2 * Copyright (c) 2008, 2009, 2010, 2011, 2012 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.
18 #include "mac-learning.h"
27 #include "poll-loop.h"
29 #include "unaligned.h"
31 #include "vlan-bitmap.h"
34 VLOG_DEFINE_THIS_MODULE(mac_learning);
36 COVERAGE_DEFINE(mac_learning_learned);
37 COVERAGE_DEFINE(mac_learning_expired);
39 /* Returns the number of seconds since 'e' (within 'ml') was last learned. */
41 mac_entry_age(const struct mac_learning *ml, const struct mac_entry *e)
43 time_t remaining = e->expires - time_now();
44 return ml->idle_time - remaining;
48 mac_table_hash(const struct mac_learning *ml, const uint8_t mac[ETH_ADDR_LEN],
51 unsigned int mac1 = get_unaligned_u32(ALIGNED_CAST(uint32_t *, mac));
52 unsigned int mac2 = get_unaligned_u16(ALIGNED_CAST(uint16_t *, mac + 4));
53 return hash_3words(mac1, mac2 | (vlan << 16), ml->secret);
56 static struct mac_entry *
57 mac_entry_from_lru_node(struct list *list)
59 return CONTAINER_OF(list, struct mac_entry, lru_node);
62 static struct mac_entry *
63 mac_entry_lookup(const struct mac_learning *ml,
64 const uint8_t mac[ETH_ADDR_LEN], uint16_t vlan)
68 HMAP_FOR_EACH_WITH_HASH (e, hmap_node, mac_table_hash(ml, mac, vlan),
70 if (e->vlan == vlan && eth_addr_equals(e->mac, mac)) {
77 /* If the LRU list is not empty, stores the least-recently-used entry in '*e'
78 * and returns true. Otherwise, if the LRU list is empty, stores NULL in '*e'
79 * and return false. */
81 get_lru(struct mac_learning *ml, struct mac_entry **e)
82 OVS_REQ_RDLOCK(ml->rwlock)
84 if (!list_is_empty(&ml->lrus)) {
85 *e = mac_entry_from_lru_node(ml->lrus.next);
94 normalize_idle_time(unsigned int idle_time)
96 return (idle_time < 15 ? 15
97 : idle_time > 3600 ? 3600
101 /* Creates and returns a new MAC learning table with an initial MAC aging
102 * timeout of 'idle_time' seconds and an initial maximum of MAC_DEFAULT_MAX
104 struct mac_learning *
105 mac_learning_create(unsigned int idle_time)
107 struct mac_learning *ml;
109 ml = xmalloc(sizeof *ml);
110 list_init(&ml->lrus);
111 hmap_init(&ml->table);
112 ml->secret = random_uint32();
113 ml->flood_vlans = NULL;
114 ml->idle_time = normalize_idle_time(idle_time);
115 ml->max_entries = MAC_DEFAULT_MAX;
116 ml->need_revalidate = false;
117 atomic_init(&ml->ref_cnt, 1);
118 ovs_rwlock_init(&ml->rwlock);
122 struct mac_learning *
123 mac_learning_ref(const struct mac_learning *ml_)
125 struct mac_learning *ml = CONST_CAST(struct mac_learning *, ml_);
128 atomic_add(&ml->ref_cnt, 1, &orig);
129 ovs_assert(orig > 0);
134 /* Unreferences (and possibly destroys) MAC learning table 'ml'. */
136 mac_learning_unref(struct mac_learning *ml)
144 atomic_sub(&ml->ref_cnt, 1, &orig);
145 ovs_assert(orig > 0);
147 struct mac_entry *e, *next;
149 HMAP_FOR_EACH_SAFE (e, next, hmap_node, &ml->table) {
150 hmap_remove(&ml->table, &e->hmap_node);
153 hmap_destroy(&ml->table);
155 bitmap_free(ml->flood_vlans);
156 ovs_rwlock_destroy(&ml->rwlock);
161 /* Provides a bitmap of VLANs which have learning disabled, that is, VLANs on
162 * which all packets are flooded. Returns true if the set has changed from the
165 mac_learning_set_flood_vlans(struct mac_learning *ml,
166 const unsigned long *bitmap)
168 if (vlan_bitmap_equal(ml->flood_vlans, bitmap)) {
171 bitmap_free(ml->flood_vlans);
172 ml->flood_vlans = vlan_bitmap_clone(bitmap);
177 /* Changes the MAC aging timeout of 'ml' to 'idle_time' seconds. */
179 mac_learning_set_idle_time(struct mac_learning *ml, unsigned int idle_time)
181 idle_time = normalize_idle_time(idle_time);
182 if (idle_time != ml->idle_time) {
186 delta = (int) idle_time - (int) ml->idle_time;
187 LIST_FOR_EACH (e, lru_node, &ml->lrus) {
190 ml->idle_time = idle_time;
194 /* Sets the maximum number of entries in 'ml' to 'max_entries', adjusting it
195 * to be within a reasonable range. */
197 mac_learning_set_max_entries(struct mac_learning *ml, size_t max_entries)
199 ml->max_entries = (max_entries < 10 ? 10
200 : max_entries > 1000 * 1000 ? 1000 * 1000
205 is_learning_vlan(const struct mac_learning *ml, uint16_t vlan)
207 return !ml->flood_vlans || !bitmap_is_set(ml->flood_vlans, vlan);
210 /* Returns true if 'src_mac' may be learned on 'vlan' for 'ml'.
