2 * Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
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:
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 #ifndef NETDEV_PROVIDER_H
18 #define NETDEV_PROVIDER_H 1
20 /* Generic interface to network devices. */
31 /* A network device (e.g. an Ethernet device).
33 * Network device implementations may read these members but should not modify
36 /* The following do not change during the lifetime of a struct netdev. */
37 char *name; /* Name of network device. */
38 const struct netdev_class *netdev_class; /* Functions to control
41 /* The following are protected by 'netdev_mutex' (internal to netdev.c). */
42 int ref_cnt; /* Times this devices was opened. */
43 struct shash_node *node; /* Pointer to element in global map. */
44 struct list saved_flags_list; /* Contains "struct netdev_saved_flags". */
47 const char *netdev_get_type(const struct netdev *);
48 const struct netdev_class *netdev_get_class(const struct netdev *);
49 const char *netdev_get_name(const struct netdev *);
50 struct netdev *netdev_from_name(const char *name);
51 void netdev_get_devices(const struct netdev_class *,
52 struct shash *device_list);
54 /* A data structure for capturing packets received by a network device.
56 * Network device implementations may read these members but should not modify
59 * None of these members change during the lifetime of a struct netdev_rx. */
61 struct netdev *netdev; /* Owns a reference to the netdev. */
64 struct netdev *netdev_rx_get_netdev(const struct netdev_rx *);
66 /* Network device class structure, to be defined by each implementation of a
69 * These functions return 0 if successful or a positive errno value on failure,
70 * except where otherwise noted.
76 * These functions work primarily with two different kinds of data structures:
78 * - "struct netdev", which represents a network device.
80 * - "struct netdev_rx", which represents a handle for capturing packets
81 * received on a network device
83 * Each of these data structures contains all of the implementation-independent
84 * generic state for the respective concept, called the "base" state. None of
85 * them contains any extra space for implementations to use. Instead, each
86 * implementation is expected to declare its own data structure that contains
87 * an instance of the generic data structure plus additional
88 * implementation-specific members, called the "derived" state. The
89 * implementation can use casts or (preferably) the CONTAINER_OF macro to
90 * obtain access to derived state given only a pointer to the embedded generic
97 * Four stylized functions accompany each of these data structures:
99 * "alloc" "construct" "destruct" "dealloc"
100 * ------------ ---------------- --------------- --------------
101 * netdev ->alloc ->construct ->destruct ->dealloc
102 * netdev_rx ->rx_alloc ->rx_construct ->rx_destruct ->rx_dealloc
104 * Any instance of a given data structure goes through the following life
107 * 1. The client calls the "alloc" function to obtain raw memory. If "alloc"
108 * fails, skip all the other steps.
110 * 2. The client initializes all of the data structure's base state. If this
111 * fails, skip to step 7.
113 * 3. The client calls the "construct" function. The implementation
114 * initializes derived state. It may refer to the already-initialized
115 * base state. If "construct" fails, skip to step 6.
117 * 4. The data structure is now initialized and in use.
119 * 5. When the data structure is no longer needed, the client calls the
120 * "destruct" function. The implementation uninitializes derived state.
121 * The base state has not been uninitialized yet, so the implementation
122 * may still refer to it.
124 * 6. The client uninitializes all of the data structure's base state.
126 * 7. The client calls the "dealloc" to free the raw memory. The
127 * implementation must not refer to base or derived state in the data
128 * structure, because it has already been uninitialized.
130 * Each "alloc" function allocates and returns a new instance of the respective
131 * data structure. The "alloc" function is not given any information about the
132 * use of the new data structure, so it cannot perform much initialization.
133 * Its purpose is just to ensure that the new data structure has enough room
134 * for base and derived state. It may return a null pointer if memory is not
135 * available, in which case none of the other functions is called.
137 * Each "construct" function initializes derived state in its respective data
138 * structure. When "construct" is called, all of the base state has already
139 * been initialized, so the "construct" function may refer to it. The
140 * "construct" function is allowed to fail, in which case the client calls the
141 * "dealloc" function (but not the "destruct" function).
