * '*netdev_name' (by calling free()).
 515      *
 516      * This function may be set to null if it would always return EOPNOTSUPP
 517      * anyhow. */
 518     int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
 519                         char **netdev_name);
 520
 521     /* Looks up the name of the interface out of which traffic will egress if
 522      * 'netdev' is a tunnel.  If unsuccessful, or 'netdev' is not a tunnel,
 523      * will return null.  This function does not necessarily return the
 524      * physical interface out which traffic will egress.  Instead it returns
 525      * the interface which is assigned 'netdev's remote_ip.  This may be an
 526      * internal interface such as a bridge port.
 527      *
 528      * This function may be set to null if 'netdev' is not a tunnel or it is
 529      * not supported. */
 530     const char *(*get_tnl_iface)(const struct netdev *netdev);
 531
 532     /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
 533      * corresponding MAC address in 'mac'.  A return value of ENXIO, in
 534      * particular, indicates that there is no ARP table entry for 'ip' on
 535      * 'netdev'.
 536      *
 537      * This function may be set to null if it would always return EOPNOTSUPP
 538      * anyhow. */
 539     int (*arp_lookup)(const struct netdev *netdev, uint32_t ip, uint8_t mac[6]);
 540
 541     /* Retrieves the current set of flags on 'netdev' into '*old_flags'.
 542      * Then, turns off the flags that are set to 1 in 'off' and turns on the
 543      * flags that are set to 1 in 'on'.  (No bit will be set to 1 in both 'off'
 544      * and 'on'; that is, off & on == 0.)
 545      *
 546      * This function may be invoked from a signal handler.  Therefore, it
 547      * should not do anything that is not signal-safe (such as logging). */
 548     int (*update_flags)(struct netdev *netdev, enum netdev_flags off,
 549                         enum netdev_flags on, enum netdev_flags *old_flags);
 550
 551     /* Arranges for 'cb' to be called whenever one of the attributes of
 552      * 'netdev' changes and sets '*notifierp' to a newly created
 553      * netdev_notifier that represents this arrangement.  The created notifier
 554      * will have its 'netdev', 'cb', and 'aux' members set to the values of the
 555      * corresponding parameters. */
 556     int (*poll_add)(struct netdev *netdev,
 557                     void (*cb)(struct netdev_notifier *notifier), void *aux,
 558                     struct netdev_notifier **notifierp);
 559
 560     /* Cancels poll notification for 'notifier'. */
 561     void (*poll_remove)(struct netdev_notifier *notifier);
 562 };
 563
 564 int netdev_register_provider(const struct netdev_class *);
 565 int netdev_unregister_provider(const char *type);
 566 const struct netdev_class *netdev_lookup_provider(const char *type);
 567
 568 extern const struct netdev_class netdev_linux_class;
 569 extern const struct netdev_class netdev_internal_class;
 570 extern const struct netdev_class netdev_tap_class;
 571
 572 #ifdef  __cplusplus
 573 }
 574 #endif
 575
 576 #endif /* netdev.h */