net/mac80211/mesh_pathtbl.c

   1 /*
   2  * Copyright (c) 2008 open80211s Ltd.
   3  * Author:     Luis Carlos Cobo <luisca@cozybit.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/etherdevice.h>
  11 #include <linux/list.h>
  12 #include <linux/netdevice.h>
  13 #include <linux/random.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/string.h>
  16 #include <net/mac80211.h>
  17 #include "ieee80211_i.h"
  18 #include "mesh.h"
  19
  20 /* There will be initially 2^INIT_PATHS_SIZE_ORDER buckets */
  21 #define INIT_PATHS_SIZE_ORDER   2
  22
  23 /* Keep the mean chain length below this constant */
  24 #define MEAN_CHAIN_LEN          2
  25
  26 #define MPATH_EXPIRED(mpath) ((mpath->flags & MESH_PATH_ACTIVE) && \
  27                                 time_after(jiffies, mpath->exp_time) && \
  28                                 !(mpath->flags & MESH_PATH_FIXED))
  29
  30 struct mpath_node {
  31         struct hlist_node list;
  32         struct rcu_head rcu;
  33         /* This indirection allows two different tables to point to the same
  34          * mesh_path structure, useful when resizing
  35          */
  36         struct mesh_path *mpath;
  37 };
  38
  39 static struct mesh_table *mesh_paths;
  40
  41 /* This lock will have the grow table function as writer and add / delete nodes
  42  * as readers. When reading the table (i.e. doing lookups) we are well protected
  43  * by RCU
  44  */
  45 static DEFINE_RWLOCK(pathtbl_resize_lock);
  46
  47 /**
  48  *
  49  * mesh_path_assign_nexthop - update mesh path next hop
  50  *
  51  * @mpath: mesh path to update
  52  * @sta: next hop to assign
  53  *
  54  * Locking: mpath->state_lock must be held when calling this function
  55  */
  56 void mesh_path_assign_nexthop(struct mesh_path *mpath, struct sta_info *sta)
  57 {
  58         rcu_assign_pointer(mpath->next_hop, sta);
  59 }
  60
  61
  62 /**
  63  * mesh_path_lookup - look up a path in the mesh path table
  64  * @dst: hardware address (ETH_ALEN length) of destination
  65  * @dev: local interface
  66  *
  67  * Returns: pointer to the mesh path structure, or NULL if not found
  68  *
  69  * Locking: must be called within a read rcu section.
  70  */
  71 struct mesh_path *mesh_path_lookup(u8 *dst, struct net_device *dev)
  72 {
  73         struct mesh_path *mpath;
  74         struct hlist_node *n;
  75         struct hlist_head *bucket;
  76         struct mesh_table *tbl;
  77         struct mpath_node *node;
  78
  79         tbl = rcu_dereference(mesh_paths);
  80
  81         bucket = &tbl->hash_buckets[mesh_table_hash(dst, dev, tbl)];
  82         hlist_for_each_entry_rcu(node, n, bucket, list) {
  83                 mpath = node->mpath;
  84                 if (mpath->dev == dev &&
  85                                 memcmp(dst, mpath->dst, ETH_ALEN) == 0) {
  86                         if (MPATH_EXPIRED(mpath)) {
  87                                 spin_lock_bh(&mpath->state_lock);
  88                                 if (MPATH_EXPIRED(mpath))
  89                                         mpath->flags &= ~MESH_PATH_ACTIVE;
  90                                 spin_unlock_bh(&mpath->state_lock);
  91                         }
  92                         return mpath;
  93                 }
  94         }
  95         return NULL;
  96 }
  97
  98 /**
  99  * mesh_path_lookup_by_idx - look up a path in the mesh path table by its index
 100  * @idx: index
 101  * @dev: local interface, or NULL for all entries
 102  *
 103  * Returns: pointer to the mesh path structure, or NULL if not found.
 104  *
 105  * Locking: must be called within a read rcu section.