143 * Each "destruct" function uninitializes and frees derived state in its
144 * respective data structure. When "destruct" is called, the base state has
145 * not yet been uninitialized, so the "destruct" function may refer to it. The
146 * "destruct" function is not allowed to fail.
148 * Each "dealloc" function frees raw memory that was allocated by the the
149 * "alloc" function. The memory's base and derived members might not have ever
150 * been initialized (but if "construct" returned successfully, then it has been
151 * "destruct"ed already). The "dealloc" function is not allowed to fail.
154 * Device Change Notification
155 * ==========================
157 * Minimally, implementations are required to report changes to netdev flags,
158 * features, ethernet address or carrier through connectivity_seq. Changes to
159 * other properties are allowed to cause notification through this interface,
160 * although implementations should try to avoid this. connectivity_seq_get()
161 * can be used to acquire a reference to the struct seq. The interface is
162 * described in detail in seq.h. */
163 struct netdev_class {
164 /* Type of netdevs in this class, e.g. "system", "tap", "gre", etc.
166 * One of the providers should supply a "system" type, since this is
167 * the type assumed if no type is specified when opening a netdev.
168 * The "system" type corresponds to an existing network device on
172 /* ## ------------------- ## */
173 /* ## Top-Level Functions ## */
174 /* ## ------------------- ## */
176 /* Called when the netdev provider is registered, typically at program
177 * startup. Returning an error from this function will prevent any network
178 * device in this class from being opened.
180 * This function may be set to null if a network device class needs no
181 * initialization at registration time. */
184 /* Performs periodic work needed by netdevs of this class. May be null if
185 * no periodic work is necessary. */
188 /* Arranges for poll_block() to wake up if the "run" member function needs
189 * to be called. Implementations are additionally required to wake
190 * whenever something changes in any of its netdevs which would cause their
191 * ->change_seq() function to change its result. May be null if nothing is
195 /* ## ---------------- ## */
196 /* ## netdev Functions ## */
197 /* ## ---------------- ## */
199 /* Life-cycle functions for a netdev. See the large comment above on
200 * struct netdev_class. */
201 struct netdev *(*alloc)(void);
202 int (*construct)(struct netdev *);
203 void (*destruct)(struct netdev *);
204 void (*dealloc)(struct netdev *);
206 /* Fetches the device 'netdev''s configuration, storing it in 'args'.
207 * The caller owns 'args' and pre-initializes it to an empty smap.
209 * If this netdev class does not have any configuration options, this may
210 * be a null pointer. */
211 int (*get_config)(const struct netdev *netdev, struct smap *args);
213 /* Changes the device 'netdev''s configuration to 'args'.
215 * If this netdev class does not support configuration, this may be a null
217 int (*set_config)(struct netdev *netdev, const struct smap *args);
219 /* Returns the tunnel configuration of 'netdev'. If 'netdev' is
220 * not a tunnel, returns null.
222 * If this function would always return null, it may be null instead. */
223 const struct netdev_tunnel_config *
224 (*get_tunnel_config)(const struct netdev *netdev);
226 /* Sends the 'size'-byte packet in 'buffer' on 'netdev'. Returns 0 if
227 * successful, otherwise a positive errno value. Returns EAGAIN without
228 * blocking if the packet cannot be queued immediately. Returns EMSGSIZE
229 * if a partial packet was transmitted or if the packet is too big or too
230 * small to transmit on the device.
232 * The caller retains ownership of 'buffer' in all cases.
234 * The network device is expected to maintain a packet transmission queue,
235 * so that the caller does not ordinarily have to do additional queuing of
238 * May return EOPNOTSUPP if a network device does not implement packet
239 * transmission through this interface. This function may be set to null
240 * if it would always return EOPNOTSUPP anyhow. (This will prevent the
241 * network device from being usefully used by the netdev-based "userspace
242 * datapath". It will also prevent the OVS implementation of bonding from
243 * working properly over 'netdev'.) */
244 int (*send)(struct netdev *netdev, const void *buffer, size_t size);
246 /* Registers with the poll loop to wake up from the next call to
247 * poll_block() when the packet transmission queue for 'netdev' has
248 * sufficient room to transmit a packet with netdev_send().
250 * The network device is expected to maintain a packet transmission queue,
251 * so that the caller does not ordinarily have to do additional queuing of
252 * packets. Thus, this function is unlikely to ever be useful.
