2 * Copyright (c) 2003-2008 Chelsio, Inc. All rights reserved.
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32 #include <linux/skbuff.h>
33 #include <linux/netdevice.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>
42 #include "cxgb3_defs.h"
45 #include "firmware_exports.h"
47 #define VLAN_NONE 0xfff
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.
63 static inline unsigned int vlan_prio(const struct l2t_entry *e)
68 static inline unsigned int arp_hash(u32 key, int ifindex,
69 const struct l2t_data *d)
71 return jhash_2words(key, ifindex, 0) & (d->nentries - 1);
74 static inline void neigh_replace(struct l2t_entry *e, struct neighbour *n)
78 neigh_release(e->neigh);
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
87 static int setup_l2e_send_pending(struct t3cdev *dev, struct sk_buff *skb,
90 struct cpl_l2t_write_req *req;
94 skb = alloc_skb(sizeof(*req), GFP_ATOMIC);
99 req = (struct cpl_l2t_write_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);
110 skb_queue_walk_safe(&e->arpq, skb, tmp) {
111 __skb_unlink(skb, &e->arpq);
112 cxgb3_ofld_send(dev, skb);
114 e->state = L2T_STATE_VALID;
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.
123 static inline void arpq_enqueue(struct l2t_entry *e, struct sk_buff *skb)
125 __skb_queue_tail(&e->arpq, skb);
128 int t3_l2t_send_slow(struct t3cdev *dev, struct sk_buff *skb,
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 case L2T_STATE_VALID: /* fast-path, send the packet on */
140 return cxgb3_ofld_send(dev, skb);
141 case L2T_STATE_RESOLVING:
142 spin_lock_bh(&e->lock);
143 if (e->state != L2T_STATE_RESOLVING) {
144 /* ARP already completed */
145 spin_unlock_bh(&e->lock);
148 arpq_enqueue(e, skb);
149 spin_unlock_bh(&e->lock);
152 * Only the first packet added to the arpq should kick off
153 * resolution. However, because the alloc_skb below can fail,
154 * we allow each packet added to the arpq to retry resolution
155 * as a way of recovering from transient memory exhaustion.
156 * A better way would be to use a work request to retry L2T
157 * entries when there's no memory.
159 if (!neigh_event_send(e->neigh, NULL)) {
160 skb = alloc_skb(sizeof(struct cpl_l2t_write_req),
165 spin_lock_bh(&e->lock);
166 if (!skb_queue_empty(&e->arpq))
167 setup_l2e_send_pending(dev, skb, e);
168 else /* we lost the race */
170 spin_unlock_bh(&e->lock);
176 EXPORT_SYMBOL(t3_l2t_send_slow);
178 void t3_l2t_send_event(struct t3cdev *dev, struct l2t_entry *e)
182 case L2T_STATE_STALE: /* entry is stale, kick off revalidation */
183 neigh_event_send(e->neigh, NULL);
184 spin_lock_bh(&e->lock);
185 if (e->state == L2T_STATE_STALE) {
186 e->state = L2T_STATE_VALID;
188 spin_unlock_bh(&e->lock);
190 case L2T_STATE_VALID: /* fast-path, send the packet on */
192 case L2T_STATE_RESOLVING:
193 spin_lock_bh(&e->lock);
194 if (e->state != L2T_STATE_RESOLVING) {
195 /* ARP already completed */
196 spin_unlock_bh(&e->lock);
199 spin_unlock_bh(&e->lock);
202 * Only the first packet added to the arpq should kick off
203 * resolution. However, because the alloc_skb below can fail,
204 * we allow each packet added to the arpq to retry resolution
205 * as a way of recovering from transient memory exhaustion.
206 * A better way would be to use a work request to retry L2T
207 * entries when there's no memory.
209 neigh_event_send(e->neigh, NULL);
213 EXPORT_SYMBOL(t3_l2t_send_event);
216 * Allocate a free L2T entry. Must be called with l2t_data.lock held.
218 static struct l2t_entry *alloc_l2e(struct l2t_data *d)
220 struct l2t_entry *end, *e, **p;
222 if (!atomic_read(&d->nfree))
225 /* there's definitely a free entry */
226 for (e = d->rover, end = &d->l2tab[d->nentries]; e != end; ++e)
227 if (atomic_read(&e->refcnt) == 0)
230 for (e = &d->l2tab[1]; atomic_read(&e->refcnt); ++e) ;
233 atomic_dec(&d->nfree);
236 * The entry we found may be an inactive entry that is
237 * presently in the hash table. We need to remove it.
239 if (e->state != L2T_STATE_UNUSED) {
240 int hash = arp_hash(e->addr, e->ifindex, d);
242 for (p = &d->l2tab[hash].first; *p; p = &(*p)->next)
247 e->state = L2T_STATE_UNUSED;
253 * Called when an L2T entry has no more users. The entry is left in the hash
254 * table since it is likely to be reused but we also bump nfree to indicate
255 * that the entry can be reallocated for a different neighbor. We also drop
256 * the existing neighbor reference in case the neighbor is going away and is
257 * waiting on our reference.
259 * Because entries can be reallocated to other neighbors once their ref count
260 * drops to 0 we need to take the entry's lock to avoid races with a new
263 void t3_l2e_free(struct l2t_data *d, struct l2t_entry *e)
265 spin_lock_bh(&e->lock);
266 if (atomic_read(&e->refcnt) == 0) { /* hasn't been recycled */
268 neigh_release(e->neigh);
272 spin_unlock_bh(&e->lock);
273 atomic_inc(&d->nfree);
276 EXPORT_SYMBOL(t3_l2e_free);
279 * Update an L2T entry that was previously used for the same next hop as neigh.
