1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Shared Memory Communications over RDMA (SMC-R) and RoCE
4 *
5 * Connection Data Control (CDC)
6 * handles flow control
7 *
8 * Copyright IBM Corp. 2016
9 *
10 * Author(s): Ursula Braun <ubraun@linux.vnet.ibm.com>
11 */
12
13#include <linux/spinlock.h>
14
15#include "smc.h"
16#include "smc_wr.h"
17#include "smc_cdc.h"
18#include "smc_tx.h"
19#include "smc_rx.h"
20#include "smc_close.h"
21
22/********************************** send *************************************/
23
24/* handler for send/transmission completion of a CDC msg */
25static void smc_cdc_tx_handler(struct smc_wr_tx_pend_priv *pnd_snd,
26 struct smc_link *link,
27 enum ib_wc_status wc_status)
28{
29 struct smc_cdc_tx_pend *cdcpend = (struct smc_cdc_tx_pend *)pnd_snd;
30 struct smc_connection *conn = cdcpend->conn;
31 struct smc_buf_desc *sndbuf_desc;
32 struct smc_sock *smc;
33 int diff;
34
35 sndbuf_desc = conn->sndbuf_desc;
36 smc = container_of(conn, struct smc_sock, conn);
37 bh_lock_sock(&smc->sk);
38 if (!wc_status && sndbuf_desc) {
39 diff = smc_curs_diff(size: sndbuf_desc->len,
40 old: &cdcpend->conn->tx_curs_fin,
41 new: &cdcpend->cursor);
42 /* sndbuf_space is decreased in smc_sendmsg */
43 smp_mb__before_atomic();
44 atomic_add(i: diff, v: &cdcpend->conn->sndbuf_space);
45 /* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
46 smp_mb__after_atomic();
47 smc_curs_copy(tgt: &conn->tx_curs_fin, src: &cdcpend->cursor, conn);
48 smc_curs_copy(tgt: &conn->local_tx_ctrl_fin, src: &cdcpend->p_cursor,
49 conn);
50 conn->tx_cdc_seq_fin = cdcpend->ctrl_seq;
51 }
52
53 if (atomic_dec_and_test(v: &conn->cdc_pend_tx_wr)) {
54 /* If user owns the sock_lock, mark the connection need sending.
55 * User context will later try to send when it release sock_lock
56 * in smc_release_cb()
57 */
58 if (sock_owned_by_user(sk: &smc->sk))
59 conn->tx_in_release_sock = true;
60 else
61 smc_tx_pending(conn);
62
63 if (unlikely(wq_has_sleeper(&conn->cdc_pend_tx_wq)))
64 wake_up(&conn->cdc_pend_tx_wq);
65 }
66 WARN_ON(atomic_read(&conn->cdc_pend_tx_wr) < 0);
67
68 smc_tx_sndbuf_nonfull(smc);
69 bh_unlock_sock(&smc->sk);
70}
71
72int smc_cdc_get_free_slot(struct smc_connection *conn,
73 struct smc_link *link,
74 struct smc_wr_buf **wr_buf,
75 struct smc_rdma_wr **wr_rdma_buf,
76 struct smc_cdc_tx_pend **pend)
77{
78 int rc;
79
80 rc = smc_wr_tx_get_free_slot(link, handler: smc_cdc_tx_handler, wr_buf,
81 wrs: wr_rdma_buf,
82 wr_pend_priv: (struct smc_wr_tx_pend_priv **)pend);
83 if (conn->killed) {
84 /* abnormal termination */
85 if (!rc)
86 smc_wr_tx_put_slot(link,
87 wr_pend_priv: (struct smc_wr_tx_pend_priv *)(*pend));
88 rc = -EPIPE;
89 }
90 return rc;
91}
92
93static inline void smc_cdc_add_pending_send(struct smc_connection *conn,
94 struct smc_cdc_tx_pend *pend)
95{
96 BUILD_BUG_ON_MSG(
97 sizeof(struct smc_cdc_msg) > SMC_WR_BUF_SIZE,
98 "must increase SMC_WR_BUF_SIZE to at least sizeof(struct smc_cdc_msg)");
99 BUILD_BUG_ON_MSG(
100 offsetofend(struct smc_cdc_msg, reserved) > SMC_WR_TX_SIZE,
101 "must adapt SMC_WR_TX_SIZE to sizeof(struct smc_cdc_msg); if not all smc_wr upper layer protocols use the same message size any more, must start to set link->wr_tx_sges[i].length on each individual smc_wr_tx_send()");
102 BUILD_BUG_ON_MSG(
103 sizeof(struct smc_cdc_tx_pend) > SMC_WR_TX_PEND_PRIV_SIZE,
104 "must increase SMC_WR_TX_PEND_PRIV_SIZE to at least sizeof(struct smc_cdc_tx_pend)");