254 * May be null if not needed, such as for a network device that does not
255 * implement packet transmission through the 'send' member function. */
256 void (*send_wait)(struct netdev *netdev);
258 /* Sets 'netdev''s Ethernet address to 'mac' */
259 int (*set_etheraddr)(struct netdev *netdev, const uint8_t mac[6]);
261 /* Retrieves 'netdev''s Ethernet address into 'mac'.
263 * This address will be advertised as 'netdev''s MAC address through the
264 * OpenFlow protocol, among other uses. */
265 int (*get_etheraddr)(const struct netdev *netdev, uint8_t mac[6]);
267 /* Retrieves 'netdev''s MTU into '*mtup'.
269 * The MTU is the maximum size of transmitted (and received) packets, in
270 * bytes, not including the hardware header; thus, this is typically 1500
271 * bytes for Ethernet devices.
273 * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
274 * this function should return EOPNOTSUPP. This function may be set to
275 * null if it would always return EOPNOTSUPP. */
276 int (*get_mtu)(const struct netdev *netdev, int *mtup);
278 /* Sets 'netdev''s MTU to 'mtu'.
280 * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
281 * this function should return EOPNOTSUPP. This function may be set to
282 * null if it would always return EOPNOTSUPP. */
283 int (*set_mtu)(const struct netdev *netdev, int mtu);
285 /* Returns the ifindex of 'netdev', if successful, as a positive number.
286 * On failure, returns a negative errno value.
288 * The desired semantics of the ifindex value are a combination of those
289 * specified by POSIX for if_nametoindex() and by SNMP for ifIndex. An
290 * ifindex value should be unique within a host and remain stable at least
291 * until reboot. SNMP says an ifindex "ranges between 1 and the value of
292 * ifNumber" but many systems do not follow this rule anyhow.
294 * This function may be set to null if it would always return -EOPNOTSUPP.
296 int (*get_ifindex)(const struct netdev *netdev);
298 /* Sets 'carrier' to true if carrier is active (link light is on) on
301 * May be null if device does not provide carrier status (will be always
302 * up as long as device is up).
304 int (*get_carrier)(const struct netdev *netdev, bool *carrier);
306 /* Returns the number of times 'netdev''s carrier has changed since being
309 * If null, callers will assume the number of carrier resets is zero. */
310 long long int (*get_carrier_resets)(const struct netdev *netdev);
312 /* Forces ->get_carrier() to poll 'netdev''s MII registers for link status
313 * instead of checking 'netdev''s carrier. 'netdev''s MII registers will
314 * be polled once ever 'interval' milliseconds. If 'netdev' does not
315 * support MII, another method may be used as a fallback. If 'interval' is
316 * less than or equal to zero, reverts ->get_carrier() to its normal
319 * Most network devices won't support this feature and will set this
320 * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
322 int (*set_miimon_interval)(struct netdev *netdev, long long int interval);
324 /* Retrieves current device stats for 'netdev' into 'stats'.
326 * A network device that supports some statistics but not others, it should
327 * set the values of the unsupported statistics to all-1-bits
329 int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
331 /* Sets the device stats for 'netdev' to 'stats'.
333 * Most network devices won't support this feature and will set this
334 * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
336 * Some network devices might only allow setting their stats to 0. */
337 int (*set_stats)(struct netdev *netdev, const struct netdev_stats *);
339 /* Stores the features supported by 'netdev' into each of '*current',
340 * '*advertised', '*supported', and '*peer'. Each value is a bitmap of
343 * This function may be set to null if it would always return EOPNOTSUPP.
345 int (*get_features)(const struct netdev *netdev,
346 enum netdev_features *current,
347 enum netdev_features *advertised,
348 enum netdev_features *supported,
349 enum netdev_features *peer);
351 /* Set the features advertised by 'netdev' to 'advertise', which is a
352 * set of NETDEV_F_* bits.
354 * This function may be set to null for a network device that does not
355 * support configuring advertisements. */
356 int (*set_advertisements)(struct netdev *netdev,
357 enum netdev_features advertise);
359 /* Attempts to set input rate limiting (policing) policy, such that up to
360 * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative
361 * burst size of 'kbits' kb.
