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