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_sock *smc;
 32	int diff;
 33
 34	if (!conn)
 35		/* already dismissed */
 36		return;
 37
 38	smc = container_of(conn, struct smc_sock, conn);
 39	bh_lock_sock(&smc->sk);
 40	if (!wc_status) {
 41		diff = smc_curs_diff(cdcpend->conn->sndbuf_desc->len,
 42				     &cdcpend->conn->tx_curs_fin,
 43				     &cdcpend->cursor);
 44		/* sndbuf_space is decreased in smc_sendmsg */
 45		smp_mb__before_atomic();
 46		atomic_add(diff, &cdcpend->conn->sndbuf_space);
 47		/* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
 48		smp_mb__after_atomic();
 49		smc_curs_copy(&conn->tx_curs_fin, &cdcpend->cursor, conn);
 50	}
 51	smc_tx_sndbuf_nonfull(smc);
 52	bh_unlock_sock(&smc->sk);
 53}
 54
 55int smc_cdc_get_free_slot(struct smc_connection *conn,
 56			  struct smc_wr_buf **wr_buf,
 57			  struct smc_rdma_wr **wr_rdma_buf,
 58			  struct smc_cdc_tx_pend **pend)
 59{
 60	struct smc_link *link = &conn->lgr->lnk[SMC_SINGLE_LINK];
 61	int rc;
 62
 63	rc = smc_wr_tx_get_free_slot(link, smc_cdc_tx_handler, wr_buf,
 64				     wr_rdma_buf,
 65				     (struct smc_wr_tx_pend_priv **)pend);
 66	if (!conn->alert_token_local)
 67		/* abnormal termination */
 68		rc = -EPIPE;
 69	return rc;
 70}
 71
 72static inline void smc_cdc_add_pending_send(struct smc_connection *conn,
 73					    struct smc_cdc_tx_pend *pend)
 74{
 75	BUILD_BUG_ON_MSG(
 76		sizeof(struct smc_cdc_msg) > SMC_WR_BUF_SIZE,
 77		"must increase SMC_WR_BUF_SIZE to at least sizeof(struct smc_cdc_msg)");
 78	BUILD_BUG_ON_MSG(
 79		offsetofend(struct smc_cdc_msg, reserved) > SMC_WR_TX_SIZE,
 80		"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()");
 81	BUILD_BUG_ON_MSG(
 82		sizeof(struct smc_cdc_tx_pend) > SMC_WR_TX_PEND_PRIV_SIZE,
 83		"must increase SMC_WR_TX_PEND_PRIV_SIZE to at least sizeof(struct smc_cdc_tx_pend)");
 84	pend->conn = conn;
 85	pend->cursor = conn->tx_curs_sent;
 86	pend->p_cursor = conn->local_tx_ctrl.prod;
 87	pend->ctrl_seq = conn->tx_cdc_seq;
 88}
 89
 90int smc_cdc_msg_send(struct smc_connection *conn,
 91		     struct smc_wr_buf *wr_buf,
 92		     struct smc_cdc_tx_pend *pend)
 93{
 94	union smc_host_cursor cfed;
 95	struct smc_link *link;
 96	int rc;
 97
 98	link = &conn->lgr->lnk[SMC_SINGLE_LINK];
 99
100	smc_cdc_add_pending_send(conn, pend);
101
102	conn->tx_cdc_seq++;
103	conn->local_tx_ctrl.seqno = conn->tx_cdc_seq;
104	smc_host_msg_to_cdc((struct smc_cdc_msg *)wr_buf, conn, &cfed);
105	rc = smc_wr_tx_send(link, (struct smc_wr_tx_pend_priv *)pend);
106	if (!rc) {
107		smc_curs_copy(&conn->rx_curs_confirmed, &cfed, conn);
108		conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0;
109	}
110
111	return rc;
112}
113
114static int smcr_cdc_get_slot_and_msg_send(struct smc_connection *conn)
115{
116	struct smc_cdc_tx_pend *pend;
117	struct smc_wr_buf *wr_buf;
118	int rc;
119
120	rc = smc_cdc_get_free_slot(conn, &wr_buf, NULL, &pend);
121	if (rc)
122		return rc;
123
124	spin_lock_bh(&conn->send_lock);
125	rc = smc_cdc_msg_send(conn, wr_buf, pend);
126	spin_unlock_bh(&conn->send_lock);
127	return rc;
128}
129
130int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn)
131{
132	int rc;
133
134	if (conn->lgr->is_smcd) {
135		spin_lock_bh(&conn->send_lock);
