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 	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);
146 			goto again;
147 		}
148 		arpq_enqueue(e, skb);
149 		spin_unlock_bh(&e->lock);
150 
151 		/*
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.
158 		 */
159 		if (!neigh_event_send(e->neigh, NULL)) {
160 			skb = alloc_skb(sizeof(struct cpl_l2t_write_req),
161 					GFP_ATOMIC);
162 			if (!skb)
163 				break;
164 
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 */
169 				__kfree_skb(skb);
170 			spin_unlock_bh(&e->lock);
171 		}
172 	}
173 	return 0;
174 }
175 
176 EXPORT_SYMBOL(t3_l2t_send_slow);
177 
178 void t3_l2t_send_event(struct t3cdev *dev, struct l2t_entry *e)
179 {
180 again:
181 	switch (e->state) {
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;
187 		}
188 		spin_unlock_bh(&e->lock);
189 		return;
190 	case L2T_STATE_VALID:	/* fast-path, send the packet on */
191 		return;
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);
197 			goto again;
198 		}
199 		spin_unlock_bh(&e->lock);
200 
201 		/*
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.
208 		 */
209 		neigh_event_send(e->neigh, NULL);
210 	}
211 }
212 
213 EXPORT_SYMBOL(t3_l2t_send_event);
214 
215 /*
216  * Allocate a free L2T entry.  Must be called with l2t_data.lock held.
217  */
218 static struct l2t_entry *alloc_l2e(struct l2t_data *d)
219 {
220 	struct l2t_entry *end, *e, **p;
221 
222 	if (!atomic_read(&d->nfree))
223 		return NULL;
224 
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)
228 			goto found;
229 
230 	for (e = &d->l2tab[1]; atomic_read(&e->refcnt); ++e) ;
231 found:
232 	d->rover = e + 1;
233 	atomic_dec(&d->nfree);
234 
235 	/*
236 	 * The entry we found may be an inactive entry that is
237 	 * presently in the hash table.  We need to remove it.
238 	 */
239 	if (e->state != L2T_STATE_UNUSED) {
240 		int hash = arp_hash(e->addr, e->ifindex, d);
241 
242 		for (p = &d->l2tab[hash].first; *p; p = &(*p)->next)
243 			if (*p == e) {
244 				*p = e->next;
245 				break;
246 			}
247 		e->state = L2T_STATE_UNUSED;
248 	}
249 	return e;
250 }
251 
252 /*
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.
258  *
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
261  * incarnation.
262  */
263 void t3_l2e_free(struct l2t_data *d, struct l2t_entry *e)
264 {
265 	spin_lock_bh(&e->lock);
266 	if (atomic_read(&e->refcnt) == 0) {	/* hasn't been recycled */
267 		if (e->neigh) {
268 			neigh_release(e->neigh);
269 			e->neigh = NULL;
270 		}
271 	}
272 	spin_unlock_bh(&e->lock);
273 	atomic_inc(&d->nfree);
274 }
275 
276 EXPORT_SYMBOL(t3_l2e_free);
277 
278 /*
279  * Update an L2T entry that was previously used for the same next hop as neigh.
280  * Must be called with softirqs disabled.
281  */
282 static inline void reuse_entry(struct l2t_entry *e, struct neighbour *neigh)
283 {
284 	unsigned int nud_state;
285 
286 	spin_lock(&e->lock);	/* avoid race with t3_l2t_free */
287 
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;
296 	else
297 		e->state = L2T_STATE_STALE;
298 	spin_unlock(&e->lock);
299 }
300 
301 struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct dst_entry *dst,
302 			     struct net_device *dev, const void *daddr)
303 {
304 	struct l2t_entry *e = NULL;
305 	struct neighbour *neigh;
306 	struct port_info *p;
307 	struct l2t_data *d;
308 	int hash;
309 	u32 addr;
310 	int ifidx;
311 	int smt_idx;
312 
313 	rcu_read_lock();
314 	neigh = dst_neigh_lookup(dst, daddr);
315 	if (!neigh)
316 		goto done_rcu;
317 
318 	addr = *(u32 *) neigh->primary_key;
319 	ifidx = neigh->dev->ifindex;
320 
321 	if (!dev)
322 		dev = neigh->dev;
323 	p = netdev_priv(dev);
324 	smt_idx = p->port_id;
325 
326 	d = L2DATA(cdev);
327 	if (!d)
328 		goto done_rcu;
329 
330 	hash = arp_hash(addr, ifidx, d);
331 
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) {
336 			l2t_hold(d, e);
337 			if (atomic_read(&e->refcnt) == 1)
338 				reuse_entry(e, neigh);
339 			goto done_unlock;
340 		}
341 
342 	/* Need to allocate a new entry */
343 	e = alloc_l2e(d);
344 	if (e) {
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;
349 		e->addr = addr;
350 		e->ifindex = ifidx;
351 		e->smt_idx = smt_idx;
352 		atomic_set(&e->refcnt, 1);
353 		neigh_replace(e, neigh);
354 		if (is_vlan_dev(neigh->dev))
355 			e->vlan = vlan_dev_vlan_id(neigh->dev);
356 		else
357 			e->vlan = VLAN_NONE;
358 		spin_unlock(&e->lock);
359 	}
360 done_unlock:
361 	write_unlock_bh(&d->lock);
362 done_rcu:
363 	if (neigh)
364 		neigh_release(neigh);
365 	rcu_read_unlock();
366 	return e;
367 }
368 
369 EXPORT_SYMBOL(t3_l2t_get);
370 
371 /*
372  * Called when address resolution fails for an L2T entry to handle packets
373  * on the arpq head.  If a packet specifies a failure handler it is invoked,
374  * otherwise the packets is sent to the offload device.
