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