136		rc = smcd_cdc_msg_send(conn);
137		spin_unlock_bh(&conn->send_lock);
138	} else {
139		rc = smcr_cdc_get_slot_and_msg_send(conn);
140	}
141
142	return rc;
143}
144
145static bool smc_cdc_tx_filter(struct smc_wr_tx_pend_priv *tx_pend,
146			      unsigned long data)
147{
148	struct smc_connection *conn = (struct smc_connection *)data;
149	struct smc_cdc_tx_pend *cdc_pend =
150		(struct smc_cdc_tx_pend *)tx_pend;
151
152	return cdc_pend->conn == conn;
153}
154
155static void smc_cdc_tx_dismisser(struct smc_wr_tx_pend_priv *tx_pend)
156{
157	struct smc_cdc_tx_pend *cdc_pend =
158		(struct smc_cdc_tx_pend *)tx_pend;
159
160	cdc_pend->conn = NULL;
161}
162
163void smc_cdc_tx_dismiss_slots(struct smc_connection *conn)
164{
165	struct smc_link *link = &conn->lgr->lnk[SMC_SINGLE_LINK];
166
167	smc_wr_tx_dismiss_slots(link, SMC_CDC_MSG_TYPE,
168				smc_cdc_tx_filter, smc_cdc_tx_dismisser,
169				(unsigned long)conn);
170}
171
172/* Send a SMC-D CDC header.
173 * This increments the free space available in our send buffer.
174 * Also update the confirmed receive buffer with what was sent to the peer.
175 */
176int smcd_cdc_msg_send(struct smc_connection *conn)
177{
178	struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
179	union smc_host_cursor curs;
180	struct smcd_cdc_msg cdc;
181	int rc, diff;
182
183	memset(&cdc, 0, sizeof(cdc));
184	cdc.common.type = SMC_CDC_MSG_TYPE;
185	curs.acurs.counter = atomic64_read(&conn->local_tx_ctrl.prod.acurs);
186	cdc.prod.wrap = curs.wrap;
187	cdc.prod.count = curs.count;
188	curs.acurs.counter = atomic64_read(&conn->local_tx_ctrl.cons.acurs);
189	cdc.cons.wrap = curs.wrap;
190	cdc.cons.count = curs.count;
191	cdc.cons.prod_flags = conn->local_tx_ctrl.prod_flags;
192	cdc.cons.conn_state_flags = conn->local_tx_ctrl.conn_state_flags;
193	rc = smcd_tx_ism_write(conn, &cdc, sizeof(cdc), 0, 1);
194	if (rc)
195		return rc;
196	smc_curs_copy(&conn->rx_curs_confirmed, &curs, conn);
197	conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0;
198	/* Calculate transmitted data and increment free send buffer space */
199	diff = smc_curs_diff(conn->sndbuf_desc->len, &conn->tx_curs_fin,
200			     &conn->tx_curs_sent);
201	/* increased by confirmed number of bytes */
202	smp_mb__before_atomic();
203	atomic_add(diff, &conn->sndbuf_space);
204	/* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
205	smp_mb__after_atomic();
206	smc_curs_copy(&conn->tx_curs_fin, &conn->tx_curs_sent, conn);
207
208	smc_tx_sndbuf_nonfull(smc);
209	return rc;
210}
211
212/********************************* receive ***********************************/
213
214static inline bool smc_cdc_before(u16 seq1, u16 seq2)
215{
216	return (s16)(seq1 - seq2) < 0;
217}
218
219static void smc_cdc_handle_urg_data_arrival(struct smc_sock *smc,
220					    int *diff_prod)
221{
222	struct smc_connection *conn = &smc->conn;
223	char *base;
224
225	/* new data included urgent business */
226	smc_curs_copy(&conn->urg_curs, &conn->local_rx_ctrl.prod, conn);
227	conn->urg_state = SMC_URG_VALID;
228	if (!sock_flag(&smc->sk, SOCK_URGINLINE))
229		/* we'll skip the urgent byte, so don't account for it */
230		(*diff_prod)--;
231	base = (char *)conn->rmb_desc->cpu_addr + conn->rx_off;
