xref: /openbmc/linux/net/smc/smc_cdc.c (revision 68198dca)
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 struct smc_cdc_tx_pend {
25 	struct smc_connection	*conn;		/* socket connection */
26 	union smc_host_cursor	cursor;	/* tx sndbuf cursor sent */
27 	union smc_host_cursor	p_cursor;	/* rx RMBE cursor produced */
28 	u16			ctrl_seq;	/* conn. tx sequence # */
29 };
30 
31 /* handler for send/transmission completion of a CDC msg */
32 static void smc_cdc_tx_handler(struct smc_wr_tx_pend_priv *pnd_snd,
33 			       struct smc_link *link,
34 			       enum ib_wc_status wc_status)
35 {
36 	struct smc_cdc_tx_pend *cdcpend = (struct smc_cdc_tx_pend *)pnd_snd;
37 	struct smc_sock *smc;
38 	int diff;
39 
40 	if (!cdcpend->conn)
41 		/* already dismissed */
42 		return;
43 
44 	smc = container_of(cdcpend->conn, struct smc_sock, conn);
45 	bh_lock_sock(&smc->sk);
46 	if (!wc_status) {
47 		diff = smc_curs_diff(cdcpend->conn->sndbuf_size,
48 				     &cdcpend->conn->tx_curs_fin,
49 				     &cdcpend->cursor);
50 		/* sndbuf_space is decreased in smc_sendmsg */
51 		smp_mb__before_atomic();
52 		atomic_add(diff, &cdcpend->conn->sndbuf_space);
53 		/* guarantee 0 <= sndbuf_space <= sndbuf_size */
54 		smp_mb__after_atomic();
55 		smc_curs_write(&cdcpend->conn->tx_curs_fin,
56 			       smc_curs_read(&cdcpend->cursor, cdcpend->conn),
57 			       cdcpend->conn);
58 	}
59 	smc_tx_sndbuf_nonfull(smc);
60 	if (smc->sk.sk_state != SMC_ACTIVE)
61 		/* wake up smc_close_wait_tx_pends() */
62 		smc->sk.sk_state_change(&smc->sk);
63 	bh_unlock_sock(&smc->sk);
64 }
65 
66 int smc_cdc_get_free_slot(struct smc_connection *conn,
67 			  struct smc_wr_buf **wr_buf,
68 			  struct smc_cdc_tx_pend **pend)
69 {
70 	struct smc_link *link = &conn->lgr->lnk[SMC_SINGLE_LINK];
71 
72 	return smc_wr_tx_get_free_slot(link, smc_cdc_tx_handler, wr_buf,
73 				       (struct smc_wr_tx_pend_priv **)pend);
74 }
75 
76 static inline void smc_cdc_add_pending_send(struct smc_connection *conn,
77 					    struct smc_cdc_tx_pend *pend)
78 {
79 	BUILD_BUG_ON_MSG(
80 		sizeof(struct smc_cdc_msg) > SMC_WR_BUF_SIZE,
81 		"must increase SMC_WR_BUF_SIZE to at least sizeof(struct smc_cdc_msg)");
82 	BUILD_BUG_ON_MSG(
83 		offsetof(struct smc_cdc_msg, reserved) > SMC_WR_TX_SIZE,
84 		"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()");
85 	BUILD_BUG_ON_MSG(
86 		sizeof(struct smc_cdc_tx_pend) > SMC_WR_TX_PEND_PRIV_SIZE,
87 		"must increase SMC_WR_TX_PEND_PRIV_SIZE to at least sizeof(struct smc_cdc_tx_pend)");
88 	pend->conn = conn;
89 	pend->cursor = conn->tx_curs_sent;
90 	pend->p_cursor = conn->local_tx_ctrl.prod;
91 	pend->ctrl_seq = conn->tx_cdc_seq;
92 }
93 
94 int smc_cdc_msg_send(struct smc_connection *conn,
95 		     struct smc_wr_buf *wr_buf,
96 		     struct smc_cdc_tx_pend *pend)
97 {
98 	struct smc_link *link;
99 	int rc;
100 
101 	link = &conn->lgr->lnk[SMC_SINGLE_LINK];
102 
103 	smc_cdc_add_pending_send(conn, pend);
104 
105 	conn->tx_cdc_seq++;
106 	conn->local_tx_ctrl.seqno = conn->tx_cdc_seq;
107 	smc_host_msg_to_cdc((struct smc_cdc_msg *)wr_buf,
108 			    &conn->local_tx_ctrl, conn);
