net/smc/smc_tx.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Shared Memory Communications over RDMA (SMC-R) and RoCE
   4  *
   5  * Manage send buffer.
   6  * Producer:
   7  * Copy user space data into send buffer, if send buffer space available.
   8  * Consumer:
   9  * Trigger RDMA write into RMBE of peer and send CDC, if RMBE space available.
  10  *
  11  * Copyright IBM Corp. 2016
  12  *
  13  * Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
  14  */
  15
  16 #include <linux/net.h>
  17 #include <linux/rcupdate.h>
  18 #include <linux/workqueue.h>
  19 #include <linux/sched/signal.h>
  20
  21 #include <net/sock.h>
  22
  23 #include "smc.h"
  24 #include "smc_wr.h"
  25 #include "smc_cdc.h"
  26 #include "smc_tx.h"
  27
  28 #define SMC_TX_WORK_DELAY       HZ
  29
  30 /***************************** sndbuf producer *******************************/
  31
  32 /* callback implementation for sk.sk_write_space()
  33  * to wakeup sndbuf producers that blocked with smc_tx_wait_memory().
  34  * called under sk_socket lock.
  35  */
  36 static void smc_tx_write_space(struct sock *sk)
  37 {
  38         struct socket *sock = sk->sk_socket;
  39         struct smc_sock *smc = smc_sk(sk);
  40         struct socket_wq *wq;
  41
  42         /* similar to sk_stream_write_space */
  43         if (atomic_read(&smc->conn.sndbuf_space) && sock) {
  44                 clear_bit(SOCK_NOSPACE, &sock->flags);
  45                 rcu_read_lock();
  46                 wq = rcu_dereference(sk->sk_wq);
  47                 if (skwq_has_sleeper(wq))
  48                         wake_up_interruptible_poll(&wq->wait,
  49                                                    POLLOUT | POLLWRNORM |
  50                                                    POLLWRBAND);
  51                 if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  52                         sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
  53                 rcu_read_unlock();
  54         }
  55 }
  56
  57 /* Wakeup sndbuf producers that blocked with smc_tx_wait_memory().
  58  * Cf. tcp_data_snd_check()=>tcp_check_space()=>tcp_new_space().
  59  */
  60 void smc_tx_sndbuf_nonfull(struct smc_sock *smc)
  61 {
  62         if (smc->sk.sk_socket &&
  63             test_bit(SOCK_NOSPACE, &smc->sk.sk_socket->flags))
  64                 smc->sk.sk_write_space(&smc->sk);
  65 }
  66
  67 /* blocks sndbuf producer until at least one byte of free space available */
  68 static int smc_tx_wait_memory(struct smc_sock *smc, int flags)
  69 {
  70         DEFINE_WAIT_FUNC(wait, woken_wake_function);
  71         struct smc_connection *conn = &smc->conn;
  72         struct sock *sk = &smc->sk;
  73         bool noblock;
  74         long timeo;
  75         int rc = 0;
  76
  77         /* similar to sk_stream_wait_memory */
  78         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
  79         noblock = timeo ? false : true;
  80         add_wait_queue(sk_sleep(sk), &wait);
  81         while (1) {
  82                 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
  83                 if (sk->sk_err ||
  84                     (sk->sk_shutdown & SEND_SHUTDOWN) ||
  85                     conn->local_tx_ctrl.conn_state_flags.peer_done_writing) {
  86                         rc = -EPIPE;
  87                         break;
  88                 }
  89                 if (conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) {
  90                         rc = -ECONNRESET;
  91                         break;
  92                 }
  93                 if (!timeo) {
  94                         if (noblock)
  95                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
  96                         rc = -EAGAIN;
  97                         break;
  98                 }
  99                 if (signal_pending(current)) {
 100                         rc = sock_intr_errno(timeo);
 101                         break;
 102                 }
 103                 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 104                 if (atomic_read(&conn->sndbuf_space))
 105                         break; /* at least 1 byte of free space available */
 106                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 107                 sk->sk_write_pending++;
 108                 sk_wait_event(sk, &timeo,
 109                               sk->sk_err ||
 110                               (sk->sk_shutdown & SEND_SHUTDOWN) ||
 111                               smc_cdc_rxed_any_close_or_senddone(conn) ||
 112                               atomic_read(&conn->sndbuf_space),
 113                               &wait);
 114                 sk->sk_write_pending--;
 115         }
 116         remove_wait_queue(sk_sleep(sk), &wait);
 117         return rc;
 118 }
 119
 120 /* sndbuf producer: main API called by socket layer.
