ofproto/ofproto-dpif-rid.c

   1 /*
   2  * Copyright (c) 2014, 2015 Nicira, Inc.
   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 #include <config.h>
  18
  19 #include "ofpbuf.h"
  20 #include "ofproto-dpif.h"
  21 #include "ofproto-dpif-rid.h"
  22 #include "ofproto-provider.h"
  23 #include "openvswitch/vlog.h"
  24
  25 VLOG_DEFINE_THIS_MODULE(ofproto_dpif_rid);
  26
  27 static struct ovs_mutex mutex;
  28
  29 static struct cmap id_map;
  30 static struct cmap metadata_map;
  31
  32 static struct ovs_list expiring OVS_GUARDED_BY(mutex);
  33 static struct ovs_list expired OVS_GUARDED_BY(mutex);
  34
  35 static uint32_t next_id OVS_GUARDED_BY(mutex); /* Possible next free id. */
  36
  37 #define RECIRC_POOL_STATIC_IDS 1024
  38
  39 void
  40 recirc_init(void)
  41 {
  42     static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
  43
  44     if (ovsthread_once_start(&once)) {
  45         ovs_mutex_init(&mutex);
  46         ovs_mutex_lock(&mutex);
  47         next_id = 1; /* 0 is not a valid ID. */
  48         cmap_init(&id_map);
  49         cmap_init(&metadata_map);
  50         list_init(&expiring);
  51         list_init(&expired);
  52         ovs_mutex_unlock(&mutex);
  53
  54         ovsthread_once_done(&once);
  55     }
  56
  57 }
  58
  59 /* This should be called by the revalidator once at each round (every 500ms or
  60  * more). */
  61 void
  62 recirc_run(void)
  63 {
  64     static long long int last = 0;
  65     long long int now = time_msec();
  66
  67     /* Do maintenance at most 4 times / sec. */
  68     ovs_mutex_lock(&mutex);
  69     if (now - last > 250) {
  70         struct recirc_id_node *node;
  71
  72         last = now;
  73
  74         /* Nodes in 'expiring' and 'expired' lists have the refcount of zero,
  75          * which means that while they can still be found (by id), no new
  76          * references can be taken on them.  We have removed the entry from the
  77          * 'metadata_map', at the time when refcount reached zero, causing any
  78          * new translations to allocate a new ID.  This allows the expiring
  79          * entry to be safely deleted while any sudden new use of the similar
  80          * recirculation will safely start using a new recirculation ID.  When
  81          * the refcount gets to zero, the node is also added to the 'expiring'
  82          * list.  At any time after that the nodes in the 'expiring' list can
  83          * be moved to the 'expired' list, from which they are deleted at least
  84          * 250ms afterwards. */
  85
  86         /* Delete the expired.  These have been lingering for at least 250 ms,
  87          * which should be enough for any ongoing recirculations to be
  88          * finished. */
  89         LIST_FOR_EACH_POP (node, exp_node, &expired) {
  90             cmap_remove(&id_map, &node->id_node, node->id);
  91             ovsrcu_postpone(free, node);
  92         }
  93
  94         if (!list_is_empty(&expiring)) {
  95             /* 'expired' is now empty, move nodes in 'expiring' to it. */
  96             list_splice(&expired, list_front(&expiring), &expiring);
  97         }
  98     }
  99     ovs_mutex_unlock(&mutex);
 100 }
 101
 102 /* We use the id as the hash value, which works due to cmap internal rehashing.