232	if (conn->urg_curs.count)
233		conn->urg_rx_byte = *(base + conn->urg_curs.count - 1);
234	else
235		conn->urg_rx_byte = *(base + conn->rmb_desc->len - 1);
236	sk_send_sigurg(&smc->sk);
237}
238
239static void smc_cdc_msg_recv_action(struct smc_sock *smc,
240				    struct smc_cdc_msg *cdc)
241{
242	union smc_host_cursor cons_old, prod_old;
243	struct smc_connection *conn = &smc->conn;
244	int diff_cons, diff_prod;
245
246	smc_curs_copy(&prod_old, &conn->local_rx_ctrl.prod, conn);
247	smc_curs_copy(&cons_old, &conn->local_rx_ctrl.cons, conn);
248	smc_cdc_msg_to_host(&conn->local_rx_ctrl, cdc, conn);
249
250	diff_cons = smc_curs_diff(conn->peer_rmbe_size, &cons_old,
251				  &conn->local_rx_ctrl.cons);
252	if (diff_cons) {
253		/* peer_rmbe_space is decreased during data transfer with RDMA
254		 * write
255		 */
256		smp_mb__before_atomic();
257		atomic_add(diff_cons, &conn->peer_rmbe_space);
258		/* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
259		smp_mb__after_atomic();
260	}
261
262	diff_prod = smc_curs_diff(conn->rmb_desc->len, &prod_old,
263				  &conn->local_rx_ctrl.prod);
264	if (diff_prod) {
265		if (conn->local_rx_ctrl.prod_flags.urg_data_present)
266			smc_cdc_handle_urg_data_arrival(smc, &diff_prod);
267		/* bytes_to_rcv is decreased in smc_recvmsg */
268		smp_mb__before_atomic();
269		atomic_add(diff_prod, &conn->bytes_to_rcv);
270		/* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
271		smp_mb__after_atomic();
272		smc->sk.sk_data_ready(&smc->sk);
273	} else {
274		if (conn->local_rx_ctrl.prod_flags.write_blocked)
275			smc->sk.sk_data_ready(&smc->sk);
276		if (conn->local_rx_ctrl.prod_flags.urg_data_pending)
277			conn->urg_state = SMC_URG_NOTYET;
278	}
279
280	/* trigger sndbuf consumer: RDMA write into peer RMBE and CDC */
281	if ((diff_cons && smc_tx_prepared_sends(conn)) ||
282	    conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
283	    conn->local_rx_ctrl.prod_flags.urg_data_pending)
284		smc_tx_sndbuf_nonempty(conn);
285
286	if (diff_cons && conn->urg_tx_pend &&
287	    atomic_read(&conn->peer_rmbe_space) == conn->peer_rmbe_size) {
288		/* urg data confirmed by peer, indicate we're ready for more */
289		conn->urg_tx_pend = false;
290		smc->sk.sk_write_space(&smc->sk);
291	}
292
293	if (conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) {
294		smc->sk.sk_err = ECONNRESET;
295		conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
296	}
297	if (smc_cdc_rxed_any_close_or_senddone(conn)) {
298		smc->sk.sk_shutdown |= RCV_SHUTDOWN;
299		if (smc->clcsock && smc->clcsock->sk)
300			smc->clcsock->sk->sk_shutdown |= RCV_SHUTDOWN;
301		sock_set_flag(&smc->sk, SOCK_DONE);
302		sock_hold(&smc->sk); /* sock_put in close_work */
303		if (!schedule_work(&conn->close_work))
304			sock_put(&smc->sk);
305	}
306}
307
308/* called under tasklet context */
309static void smc_cdc_msg_recv(struct smc_sock *smc, struct smc_cdc_msg *cdc)
310{
311	sock_hold(&smc->sk);
312	bh_lock_sock(&smc->sk);
313	smc_cdc_msg_recv_action(smc, cdc);
314	bh_unlock_sock(&smc->sk);
315	sock_put(&smc->sk); /* no free sk in softirq-context */
316}
317
318/* Schedule a tasklet for this connection. Triggered from the ISM device IRQ
319 * handler to indicate update in the DMBE.