 121  * called under sock lock.
 122  */
 123 int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
 124 {
 125         size_t copylen, send_done = 0, send_remaining = len;
 126         size_t chunk_len, chunk_off, chunk_len_sum;
 127         struct smc_connection *conn = &smc->conn;
 128         union smc_host_cursor prep;
 129         struct sock *sk = &smc->sk;
 130         char *sndbuf_base;
 131         int tx_cnt_prep;
 132         int writespace;
 133         int rc, chunk;
 134
 135         /* This should be in poll */
 136         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 137
 138         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
 139                 rc = -EPIPE;
 140                 goto out_err;
 141         }
 142
 143         while (msg_data_left(msg)) {
 144                 if (sk->sk_state == SMC_INIT)
 145                         return -ENOTCONN;
 146                 if (smc->sk.sk_shutdown & SEND_SHUTDOWN ||
 147                     (smc->sk.sk_err == ECONNABORTED) ||
 148                     conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
 149                         return -EPIPE;
 150                 if (smc_cdc_rxed_any_close(conn))
 151                         return send_done ?: -ECONNRESET;
 152
 153                 if (!atomic_read(&conn->sndbuf_space)) {
 154                         rc = smc_tx_wait_memory(smc, msg->msg_flags);
 155                         if (rc) {
 156                                 if (send_done)
 157                                         return send_done;
 158                                 goto out_err;
 159                         }
 160                         continue;
 161                 }
 162
 163                 /* initialize variables for 1st iteration of subsequent loop */
 164                 /* could be just 1 byte, even after smc_tx_wait_memory above */
 165                 writespace = atomic_read(&conn->sndbuf_space);
 166                 /* not more than what user space asked for */
 167                 copylen = min_t(size_t, send_remaining, writespace);
 168                 /* determine start of sndbuf */
 169                 sndbuf_base = conn->sndbuf_desc->cpu_addr;
 170                 smc_curs_write(&prep,
 171                                smc_curs_read(&conn->tx_curs_prep, conn),
 172                                conn);
 173                 tx_cnt_prep = prep.count;
 174                 /* determine chunks where to write into sndbuf */
 175                 /* either unwrapped case, or 1st chunk of wrapped case */
 176                 chunk_len = min_t(size_t,
 177                                   copylen, conn->sndbuf_size - tx_cnt_prep);
 178                 chunk_len_sum = chunk_len;
 179                 chunk_off = tx_cnt_prep;
 180                 smc_sndbuf_sync_sg_for_cpu(conn);
 181                 for (chunk = 0; chunk < 2; chunk++) {
 182                         rc = memcpy_from_msg(sndbuf_base + chunk_off,
 183                                              msg, chunk_len);
 184                         if (rc) {
 185                                 smc_sndbuf_sync_sg_for_device(conn);
 186                                 if (send_done)
 187                                         return send_done;
 188                                 goto out_err;
 189                         }
 190                         send_done += chunk_len;
 191                         send_remaining -= chunk_len;
 192
 193                         if (chunk_len_sum == copylen)
 194                                 break; /* either on 1st or 2nd iteration */
 195                         /* prepare next (== 2nd) iteration */
 196                         chunk_len = copylen - chunk_len; /* remainder */
 197                         chunk_len_sum += chunk_len;
 198                         chunk_off = 0; /* modulo offset in send ring buffer */
 199                 }
 200                 smc_sndbuf_sync_sg_for_device(conn);
 201                 /* update cursors */
 202                 smc_curs_add(conn->sndbuf_size, &prep, copylen);
 203                 smc_curs_write(&conn->tx_curs_prep,
 204                                smc_curs_read(&prep, conn),
 205                                conn);
 206                 /* increased in send tasklet smc_cdc_tx_handler() */
 207                 smp_mb__before_atomic();
 208                 atomic_sub(copylen, &conn->sndbuf_space);