105 pend->conn = conn;
106 pend->cursor = conn->tx_curs_sent;
107 pend->p_cursor = conn->local_tx_ctrl.prod;
108 pend->ctrl_seq = conn->tx_cdc_seq;
109}
110
111int smc_cdc_msg_send(struct smc_connection *conn,
112 struct smc_wr_buf *wr_buf,
113 struct smc_cdc_tx_pend *pend)
114{
115 struct smc_link *link = conn->lnk;
116 union smc_host_cursor cfed;
117 int rc;
118
119 smc_cdc_add_pending_send(conn, pend);
120
121 conn->tx_cdc_seq++;
122 conn->local_tx_ctrl.seqno = conn->tx_cdc_seq;
123 smc_host_msg_to_cdc(peer: (struct smc_cdc_msg *)wr_buf, conn, save: &cfed);
124
125 atomic_inc(v: &conn->cdc_pend_tx_wr);
126 smp_mb__after_atomic(); /* Make sure cdc_pend_tx_wr added before post */
127
128 rc = smc_wr_tx_send(link, wr_pend_priv: (struct smc_wr_tx_pend_priv *)pend);
129 if (!rc) {
130 smc_curs_copy(tgt: &conn->rx_curs_confirmed, src: &cfed, conn);
131 conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0;
132 } else {
133 conn->tx_cdc_seq--;
134 conn->local_tx_ctrl.seqno = conn->tx_cdc_seq;
135 atomic_dec(v: &conn->cdc_pend_tx_wr);
136 }
137
138 return rc;
139}
140
141/* send a validation msg indicating the move of a conn to an other QP link */
142int smcr_cdc_msg_send_validation(struct smc_connection *conn,
143 struct smc_cdc_tx_pend *pend,
144 struct smc_wr_buf *wr_buf)
145{
146 struct smc_host_cdc_msg *local = &conn->local_tx_ctrl;
147 struct smc_link *link = conn->lnk;
148 struct smc_cdc_msg *peer;
149 int rc;
150
151 peer = (struct smc_cdc_msg *)wr_buf;
152 peer->common.type = local->common.type;
153 peer->len = local->len;
154 peer->seqno = htons(conn->tx_cdc_seq_fin); /* seqno last compl. tx */
155 peer->token = htonl(local->token);
156 peer->prod_flags.failover_validation = 1;
157
158 /* We need to set pend->conn here to make sure smc_cdc_tx_handler()
159 * can handle properly
160 */
161 smc_cdc_add_pending_send(conn, pend);
162
163 atomic_inc(v: &conn->cdc_pend_tx_wr);
164 smp_mb__after_atomic(); /* Make sure cdc_pend_tx_wr added before post */
165
166 rc = smc_wr_tx_send(link, wr_pend_priv: (struct smc_wr_tx_pend_priv *)pend);
167 if (unlikely(rc))
168 atomic_dec(v: &conn->cdc_pend_tx_wr);
169
170 return rc;
171}
172
173static int smcr_cdc_get_slot_and_msg_send(struct smc_connection *conn)
174{
175 struct smc_cdc_tx_pend *pend;
176 struct smc_wr_buf *wr_buf;
177 struct smc_link *link;
178 bool again = false;
179 int rc;
180
181again:
182 link = conn->lnk;
183 if (!smc_wr_tx_link_hold(link))
184 return -ENOLINK;
185 rc = smc_cdc_get_free_slot(conn, link, wr_buf: &wr_buf, NULL, pend: &pend);
186 if (rc)
187 goto put_out;
188
189 spin_lock_bh(lock: &conn->send_lock);
190 if (link != conn->lnk) {
191 /* link of connection changed, try again one time*/
192 spin_unlock_bh(lock: &conn->send_lock);
193 smc_wr_tx_put_slot(link,
194 wr_pend_priv: (struct smc_wr_tx_pend_priv *)pend);
195 smc_wr_tx_link_put(link);
196 if (again)
197 return -ENOLINK;
198 again = true;
199 goto again;
200 }
201 rc = smc_cdc_msg_send(conn, wr_buf, pend);
202 spin_unlock_bh(lock: &conn->send_lock);
203put_out:
204 smc_wr_tx_link_put(link);
205 return rc;
206}
207
208int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn)
209{
210 int rc;
211
212 if (!smc_conn_lgr_valid(conn) ||
213 (conn->lgr->is_smcd && conn->lgr->peer_shutdown))
214 return -EPIPE;
215
216 if (conn->lgr->is_smcd) {
217 spin_lock_bh(lock: &conn->send_lock);
218 rc = smcd_cdc_msg_send(conn);