320 *
321 * Context:
322 * - tasklet context
323 */
324static void smcd_cdc_rx_tsklet(unsigned long data)
325{
326	struct smc_connection *conn = (struct smc_connection *)data;
327	struct smcd_cdc_msg *data_cdc;
328	struct smcd_cdc_msg cdc;
329	struct smc_sock *smc;
330
331	if (!conn)
332		return;
333
334	data_cdc = (struct smcd_cdc_msg *)conn->rmb_desc->cpu_addr;
335	smcd_curs_copy(&cdc.prod, &data_cdc->prod, conn);
336	smcd_curs_copy(&cdc.cons, &data_cdc->cons, conn);
337	smc = container_of(conn, struct smc_sock, conn);
338	smc_cdc_msg_recv(smc, (struct smc_cdc_msg *)&cdc);
339}
340
341/* Initialize receive tasklet. Called from ISM device IRQ handler to start
342 * receiver side.
343 */
344void smcd_cdc_rx_init(struct smc_connection *conn)
345{
346	tasklet_init(&conn->rx_tsklet, smcd_cdc_rx_tsklet, (unsigned long)conn);
347}
348
349/***************************** init, exit, misc ******************************/
350
351static void smc_cdc_rx_handler(struct ib_wc *wc, void *buf)
352{
353	struct smc_link *link = (struct smc_link *)wc->qp->qp_context;
354	struct smc_cdc_msg *cdc = buf;
355	struct smc_connection *conn;
356	struct smc_link_group *lgr;
357	struct smc_sock *smc;
358
359	if (wc->byte_len < offsetof(struct smc_cdc_msg, reserved))
360		return; /* short message */
361	if (cdc->len != SMC_WR_TX_SIZE)
362		return; /* invalid message */
363
364	/* lookup connection */
365	lgr = smc_get_lgr(link);
366	read_lock_bh(&lgr->conns_lock);
367	conn = smc_lgr_find_conn(ntohl(cdc->token), lgr);
368	read_unlock_bh(&lgr->conns_lock);
369	if (!conn)
370		return;
371	smc = container_of(conn, struct smc_sock, conn);
372
373	if (!cdc->prod_flags.failover_validation) {
374		if (smc_cdc_before(ntohs(cdc->seqno),
375				   conn->local_rx_ctrl.seqno))
376			/* received seqno is old */
377			return;
378	}
379	smc_cdc_msg_recv(smc, cdc);
380}
381
382static struct smc_wr_rx_handler smc_cdc_rx_handlers[] = {
383	{
384		.handler	= smc_cdc_rx_handler,
385		.type		= SMC_CDC_MSG_TYPE
386	},
387	{
388		.handler	= NULL,
389	}
390};
391
392int __init smc_cdc_init(void)
393{
394	struct smc_wr_rx_handler *handler;
395	int rc = 0;
396
397	for (handler = smc_cdc_rx_handlers; handler->handler; handler++) {
398		INIT_HLIST_NODE(&handler->list);
399		rc = smc_wr_rx_register_handler(handler);
400		if (rc)
401			break;
402	}
403	return rc;
404}