root/drivers/net/ethernet/chelsio/cxgb3/l2t.c

DEFINITIONS

1. vlan_prio
2. arp_hash
3. neigh_replace
4. setup_l2e_send_pending
5. arpq_enqueue
6. t3_l2t_send_slow
7. t3_l2t_send_event
8. alloc_l2e
9. t3_l2e_free
10. reuse_entry
11. t3_l2t_get
12. handle_failed_resolution
13. t3_l2t_update
14. t3_init_l2t

   1 /*
   2  * Copyright (c) 2003-2008 Chelsio, Inc. All rights reserved.
   3  *
   4  * This software is available to you under a choice of one of two
   5  * licenses.  You may choose to be licensed under the terms of the GNU
   6  * General Public License (GPL) Version 2, available from the file
   7  * COPYING in the main directory of this source tree, or the
   8  * OpenIB.org BSD license below:
   9  *
  10  *     Redistribution and use in source and binary forms, with or
  11  *     without modification, are permitted provided that the following
  12  *     conditions are met:
  13  *
  14  *      - Redistributions of source code must retain the above
  15  *        copyright notice, this list of conditions and the following
  16  *        disclaimer.
  17  *
  18  *      - Redistributions in binary form must reproduce the above
  19  *        copyright notice, this list of conditions and the following
  20  *        disclaimer in the documentation and/or other materials
  21  *        provided with the distribution.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  */
  32 #include <linux/skbuff.h>
  33 #include <linux/netdevice.h>
  34 #include <linux/if.h>
  35 #include <linux/if_vlan.h>
  36 #include <linux/jhash.h>
  37 #include <linux/slab.h>
  38 #include <linux/export.h>
  39 #include <net/neighbour.h>
  40 #include "common.h"
  41 #include "t3cdev.h"
  42 #include "cxgb3_defs.h"
  43 #include "l2t.h"
  44 #include "t3_cpl.h"
  45 #include "firmware_exports.h"
  46 
  47 #define VLAN_NONE 0xfff
  48 
  49 /*
  50  * Module locking notes:  There is a RW lock protecting the L2 table as a
  51  * whole plus a spinlock per L2T entry.  Entry lookups and allocations happen
  52  * under the protection of the table lock, individual entry changes happen
  53  * while holding that entry's spinlock.  The table lock nests outside the
  54  * entry locks.  Allocations of new entries take the table lock as writers so
  55  * no other lookups can happen while allocating new entries.  Entry updates
  56  * take the table lock as readers so multiple entries can be updated in
  57  * parallel.  An L2T entry can be dropped by decrementing its reference count
  58  * and therefore can happen in parallel with entry allocation but no entry
  59  * can change state or increment its ref count during allocation as both of
  60  * these perform lookups.
  61  */
  62 
  63 static inline unsigned int vlan_prio(const struct l2t_entry *e)
  64 {
  65         return e->vlan >> 13;
  66 }
  67 
  68 static inline unsigned int arp_hash(u32 key, int ifindex,
  69                                     const struct l2t_data *d)
  70 {
  71         return jhash_2words(key, ifindex, 0) & (d->nentries - 1);
  72 }
  73 
  74 static inline void neigh_replace(struct l2t_entry *e, struct neighbour *n)
  75 {
  76         neigh_hold(n);
  77         if (e->neigh)
  78                 neigh_release(e->neigh);
  79         e->neigh = n;
  80 }
  81 
  82 /*
  83  * Set up an L2T entry and send any packets waiting in the arp queue.  The
  84  * supplied skb is used for the CPL_L2T_WRITE_REQ.  Must be called with the
  85  * entry locked.
