1 // SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
2 /*
3 * Copyright (c) 2022 Hewlett Packard Enterprise, Inc. All rights reserved.
4 * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
5 * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
6 */
7
8 /*
9 * rxe_mcast.c implements driver support for multicast transport.
10 * It is based on two data structures struct rxe_mcg ('mcg') and
11 * struct rxe_mca ('mca'). An mcg is allocated each time a qp is
12 * attached to a new mgid for the first time. These are indexed by
13 * a red-black tree using the mgid. This data structure is searched
14 * for the mcg when a multicast packet is received and when another
15 * qp is attached to the same mgid. It is cleaned up when the last qp
16 * is detached from the mcg. Each time a qp is attached to an mcg an
17 * mca is created. It holds a pointer to the qp and is added to a list
18 * of qp's that are attached to the mcg. The qp_list is used to replicate
19 * mcast packets in the rxe receive path.
20 */
21
22 #include "rxe.h"
23
24 /**
25 * rxe_mcast_add - add multicast address to rxe device
26 * @rxe: rxe device object
27 * @mgid: multicast address as a gid
28 *
29 * Returns 0 on success else an error
30 */
rxe_mcast_add(struct rxe_dev * rxe,union ib_gid * mgid)31 static int rxe_mcast_add(struct rxe_dev *rxe, union ib_gid *mgid)
32 {
33 unsigned char ll_addr[ETH_ALEN];
34
35 ipv6_eth_mc_map((struct in6_addr *)mgid->raw, ll_addr);
36
37 return dev_mc_add(rxe->ndev, ll_addr);
38 }
39
40 /**
41 * rxe_mcast_del - delete multicast address from rxe device
42 * @rxe: rxe device object
43 * @mgid: multicast address as a gid
44 *
45 * Returns 0 on success else an error
46 */
rxe_mcast_del(struct rxe_dev * rxe,union ib_gid * mgid)47 static int rxe_mcast_del(struct rxe_dev *rxe, union ib_gid *mgid)
48 {
49 unsigned char ll_addr[ETH_ALEN];
50
51 ipv6_eth_mc_map((struct in6_addr *)mgid->raw, ll_addr);
52
53 return dev_mc_del(rxe->ndev, ll_addr);
54 }
55
56 /**
57 * __rxe_insert_mcg - insert an mcg into red-black tree (rxe->mcg_tree)
58 * @mcg: mcg object with an embedded red-black tree node
59 *
60 * Context: caller must hold a reference to mcg and rxe->mcg_lock and
61 * is responsible to avoid adding the same mcg twice to the tree.
62 */
__rxe_insert_mcg(struct rxe_mcg * mcg)63 static void __rxe_insert_mcg(struct rxe_mcg *mcg)
64 {
65 struct rb_root *tree = &mcg->rxe->mcg_tree;
66 struct rb_node **link = &tree->rb_node;
67 struct rb_node *node = NULL;
68 struct rxe_mcg *tmp;
69 int cmp;
70
71 while (*link) {
72 node = *link;
73 tmp = rb_entry(node, struct rxe_mcg, node);
74
75 cmp = memcmp(&tmp->mgid, &mcg->mgid, sizeof(mcg->mgid));
76 if (cmp > 0)
77 link = &(*link)->rb_left;
78 else
79 link = &(*link)->rb_right;
80 }
81
82 rb_link_node(&mcg->node, node, link);
83 rb_insert_color(&mcg->node, tree);
84 }
85
86 /**
87 * __rxe_remove_mcg - remove an mcg from red-black tree holding lock
88 * @mcg: mcast group object with an embedded red-black tree node
89 *
90 * Context: caller must hold a reference to mcg and rxe->mcg_lock
91 */
__rxe_remove_mcg(struct rxe_mcg * mcg)92 static void __rxe_remove_mcg(struct rxe_mcg *mcg)
93 {
94 rb_erase(&mcg->node, &mcg->rxe->mcg_tree);
95 }
96
97 /**
98 * __rxe_lookup_mcg - lookup mcg in rxe->mcg_tree while holding lock
99 * @rxe: rxe device object
100 * @mgid: multicast IP address
101 *
102 * Context: caller must hold rxe->mcg_lock
103 * Returns: mcg on success and takes a ref to mcg else NULL
104 */
__rxe_lookup_mcg(struct rxe_dev * rxe,union ib_gid * mgid)105 static struct rxe_mcg *__rxe_lookup_mcg(struct rxe_dev *rxe,
106 union ib_gid *mgid)
107 {
108 struct rb_root *tree = &rxe->mcg_tree;
109 struct rxe_mcg *mcg;
110 struct rb_node *node;