363 * This function may be set to null if policing is not supported. */
364 int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
365 unsigned int kbits_burst);
367 /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves
368 * it empty if 'netdev' does not support QoS. Any names added to 'types'
369 * should be documented as valid for the "type" column in the "QoS" table
370 * in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
372 * Every network device must support disabling QoS with a type of "", but
373 * this function must not add "" to 'types'.
375 * The caller is responsible for initializing 'types' (e.g. with
376 * sset_init()) before calling this function. The caller retains ownership
379 * May be NULL if 'netdev' does not support QoS at all. */
380 int (*get_qos_types)(const struct netdev *netdev, struct sset *types);
382 /* Queries 'netdev' for its capabilities regarding the specified 'type' of
383 * QoS. On success, initializes 'caps' with the QoS capabilities.
385 * Should return EOPNOTSUPP if 'netdev' does not support 'type'. May be
386 * NULL if 'netdev' does not support QoS at all. */
387 int (*get_qos_capabilities)(const struct netdev *netdev,
389 struct netdev_qos_capabilities *caps);
391 /* Queries 'netdev' about its currently configured form of QoS. If
392 * successful, stores the name of the current form of QoS into '*typep'
393 * and any details of configuration as string key-value pairs in
396 * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
398 * The caller initializes 'details' before calling this function. The
399 * caller takes ownership of the string key-values pairs added to
402 * The netdev retains ownership of '*typep'.
404 * '*typep' will be one of the types returned by netdev_get_qos_types() for
405 * 'netdev'. The contents of 'details' should be documented as valid for
406 * '*typep' in the "other_config" column in the "QoS" table in
407 * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
409 * May be NULL if 'netdev' does not support QoS at all. */
410 int (*get_qos)(const struct netdev *netdev,
411 const char **typep, struct smap *details);
413 /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
414 * 'type' with details of configuration from 'details'.
416 * On error, the previous QoS configuration is retained.
418 * When this function changes the type of QoS (not just 'details'), this
419 * also resets all queue configuration for 'netdev' to their defaults
420 * (which depend on the specific type of QoS). Otherwise, the queue
421 * configuration for 'netdev' is unchanged.
423 * 'type' should be "" (to disable QoS) or one of the types returned by
424 * netdev_get_qos_types() for 'netdev'. The contents of 'details' should
425 * be documented as valid for the given 'type' in the "other_config" column
426 * in the "QoS" table in vswitchd/vswitch.xml (which is built as
427 * ovs-vswitchd.conf.db(8)).
429 * May be NULL if 'netdev' does not support QoS at all. */
430 int (*set_qos)(struct netdev *netdev,
431 const char *type, const struct smap *details);
433 /* Queries 'netdev' for information about the queue numbered 'queue_id'.
434 * If successful, adds that information as string key-value pairs to
435 * 'details'. Returns 0 if successful, otherwise a positive errno value.
437 * Should return EINVAL if 'queue_id' is greater than or equal to the
438 * number of supported queues (as reported in the 'n_queues' member of
439 * struct netdev_qos_capabilities by 'get_qos_capabilities').
441 * The caller initializes 'details' before calling this function. The
442 * caller takes ownership of the string key-values pairs added to
445 * The returned contents of 'details' should be documented as valid for the
446 * given 'type' in the "other_config" column in the "Queue" table in
447 * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
449 int (*get_queue)(const struct netdev *netdev,
450 unsigned int queue_id, struct smap *details);
452 /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
453 * string pairs in 'details'. The contents of 'details' should be
454 * documented as valid for the given 'type' in the "other_config" column in
455 * the "Queue" table in vswitchd/vswitch.xml (which is built as
456 * ovs-vswitchd.conf.db(8)). Returns 0 if successful, otherwise a positive
457 * errno value. On failure, the given queue's configuration should be
460 * Should return EINVAL if 'queue_id' is greater than or equal to the
461 * number of supported queues (as reported in the 'n_queues' member of
462 * struct netdev_qos_capabilities by 'get_qos_capabilities'), or if
463 * 'details' is invalid for the type of queue.