280 * Must be called with softirqs disabled.
282 static inline void reuse_entry(struct l2t_entry *e, struct neighbour *neigh)
284 unsigned int nud_state;
286 spin_lock(&e->lock); /* avoid race with t3_l2t_free */
288 if (neigh != e->neigh)
289 neigh_replace(e, neigh);
290 nud_state = neigh->nud_state;
291 if (memcmp(e->dmac, neigh->ha, sizeof(e->dmac)) ||
292 !(nud_state & NUD_VALID))
293 e->state = L2T_STATE_RESOLVING;
294 else if (nud_state & NUD_CONNECTED)
295 e->state = L2T_STATE_VALID;
297 e->state = L2T_STATE_STALE;
298 spin_unlock(&e->lock);
301 struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct dst_entry *dst,
302 struct net_device *dev)
304 struct l2t_entry *e = NULL;
305 struct neighbour *neigh;
314 neigh = dst_get_neighbour_noref(dst);
318 addr = *(u32 *) neigh->primary_key;
319 ifidx = neigh->dev->ifindex;
323 p = netdev_priv(dev);
324 smt_idx = p->port_id;
330 hash = arp_hash(addr, ifidx, d);
332 write_lock_bh(&d->lock);
333 for (e = d->l2tab[hash].first; e; e = e->next)
334 if (e->addr == addr && e->ifindex == ifidx &&
335 e->smt_idx == smt_idx) {
337 if (atomic_read(&e->refcnt) == 1)
338 reuse_entry(e, neigh);
342 /* Need to allocate a new entry */
345 spin_lock(&e->lock); /* avoid race with t3_l2t_free */
346 e->next = d->l2tab[hash].first;
347 d->l2tab[hash].first = e;
348 e->state = L2T_STATE_RESOLVING;
351 e->smt_idx = smt_idx;
352 atomic_set(&e->refcnt, 1);
353 neigh_replace(e, neigh);
354 if (neigh->dev->priv_flags & IFF_802_1Q_VLAN)
355 e->vlan = vlan_dev_vlan_id(neigh->dev);
358 spin_unlock(&e->lock);
361 write_unlock_bh(&d->lock);
367 EXPORT_SYMBOL(t3_l2t_get);
370 * Called when address resolution fails for an L2T entry to handle packets
371 * on the arpq head. If a packet specifies a failure handler it is invoked,
372 * otherwise the packets is sent to the offload device.
374 * XXX: maybe we should abandon the latter behavior and just require a failure
377 static void handle_failed_resolution(struct t3cdev *dev, struct sk_buff_head *arpq)
379 struct sk_buff *skb, *tmp;
381 skb_queue_walk_safe(arpq, skb, tmp) {
382 struct l2t_skb_cb *cb = L2T_SKB_CB(skb);
384 __skb_unlink(skb, arpq);
385 if (cb->arp_failure_handler)
386 cb->arp_failure_handler(dev, skb);
388 cxgb3_ofld_send(dev, skb);
393 * Called when the host's ARP layer makes a change to some entry that is
394 * loaded into the HW L2 table.
396 void t3_l2t_update(struct t3cdev *dev, struct neighbour *neigh)
398 struct sk_buff_head arpq;
400 struct l2t_data *d = L2DATA(dev);
401 u32 addr = *(u32 *) neigh->primary_key;
402 int ifidx = neigh->dev->ifindex;
403 int hash = arp_hash(addr, ifidx, d);
405 read_lock_bh(&d->lock);
406 for (e = d->l2tab[hash].first; e; e = e->next)
407 if (e->addr == addr && e->ifindex == ifidx) {
411 read_unlock_bh(&d->lock);
415 __skb_queue_head_init(&arpq);
417 read_unlock(&d->lock);
418 if (atomic_read(&e->refcnt)) {
419 if (neigh != e->neigh)
420 neigh_replace(e, neigh);
422 if (e->state == L2T_STATE_RESOLVING) {
423 if (neigh->nud_state & NUD_FAILED) {
424 skb_queue_splice_init(&e->arpq, &arpq);
425 } else if (neigh->nud_state & (NUD_CONNECTED|NUD_STALE))
426 setup_l2e_send_pending(dev, NULL, e);
428 e->state = neigh->nud_state & NUD_CONNECTED ?
429 L2T_STATE_VALID : L2T_STATE_STALE;
430 if (memcmp(e->dmac, neigh->ha, 6))
431 setup_l2e_send_pending(dev, NULL, e);
434 spin_unlock_bh(&e->lock);
436 if (!skb_queue_empty(&arpq))
437 handle_failed_resolution(dev, &arpq);
440 struct l2t_data *t3_init_l2t(unsigned int l2t_capacity)
443 int i, size = sizeof(*d) + l2t_capacity * sizeof(struct l2t_entry);
445 d = cxgb_alloc_mem(size);
449 d->nentries = l2t_capacity;
450 d->rover = &d->l2tab[1]; /* entry 0 is not used */
451 atomic_set(&d->nfree, l2t_capacity - 1);
452 rwlock_init(&d->lock);
454 for (i = 0; i < l2t_capacity; ++i) {
456 d->l2tab[i].state = L2T_STATE_UNUSED;
457 __skb_queue_head_init(&d->l2tab[i].arpq);
458 spin_lock_init(&d->l2tab[i].lock);
459 atomic_set(&d->l2tab[i].refcnt, 0);
464 void t3_free_l2t(struct l2t_data *d)