109 	rc = smc_wr_tx_send(link, (struct smc_wr_tx_pend_priv *)pend);
110 	if (!rc)
111 		smc_curs_write(&conn->rx_curs_confirmed,
112 			       smc_curs_read(&conn->local_tx_ctrl.cons, conn),
113 			       conn);
114 
115 	return rc;
116 }
117 
118 int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn)
119 {
120 	struct smc_cdc_tx_pend *pend;
121 	struct smc_wr_buf *wr_buf;
122 	int rc;
123 
124 	rc = smc_cdc_get_free_slot(conn, &wr_buf, &pend);
125 	if (rc)
126 		return rc;
127 
128 	return smc_cdc_msg_send(conn, wr_buf, pend);
129 }
130 
131 static bool smc_cdc_tx_filter(struct smc_wr_tx_pend_priv *tx_pend,
132 			      unsigned long data)
133 {
134 	struct smc_connection *conn = (struct smc_connection *)data;
135 	struct smc_cdc_tx_pend *cdc_pend =
136 		(struct smc_cdc_tx_pend *)tx_pend;
137 
138 	return cdc_pend->conn == conn;
139 }
140 
141 static void smc_cdc_tx_dismisser(struct smc_wr_tx_pend_priv *tx_pend)
142 {
143 	struct smc_cdc_tx_pend *cdc_pend =
144 		(struct smc_cdc_tx_pend *)tx_pend;
145 
146 	cdc_pend->conn = NULL;
147 }
148 
149 void smc_cdc_tx_dismiss_slots(struct smc_connection *conn)
150 {
151 	struct smc_link *link = &conn->lgr->lnk[SMC_SINGLE_LINK];
152 
153 	smc_wr_tx_dismiss_slots(link, SMC_CDC_MSG_TYPE,
154 				smc_cdc_tx_filter, smc_cdc_tx_dismisser,
155 				(unsigned long)conn);
156 }
157 
158 bool smc_cdc_tx_has_pending(struct smc_connection *conn)
159 {
160 	struct smc_link *link = &conn->lgr->lnk[SMC_SINGLE_LINK];
161 
162 	return smc_wr_tx_has_pending(link, SMC_CDC_MSG_TYPE,
163 				     smc_cdc_tx_filter, (unsigned long)conn);
164 }
165 
166 /********************************* receive ***********************************/
167 
168 static inline bool smc_cdc_before(u16 seq1, u16 seq2)
169 {
170 	return (s16)(seq1 - seq2) < 0;
171 }
172 
173 static void smc_cdc_msg_recv_action(struct smc_sock *smc,
174 				    struct smc_link *link,
175 				    struct smc_cdc_msg *cdc)
176 {
177 	union smc_host_cursor cons_old, prod_old;
178 	struct smc_connection *conn = &smc->conn;
179 	int diff_cons, diff_prod;
180 
181 	if (!cdc->prod_flags.failover_validation) {
182 		if (smc_cdc_before(ntohs(cdc->seqno),
183 				   conn->local_rx_ctrl.seqno))
184 			/* received seqno is old */
185 			return;
186 	}
187 	smc_curs_write(&prod_old,
188 		       smc_curs_read(&conn->local_rx_ctrl.prod, conn),
189 		       conn);
190 	smc_curs_write(&cons_old,
191 		       smc_curs_read(&conn->local_rx_ctrl.cons, conn),
192 		       conn);
193 	smc_cdc_msg_to_host(&conn->local_rx_ctrl, cdc, conn);
194 
195 	diff_cons = smc_curs_diff(conn->peer_rmbe_size, &cons_old,
196 				  &conn->local_rx_ctrl.cons);
197 	if (diff_cons) {
198 		/* peer_rmbe_space is decreased during data transfer with RDMA
199 		 * write
200 		 */
201 		smp_mb__before_atomic();
202 		atomic_add(diff_cons, &conn->peer_rmbe_space);
203 		/* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
204 		smp_mb__after_atomic();
205 	}
206 
207 	diff_prod = smc_curs_diff(conn->rmbe_size, &prod_old,
208 				  &conn->local_rx_ctrl.prod);
209 	if (diff_prod) {
210 		/* bytes_to_rcv is decreased in smc_recvmsg */
