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"
33 COVERAGE_DEFINE(mac_learning_learned);
34 COVERAGE_DEFINE(mac_learning_expired);
36 /* Returns the number of seconds since 'e' (within 'ml') was last learned. */
38 mac_entry_age(const struct mac_learning *ml, const struct mac_entry *e)
40 time_t remaining = e->expires - time_now();
41 return ml->idle_time - remaining;
45 mac_table_hash(const struct mac_learning *ml, const uint8_t mac[ETH_ADDR_LEN],
48 unsigned int mac1 = get_unaligned_u32(ALIGNED_CAST(uint32_t *, mac));
49 unsigned int mac2 = get_unaligned_u16(ALIGNED_CAST(uint16_t *, mac + 4));
50 return hash_3words(mac1, mac2 | (vlan << 16), ml->secret);
53 static struct mac_entry *
54 mac_entry_from_lru_node(struct list *list)
56 return CONTAINER_OF(list, struct mac_entry, lru_node);
59 static struct mac_entry *
60 mac_entry_lookup(const struct mac_learning *ml,
61 const uint8_t mac[ETH_ADDR_LEN], uint16_t vlan)
65 HMAP_FOR_EACH_WITH_HASH (e, hmap_node, mac_table_hash(ml, mac, vlan),
67 if (e->vlan == vlan && eth_addr_equals(e->mac, mac)) {
74 /* If the LRU list is not empty, stores the least-recently-used entry in '*e'
75 * and returns true. Otherwise, if the LRU list is empty, stores NULL in '*e'
76 * and return false. */
78 get_lru(struct mac_learning *ml, struct mac_entry **e)
79 OVS_REQ_RDLOCK(ml->rwlock)
81 if (!list_is_empty(&ml->lrus)) {
82 *e = mac_entry_from_lru_node(ml->lrus.next);
91 normalize_idle_time(unsigned int idle_time)
93 return (idle_time < 15 ? 15
94 : idle_time > 3600 ? 3600
98 /* Creates and returns a new MAC learning table with an initial MAC aging
99 * timeout of 'idle_time' seconds and an initial maximum of MAC_DEFAULT_MAX
101 struct mac_learning *
102 mac_learning_create(unsigned int idle_time)
104 struct mac_learning *ml;
106 ml = xmalloc(sizeof *ml);
107 list_init(&ml->lrus);
108 hmap_init(&ml->table);
109 ml->secret = random_uint32();
110 ml->flood_vlans = NULL;
111 ml->idle_time = normalize_idle_time(idle_time);
112 ml->max_entries = MAC_DEFAULT_MAX;
113 ml->need_revalidate = false;
114 atomic_init(&ml->ref_cnt, 1);
115 ovs_rwlock_init(&ml->rwlock);
119 struct mac_learning *
120 mac_learning_ref(const struct mac_learning *ml_)
122 struct mac_learning *ml = CONST_CAST(struct mac_learning *, ml_);
125 atomic_add(&ml->ref_cnt, 1, &orig);
126 ovs_assert(orig > 0);
131 /* Unreferences (and possibly destroys) MAC learning table 'ml'. */
133 mac_learning_unref(struct mac_learning *ml)
141 atomic_sub(&ml->ref_cnt, 1, &orig);
142 ovs_assert(orig > 0);
144 struct mac_entry *e, *next;
146 HMAP_FOR_EACH_SAFE (e, next, hmap_node, &ml->table) {
147 hmap_remove(&ml->table, &e->hmap_node);
150 hmap_destroy(&ml->table);
152 bitmap_free(ml->flood_vlans);
153 ovs_rwlock_destroy(&ml->rwlock);
158 /* Provides a bitmap of VLANs which have learning disabled, that is, VLANs on
159 * which all packets are flooded. Returns true if the set has changed from the
162 mac_learning_set_flood_vlans(struct mac_learning *ml,
163 const unsigned long *bitmap)
165 if (vlan_bitmap_equal(ml->flood_vlans, bitmap)) {
168 bitmap_free(ml->flood_vlans);
169 ml->flood_vlans = vlan_bitmap_clone(bitmap);
174 /* Changes the MAC aging timeout of 'ml' to 'idle_time' seconds. */
176 mac_learning_set_idle_time(struct mac_learning *ml, unsigned int idle_time)
178 idle_time = normalize_idle_time(idle_time);
179 if (idle_time != ml->idle_time) {
183 delta = (int) idle_time - (int) ml->idle_time;
184 LIST_FOR_EACH (e, lru_node, &ml->lrus) {
187 ml->idle_time = idle_time;
191 /* Sets the maximum number of entries in 'ml' to 'max_entries', adjusting it
192 * to be within a reasonable range. */
194 mac_learning_set_max_entries(struct mac_learning *ml, size_t max_entries)
196 ml->max_entries = (max_entries < 10 ? 10
197 : max_entries > 1000 * 1000 ? 1000 * 1000
202 is_learning_vlan(const struct mac_learning *ml, uint16_t vlan)
204 return !ml->flood_vlans || !bitmap_is_set(ml->flood_vlans, vlan);
207 /* Returns true if 'src_mac' may be learned on 'vlan' for 'ml'.
