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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 two5 * licenses. You may choose to be licensed under the terms of the GNU6 * General Public License (GPL) Version 2, available from the file7 * COPYING in the main directory of this source tree, or the8 * OpenIB.org BSD license below:9 *10 * Redistribution and use in source and binary forms, with or11 * without modification, are permitted provided that the following12 * conditions are met:13 *14 * - Redistributions of source code must retain the above15 * copyright notice, this list of conditions and the following16 * disclaimer.17 *18 * - Redistributions in binary form must reproduce the above19 * copyright notice, this list of conditions and the following20 * disclaimer in the documentation and/or other materials21 * 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 OF25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE30 * 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 0xfff48 49/*50 * Module locking notes: There is a RW lock protecting the L2 table as a51 * whole plus a spinlock per L2T entry. Entry lookups and allocations happen52 * under the protection of the table lock, individual entry changes happen53 * while holding that entry's spinlock. The table lock nests outside the54 * entry locks. Allocations of new entries take the table lock as writers so55 * no other lookups can happen while allocating new entries. Entry updates56 * take the table lock as readers so multiple entries can be updated in57 * parallel. An L2T entry can be dropped by decrementing its reference count58 * and therefore can happen in parallel with entry allocation but no entry59 * can change state or increment its ref count during allocation as both of60 * these perform lookups.61 */62 63static inline unsigned int vlan_prio(const struct l2t_entry *e)64{65 return e->vlan >> 13;66}67 68static 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 74static 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. The84 * supplied skb is used for the CPL_L2T_WRITE_REQ. Must be called with the85 * entry locked.86 */87static 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 */123static inline void arpq_enqueue(struct l2t_entry *e, struct sk_buff *skb)124{125 __skb_queue_tail(&e->arpq, skb);126}127 128int t3_l2t_send_slow(struct t3cdev *dev, struct sk_buff *skb,129 struct l2t_entry *e)130{131again: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 fallthrough;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 off154 * resolution. However, because the alloc_skb below can fail,155 * we allow each packet added to the arpq to retry resolution156 * as a way of recovering from transient memory exhaustion.157 * A better way would be to use a work request to retry L2T158 * 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 177EXPORT_SYMBOL(t3_l2t_send_slow);178 179void t3_l2t_send_event(struct t3cdev *dev, struct l2t_entry *e)180{181again: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 off204 * resolution. However, because the alloc_skb below can fail,205 * we allow each packet added to the arpq to retry resolution206 * as a way of recovering from transient memory exhaustion.207 * A better way would be to use a work request to retry L2T208 * entries when there's no memory.209 */210 neigh_event_send(e->neigh, NULL);211 }212}213 214EXPORT_SYMBOL(t3_l2t_send_event);215 216/*217 * Allocate a free L2T entry. Must be called with l2t_data.lock held.218 */219static 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) ;232found:233 d->rover = e + 1;234 atomic_dec(&d->nfree);235 236 /*237 * The entry we found may be an inactive entry that is238 * 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 hash255 * table since it is likely to be reused but we also bump nfree to indicate256 * that the entry can be reallocated for a different neighbor. We also drop257 * the existing neighbor reference in case the neighbor is going away and is258 * waiting on our reference.259 *260 * Because entries can be reallocated to other neighbors once their ref count261 * drops to 0 we need to take the entry's lock to avoid races with a new262 * incarnation.263 */264void 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 277EXPORT_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 */283static 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 else298 e->state = L2T_STATE_STALE;299 spin_unlock(&e->lock);300}301 302struct 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 else358 e->vlan = VLAN_NONE;359 spin_unlock(&e->lock);360 }361done_unlock:362 write_unlock_bh(&d->lock);363done_rcu:364 if (neigh)365 neigh_release(neigh);366 rcu_read_unlock();367 return e;368}369 370EXPORT_SYMBOL(t3_l2t_get);371 372/*373 * Called when address resolution fails for an L2T entry to handle packets374 * 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 failure378 * handler.379 */380static 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 else391 cxgb3_ofld_send(dev, skb);392 }393}394 395/*396 * Called when the host's ARP layer makes a change to some entry that is397 * loaded into the HW L2 table.398 */399void 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 417found: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 443struct 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}466