465 * This function does not modify 'details', and the caller retains
468 * May be NULL if 'netdev' does not support QoS at all. */
469 int (*set_queue)(struct netdev *netdev,
470 unsigned int queue_id, const struct smap *details);
472 /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
474 * Should return EINVAL if 'queue_id' is greater than or equal to the
475 * number of supported queues (as reported in the 'n_queues' member of
476 * struct netdev_qos_capabilities by 'get_qos_capabilities'). Should
477 * return EOPNOTSUPP if 'queue_id' is valid but may not be deleted (e.g. if
478 * 'netdev' has a fixed set of queues with the current QoS mode).
480 * May be NULL if 'netdev' does not support QoS at all, or if all of its
481 * QoS modes have fixed sets of queues. */
482 int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
484 /* Obtains statistics about 'queue_id' on 'netdev'. Fills 'stats' with the
485 * queue's statistics. May set individual members of 'stats' to all-1-bits
486 * if the statistic is unavailable.
488 * May be NULL if 'netdev' does not support QoS at all. */
489 int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
490 struct netdev_queue_stats *stats);
492 /* Attempts to begin dumping the queues in 'netdev'. On success, returns 0
493 * and initializes '*statep' with any data needed for iteration. On
494 * failure, returns a positive errno value.
496 * May be NULL if 'netdev' does not support QoS at all. */
497 int (*queue_dump_start)(const struct netdev *netdev, void **statep);
499 /* Attempts to retrieve another queue from 'netdev' for 'state', which was
500 * initialized by a successful call to the 'queue_dump_start' function for
501 * 'netdev'. On success, stores a queue ID into '*queue_id' and fills
502 * 'details' with the configuration of the queue with that ID. Returns EOF
503 * if the last queue has been dumped, or a positive errno value on error.
504 * This function will not be called again once it returns nonzero once for
505 * a given iteration (but the 'queue_dump_done' function will be called
508 * The caller initializes and clears 'details' before calling this
509 * function. The caller takes ownership of the string key-values pairs
510 * added to 'details'.
512 * The returned contents of 'details' should be documented as valid for the
513 * given 'type' in the "other_config" column in the "Queue" table in
514 * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
516 * May be NULL if 'netdev' does not support QoS at all. */
517 int (*queue_dump_next)(const struct netdev *netdev, void *state,
518 unsigned int *queue_id, struct smap *details);
520 /* Releases resources from 'netdev' for 'state', which was initialized by a
521 * successful call to the 'queue_dump_start' function for 'netdev'.
523 * May be NULL if 'netdev' does not support QoS at all. */
524 int (*queue_dump_done)(const struct netdev *netdev, void *state);
526 /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
527 * ID, its statistics, and the 'aux' specified by the caller. The order of
528 * iteration is unspecified, but (when successful) each queue must be
529 * visited exactly once.
531 * 'cb' will not modify or free the statistics passed in. */
532 int (*dump_queue_stats)(const struct netdev *netdev,
533 void (*cb)(unsigned int queue_id,
534 struct netdev_queue_stats *,
538 /* If 'netdev' has an assigned IPv4 address, sets '*address' to that
539 * address and '*netmask' to the associated netmask.
541 * The following error values have well-defined meanings:
543 * - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
545 * - EOPNOTSUPP: No IPv4 network stack attached to 'netdev'.
547 * This function may be set to null if it would always return EOPNOTSUPP
549 int (*get_in4)(const struct netdev *netdev, struct in_addr *address,
550 struct in_addr *netmask);
552 /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask. If
553 * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.
555 * This function may be set to null if it would always return EOPNOTSUPP
557 int (*set_in4)(struct netdev *netdev, struct in_addr addr,
558 struct in_addr mask);
560 /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address.
562 * The following error values have well-defined meanings:
564 * - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
566 * - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
568 * This function may be set to null if it would always return EOPNOTSUPP
570 int (*get_in6)(const struct netdev *netdev, struct in6_addr *in6);
572 /* Adds 'router' as a default IP gateway for the TCP/IP stack that
573 * corresponds to 'netdev'.