  86  */
  87 static int setup_l2e_send_pending(struct t3cdev *dev, struct sk_buff *skb,
  88                                   struct l2t_entry *e)
  89 {
  90         struct cpl_l2t_write_req *req;
  91         struct sk_buff *tmp;
  92 
  93         if (!skb) {
  94                 skb = alloc_skb(sizeof(*req), GFP_ATOMIC);
  95                 if (!skb)
  96                         return -ENOMEM;
  97         }
  98 
  99         req = __skb_put(skb, sizeof(*req));
 100         req->wr.wr_hi = htonl(V_WR_OP(FW_WROPCODE_FORWARD));
 101         OPCODE_TID(req) = htonl(MK_OPCODE_TID(CPL_L2T_WRITE_REQ, e->idx));
 102         req->params = htonl(V_L2T_W_IDX(e->idx) | V_L2T_W_IFF(e->smt_idx) |
 103                             V_L2T_W_VLAN(e->vlan & VLAN_VID_MASK) |
 104                             V_L2T_W_PRIO(vlan_prio(e)));
 105         memcpy(e->dmac, e->neigh->ha, sizeof(e->dmac));
 106         memcpy(req->dst_mac, e->dmac, sizeof(req->dst_mac));
 107         skb->priority = CPL_PRIORITY_CONTROL;
 108         cxgb3_ofld_send(dev, skb);
 109 
 110         skb_queue_walk_safe(&e->arpq, skb, tmp) {
 111                 __skb_unlink(skb, &e->arpq);
 112                 cxgb3_ofld_send(dev, skb);
 113         }
 114         e->state = L2T_STATE_VALID;
 115 
 116         return 0;
 117 }
 118 
 119 /*
 120  * Add a packet to the an L2T entry's queue of packets awaiting resolution.
 121  * Must be called with the entry's lock held.
 122  */
 123 static inline void arpq_enqueue(struct l2t_entry *e, struct sk_buff *skb)
 124 {
 125         __skb_queue_tail(&e->arpq, skb);
 126 }
 127 
 128 int t3_l2t_send_slow(struct t3cdev *dev, struct sk_buff *skb,
 129                      struct l2t_entry *e)
 130 {
 131 again:
 132         switch (e->state) {
 133         case L2T_STATE_STALE:   /* entry is stale, kick off revalidation */
 134                 neigh_event_send(e->neigh, NULL);
 135                 spin_lock_bh(&e->lock);
 136                 if (e->state == L2T_STATE_STALE)
 137                         e->state = L2T_STATE_VALID;
 138                 spin_unlock_bh(&e->lock);
 139                 /* fall through */
 140         case L2T_STATE_VALID:   /* fast-path, send the packet on */
 141                 return cxgb3_ofld_send(dev, skb);
 142         case L2T_STATE_RESOLVING:
 143                 spin_lock_bh(&e->lock);
 144                 if (e->state != L2T_STATE_RESOLVING) {
 145                         /* ARP already completed */
 146                         spin_unlock_bh(&e->lock);
 147                         goto again;
 148                 }
 149                 arpq_enqueue(e, skb);
 150                 spin_unlock_bh(&e->lock);
 151 
 152                 /*
 153                  * Only the first packet added to the arpq should kick off
 154                  * resolution.  However, because the alloc_skb below can fail,
 155                  * we allow each packet added to the arpq to retry resolution
 156                  * as a way of recovering from transient memory exhaustion.
 157                  * A better way would be to use a work request to retry L2T
 158                  * entries when there's no memory.