111 int cmp;
112
113 node = tree->rb_node;
114
115 while (node) {
116 mcg = rb_entry(node, struct rxe_mcg, node);
117
118 cmp = memcmp(&mcg->mgid, mgid, sizeof(*mgid));
119
120 if (cmp > 0)
121 node = node->rb_left;
122 else if (cmp < 0)
123 node = node->rb_right;
124 else
125 break;
126 }
127
128 if (node) {
129 kref_get(&mcg->ref_cnt);
130 return mcg;
131 }
132
133 return NULL;
134 }
135
136 /**
137 * rxe_lookup_mcg - lookup up mcg in red-back tree
138 * @rxe: rxe device object
139 * @mgid: multicast IP address
140 *
141 * Returns: mcg if found else NULL
142 */
rxe_lookup_mcg(struct rxe_dev * rxe,union ib_gid * mgid)143 struct rxe_mcg *rxe_lookup_mcg(struct rxe_dev *rxe, union ib_gid *mgid)
144 {
145 struct rxe_mcg *mcg;
146
147 spin_lock_bh(&rxe->mcg_lock);
148 mcg = __rxe_lookup_mcg(rxe, mgid);
149 spin_unlock_bh(&rxe->mcg_lock);
150
151 return mcg;
152 }
153
154 /**
155 * __rxe_init_mcg - initialize a new mcg
156 * @rxe: rxe device
157 * @mgid: multicast address as a gid
158 * @mcg: new mcg object
159 *
160 * Context: caller should hold rxe->mcg lock
161 */
__rxe_init_mcg(struct rxe_dev * rxe,union ib_gid * mgid,struct rxe_mcg * mcg)162 static void __rxe_init_mcg(struct rxe_dev *rxe, union ib_gid *mgid,
163 struct rxe_mcg *mcg)
164 {
165 kref_init(&mcg->ref_cnt);
166 memcpy(&mcg->mgid, mgid, sizeof(mcg->mgid));
167 INIT_LIST_HEAD(&mcg->qp_list);
168 mcg->rxe = rxe;
169
170 /* caller holds a ref on mcg but that will be
171 * dropped when mcg goes out of scope. We need to take a ref
172 * on the pointer that will be saved in the red-black tree
173 * by __rxe_insert_mcg and used to lookup mcg from mgid later.
174 * Inserting mcg makes it visible to outside so this should
175 * be done last after the object is ready.
176 */
177 kref_get(&mcg->ref_cnt);
178 __rxe_insert_mcg(mcg);
179 }
180
181 /**
182 * rxe_get_mcg - lookup or allocate a mcg
183 * @rxe: rxe device object
184 * @mgid: multicast IP address as a gid
185 *
186 * Returns: mcg on success else ERR_PTR(error)
187 */
rxe_get_mcg(struct rxe_dev * rxe,union ib_gid * mgid)188 static struct rxe_mcg *rxe_get_mcg(struct rxe_dev *rxe, union ib_gid *mgid)
189 {
190 struct rxe_mcg *mcg, *tmp;
191 int err;
192
193 if (rxe->attr.max_mcast_grp == 0)
194 return ERR_PTR(-EINVAL);
195
196 /* check to see if mcg already exists */
197 mcg = rxe_lookup_mcg(rxe, mgid);
198 if (mcg)
199 return mcg;
200
201 /* check to see if we have reached limit */
202 if (atomic_inc_return(&rxe->mcg_num) > rxe->attr.max_mcast_grp) {
203 err = -ENOMEM;
204 goto err_dec;
205 }
206
207 /* speculative alloc of new mcg */
208 mcg = kzalloc(sizeof(*mcg), GFP_KERNEL);
209 if (!mcg) {
210 err = -ENOMEM;
211 goto err_dec;
212 }
213
214 spin_lock_bh(&rxe->mcg_lock);
215 /* re-check to see if someone else just added it */
216 tmp = __rxe_lookup_mcg(rxe, mgid);
217 if (tmp) {
218 spin_unlock_bh(&rxe->mcg_lock);
219 atomic_dec(&rxe->mcg_num);
220 kfree(mcg);
221 return tmp;
222 }
223
224 __rxe_init_mcg(rxe, mgid, mcg);
225 spin_unlock_bh(&rxe->mcg_lock);
226
227 /* add mcast address outside of lock */
228 err = rxe_mcast_add(rxe, mgid);
229 if (!err)
230 return mcg;
231
232 kfree(mcg);
233 err_dec:
234 atomic_dec(&rxe->mcg_num);
235 return ERR_PTR(err);
236 }
237
238 /**
239 * rxe_cleanup_mcg - cleanup mcg for kref_put
240 * @kref: struct kref embnedded in mcg
241 */
rxe_cleanup_mcg(struct kref * kref)242 void rxe_cleanup_mcg(struct kref *kref)
243 {
244 struct rxe_mcg *mcg = container_of(kref, typeof(*mcg), ref_cnt);
245
246 kfree(mcg);
247 }
248
249 /**
250 * __rxe_destroy_mcg - destroy mcg object holding rxe->mcg_lock
251 * @mcg: the mcg object
252 *
253 * Context: caller is holding rxe->mcg_lock
254 * no qp's are attached to mcg
255 */