575 * This function may be set to null if it would always return EOPNOTSUPP
577 int (*add_router)(struct netdev *netdev, struct in_addr router);
579 /* Looks up the next hop for 'host'. If successful, stores the next hop
580 * gateway's address (0 if 'host' is on a directly connected network) in
581 * '*next_hop' and a copy of the name of the device to reach 'host' in
582 * '*netdev_name', and returns 0. The caller is responsible for freeing
583 * '*netdev_name' (by calling free()).
585 * This function may be set to null if it would always return EOPNOTSUPP
587 int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
590 /* Retrieves driver information of the device.
592 * Populates 'smap' with key-value pairs representing the status of the
593 * device. 'smap' is a set of key-value string pairs representing netdev
594 * type specific information. For more information see
595 * ovs-vswitchd.conf.db(5).
597 * The caller is responsible for destroying 'smap' and its data.
599 * This function may be set to null if it would always return EOPNOTSUPP
601 int (*get_status)(const struct netdev *netdev, struct smap *smap);
603 /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
604 * corresponding MAC address in 'mac'. A return value of ENXIO, in
605 * particular, indicates that there is no ARP table entry for 'ip' on
608 * This function may be set to null if it would always return EOPNOTSUPP
610 int (*arp_lookup)(const struct netdev *netdev, ovs_be32 ip,
613 /* Retrieves the current set of flags on 'netdev' into '*old_flags'. Then,
614 * turns off the flags that are set to 1 in 'off' and turns on the flags
615 * that are set to 1 in 'on'. (No bit will be set to 1 in both 'off' and
616 * 'on'; that is, off & on == 0.)
618 * This function may be invoked from a signal handler. Therefore, it
619 * should not do anything that is not signal-safe (such as logging). */
620 int (*update_flags)(struct netdev *netdev, enum netdev_flags off,
621 enum netdev_flags on, enum netdev_flags *old_flags);
623 /* ## ------------------- ## */
624 /* ## netdev_rx Functions ## */
625 /* ## ------------------- ## */
627 /* If a particular netdev class does not support receiving packets, all these
628 * function pointers must be NULL. */
630 /* Life-cycle functions for a netdev_rx. See the large comment above on
631 * struct netdev_class. */
632 struct netdev_rx *(*rx_alloc)(void);
633 int (*rx_construct)(struct netdev_rx *);
634 void (*rx_destruct)(struct netdev_rx *);
635 void (*rx_dealloc)(struct netdev_rx *);
637 /* Attempts to receive a packet from 'rx' into the tailroom of 'buffer',
638 * which should initially be empty. If successful, returns 0 and
639 * increments 'buffer->size' by the number of bytes in the received packet,
640 * otherwise a positive errno value. Returns EAGAIN immediately if no
641 * packet is ready to be received.
643 * Must return EMSGSIZE, and discard the packet, if the received packet
644 * is longer than 'ofpbuf_tailroom(buffer)'.
646 * Implementations may make use of VLAN_HEADER_LEN bytes of tailroom to
647 * add a VLAN header which is obtained out-of-band to the packet. If
648 * this occurs then VLAN_HEADER_LEN bytes of tailroom will no longer be
649 * available for the packet, otherwise it may be used for the packet
652 * It is advised that the tailroom of 'buffer' should be
653 * VLAN_HEADER_LEN bytes longer than the MTU to allow space for an
654 * out-of-band VLAN header to be added to the packet.
656 * This function may be set to null if it would always return EOPNOTSUPP
658 int (*rx_recv)(struct netdev_rx *rx, struct ofpbuf *buffer);
660 /* Registers with the poll loop to wake up from the next call to
661 * poll_block() when a packet is ready to be received with netdev_rx_recv()
663 void (*rx_wait)(struct netdev_rx *rx);
665 /* Discards all packets waiting to be received from 'rx'. */
666 int (*rx_drain)(struct netdev_rx *rx);
669 int netdev_register_provider(const struct netdev_class *);
670 int netdev_unregister_provider(const char *type);
672 extern const struct netdev_class netdev_linux_class;
673 extern const struct netdev_class netdev_internal_class;
674 extern const struct netdev_class netdev_tap_class;
675 #if defined(__FreeBSD__) || defined(__NetBSD__)
676 extern const struct netdev_class netdev_bsd_class;
683 #endif /* netdev.h */