 106  */
 107 struct mesh_path *mesh_path_lookup_by_idx(int idx, struct net_device *dev)
 108 {
 109         struct mpath_node *node;
 110         struct hlist_node *p;
 111         int i;
 112         int j = 0;
 113
 114         for_each_mesh_entry(mesh_paths, p, node, i) {
 115                 if (dev && node->mpath->dev != dev)
 116                         continue;
 117                 if (j++ == idx) {
 118                         if (MPATH_EXPIRED(node->mpath)) {
 119                                 spin_lock_bh(&node->mpath->state_lock);
 120                                 if (MPATH_EXPIRED(node->mpath))
 121                                         node->mpath->flags &= ~MESH_PATH_ACTIVE;
 122                                 spin_unlock_bh(&node->mpath->state_lock);
 123                         }
 124                         return node->mpath;
 125                 }
 126         }
 127
 128         return NULL;
 129 }
 130
 131 /**
 132  * mesh_path_add - allocate and add a new path to the mesh path table
 133  * @addr: destination address of the path (ETH_ALEN length)
 134  * @dev: local interface
 135  *
 136  * Returns: 0 on sucess
 137  *
 138  * State: the initial state of the new path is set to 0
 139  */
 140 int mesh_path_add(u8 *dst, struct net_device *dev)
 141 {
 142         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 143         struct mesh_path *mpath, *new_mpath;
 144         struct mpath_node *node, *new_node;
 145         struct hlist_head *bucket;
 146         struct hlist_node *n;
 147         int grow = 0;
 148         int err = 0;
 149         u32 hash_idx;
 150
 151         if (memcmp(dst, dev->dev_addr, ETH_ALEN) == 0)
 152                 /* never add ourselves as neighbours */
 153                 return -ENOTSUPP;
 154
 155         if (is_multicast_ether_addr(dst))
 156                 return -ENOTSUPP;
 157
 158         if (atomic_add_unless(&sdata->u.sta.mpaths, 1, MESH_MAX_MPATHS) == 0)
 159                 return -ENOSPC;
 160
 161         err = -ENOMEM;
 162         new_mpath = kzalloc(sizeof(struct mesh_path), GFP_KERNEL);
 163         if (!new_mpath)
 164                 goto err_path_alloc;
 165
 166         new_node = kmalloc(sizeof(struct mpath_node), GFP_KERNEL);
 167         if (!new_node)
 168                 goto err_node_alloc;
 169
 170         read_lock(&pathtbl_resize_lock);
 171         memcpy(new_mpath->dst, dst, ETH_ALEN);
 172         new_mpath->dev = dev;
 173         new_mpath->flags = 0;
 174         skb_queue_head_init(&new_mpath->frame_queue);
 175         new_node->mpath = new_mpath;
 176         new_mpath->timer.data = (unsigned long) new_mpath;
 177         new_mpath->timer.function = mesh_path_timer;
 178         new_mpath->exp_time = jiffies;
 179         spin_lock_init(&new_mpath->state_lock);
 180         init_timer(&new_mpath->timer);
 181
 182         hash_idx = mesh_table_hash(dst, dev, mesh_paths);
 183         bucket = &mesh_paths->hash_buckets[hash_idx];
 184
 185         spin_lock(&mesh_paths->hashwlock[hash_idx]);
 186
 187         err = -EEXIST;
 188         hlist_for_each_entry(node, n, bucket, list) {
 189                 mpath = node->mpath;
 190                 if (mpath->dev == dev && memcmp(dst, mpath->dst, ETH_ALEN) == 0)
 191                         goto err_exists;
 192         }
 193
 194         hlist_add_head_rcu(&new_node->list, bucket);
 195         if (atomic_inc_return(&mesh_paths->entries) >=
 196                 mesh_paths->mean_chain_len * (mesh_paths->hash_mask + 1))
 197                 grow = 1;
 198
 199         spin_unlock(&mesh_paths->hashwlock[hash_idx]);
 200         read_unlock(&pathtbl_resize_lock);
 201         if (grow) {
 202                 struct mesh_table *oldtbl, *newtbl;
 203
 204                 write_lock(&pathtbl_resize_lock);
 205                 oldtbl = mesh_paths;
 206                 newtbl = mesh_table_grow(mesh_paths);
 207                 if (!newtbl) {
 208                         write_unlock(&pathtbl_resize_lock);
 209                         return 0;
 210                 }
 211                 rcu_assign_pointer(mesh_paths, newtbl);
 212                 write_unlock(&pathtbl_resize_lock);
 213
 214                 synchronize_rcu();
 215                 mesh_table_free(oldtbl, false);
 216         }
 217         return 0;
 218
 219 err_exists:
 220         spin_unlock(&mesh_paths->hashwlock[hash_idx]);
 221         read_unlock(&pathtbl_resize_lock);
 222         kfree(new_node);
 223 err_node_alloc:
 224         kfree(new_mpath);
 225 err_path_alloc:
 226         atomic_dec(&sdata->u.sta.mpaths);
 227         return err;
 228 }
 229
 230
 231 /**
 232  * mesh_plink_broken - deactivates paths and sends perr when a link breaks
 233  *
 234  * @sta: broken peer link
 235  *
 236  * This function must be called from the rate control algorithm if enough
 237  * delivery errors suggest that a peer link is no longer usable.
