net/smc: atomic SMCD cursor handling
[sfrench/cifs-2.6.git] / net / smc / smc_cdc.c
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_connection *conn = cdcpend->conn;
38         struct smc_sock *smc;
39         int diff;
40
41         if (!conn)
42                 /* already dismissed */
43                 return;
44
45         smc = container_of(conn, struct smc_sock, conn);
46         bh_lock_sock(&smc->sk);
47         if (!wc_status) {
48                 diff = smc_curs_diff(cdcpend->conn->sndbuf_desc->len,
49                                      &cdcpend->conn->tx_curs_fin,
50                                      &cdcpend->cursor);
51                 /* sndbuf_space is decreased in smc_sendmsg */
52                 smp_mb__before_atomic();
53                 atomic_add(diff, &cdcpend->conn->sndbuf_space);
54                 /* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
55                 smp_mb__after_atomic();
56                 smc_curs_copy(&conn->tx_curs_fin, &cdcpend->cursor, conn);
57         }
58         smc_tx_sndbuf_nonfull(smc);
59         bh_unlock_sock(&smc->sk);
60 }
61
62 int smc_cdc_get_free_slot(struct smc_connection *conn,
63                           struct smc_wr_buf **wr_buf,
64                           struct smc_cdc_tx_pend **pend)
65 {
66         struct smc_link *link = &conn->lgr->lnk[SMC_SINGLE_LINK];
67         int rc;
68
69         rc = smc_wr_tx_get_free_slot(link, smc_cdc_tx_handler, wr_buf,
70                                      (struct smc_wr_tx_pend_priv **)pend);
71         if (!conn->alert_token_local)
72                 /* abnormal termination */
73                 rc = -EPIPE;
74         return rc;
75 }
76
77 static inline void smc_cdc_add_pending_send(struct smc_connection *conn,
78                                             struct smc_cdc_tx_pend *pend)
79 {
80         BUILD_BUG_ON_MSG(
81                 sizeof(struct smc_cdc_msg) > SMC_WR_BUF_SIZE,
82                 "must increase SMC_WR_BUF_SIZE to at least sizeof(struct smc_cdc_msg)");
83         BUILD_BUG_ON_MSG(
84                 offsetofend(struct smc_cdc_msg, reserved) > SMC_WR_TX_SIZE,
85                 "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()");
86         BUILD_BUG_ON_MSG(
87                 sizeof(struct smc_cdc_tx_pend) > SMC_WR_TX_PEND_PRIV_SIZE,
88                 "must increase SMC_WR_TX_PEND_PRIV_SIZE to at least sizeof(struct smc_cdc_tx_pend)");
89         pend->conn = conn;
90         pend->cursor = conn->tx_curs_sent;
91         pend->p_cursor = conn->local_tx_ctrl.prod;
92         pend->ctrl_seq = conn->tx_cdc_seq;
93 }
94
95 int smc_cdc_msg_send(struct smc_connection *conn,
96                      struct smc_wr_buf *wr_buf,
97                      struct smc_cdc_tx_pend *pend)
98 {
99         struct smc_link *link;
100         int rc;
101
102         link = &conn->lgr->lnk[SMC_SINGLE_LINK];
103
104         smc_cdc_add_pending_send(conn, pend);
105
106         conn->tx_cdc_seq++;
107         conn->local_tx_ctrl.seqno = conn->tx_cdc_seq;
108         smc_host_msg_to_cdc((struct smc_cdc_msg *)wr_buf,
109                             &conn->local_tx_ctrl, conn);
110         rc = smc_wr_tx_send(link, (struct smc_wr_tx_pend_priv *)pend);
111         if (!rc)
112                 smc_curs_copy(&conn->rx_curs_confirmed,
113                               &conn->local_tx_ctrl.cons, conn);
114
115         return rc;
116 }
117
118 static int smcr_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 int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn)
132 {
133         int rc;
134
135         if (conn->lgr->is_smcd) {
136                 spin_lock_bh(&conn->send_lock);
137                 rc = smcd_cdc_msg_send(conn);
138                 spin_unlock_bh(&conn->send_lock);
139         } else {
140                 rc = smcr_cdc_get_slot_and_msg_send(conn);
141         }
142
143         return rc;
144 }
145
146 static bool smc_cdc_tx_filter(struct smc_wr_tx_pend_priv *tx_pend,
147                               unsigned long data)
148 {
149         struct smc_connection *conn = (struct smc_connection *)data;
150         struct smc_cdc_tx_pend *cdc_pend =
151                 (struct smc_cdc_tx_pend *)tx_pend;
152
153         return cdc_pend->conn == conn;
154 }
155
156 static void smc_cdc_tx_dismisser(struct smc_wr_tx_pend_priv *tx_pend)
157 {
158         struct smc_cdc_tx_pend *cdc_pend =
159                 (struct smc_cdc_tx_pend *)tx_pend;
160
161         cdc_pend->conn = NULL;
162 }
163
164 void smc_cdc_tx_dismiss_slots(struct smc_connection *conn)
165 {
166         struct smc_link *link = &conn->lgr->lnk[SMC_SINGLE_LINK];
167
168         smc_wr_tx_dismiss_slots(link, SMC_CDC_MSG_TYPE,
169                                 smc_cdc_tx_filter, smc_cdc_tx_dismisser,
170                                 (unsigned long)conn);
171 }
172
173 /* Send a SMC-D CDC header.