208 * Returns false if 'ml' is NULL, if src_mac is not valid for learning, or if
209 * 'vlan' is configured on 'ml' to flood all packets. */
211 mac_learning_may_learn(const struct mac_learning *ml,
212 const uint8_t src_mac[ETH_ADDR_LEN], uint16_t vlan)
214 return ml && is_learning_vlan(ml, vlan) && !eth_addr_is_multicast(src_mac);
217 /* Searches 'ml' for and returns a MAC learning entry for 'src_mac' in 'vlan',
218 * inserting a new entry if necessary. The caller must have already verified,
219 * by calling mac_learning_may_learn(), that 'src_mac' and 'vlan' are
222 * If the returned MAC entry is new (as may be determined by calling
223 * mac_entry_is_new()), then the caller must pass the new entry to
224 * mac_learning_changed(). The caller must also initialize the new entry's
225 * 'port' member. Otherwise calling those functions is at the caller's
228 mac_learning_insert(struct mac_learning *ml,
229 const uint8_t src_mac[ETH_ADDR_LEN], uint16_t vlan)
233 e = mac_entry_lookup(ml, src_mac, vlan);
235 uint32_t hash = mac_table_hash(ml, src_mac, vlan);
237 if (hmap_count(&ml->table) >= ml->max_entries) {
239 mac_learning_expire(ml, e);
242 e = xmalloc(sizeof *e);
243 hmap_insert(&ml->table, &e->hmap_node, hash);
244 memcpy(e->mac, src_mac, ETH_ADDR_LEN);
246 e->grat_arp_lock = TIME_MIN;
249 list_remove(&e->lru_node);
252 /* Mark 'e' as recently used. */
253 list_push_back(&ml->lrus, &e->lru_node);
254 e->expires = time_now() + ml->idle_time;
259 /* Changes 'e''s tag to a new, randomly selected one. Causes
260 * mac_learning_run() to flag for revalidation the tag that would have been
261 * previously used for this entry's MAC and VLAN (either before 'e' was
262 * inserted, if it is new, or otherwise before its port was updated.)
264 * The client should call this function after obtaining a MAC learning entry
265 * from mac_learning_insert(), if the entry is either new or if its learned
266 * port has changed. */
268 mac_learning_changed(struct mac_learning *ml)
270 COVERAGE_INC(mac_learning_learned);
271 ml->need_revalidate = true;
274 /* Looks up MAC 'dst' for VLAN 'vlan' in 'ml' and returns the associated MAC
275 * learning entry, if any. If 'tag' is nonnull, then the tag that associates
276 * 'dst' and 'vlan' with its currently learned port will be OR'd into
279 mac_learning_lookup(const struct mac_learning *ml,
280 const uint8_t dst[ETH_ADDR_LEN], uint16_t vlan)
282 if (eth_addr_is_multicast(dst)) {
283 /* No tag because the treatment of multicast destinations never
286 } else if (!is_learning_vlan(ml, vlan)) {
287 /* We don't tag this property. The set of learning VLANs changes so
288 * rarely that we revalidate every flow when it changes. */
291 struct mac_entry *e = mac_entry_lookup(ml, dst, vlan);
293 ovs_assert(e == NULL || e->port.p != NULL)
298 /* Expires 'e' from the 'ml' hash table. */
300 mac_learning_expire(struct mac_learning *ml, struct mac_entry *e)
302 hmap_remove(&ml->table, &e->hmap_node);
303 list_remove(&e->lru_node);
307 /* Expires all the mac-learning entries in 'ml'. If not NULL, the tags in 'ml'
308 * are added to 'tags'. Otherwise the tags in 'ml' are discarded. The client
309 * is responsible for revalidating any flows that depend on 'ml', if
312 mac_learning_flush(struct mac_learning *ml)
315 while (get_lru(ml, &e)){
316 ml->need_revalidate = true;
317 mac_learning_expire(ml, e);
319 hmap_shrink(&ml->table);
322 /* Does periodic work required by 'ml'. Returns true if something changed that
323 * may require flow revalidation. */
325 mac_learning_run(struct mac_learning *ml)
327 bool need_revalidate;
330 while (get_lru(ml, &e)
331 && (hmap_count(&ml->table) > ml->max_entries
332 || time_now() >= e->expires)) {
333 COVERAGE_INC(mac_learning_expired);
334 ml->need_revalidate = true;
335 mac_learning_expire(ml, e);
338 need_revalidate = ml->need_revalidate;
339 ml->need_revalidate = false;
340 return need_revalidate;
344 mac_learning_wait(struct mac_learning *ml)
346 if (hmap_count(&ml->table) > ml->max_entries
347 || ml->need_revalidate) {
348 poll_immediate_wake();
349 } else if (!list_is_empty(&ml->lrus)) {
350 struct mac_entry *e = mac_entry_from_lru_node(ml->lrus.next);
351 poll_timer_wait_until(e->expires * 1000LL);