211 		smp_mb__before_atomic();
212 		atomic_add(diff_prod, &conn->bytes_to_rcv);
213 		/* guarantee 0 <= bytes_to_rcv <= rmbe_size */
214 		smp_mb__after_atomic();
215 		smc->sk.sk_data_ready(&smc->sk);
216 	}
217 
218 	if (conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) {
219 		smc->sk.sk_err = ECONNRESET;
220 		conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
221 	}
222 	if (smc_cdc_rxed_any_close_or_senddone(conn)) {
223 		smc->sk.sk_shutdown |= RCV_SHUTDOWN;
224 		if (smc->clcsock && smc->clcsock->sk)
225 			smc->clcsock->sk->sk_shutdown |= RCV_SHUTDOWN;
226 		sock_set_flag(&smc->sk, SOCK_DONE);
227 		schedule_work(&conn->close_work);
228 	}
229 
230 	/* piggy backed tx info */
231 	/* trigger sndbuf consumer: RDMA write into peer RMBE and CDC */
232 	if (diff_cons && smc_tx_prepared_sends(conn)) {
233 		smc_tx_sndbuf_nonempty(conn);
234 		/* trigger socket release if connection closed */
235 		smc_close_wake_tx_prepared(smc);
236 	}
237 
238 	/* socket connected but not accepted */
239 	if (!smc->sk.sk_socket)
240 		return;
241 
242 	/* data available */
243 	if ((conn->local_rx_ctrl.prod_flags.write_blocked) ||
244 	    (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req))
245 		smc_tx_consumer_update(conn);
246 }
247 
248 /* called under tasklet context */
249 static inline void smc_cdc_msg_recv(struct smc_cdc_msg *cdc,
250 				    struct smc_link *link, u64 wr_id)
251 {
252 	struct smc_link_group *lgr = container_of(link, struct smc_link_group,
253 						  lnk[SMC_SINGLE_LINK]);
254 	struct smc_connection *connection;
255 	struct smc_sock *smc;
256 
257 	/* lookup connection */
258 	read_lock_bh(&lgr->conns_lock);
259 	connection = smc_lgr_find_conn(ntohl(cdc->token), lgr);
260 	if (!connection) {
261 		read_unlock_bh(&lgr->conns_lock);
262 		return;
263 	}
264 	smc = container_of(connection, struct smc_sock, conn);
265 	sock_hold(&smc->sk);
266 	read_unlock_bh(&lgr->conns_lock);
267 	bh_lock_sock(&smc->sk);
268 	smc_cdc_msg_recv_action(smc, link, cdc);
269 	bh_unlock_sock(&smc->sk);
270 	sock_put(&smc->sk); /* no free sk in softirq-context */
271 }
272 
273 /***************************** init, exit, misc ******************************/
274 
275 static void smc_cdc_rx_handler(struct ib_wc *wc, void *buf)
276 {
277 	struct smc_link *link = (struct smc_link *)wc->qp->qp_context;
278 	struct smc_cdc_msg *cdc = buf;
279 
280 	if (wc->byte_len < offsetof(struct smc_cdc_msg, reserved))
281 		return; /* short message */
282 	if (cdc->len != sizeof(*cdc))
283 		return; /* invalid message */
284 	smc_cdc_msg_recv(cdc, link, wc->wr_id);
285 }
286 
287 static struct smc_wr_rx_handler smc_cdc_rx_handlers[] = {
288 	{
289 		.handler	= smc_cdc_rx_handler,
290 		.type		= SMC_CDC_MSG_TYPE
291 	},
292 	{
293 		.handler	= NULL,
294 	}
295 };
296 
297 int __init smc_cdc_init(void)
298 {
299 	struct smc_wr_rx_handler *handler;
300 	int rc = 0;
301 
302 	for (handler = smc_cdc_rx_handlers; handler->handler; handler++) {
303 		INIT_HLIST_NODE(&handler->list);
304 		rc = smc_wr_rx_register_handler(handler);
305 		if (rc)
306 			break;
307 	}
308 	return rc;
309 }
310