 159                  */
 160                 if (!neigh_event_send(e->neigh, NULL)) {
 161                         skb = alloc_skb(sizeof(struct cpl_l2t_write_req),
 162                                         GFP_ATOMIC);
 163                         if (!skb)
 164                                 break;
 165 
 166                         spin_lock_bh(&e->lock);
 167                         if (!skb_queue_empty(&e->arpq))
 168                                 setup_l2e_send_pending(dev, skb, e);
 169                         else    /* we lost the race */
 170                                 __kfree_skb(skb);
 171                         spin_unlock_bh(&e->lock);
 172                 }
 173         }
 174         return 0;
 175 }
 176 
 177 EXPORT_SYMBOL(t3_l2t_send_slow);
 178 
 179 void t3_l2t_send_event(struct t3cdev *dev, struct l2t_entry *e)
 180 {
 181 again:
 182         switch (e->state) {
 183         case L2T_STATE_STALE:   /* entry is stale, kick off revalidation */
 184                 neigh_event_send(e->neigh, NULL);
 185                 spin_lock_bh(&e->lock);
 186                 if (e->state == L2T_STATE_STALE) {
 187                         e->state = L2T_STATE_VALID;
 188                 }
 189                 spin_unlock_bh(&e->lock);
 190                 return;
 191         case L2T_STATE_VALID:   /* fast-path, send the packet on */
 192                 return;
 193         case L2T_STATE_RESOLVING:
 194                 spin_lock_bh(&e->lock);
 195                 if (e->state != L2T_STATE_RESOLVING) {
 196                         /* ARP already completed */
 197                         spin_unlock_bh(&e->lock);
 198                         goto again;
 199                 }
 200                 spin_unlock_bh(&e->lock);
 201 
 202                 /*
 203                  * Only the first packet added to the arpq should kick off
 204                  * resolution.  However, because the alloc_skb below can fail,
 205                  * we allow each packet added to the arpq to retry resolution
 206                  * as a way of recovering from transient memory exhaustion.
 207                  * A better way would be to use a work request to retry L2T
 208                  * entries when there's no memory.
 209                  */
 210                 neigh_event_send(e->neigh, NULL);
 211         }
 212 }
 213 
 214 EXPORT_SYMBOL(t3_l2t_send_event);
 215 
 216 /*
 217  * Allocate a free L2T entry.  Must be called with l2t_data.lock held.
 218  */
 219 static struct l2t_entry *alloc_l2e(struct l2t_data *d)
 220 {
 221         struct l2t_entry *end, *e, **p;
 222 
 223         if (!atomic_read(&d->nfree))
 224                 return NULL;
 225 
 226         /* there's definitely a free entry */
 227         for (e = d->rover, end = &d->l2tab[d->nentries]; e != end; ++e)
 228                 if (atomic_read(&e->refcnt) == 0)
 229                         goto found;
 230 
 231         for (e = &d->l2tab[1]; atomic_read(&e->refcnt); ++e) ;
 232 found:
 233         d->rover = e + 1;
 234         atomic_dec(&d->nfree);
 235 
 236         /*
 237          * The entry we found may be an inactive entry that is
 238          * presently in the hash table.  We need to remove it.
 239          */
 240         if (e->state != L2T_STATE_UNUSED) {
 241                 int hash = arp_hash(e->addr, e->ifindex, d);
 242 
 243                 for (p = &d->l2tab[hash].first; *p; p = &(*p)->next)
 244                         if (*p == e) {
 245                                 *p = e->next;
 246                                 break;
 247                         }
 248                 e->state = L2T_STATE_UNUSED;
 249         }
 250         return e;
 251 }
 252 
 253 /*
 254  * Called when an L2T entry has no more users.  The entry is left in the hash
 255  * table since it is likely to be reused but we also bump nfree to indicate
 256  * that the entry can be reallocated for a different neighbor.  We also drop
 257  * the existing neighbor reference in case the neighbor is going away and is
 258  * waiting on our reference.
 259  *
 260  * Because entries can be reallocated to other neighbors once their ref count
 261  * drops to 0 we need to take the entry's lock to avoid races with a new
 262  * incarnation.
 263  */
 264 void t3_l2e_free(struct l2t_data *d, struct l2t_entry *e)
 265 {
 266         spin_lock_bh(&e->lock);
 267         if (atomic_read(&e->refcnt) == 0) {     /* hasn't been recycled */
 268                 if (e->neigh) {
 269                         neigh_release(e->neigh);
 270                         e->neigh = NULL;
 271                 }
 272         }
 273         spin_unlock_bh(&e->lock);
 274         atomic_inc(&d->nfree);
 275 }
 276 
 277 EXPORT_SYMBOL(t3_l2e_free);
 278 
 279 /*
 280  * Update an L2T entry that was previously used for the same next hop as neigh.