219 spin_unlock_bh(lock: &conn->send_lock);
220 } else {
221 rc = smcr_cdc_get_slot_and_msg_send(conn);
222 }
223
224 return rc;
225}
226
227void smc_cdc_wait_pend_tx_wr(struct smc_connection *conn)
228{
229 wait_event(conn->cdc_pend_tx_wq, !atomic_read(&conn->cdc_pend_tx_wr));
230}
231
232/* Send a SMC-D CDC header.
233 * This increments the free space available in our send buffer.
234 * Also update the confirmed receive buffer with what was sent to the peer.
235 */
236int smcd_cdc_msg_send(struct smc_connection *conn)
237{
238 struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
239 union smc_host_cursor curs;
240 struct smcd_cdc_msg cdc;
241 int rc, diff;
242
243 memset(&cdc, 0, sizeof(cdc));
244 cdc.common.type = SMC_CDC_MSG_TYPE;
245 curs.acurs.counter = atomic64_read(v: &conn->local_tx_ctrl.prod.acurs);
246 cdc.prod.wrap = curs.wrap;
247 cdc.prod.count = curs.count;
248 curs.acurs.counter = atomic64_read(v: &conn->local_tx_ctrl.cons.acurs);
249 cdc.cons.wrap = curs.wrap;
250 cdc.cons.count = curs.count;
251 cdc.cons.prod_flags = conn->local_tx_ctrl.prod_flags;
252 cdc.cons.conn_state_flags = conn->local_tx_ctrl.conn_state_flags;
253 rc = smcd_tx_ism_write(conn, data: &cdc, len: sizeof(cdc), offset: 0, signal: 1);
254 if (rc)
255 return rc;
256 smc_curs_copy(tgt: &conn->rx_curs_confirmed, src: &curs, conn);
257 conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0;
258 /* Calculate transmitted data and increment free send buffer space */
259 diff = smc_curs_diff(size: conn->sndbuf_desc->len, old: &conn->tx_curs_fin,
260 new: &conn->tx_curs_sent);
261 /* increased by confirmed number of bytes */
262 smp_mb__before_atomic();
263 atomic_add(i: diff, v: &conn->sndbuf_space);
264 /* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
265 smp_mb__after_atomic();
266 smc_curs_copy(tgt: &conn->tx_curs_fin, src: &conn->tx_curs_sent, conn);
267
268 smc_tx_sndbuf_nonfull(smc);
269 return rc;
270}
271
272/********************************* receive ***********************************/
273
274static inline bool smc_cdc_before(u16 seq1, u16 seq2)
275{
276 return (s16)(seq1 - seq2) < 0;
277}
278
279static void smc_cdc_handle_urg_data_arrival(struct smc_sock *smc,
280 int *diff_prod)
281{
282 struct smc_connection *conn = &smc->conn;
283 char *base;
284
285 /* new data included urgent business */
286 smc_curs_copy(tgt: &conn->urg_curs, src: &conn->local_rx_ctrl.prod, conn);
287 conn->urg_state = SMC_URG_VALID;
288 if (!sock_flag(sk: &smc->sk, flag: SOCK_URGINLINE))
289 /* we'll skip the urgent byte, so don't account for it */
290 (*diff_prod)--;
291 base = (char *)conn->rmb_desc->cpu_addr + conn->rx_off;
292 if (conn->urg_curs.count)
293 conn->urg_rx_byte = *(base + conn->urg_curs.count - 1);
294 else
295 conn->urg_rx_byte = *(base + conn->rmb_desc->len - 1);
296 sk_send_sigurg(sk: &smc->sk);
297}
298
299static void smc_cdc_msg_validate(struct smc_sock *smc, struct smc_cdc_msg *cdc,
300 struct smc_link *link)
301{
302 struct smc_connection *conn = &smc->conn;
303 u16 recv_seq = ntohs(cdc->seqno);
304 s16 diff;
305
306 /* check that seqnum was seen before */
307 diff = conn->local_rx_ctrl.seqno - recv_seq;
308 if (diff < 0) { /* diff larger than 0x7fff */
309 /* drop connection */
310 conn->out_of_sync = 1; /* prevent any further receives */
311 spin_lock_bh(lock: &conn->send_lock);
312 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
313 conn->lnk = link;