174  * This increments the free space available in our send buffer.
175  * Also update the confirmed receive buffer with what was sent to the peer.
176  */
177 int smcd_cdc_msg_send(struct smc_connection *conn)
178 {
179         struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
180         union smc_host_cursor curs;
181         struct smcd_cdc_msg cdc;
182         int rc, diff;
183
184         memset(&cdc, 0, sizeof(cdc));
185         cdc.common.type = SMC_CDC_MSG_TYPE;
186         curs.acurs.counter = atomic64_read(&conn->local_tx_ctrl.prod.acurs);
187         cdc.prod.wrap = curs.wrap;
188         cdc.prod.count = curs.count;
189         curs.acurs.counter = atomic64_read(&conn->local_tx_ctrl.cons.acurs);
190         cdc.cons.wrap = curs.wrap;
191         cdc.cons.count = curs.count;
192         cdc.cons.prod_flags = conn->local_tx_ctrl.prod_flags;
193         cdc.cons.conn_state_flags = conn->local_tx_ctrl.conn_state_flags;
194         rc = smcd_tx_ism_write(conn, &cdc, sizeof(cdc), 0, 1);
195         if (rc)
196                 return rc;
197         smc_curs_copy(&conn->rx_curs_confirmed, &curs, conn);
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
214 static inline bool smc_cdc_before(u16 seq1, u16 seq2)
215 {
216         return (s16)(seq1 - seq2) < 0;
217 }
218
219 static 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
239 static 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                     conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
276                     conn->local_rx_ctrl.prod_flags.urg_data_pending) {
277                         if (conn->local_rx_ctrl.prod_flags.urg_data_pending)
278                                 conn->urg_state = SMC_URG_NOTYET;
279                         /* force immediate tx of current consumer cursor, but
280                          * under send_lock to guarantee arrival in seqno-order
281                          */
282                         if (smc->sk.sk_state != SMC_INIT)
283                                 smc_tx_sndbuf_nonempty(conn);
284                 }
285         }
286
287         /* piggy backed tx info */
288         /* trigger sndbuf consumer: RDMA write into peer RMBE and CDC */
289         if (diff_cons && smc_tx_prepared_sends(conn)) {
290                 smc_tx_sndbuf_nonempty(conn);
291                 /* trigger socket release if connection closed */
292                 smc_close_wake_tx_prepared(smc);
293         }
294         if (diff_cons && conn->urg_tx_pend &&
295             atomic_read(&conn->peer_rmbe_space) == conn->peer_rmbe_size) {
296                 /* urg data confirmed by peer, indicate we're ready for more */
297                 conn->urg_tx_pend = false;
298                 smc->sk.sk_write_space(&smc->sk);
299         }
300
301         if (conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) {
302                 smc->sk.sk_err = ECONNRESET;
303                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
304         }
305         if (smc_cdc_rxed_any_close_or_senddone(conn)) {
306                 smc->sk.sk_shutdown |= RCV_SHUTDOWN;
307                 if (smc->clcsock && smc->clcsock->sk)
308                         smc->clcsock->sk->sk_shutdown |= RCV_SHUTDOWN;
309                 sock_set_flag(&smc->sk, SOCK_DONE);
310                 sock_hold(&smc->sk); /* sock_put in close_work */
311                 if (!schedule_work(&conn->close_work))
312                         sock_put(&smc->sk);
313         }
314 }
315
316 /* called under tasklet context */
317 static void smc_cdc_msg_recv(struct smc_sock *smc, struct smc_cdc_msg *cdc)
318 {
319         sock_hold(&smc->sk);
320         bh_lock_sock(&smc->sk);
321         smc_cdc_msg_recv_action(smc, cdc);
322         bh_unlock_sock(&smc->sk);
323         sock_put(&smc->sk); /* no free sk in softirq-context */
324 }
325
326 /* Schedule a tasklet for this connection. Triggered from the ISM device IRQ
327  * handler to indicate update in the DMBE.