 281  * Must be called with softirqs disabled.
 282  */
 283 static inline void reuse_entry(struct l2t_entry *e, struct neighbour *neigh)
 284 {
 285         unsigned int nud_state;
 286 
 287         spin_lock(&e->lock);    /* avoid race with t3_l2t_free */
 288 
 289         if (neigh != e->neigh)
 290                 neigh_replace(e, neigh);
 291         nud_state = neigh->nud_state;
 292         if (memcmp(e->dmac, neigh->ha, sizeof(e->dmac)) ||
 293             !(nud_state & NUD_VALID))
 294                 e->state = L2T_STATE_RESOLVING;
 295         else if (nud_state & NUD_CONNECTED)
 296                 e->state = L2T_STATE_VALID;
 297         else
 298                 e->state = L2T_STATE_STALE;
 299         spin_unlock(&e->lock);
 300 }
 301 
 302 struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct dst_entry *dst,
 303                              struct net_device *dev, const void *daddr)
 304 {
 305         struct l2t_entry *e = NULL;
 306         struct neighbour *neigh;
 307         struct port_info *p;
 308         struct l2t_data *d;
 309         int hash;
 310         u32 addr;
 311         int ifidx;
 312         int smt_idx;
 313 
 314         rcu_read_lock();
 315         neigh = dst_neigh_lookup(dst, daddr);
 316         if (!neigh)
 317                 goto done_rcu;
 318 
 319         addr = *(u32 *) neigh->primary_key;
 320         ifidx = neigh->dev->ifindex;
 321 
 322         if (!dev)
 323                 dev = neigh->dev;
 324         p = netdev_priv(dev);
 325         smt_idx = p->port_id;
 326 
 327         d = L2DATA(cdev);
 328         if (!d)
 329                 goto done_rcu;
 330 
 331         hash = arp_hash(addr, ifidx, d);
 332 
 333         write_lock_bh(&d->lock);
 334         for (e = d->l2tab[hash].first; e; e = e->next)
 335                 if (e->addr == addr && e->ifindex == ifidx &&
 336                     e->smt_idx == smt_idx) {
 337                         l2t_hold(d, e);
 338                         if (atomic_read(&e->refcnt) == 1)
 339                                 reuse_entry(e, neigh);
 340                         goto done_unlock;
 341                 }
 342 
 343         /* Need to allocate a new entry */
 344         e = alloc_l2e(d);
 345         if (e) {
 346                 spin_lock(&e->lock);    /* avoid race with t3_l2t_free */
 347                 e->next = d->l2tab[hash].first;
 348                 d->l2tab[hash].first = e;
 349                 e->state = L2T_STATE_RESOLVING;
 350                 e->addr = addr;
 351                 e->ifindex = ifidx;
 352                 e->smt_idx = smt_idx;
 353                 atomic_set(&e->refcnt, 1);
 354                 neigh_replace(e, neigh);
 355                 if (is_vlan_dev(neigh->dev))
 356                         e->vlan = vlan_dev_vlan_id(neigh->dev);
 357                 else
 358                         e->vlan = VLAN_NONE;
 359                 spin_unlock(&e->lock);
 360         }
 361 done_unlock:
 362         write_unlock_bh(&d->lock);
 363 done_rcu:
 364         if (neigh)
 365                 neigh_release(neigh);
 366         rcu_read_unlock();
 367         return e;
 368 }
 369 
 370 EXPORT_SYMBOL(t3_l2t_get);
 371 
 372 /*
 373  * Called when address resolution fails for an L2T entry to handle packets
 374  * on the arpq head.  If a packet specifies a failure handler it is invoked,
 375  * otherwise the packets is sent to the offload device.
