root/net/smc/smc_cdc.c

DEFINITIONS

1. smc_cdc_tx_handler
2. smc_cdc_get_free_slot
3. smc_cdc_add_pending_send
4. smc_cdc_msg_send
5. smcr_cdc_get_slot_and_msg_send
6. smc_cdc_get_slot_and_msg_send
7. smc_cdc_tx_filter
8. smc_cdc_tx_dismisser
9. smc_cdc_tx_dismiss_slots
10. smcd_cdc_msg_send
11. smc_cdc_before
12. smc_cdc_handle_urg_data_arrival
13. smc_cdc_msg_recv_action
14. smc_cdc_msg_recv
15. smcd_cdc_rx_tsklet
16. smcd_cdc_rx_init
17. smc_cdc_rx_handler
18. smc_cdc_init

   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 */
  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         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 
  55 int 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 
  72 static 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 
  90 int 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 
 114 static 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 
 130 int 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 
 145 static 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 
 155 static 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 
 163 void 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  */
 176 int 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 
 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                         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 */
 309 static 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  */
 324 static 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  */
 344 void 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 
 351 static 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 
 382 static 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 
 392 int __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 }