 238  */
 239 void mesh_plink_broken(struct sta_info *sta)
 240 {
 241         struct mesh_path *mpath;
 242         struct mpath_node *node;
 243         struct hlist_node *p;
 244         struct net_device *dev = sta->sdata->dev;
 245         int i;
 246
 247         rcu_read_lock();
 248         for_each_mesh_entry(mesh_paths, p, node, i) {
 249                 mpath = node->mpath;
 250                 spin_lock_bh(&mpath->state_lock);
 251                 if (mpath->next_hop == sta &&
 252                     mpath->flags & MESH_PATH_ACTIVE &&
 253                     !(mpath->flags & MESH_PATH_FIXED)) {
 254                         mpath->flags &= ~MESH_PATH_ACTIVE;
 255                         ++mpath->dsn;
 256                         spin_unlock_bh(&mpath->state_lock);
 257                         mesh_path_error_tx(mpath->dst,
 258                                         cpu_to_le32(mpath->dsn),
 259                                         dev->broadcast, dev);
 260                 } else
 261                 spin_unlock_bh(&mpath->state_lock);
 262         }
 263         rcu_read_unlock();
 264 }
 265
 266 /**
 267  * mesh_path_flush_by_nexthop - Deletes mesh paths if their next hop matches
 268  *
 269  * @sta - mesh peer to match
 270  *
 271  * RCU notes: this function is called when a mesh plink transitions from
 272  * PLINK_ESTAB to any other state, since PLINK_ESTAB state is the only one that
 273  * allows path creation. This will happen before the sta can be freed (because
 274  * sta_info_destroy() calls this) so any reader in a rcu read block will be
 275  * protected against the plink disappearing.
 276  */
 277 void mesh_path_flush_by_nexthop(struct sta_info *sta)
 278 {
 279         struct mesh_path *mpath;
 280         struct mpath_node *node;
 281         struct hlist_node *p;
 282         int i;
 283
 284         for_each_mesh_entry(mesh_paths, p, node, i) {
 285                 mpath = node->mpath;
 286                 if (mpath->next_hop == sta)
 287                         mesh_path_del(mpath->dst, mpath->dev);
 288         }
 289 }
 290
 291 void mesh_path_flush(struct net_device *dev)
 292 {
 293         struct mesh_path *mpath;
 294         struct mpath_node *node;
 295         struct hlist_node *p;
 296         int i;
 297
 298         for_each_mesh_entry(mesh_paths, p, node, i) {
 299                 mpath = node->mpath;
 300                 if (mpath->dev == dev)
 301                         mesh_path_del(mpath->dst, mpath->dev);
 302         }
 303 }
 304
 305 static void mesh_path_node_reclaim(struct rcu_head *rp)
 306 {
 307         struct mpath_node *node = container_of(rp, struct mpath_node, rcu);
 308         struct ieee80211_sub_if_data *sdata =
 309                 IEEE80211_DEV_TO_SUB_IF(node->mpath->dev);
 310
 311         del_timer_sync(&node->mpath->timer);
 312         atomic_dec(&sdata->u.sta.mpaths);
 313         kfree(node->mpath);
 314         kfree(node);
 315 }
 316
 317 /**
 318  * mesh_path_del - delete a mesh path from the table
 319  *
 320  * @addr: dst address (ETH_ALEN length)
 321  * @dev: local interface
 322  *
 323  * Returns: 0 if succesful
 324  */
 325 int mesh_path_del(u8 *addr, struct net_device *dev)
 326 {
 327         struct mesh_path *mpath;
 328         struct mpath_node *node;
 329         struct hlist_head *bucket;
 330         struct hlist_node *n;
 331         int hash_idx;
 332         int err = 0;
 333