 376  *
 377  * XXX: maybe we should abandon the latter behavior and just require a failure
 378  * handler.
 379  */
 380 static void handle_failed_resolution(struct t3cdev *dev, struct sk_buff_head *arpq)
 381 {
 382         struct sk_buff *skb, *tmp;
 383 
 384         skb_queue_walk_safe(arpq, skb, tmp) {
 385                 struct l2t_skb_cb *cb = L2T_SKB_CB(skb);
 386 
 387                 __skb_unlink(skb, arpq);
 388                 if (cb->arp_failure_handler)
 389                         cb->arp_failure_handler(dev, skb);
 390                 else
 391                         cxgb3_ofld_send(dev, skb);
 392         }
 393 }
 394 
 395 /*
 396  * Called when the host's ARP layer makes a change to some entry that is
 397  * loaded into the HW L2 table.
 398  */
 399 void t3_l2t_update(struct t3cdev *dev, struct neighbour *neigh)
 400 {
 401         struct sk_buff_head arpq;
 402         struct l2t_entry *e;
 403         struct l2t_data *d = L2DATA(dev);
 404         u32 addr = *(u32 *) neigh->primary_key;
 405         int ifidx = neigh->dev->ifindex;
 406         int hash = arp_hash(addr, ifidx, d);
 407 
 408         read_lock_bh(&d->lock);
 409         for (e = d->l2tab[hash].first; e; e = e->next)
 410                 if (e->addr == addr && e->ifindex == ifidx) {
 411                         spin_lock(&e->lock);
 412                         goto found;
 413                 }
 414         read_unlock_bh(&d->lock);
 415         return;
 416 
 417 found:
 418         __skb_queue_head_init(&arpq);
 419 
 420         read_unlock(&d->lock);
 421         if (atomic_read(&e->refcnt)) {
 422                 if (neigh != e->neigh)
 423                         neigh_replace(e, neigh);
 424 
 425                 if (e->state == L2T_STATE_RESOLVING) {
 426                         if (neigh->nud_state & NUD_FAILED) {
 427                                 skb_queue_splice_init(&e->arpq, &arpq);
 428                         } else if (neigh->nud_state & (NUD_CONNECTED|NUD_STALE))
 429                                 setup_l2e_send_pending(dev, NULL, e);
 430                 } else {
 431                         e->state = neigh->nud_state & NUD_CONNECTED ?
 432                             L2T_STATE_VALID : L2T_STATE_STALE;
 433                         if (!ether_addr_equal(e->dmac, neigh->ha))
 434                                 setup_l2e_send_pending(dev, NULL, e);
 435                 }
 436         }
 437         spin_unlock_bh(&e->lock);
 438 
 439         if (!skb_queue_empty(&arpq))
 440                 handle_failed_resolution(dev, &arpq);
 441 }
 442 
 443 struct l2t_data *t3_init_l2t(unsigned int l2t_capacity)
 444 {
 445         struct l2t_data *d;
 446         int i;
 447 
 448         d = kvzalloc(struct_size(d, l2tab, l2t_capacity), GFP_KERNEL);
 449         if (!d)
 450                 return NULL;
 451 
 452         d->nentries = l2t_capacity;
 453         d->rover = &d->l2tab[1];        /* entry 0 is not used */
 454         atomic_set(&d->nfree, l2t_capacity - 1);
 455         rwlock_init(&d->lock);
 456 
 457         for (i = 0; i < l2t_capacity; ++i) {
 458                 d->l2tab[i].idx = i;
 459                 d->l2tab[i].state = L2T_STATE_UNUSED;
 460                 __skb_queue_head_init(&d->l2tab[i].arpq);
 461                 spin_lock_init(&d->l2tab[i].lock);
 462                 atomic_set(&d->l2tab[i].refcnt, 0);
 463         }
 464         return d;
 465 }