211 * Returns false if 'ml' is NULL, if src_mac is not valid for learning, or if
212 * 'vlan' is configured on 'ml' to flood all packets. */
214 mac_learning_may_learn(const struct mac_learning *ml,
215 const uint8_t src_mac[ETH_ADDR_LEN], uint16_t vlan)
217 return ml && is_learning_vlan(ml, vlan) && !eth_addr_is_multicast(src_mac);
220 /* Searches 'ml' for and returns a MAC learning entry for 'src_mac' in 'vlan',
221 * inserting a new entry if necessary. The caller must have already verified,
222 * by calling mac_learning_may_learn(), that 'src_mac' and 'vlan' are
225 * If the returned MAC entry is new (as may be determined by calling
226 * mac_entry_is_new()), then the caller must pass the new entry to
227 * mac_learning_changed(). The caller must also initialize the new entry's
228 * 'port' member. Otherwise calling those functions is at the caller's
231 mac_learning_insert(struct mac_learning *ml,
232 const uint8_t src_mac[ETH_ADDR_LEN], uint16_t vlan)
236 e = mac_entry_lookup(ml, src_mac, vlan);
238 uint32_t hash = mac_table_hash(ml, src_mac, vlan);
240 if (hmap_count(&ml->table) >= ml->max_entries) {
242 mac_learning_expire(ml, e);
245 e = xmalloc(sizeof *e);
246 hmap_insert(&ml->table, &e->hmap_node, hash);
247 memcpy(e->mac, src_mac, ETH_ADDR_LEN);
249 e->grat_arp_lock = TIME_MIN;
252 list_remove(&e->lru_node);
255 /* Mark 'e' as recently used. */
256 list_push_back(&ml->lrus, &e->lru_node);
257 e->expires = time_now() + ml->idle_time;
262 /* Changes 'e''s tag to a new, randomly selected one. Causes
263 * mac_learning_run() to flag for revalidation the tag that would have been
264 * previously used for this entry's MAC and VLAN (either before 'e' was
265 * inserted, if it is new, or otherwise before its port was updated.)
267 * The client should call this function after obtaining a MAC learning entry
268 * from mac_learning_insert(), if the entry is either new or if its learned
269 * port has changed. */
271 mac_learning_changed(struct mac_learning *ml)
273 COVERAGE_INC(mac_learning_learned);
274 ml->need_revalidate = true;
277 /* Looks up MAC 'dst' for VLAN 'vlan' in 'ml' and returns the associated MAC
278 * learning entry, if any. If 'tag' is nonnull, then the tag that associates
279 * 'dst' and 'vlan' with its currently learned port will be OR'd into
282 mac_learning_lookup(const struct mac_learning *ml,
283 const uint8_t dst[ETH_ADDR_LEN], uint16_t vlan)
285 if (eth_addr_is_multicast(dst)) {
286 /* No tag because the treatment of multicast destinations never
289 } else if (!is_learning_vlan(ml, vlan)) {
290 /* We don't tag this property. The set of learning VLANs changes so
291 * rarely that we revalidate every flow when it changes. */
294 struct mac_entry *e = mac_entry_lookup(ml, dst, vlan);
296 ovs_assert(e == NULL || e->port.p != NULL)
301 /* Expires 'e' from the 'ml' hash table. */
303 mac_learning_expire(struct mac_learning *ml, struct mac_entry *e)
305 hmap_remove(&ml->table, &e->hmap_node);
306 list_remove(&e->lru_node);
310 /* Expires all the mac-learning entries in 'ml'. If not NULL, the tags in 'ml'
311 * are added to 'tags'. Otherwise the tags in 'ml' are discarded. The client
312 * is responsible for revalidating any flows that depend on 'ml', if
315 mac_learning_flush(struct mac_learning *ml)
318 while (get_lru(ml, &e)){
319 ml->need_revalidate = true;
320 mac_learning_expire(ml, e);
322 hmap_shrink(&ml->table);
325 /* Does periodic work required by 'ml'. Returns true if something changed that
326 * may require flow revalidation. */
328 mac_learning_run(struct mac_learning *ml)
330 bool need_revalidate;
333 while (get_lru(ml, &e)
334 && (hmap_count(&ml->table) > ml->max_entries
335 || time_now() >= e->expires)) {
336 COVERAGE_INC(mac_learning_expired);
337 ml->need_revalidate = true;
338 mac_learning_expire(ml, e);
341 need_revalidate = ml->need_revalidate;
342 ml->need_revalidate = false;
343 return need_revalidate;
347 mac_learning_wait(struct mac_learning *ml)
349 if (hmap_count(&ml->table) > ml->max_entries
350 || ml->need_revalidate) {
351 poll_immediate_wake();
352 } else if (!list_is_empty(&ml->lrus)) {
353 struct mac_entry *e = mac_entry_from_lru_node(ml->lrus.next);
354 poll_timer_wait_until(e->expires * 1000LL);