 103  * We also only insert nodes with unique IDs, so all possible hash collisions
 104  * remain internal to the cmap. */
 105 static struct recirc_id_node *
 106 recirc_find__(uint32_t id)
 107     OVS_REQUIRES(mutex)
 108 {
 109     struct cmap_node *node = cmap_find_protected(&id_map, id);
 110
 111     return node ? CONTAINER_OF(node, struct recirc_id_node, id_node) : NULL;
 112 }
 113
 114 /* Lockless RCU protected lookup.  If node is needed accross RCU quiescent
 115  * state, caller should copy the contents. */
 116 const struct recirc_id_node *
 117 recirc_id_node_find(uint32_t id)
 118 {
 119     const struct cmap_node *node = cmap_find(&id_map, id);
 120
 121     return node
 122         ? CONTAINER_OF(node, const struct recirc_id_node, id_node)
 123         : NULL;
 124 }
 125
 126 static uint32_t
 127 recirc_metadata_hash(const struct recirc_state *state)
 128 {
 129     uint32_t hash;
 130
 131     hash = hash_pointer(state->ofproto, 0);
 132     hash = hash_int(state->table_id, hash);
 133     if (state->metadata.tunnel->ip_dst) {
 134         /* We may leave remainder bytes unhashed, but that is unlikely as
 135          * the tunnel is not in the datapath format. */
 136         hash = hash_words64((const uint64_t *) state->metadata.tunnel,
 137                             flow_tnl_size(state->metadata.tunnel)
 138                             / sizeof(uint64_t), hash);
 139     }
 140     hash = hash_boolean(state->conntracked, hash);
 141     hash = hash_words64((const uint64_t *) &state->metadata.metadata,
 142                         (sizeof state->metadata - sizeof state->metadata.tunnel)
 143                         / sizeof(uint64_t),
 144                         hash);
 145     if (state->stack && state->stack->size != 0) {
 146         hash = hash_words64((const uint64_t *) state->stack->data,
 147                             state->stack->size / sizeof(uint64_t), hash);
 148     }
 149     hash = hash_int(state->mirrors, hash);
 150     hash = hash_int(state->action_set_len, hash);
 151     if (state->ofpacts_len) {
 152         hash = hash_words64(ALIGNED_CAST(const uint64_t *, state->ofpacts),
 153                             state->ofpacts_len / sizeof(uint64_t),
 154                             hash);
 155     }
 156     return hash;
 157 }
 158
 159 static bool
 160 recirc_metadata_equal(const struct recirc_state *a,
 161                       const struct recirc_state *b)
 162 {
 163     return (a->table_id == b->table_id
 164             && a->ofproto == b->ofproto
 165             && flow_tnl_equal(a->metadata.tunnel, b->metadata.tunnel)
 166             && !memcmp(&a->metadata.metadata, &b->metadata.metadata,
 167                        sizeof a->metadata - sizeof a->metadata.tunnel)
 168             && (((!a->stack || !a->stack->size) &&
 169                  (!b->stack || !b->stack->size))
 170                 || (a->stack && b->stack && ofpbuf_equal(a->stack, b->stack)))
 171             && a->mirrors == b->mirrors
 172             && a->conntracked == b->conntracked
 173             && a->action_set_len == b->action_set_len
 174             && ofpacts_equal(a->ofpacts, a->ofpacts_len,
 175                              b->ofpacts, b->ofpacts_len));
 176 }
 177
 178 /* Lockless RCU protected lookup.  If node is needed accross RCU quiescent
 179  * state, caller should take a reference. */
 180 static struct recirc_id_node *
 181 recirc_find_equal(const struct recirc_state *target, uint32_t hash)
 182 {
 183     struct recirc_id_node *node;
 184
 185     CMAP_FOR_EACH_WITH_HASH (node, metadata_node, hash, &metadata_map) {
 186         if (recirc_metadata_equal(&node->state, target)) {
 187             return node;
 188         }
 189     }
 190     return NULL;
 191 }
 192
 193 static struct recirc_id_node *
 194 recirc_ref_equal(const struct recirc_state *target, uint32_t hash)
 195 {
 196     struct recirc_id_node *node;
 197
 198     do {
 199         node = recirc_find_equal(target, hash);
 200
 201         /* Try again if the node was released before we get the reference. */
 202     } while (node && !ovs_refcount_try_ref_rcu(&node->refcount));
 203
 204     return node;
 205 }
 206
 207 static void
 208 recirc_state_clone(struct recirc_state *new, const struct recirc_state *old,
 209                    struct flow_tnl *tunnel)
 210 {
 211     *new = *old;
 212     flow_tnl_copy__(tunnel, old->metadata.tunnel);
 213     new->metadata.tunnel = tunnel;
 214
 215     if (new->stack) {
 216         new->stack = new->stack->size ? ofpbuf_clone(new->stack) : NULL;
 217     }
 218     if (new->ofpacts) {
 219         new->ofpacts = (new->ofpacts_len
 220                         ? xmemdup(new->ofpacts, new->ofpacts_len)
 221                         : NULL);
 222     }
 223 }
 224
 225 /* Allocate a unique recirculation id for the given set of flow metadata.
 226  * The ID space is 2^^32, so there should never be a situation in which all
 227  * the IDs are used up.  We loop until we find a free one.