 334         read_lock(&pathtbl_resize_lock);
 335         hash_idx = mesh_table_hash(addr, dev, mesh_paths);
 336         bucket = &mesh_paths->hash_buckets[hash_idx];
 337
 338         spin_lock(&mesh_paths->hashwlock[hash_idx]);
 339         hlist_for_each_entry(node, n, bucket, list) {
 340                 mpath = node->mpath;
 341                 if (mpath->dev == dev &&
 342                                 memcmp(addr, mpath->dst, ETH_ALEN) == 0) {
 343                         spin_lock_bh(&mpath->state_lock);
 344                         mpath->flags |= MESH_PATH_RESOLVING;
 345                         hlist_del_rcu(&node->list);
 346                         call_rcu(&node->rcu, mesh_path_node_reclaim);
 347                         atomic_dec(&mesh_paths->entries);
 348                         spin_unlock_bh(&mpath->state_lock);
 349                         goto enddel;
 350                 }
 351         }
 352
 353         err = -ENXIO;
 354 enddel:
 355         spin_unlock(&mesh_paths->hashwlock[hash_idx]);
 356         read_unlock(&pathtbl_resize_lock);
 357         return err;
 358 }
 359
 360 /**
 361  * mesh_path_tx_pending - sends pending frames in a mesh path queue
 362  *
 363  * @mpath: mesh path to activate
 364  *
 365  * Locking: the state_lock of the mpath structure must NOT be held when calling
 366  * this function.
 367  */
 368 void mesh_path_tx_pending(struct mesh_path *mpath)
 369 {
 370         struct sk_buff *skb;
 371
 372         while ((skb = skb_dequeue(&mpath->frame_queue)) &&
 373                         (mpath->flags & MESH_PATH_ACTIVE))
 374                 dev_queue_xmit(skb);
 375 }
 376
 377 /**
 378  * mesh_path_discard_frame - discard a frame whose path could not be resolved
 379  *
 380  * @skb: frame to discard
 381  * @dev: network device the frame was to be sent through
 382  *
 383  * If the frame was beign forwarded from another MP, a PERR frame will be sent
 384  * to the precursor.
 385  *
 386  * Locking: the function must me called within a rcu_read_lock region
 387  */
 388 void mesh_path_discard_frame(struct sk_buff *skb, struct net_device *dev)
 389 {
 390         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 391         struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
 392         struct mesh_path *mpath;
 393         u32 dsn = 0;
 394
 395         if (memcmp(hdr->addr4, dev->dev_addr, ETH_ALEN) != 0) {
 396                 u8 *ra, *da;
 397
 398                 da = hdr->addr3;
 399                 ra = hdr->addr2;
 400                 mpath = mesh_path_lookup(da, dev);
 401                 if (mpath)
 402                         dsn = ++mpath->dsn;
 403                 mesh_path_error_tx(skb->data, cpu_to_le32(dsn), ra, dev);
 404         }
 405
 406         kfree_skb(skb);
 407         sdata->u.sta.mshstats.dropped_frames_no_route++;
 408 }
 409
 410 /**
 411  * mesh_path_flush_pending - free the pending queue of a mesh path
 412  *
 413  * @mpath: mesh path whose queue has to be freed
 414  *
 415  * Locking: the function must me called withing a rcu_read_lock region
 416  */
 417 void mesh_path_flush_pending(struct mesh_path *mpath)
 418 {
 419         struct ieee80211_sub_if_data *sdata;
 420         struct sk_buff *skb;
 421
 422         sdata = IEEE80211_DEV_TO_SUB_IF(mpath->dev);
 423
 424         while ((skb = skb_dequeue(&mpath->frame_queue)) &&
 425                         (mpath->flags & MESH_PATH_ACTIVE))