314 spin_unlock_bh(lock: &conn->send_lock);
315 sock_hold(sk: &smc->sk); /* sock_put in abort_work */
316 if (!queue_work(wq: smc_close_wq, work: &conn->abort_work))
317 sock_put(sk: &smc->sk);
318 }
319}
320
321static void smc_cdc_msg_recv_action(struct smc_sock *smc,
322 struct smc_cdc_msg *cdc)
323{
324 union smc_host_cursor cons_old, prod_old;
325 struct smc_connection *conn = &smc->conn;
326 int diff_cons, diff_prod;
327
328 smc_curs_copy(tgt: &prod_old, src: &conn->local_rx_ctrl.prod, conn);
329 smc_curs_copy(tgt: &cons_old, src: &conn->local_rx_ctrl.cons, conn);
330 smc_cdc_msg_to_host(local: &conn->local_rx_ctrl, peer: cdc, conn);
331
332 diff_cons = smc_curs_diff(size: conn->peer_rmbe_size, old: &cons_old,
333 new: &conn->local_rx_ctrl.cons);
334 if (diff_cons) {
335 /* peer_rmbe_space is decreased during data transfer with RDMA
336 * write
337 */
338 smp_mb__before_atomic();
339 atomic_add(i: diff_cons, v: &conn->peer_rmbe_space);
340 /* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
341 smp_mb__after_atomic();
342 }
343
344 diff_prod = smc_curs_diff(size: conn->rmb_desc->len, old: &prod_old,
345 new: &conn->local_rx_ctrl.prod);
346 if (diff_prod) {
347 if (conn->local_rx_ctrl.prod_flags.urg_data_present)
348 smc_cdc_handle_urg_data_arrival(smc, diff_prod: &diff_prod);
349 /* bytes_to_rcv is decreased in smc_recvmsg */
350 smp_mb__before_atomic();
351 atomic_add(i: diff_prod, v: &conn->bytes_to_rcv);
352 /* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
353 smp_mb__after_atomic();
354 smc->sk.sk_data_ready(&smc->sk);
355 } else {
356 if (conn->local_rx_ctrl.prod_flags.write_blocked)
357 smc->sk.sk_data_ready(&smc->sk);
358 if (conn->local_rx_ctrl.prod_flags.urg_data_pending)
359 conn->urg_state = SMC_URG_NOTYET;
360 }
361
362 /* trigger sndbuf consumer: RDMA write into peer RMBE and CDC */
363 if ((diff_cons && smc_tx_prepared_sends(conn)) ||
364 conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
365 conn->local_rx_ctrl.prod_flags.urg_data_pending) {
366 if (!sock_owned_by_user(sk: &smc->sk))
367 smc_tx_pending(conn);
368 else
369 conn->tx_in_release_sock = true;
370 }
371
372 if (diff_cons && conn->urg_tx_pend &&
373 atomic_read(v: &conn->peer_rmbe_space) == conn->peer_rmbe_size) {
374 /* urg data confirmed by peer, indicate we're ready for more */
375 conn->urg_tx_pend = false;
376 smc->sk.sk_write_space(&smc->sk);
377 }
378
379 if (conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) {
380 smc->sk.sk_err = ECONNRESET;
381 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
382 }
383 if (smc_cdc_rxed_any_close_or_senddone(conn)) {
384 smc->sk.sk_shutdown |= RCV_SHUTDOWN;
385 if (smc->clcsock && smc->clcsock->sk)
386 smc->clcsock->sk->sk_shutdown |= RCV_SHUTDOWN;
387 smc_sock_set_flag(sk: &smc->sk, flag: SOCK_DONE);
388 sock_hold(sk: &smc->sk); /* sock_put in close_work */
389 if (!queue_work(wq: smc_close_wq, work: &conn->close_work))
390 sock_put(sk: &smc->sk);
391 }
392}
393
394/* called under tasklet context */
395static void smc_cdc_msg_recv(struct smc_sock *smc, struct smc_cdc_msg *cdc)
396{
397 sock_hold(sk: &smc->sk);
398 bh_lock_sock(&smc->sk);
399 smc_cdc_msg_recv_action(smc, cdc);
400 bh_unlock_sock(&smc->sk);
401 sock_put(sk: &smc->sk); /* no free sk in softirq-context */
402}
403
404/* Schedule a tasklet for this connection. Triggered from the ISM device IRQ
405 * handler to indicate update in the DMBE.