__rxe_destroy_mcg(struct rxe_mcg * mcg)256 static void __rxe_destroy_mcg(struct rxe_mcg *mcg)
257 {
258 struct rxe_dev *rxe = mcg->rxe;
259
260 /* remove mcg from red-black tree then drop ref */
261 __rxe_remove_mcg(mcg);
262 kref_put(&mcg->ref_cnt, rxe_cleanup_mcg);
263
264 atomic_dec(&rxe->mcg_num);
265 }
266
267 /**
268 * rxe_destroy_mcg - destroy mcg object
269 * @mcg: the mcg object
270 *
271 * Context: no qp's are attached to mcg
272 */
rxe_destroy_mcg(struct rxe_mcg * mcg)273 static void rxe_destroy_mcg(struct rxe_mcg *mcg)
274 {
275 /* delete mcast address outside of lock */
276 rxe_mcast_del(mcg->rxe, &mcg->mgid);
277
278 spin_lock_bh(&mcg->rxe->mcg_lock);
279 __rxe_destroy_mcg(mcg);
280 spin_unlock_bh(&mcg->rxe->mcg_lock);
281 }
282
283 /**
284 * __rxe_init_mca - initialize a new mca holding lock
285 * @qp: qp object
286 * @mcg: mcg object
287 * @mca: empty space for new mca
288 *
289 * Context: caller must hold references on qp and mcg, rxe->mcg_lock
290 * and pass memory for new mca
291 *
292 * Returns: 0 on success else an error
293 */
__rxe_init_mca(struct rxe_qp * qp,struct rxe_mcg * mcg,struct rxe_mca * mca)294 static int __rxe_init_mca(struct rxe_qp *qp, struct rxe_mcg *mcg,
295 struct rxe_mca *mca)
296 {
297 struct rxe_dev *rxe = to_rdev(qp->ibqp.device);
298 int n;
299
300 n = atomic_inc_return(&rxe->mcg_attach);
301 if (n > rxe->attr.max_total_mcast_qp_attach) {
302 atomic_dec(&rxe->mcg_attach);
303 return -ENOMEM;
304 }
305
306 n = atomic_inc_return(&mcg->qp_num);
307 if (n > rxe->attr.max_mcast_qp_attach) {
308 atomic_dec(&mcg->qp_num);
309 atomic_dec(&rxe->mcg_attach);
310 return -ENOMEM;
311 }
312
313 atomic_inc(&qp->mcg_num);
314
315 rxe_get(qp);
316 mca->qp = qp;
317
318 list_add_tail(&mca->qp_list, &mcg->qp_list);
319
320 return 0;
321 }
322
323 /**
324 * rxe_attach_mcg - attach qp to mcg if not already attached
325 * @qp: qp object
326 * @mcg: mcg object
327 *
328 * Context: caller must hold reference on qp and mcg.
329 * Returns: 0 on success else an error
330 */
rxe_attach_mcg(struct rxe_mcg * mcg,struct rxe_qp * qp)331 static int rxe_attach_mcg(struct rxe_mcg *mcg, struct rxe_qp *qp)
332 {
333 struct rxe_dev *rxe = mcg->rxe;
334 struct rxe_mca *mca, *tmp;
335 int err;
336
337 /* check to see if the qp is already a member of the group */
338 spin_lock_bh(&rxe->mcg_lock);
339 list_for_each_entry(mca, &mcg->qp_list, qp_list) {
340 if (mca->qp == qp) {
341 spin_unlock_bh(&rxe->mcg_lock);
342 return 0;
343 }
344 }
345 spin_unlock_bh(&rxe->mcg_lock);
346
347 /* speculative alloc new mca without using GFP_ATOMIC */
348 mca = kzalloc(sizeof(*mca), GFP_KERNEL);
349 if (!mca)
350 return -ENOMEM;
351
352 spin_lock_bh(&rxe->mcg_lock);
353 /* re-check to see if someone else just attached qp */
354 list_for_each_entry(tmp, &mcg->qp_list, qp_list) {
355 if (tmp->qp == qp) {
356 kfree(mca);
357 err = 0;
358 goto out;
359 }
360 }
361
362 err = __rxe_init_mca(qp, mcg, mca);
363 if (err)
364 kfree(mca);
365 out:
366 spin_unlock_bh(&rxe->mcg_lock);
367 return err;
368 }
369
370 /**
371 * __rxe_cleanup_mca - cleanup mca object holding lock
372 * @mca: mca object
373 * @mcg: mcg object
374 *
375 * Context: caller must hold a reference to mcg and rxe->mcg_lock
376 */
__rxe_cleanup_mca(struct rxe_mca * mca,struct rxe_mcg * mcg)377 static void __rxe_cleanup_mca(struct rxe_mca *mca, struct rxe_mcg *mcg)
378 {
379 list_del(&mca->qp_list);
380
381 atomic_dec(&mcg->qp_num);
382 atomic_dec(&mcg->rxe->mcg_attach);
383 atomic_dec(&mca->qp->mcg_num);
384 rxe_put(mca->qp);
385
386 kfree(mca);
387 }
388
389 /**
390 * rxe_detach_mcg - detach qp from mcg
391 * @mcg: mcg object
392 * @qp: qp object
393 *
394 * Returns: 0 on success else an error if qp is not attached.