375  *
376  * XXX: maybe we should abandon the latter behavior and just require a failure
377  * handler.
378  */
379 static void handle_failed_resolution(struct t3cdev *dev, struct sk_buff_head *arpq)
380 {
381 	struct sk_buff *skb, *tmp;
382 
383 	skb_queue_walk_safe(arpq, skb, tmp) {
384 		struct l2t_skb_cb *cb = L2T_SKB_CB(skb);
385 
386 		__skb_unlink(skb, arpq);
387 		if (cb->arp_failure_handler)
388 			cb->arp_failure_handler(dev, skb);
389 		else
390 			cxgb3_ofld_send(dev, skb);
391 	}
392 }
393 
394 /*
395  * Called when the host's ARP layer makes a change to some entry that is
396  * loaded into the HW L2 table.
397  */
398 void t3_l2t_update(struct t3cdev *dev, struct neighbour *neigh)
399 {
400 	struct sk_buff_head arpq;
401 	struct l2t_entry *e;
402 	struct l2t_data *d = L2DATA(dev);
403 	u32 addr = *(u32 *) neigh->primary_key;
404 	int ifidx = neigh->dev->ifindex;
405 	int hash = arp_hash(addr, ifidx, d);
406 
407 	read_lock_bh(&d->lock);
408 	for (e = d->l2tab[hash].first; e; e = e->next)
409 		if (e->addr == addr && e->ifindex == ifidx) {
410 			spin_lock(&e->lock);
411 			goto found;
412 		}
413 	read_unlock_bh(&d->lock);
414 	return;
415 
416 found:
417 	__skb_queue_head_init(&arpq);
418 
419 	read_unlock(&d->lock);
420 	if (atomic_read(&e->refcnt)) {
421 		if (neigh != e->neigh)
422 			neigh_replace(e, neigh);
423 
424 		if (e->state == L2T_STATE_RESOLVING) {
425 			if (neigh->nud_state & NUD_FAILED) {
426 				skb_queue_splice_init(&e->arpq, &arpq);
427 			} else if (neigh->nud_state & (NUD_CONNECTED|NUD_STALE))
428 				setup_l2e_send_pending(dev, NULL, e);
429 		} else {
430 			e->state = neigh->nud_state & NUD_CONNECTED ?
431 			    L2T_STATE_VALID : L2T_STATE_STALE;
432 			if (!ether_addr_equal(e->dmac, neigh->ha))
433 				setup_l2e_send_pending(dev, NULL, e);
434 		}
435 	}
436 	spin_unlock_bh(&e->lock);
437 
438 	if (!skb_queue_empty(&arpq))
439 		handle_failed_resolution(dev, &arpq);
440 }
441 
442 struct l2t_data *t3_init_l2t(unsigned int l2t_capacity)
443 {
444 	struct l2t_data *d;
445 	int i, size = sizeof(*d) + l2t_capacity * sizeof(struct l2t_entry);
446 
447 	d = kvzalloc(size, GFP_KERNEL);
448 	if (!d)
449 		return NULL;
450 
451 	d->nentries = l2t_capacity;
452 	d->rover = &d->l2tab[1];	/* entry 0 is not used */
453 	atomic_set(&d->nfree, l2t_capacity - 1);
454 	rwlock_init(&d->lock);
455 
456 	for (i = 0; i < l2t_capacity; ++i) {
457 		d->l2tab[i].idx = i;
458 		d->l2tab[i].state = L2T_STATE_UNUSED;
459 		__skb_queue_head_init(&d->l2tab[i].arpq);
460 		spin_lock_init(&d->l2tab[i].lock);
461 		atomic_set(&d->l2tab[i].refcnt, 0);
462 	}
463 	return d;
464 }
465