406 *
407 * Context:
408 * - tasklet context
409 */
410static void smcd_cdc_rx_tsklet(struct tasklet_struct *t)
411{
412 struct smc_connection *conn = from_tasklet(conn, t, rx_tsklet);
413 struct smcd_cdc_msg *data_cdc;
414 struct smcd_cdc_msg cdc;
415 struct smc_sock *smc;
416
417 if (!conn || conn->killed)
418 return;
419
420 data_cdc = (struct smcd_cdc_msg *)conn->rmb_desc->cpu_addr;
421 smcd_curs_copy(tgt: &cdc.prod, src: &data_cdc->prod, conn);
422 smcd_curs_copy(tgt: &cdc.cons, src: &data_cdc->cons, conn);
423 smc = container_of(conn, struct smc_sock, conn);
424 smc_cdc_msg_recv(smc, cdc: (struct smc_cdc_msg *)&cdc);
425}
426
427/* Initialize receive tasklet. Called from ISM device IRQ handler to start
428 * receiver side.
429 */
430void smcd_cdc_rx_init(struct smc_connection *conn)
431{
432 tasklet_setup(t: &conn->rx_tsklet, callback: smcd_cdc_rx_tsklet);
433}
434
435/***************************** init, exit, misc ******************************/
436
437static void smc_cdc_rx_handler(struct ib_wc *wc, void *buf)
438{
439 struct smc_link *link = (struct smc_link *)wc->qp->qp_context;
440 struct smc_cdc_msg *cdc = buf;
441 struct smc_connection *conn;
442 struct smc_link_group *lgr;
443 struct smc_sock *smc;
444
445 if (wc->byte_len < offsetof(struct smc_cdc_msg, reserved))
446 return; /* short message */
447 if (cdc->len != SMC_WR_TX_SIZE)
448 return; /* invalid message */
449
450 /* lookup connection */
451 lgr = smc_get_lgr(link);
452 read_lock_bh(&lgr->conns_lock);
453 conn = smc_lgr_find_conn(ntohl(cdc->token), lgr);
454 read_unlock_bh(&lgr->conns_lock);
455 if (!conn || conn->out_of_sync)
456 return;
457 smc = container_of(conn, struct smc_sock, conn);
458
459 if (cdc->prod_flags.failover_validation) {
460 smc_cdc_msg_validate(smc, cdc, link);
461 return;
462 }
463 if (smc_cdc_before(ntohs(cdc->seqno),
464 seq2: conn->local_rx_ctrl.seqno))
465 /* received seqno is old */
466 return;
467
468 smc_cdc_msg_recv(smc, cdc);
469}
470
471static struct smc_wr_rx_handler smc_cdc_rx_handlers[] = {
472 {
473 .handler = smc_cdc_rx_handler,
474 .type = SMC_CDC_MSG_TYPE
475 },
476 {
477 .handler = NULL,
478 }
479};
480
481int __init smc_cdc_init(void)
482{
483 struct smc_wr_rx_handler *handler;
484 int rc = 0;
485
486 for (handler = smc_cdc_rx_handlers; handler->handler; handler++) {
487 INIT_HLIST_NODE(h: &handler->list);
488 rc = smc_wr_rx_register_handler(handler);
489 if (rc)
490 break;
491 }
492 return rc;
493}
494

source code of linux/net/smc/smc_cdc.c