 426                 mesh_path_discard_frame(skb, mpath->dev);
 427 }
 428
 429 /**
 430  * mesh_path_fix_nexthop - force a specific next hop for a mesh path
 431  *
 432  * @mpath: the mesh path to modify
 433  * @next_hop: the next hop to force
 434  *
 435  * Locking: this function must be called holding mpath->state_lock
 436  */
 437 void mesh_path_fix_nexthop(struct mesh_path *mpath, struct sta_info *next_hop)
 438 {
 439         spin_lock_bh(&mpath->state_lock);
 440         mesh_path_assign_nexthop(mpath, next_hop);
 441         mpath->dsn = 0xffff;
 442         mpath->metric = 0;
 443         mpath->hop_count = 0;
 444         mpath->exp_time = 0;
 445         mpath->flags |= MESH_PATH_FIXED;
 446         mesh_path_activate(mpath);
 447         spin_unlock_bh(&mpath->state_lock);
 448         mesh_path_tx_pending(mpath);
 449 }
 450
 451 static void mesh_path_node_free(struct hlist_node *p, bool free_leafs)
 452 {
 453         struct mesh_path *mpath;
 454         struct mpath_node *node = hlist_entry(p, struct mpath_node, list);
 455         mpath = node->mpath;
 456         hlist_del_rcu(p);
 457         if (free_leafs)
 458                 kfree(mpath);
 459         kfree(node);
 460 }
 461
 462 static int mesh_path_node_copy(struct hlist_node *p, struct mesh_table *newtbl)
 463 {
 464         struct mesh_path *mpath;
 465         struct mpath_node *node, *new_node;
 466         u32 hash_idx;
 467
 468         new_node = kmalloc(sizeof(struct mpath_node), GFP_ATOMIC);
 469         if (new_node == NULL)
 470                 return -ENOMEM;
 471
 472         node = hlist_entry(p, struct mpath_node, list);
 473         mpath = node->mpath;
 474         new_node->mpath = mpath;
 475         hash_idx = mesh_table_hash(mpath->dst, mpath->dev, newtbl);
 476         hlist_add_head(&new_node->list,
 477                         &newtbl->hash_buckets[hash_idx]);
 478         return 0;
 479 }
 480
 481 int mesh_pathtbl_init(void)
 482 {
 483         mesh_paths = mesh_table_alloc(INIT_PATHS_SIZE_ORDER);
 484         mesh_paths->free_node = &mesh_path_node_free;
 485         mesh_paths->copy_node = &mesh_path_node_copy;
 486         mesh_paths->mean_chain_len = MEAN_CHAIN_LEN;
 487         if (!mesh_paths)
 488                 return -ENOMEM;
 489         return 0;
 490 }
 491
 492 void mesh_path_expire(struct net_device *dev)
 493 {
 494         struct mesh_path *mpath;
 495         struct mpath_node *node;
 496         struct hlist_node *p;
 497         int i;
 498
 499         read_lock(&pathtbl_resize_lock);
 500         for_each_mesh_entry(mesh_paths, p, node, i) {
 501                 if (node->mpath->dev != dev)
 502                         continue;
 503                 mpath = node->mpath;
 504                 spin_lock_bh(&mpath->state_lock);
 505                 if ((!(mpath->flags & MESH_PATH_RESOLVING)) &&
 506                     (!(mpath->flags & MESH_PATH_FIXED)) &&
 507                         time_after(jiffies,
 508                          mpath->exp_time + MESH_PATH_EXPIRE)) {
 509                         spin_unlock_bh(&mpath->state_lock);
 510                         mesh_path_del(mpath->dst, mpath->dev);
 511                 } else
 512                         spin_unlock_bh(&mpath->state_lock);
 513         }
 514         read_unlock(&pathtbl_resize_lock);
 515 }
 516
 517 void mesh_pathtbl_unregister(void)
 518 {
 519         mesh_table_free(mesh_paths, true);
 520 }