395 */
rxe_detach_mcg(struct rxe_mcg * mcg,struct rxe_qp * qp)396 static int rxe_detach_mcg(struct rxe_mcg *mcg, struct rxe_qp *qp)
397 {
398 struct rxe_dev *rxe = mcg->rxe;
399 struct rxe_mca *mca, *tmp;
400
401 spin_lock_bh(&rxe->mcg_lock);
402 list_for_each_entry_safe(mca, tmp, &mcg->qp_list, qp_list) {
403 if (mca->qp == qp) {
404 __rxe_cleanup_mca(mca, mcg);
405
406 /* if the number of qp's attached to the
407 * mcast group falls to zero go ahead and
408 * tear it down. This will not free the
409 * object since we are still holding a ref
410 * from the caller
411 */
412 if (atomic_read(&mcg->qp_num) <= 0)
413 __rxe_destroy_mcg(mcg);
414
415 spin_unlock_bh(&rxe->mcg_lock);
416 return 0;
417 }
418 }
419
420 /* we didn't find the qp on the list */
421 spin_unlock_bh(&rxe->mcg_lock);
422 return -EINVAL;
423 }
424
425 /**
426 * rxe_attach_mcast - attach qp to multicast group (see IBA-11.3.1)
427 * @ibqp: (IB) qp object
428 * @mgid: multicast IP address
429 * @mlid: multicast LID, ignored for RoCEv2 (see IBA-A17.5.6)
430 *
431 * Returns: 0 on success else an errno
432 */
rxe_attach_mcast(struct ib_qp * ibqp,union ib_gid * mgid,u16 mlid)433 int rxe_attach_mcast(struct ib_qp *ibqp, union ib_gid *mgid, u16 mlid)
434 {
435 int err;
436 struct rxe_dev *rxe = to_rdev(ibqp->device);
437 struct rxe_qp *qp = to_rqp(ibqp);
438 struct rxe_mcg *mcg;
439
440 /* takes a ref on mcg if successful */
441 mcg = rxe_get_mcg(rxe, mgid);
442 if (IS_ERR(mcg))
443 return PTR_ERR(mcg);
444
445 err = rxe_attach_mcg(mcg, qp);
446
447 /* if we failed to attach the first qp to mcg tear it down */
448 if (atomic_read(&mcg->qp_num) == 0)
449 rxe_destroy_mcg(mcg);
450
451 kref_put(&mcg->ref_cnt, rxe_cleanup_mcg);
452
453 return err;
454 }
455
456 /**
457 * rxe_detach_mcast - detach qp from multicast group (see IBA-11.3.2)
458 * @ibqp: address of (IB) qp object
459 * @mgid: multicast IP address
460 * @mlid: multicast LID, ignored for RoCEv2 (see IBA-A17.5.6)
461 *
462 * Returns: 0 on success else an errno
463 */
rxe_detach_mcast(struct ib_qp * ibqp,union ib_gid * mgid,u16 mlid)464 int rxe_detach_mcast(struct ib_qp *ibqp, union ib_gid *mgid, u16 mlid)
465 {
466 struct rxe_dev *rxe = to_rdev(ibqp->device);
467 struct rxe_qp *qp = to_rqp(ibqp);
468 struct rxe_mcg *mcg;
469 int err;
470
471 mcg = rxe_lookup_mcg(rxe, mgid);
472 if (!mcg)
473 return -EINVAL;
474
475 err = rxe_detach_mcg(mcg, qp);
476 kref_put(&mcg->ref_cnt, rxe_cleanup_mcg);
477
478 return err;
479 }
480