328  *
329  * Context:
330  * - tasklet context
331  */
332 static void smcd_cdc_rx_tsklet(unsigned long data)
333 {
334         struct smc_connection *conn = (struct smc_connection *)data;
335         struct smcd_cdc_msg *data_cdc;
336         struct smcd_cdc_msg cdc;
337         struct smc_sock *smc;
338
339         if (!conn)
340                 return;
341
342         data_cdc = (struct smcd_cdc_msg *)conn->rmb_desc->cpu_addr;
343         smcd_curs_copy(&cdc.prod, &data_cdc->prod, conn);
344         smcd_curs_copy(&cdc.cons, &data_cdc->cons, conn);
345         smc = container_of(conn, struct smc_sock, conn);
346         smc_cdc_msg_recv(smc, (struct smc_cdc_msg *)&cdc);
347 }
348
349 /* Initialize receive tasklet. Called from ISM device IRQ handler to start
350  * receiver side.
351  */
352 void smcd_cdc_rx_init(struct smc_connection *conn)
353 {
354         tasklet_init(&conn->rx_tsklet, smcd_cdc_rx_tsklet, (unsigned long)conn);
355 }
356
357 /***************************** init, exit, misc ******************************/
358
359 static void smc_cdc_rx_handler(struct ib_wc *wc, void *buf)
360 {
361         struct smc_link *link = (struct smc_link *)wc->qp->qp_context;
362         struct smc_cdc_msg *cdc = buf;
363         struct smc_connection *conn;
364         struct smc_link_group *lgr;
365         struct smc_sock *smc;
366
367         if (wc->byte_len < offsetof(struct smc_cdc_msg, reserved))
368                 return; /* short message */
369         if (cdc->len != SMC_WR_TX_SIZE)
370                 return; /* invalid message */
371
372         /* lookup connection */
373         lgr = smc_get_lgr(link);
374         read_lock_bh(&lgr->conns_lock);
375         conn = smc_lgr_find_conn(ntohl(cdc->token), lgr);
376         read_unlock_bh(&lgr->conns_lock);
377         if (!conn)
378                 return;
379         smc = container_of(conn, struct smc_sock, conn);
380
381         if (!cdc->prod_flags.failover_validation) {
382                 if (smc_cdc_before(ntohs(cdc->seqno),
383                                    conn->local_rx_ctrl.seqno))
384                         /* received seqno is old */
385                         return;
386         }
387         smc_cdc_msg_recv(smc, cdc);
388 }
389
390 static struct smc_wr_rx_handler smc_cdc_rx_handlers[] = {
391         {
392                 .handler        = smc_cdc_rx_handler,
393                 .type           = SMC_CDC_MSG_TYPE
394         },
395         {
396                 .handler        = NULL,
397         }
398 };
399
400 int __init smc_cdc_init(void)
401 {
402         struct smc_wr_rx_handler *handler;
403         int rc = 0;
404
405         for (handler = smc_cdc_rx_handlers; handler->handler; handler++) {
406                 INIT_HLIST_NODE(&handler->list);
407                 rc = smc_wr_rx_register_handler(handler);
408                 if (rc)
409                         break;
410         }
411         return rc;
412 }