 228  * hash is recomputed if it is passed in as 0. */
 229 static struct recirc_id_node *
 230 recirc_alloc_id__(const struct recirc_state *state, uint32_t hash)
 231 {
 232     ovs_assert(state->action_set_len <= state->ofpacts_len);
 233
 234     struct recirc_id_node *node = xzalloc(sizeof *node);
 235
 236     node->hash = hash;
 237     ovs_refcount_init(&node->refcount);
 238     recirc_state_clone(CONST_CAST(struct recirc_state *, &node->state), state,
 239                        &node->state_metadata_tunnel);
 240
 241     ovs_mutex_lock(&mutex);
 242     for (;;) {
 243         /* Claim the next ID.  The ID space should be sparse enough for the
 244            allocation to succeed at the first try.  We do skip the first
 245            RECIRC_POOL_STATIC_IDS IDs on the later rounds, though, as some of
 246            the initial allocations may be for long term uses (like bonds). */
 247         node->id = next_id++;
 248         if (OVS_UNLIKELY(!node->id)) {
 249             next_id = RECIRC_POOL_STATIC_IDS + 1;
 250             node->id = next_id++;
 251         }
 252         /* Find if the id is free. */
 253         if (OVS_LIKELY(!recirc_find__(node->id))) {
 254             break;
 255         }
 256     }
 257     cmap_insert(&id_map, &node->id_node, node->id);
 258     cmap_insert(&metadata_map, &node->metadata_node, node->hash);
 259     ovs_mutex_unlock(&mutex);
 260     return node;
 261 }
 262
 263 /* Look up an existing ID for the given flow's metadata and optional actions.
 264  */
 265 uint32_t
 266 recirc_find_id(const struct recirc_state *target)
 267 {
 268     uint32_t hash = recirc_metadata_hash(target);
 269     struct recirc_id_node *node = recirc_find_equal(target, hash);
 270     return node ? node->id : 0;
 271 }
 272
 273 /* Allocate a unique recirculation id for the given set of flow metadata and
 274    optional actions. */
 275 uint32_t
 276 recirc_alloc_id_ctx(const struct recirc_state *state)
 277 {
 278     uint32_t hash = recirc_metadata_hash(state);
 279     struct recirc_id_node *node = recirc_ref_equal(state, hash);
 280     if (!node) {
 281         node = recirc_alloc_id__(state, hash);
 282     }
 283     return node->id;
 284 }
 285
 286 /* Allocate a unique recirculation id. */
 287 uint32_t
 288 recirc_alloc_id(struct ofproto_dpif *ofproto)
 289 {
 290     struct flow_tnl tunnel;
 291     tunnel.ip_dst = htonl(0);
 292     struct recirc_state state = {
 293         .table_id = TBL_INTERNAL,
 294         .ofproto = ofproto,
 295         .metadata = { .tunnel = &tunnel, .in_port = OFPP_NONE },
 296     };
 297     return recirc_alloc_id__(&state, recirc_metadata_hash(&state))->id;
 298 }
 299
 300 void
 301 recirc_id_node_unref(const struct recirc_id_node *node_)
 302     OVS_EXCLUDED(mutex)
 303 {
 304     struct recirc_id_node *node = CONST_CAST(struct recirc_id_node *, node_);
 305
 306     if (node && ovs_refcount_unref(&node->refcount) == 1) {
 307         ovs_mutex_lock(&mutex);
 308         /* Prevent re-use of this node by removing the node from 'metadata_map'
 309          */
 310         cmap_remove(&metadata_map, &node->metadata_node, node->hash);
 311         /* We keep the node in the 'id_map' so that it can be found as long
 312          * as it lingers, and add it to the 'expiring' list. */
 313         list_insert(&expiring, &node->exp_node);
 314         ovs_mutex_unlock(&mutex);
 315     }
 316 }
 317
 318 void
 319 recirc_free_id(uint32_t id)
 320 {
 321     const struct recirc_id_node *node;
 322
 323     node = recirc_id_node_find(id);
 324     if (node) {
 325         recirc_id_node_unref(node);
 326     } else {
 327         VLOG_ERR("Freeing nonexistent recirculation ID: %"PRIu32, id);
 328     }
 329 }
 330
 331 /* Called when 'ofproto' is destructed.  Checks for and clears any
 332  * recirc_id leak.
 333  * No other thread may have access to the 'ofproto' being destructed.
 334  * All related datapath flows must be deleted before calling this. */
 335 void
 336 recirc_free_ofproto(struct ofproto_dpif *ofproto, const char *ofproto_name)
 337 {
 338     struct recirc_id_node *n;
 339
 340     CMAP_FOR_EACH (n, metadata_node, &metadata_map) {
 341         if (n->state.ofproto == ofproto) {
 342             VLOG_ERR("recirc_id %"PRIu32
 343                      " left allocated when ofproto (%s)"
 344                      " is destructed", n->id, ofproto_name);
 345         }
 346     }
 347 }