 209                 /* guarantee 0 <= sndbuf_space <= sndbuf_size */
 210                 smp_mb__after_atomic();
 211                 /* since we just produced more new data into sndbuf,
 212                  * trigger sndbuf consumer: RDMA write into peer RMBE and CDC
 213                  */
 214                 smc_tx_sndbuf_nonempty(conn);
 215         } /* while (msg_data_left(msg)) */
 216
 217         return send_done;
 218
 219 out_err:
 220         rc = sk_stream_error(sk, msg->msg_flags, rc);
 221         /* make sure we wake any epoll edge trigger waiter */
 222         if (unlikely(rc == -EAGAIN))
 223                 sk->sk_write_space(sk);
 224         return rc;
 225 }
 226
 227 /***************************** sndbuf consumer *******************************/
 228
 229 /* sndbuf consumer: actual data transfer of one target chunk with RDMA write */
 230 static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
 231                              int num_sges, struct ib_sge sges[])
 232 {
 233         struct smc_link_group *lgr = conn->lgr;
 234         struct ib_send_wr *failed_wr = NULL;
 235         struct ib_rdma_wr rdma_wr;
 236         struct smc_link *link;
 237         int rc;
 238
 239         memset(&rdma_wr, 0, sizeof(rdma_wr));
 240         link = &lgr->lnk[SMC_SINGLE_LINK];
 241         rdma_wr.wr.wr_id = smc_wr_tx_get_next_wr_id(link);
 242         rdma_wr.wr.sg_list = sges;
 243         rdma_wr.wr.num_sge = num_sges;
 244         rdma_wr.wr.opcode = IB_WR_RDMA_WRITE;
 245         rdma_wr.remote_addr =
 246                 lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr +
 247                 /* RMBE within RMB */
 248                 ((conn->peer_conn_idx - 1) * conn->peer_rmbe_size) +
 249                 /* offset within RMBE */
 250                 peer_rmbe_offset;
 251         rdma_wr.rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey;
 252         rc = ib_post_send(link->roce_qp, &rdma_wr.wr, &failed_wr);
 253         if (rc)
 254                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 255         return rc;
 256 }
 257
 258 /* sndbuf consumer */
 259 static inline void smc_tx_advance_cursors(struct smc_connection *conn,
 260                                           union smc_host_cursor *prod,
 261                                           union smc_host_cursor *sent,
 262                                           size_t len)
 263 {
 264         smc_curs_add(conn->peer_rmbe_size, prod, len);
 265         /* increased in recv tasklet smc_cdc_msg_rcv() */
 266         smp_mb__before_atomic();
 267         /* data in flight reduces usable snd_wnd */
 268         atomic_sub(len, &conn->peer_rmbe_space);
 269         /* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
 270         smp_mb__after_atomic();
 271         smc_curs_add(conn->sndbuf_size, sent, len);
 272 }
 273
 274 /* sndbuf consumer: prepare all necessary (src&dst) chunks of data transmit;
 275  * usable snd_wnd as max transmit
 276  */
 277 static int smc_tx_rdma_writes(struct smc_connection *conn)
 278 {
 279         size_t src_off, src_len, dst_off, dst_len; /* current chunk values */
 280         size_t len, dst_len_sum, src_len_sum, dstchunk, srcchunk;
 281         union smc_host_cursor sent, prep, prod, cons;
 282         struct ib_sge sges[SMC_IB_MAX_SEND_SGE];
 283         struct smc_link_group *lgr = conn->lgr;
 284         int to_send, rmbespace;
 285         struct smc_link *link;
 286         dma_addr_t dma_addr;
 287         int num_sges;
 288         int rc;
 289
 290         /* source: sndbuf */
 291         smc_curs_write(&sent, smc_curs_read(&conn->tx_curs_sent, conn), conn);
 292         smc_curs_write(&prep, smc_curs_read(&conn->tx_curs_prep, conn), conn);
 293         /* cf. wmem_alloc - (snd_max - snd_una) */
 294         to_send = smc_curs_diff(conn->sndbuf_size, &sent, &prep);
 295         if (to_send <= 0)
 296                 return 0;
 297
 298         /* destination: RMBE */
 299         /* cf. snd_wnd */
 300         rmbespace = atomic_read(&conn->peer_rmbe_space);
 301         if (rmbespace <= 0)
 302                 return 0;
 303         smc_curs_write(&prod,
 304                        smc_curs_read(&conn->local_tx_ctrl.prod, conn),
 305                        conn);
 306         smc_curs_write(&cons,
 307                        smc_curs_read(&conn->local_rx_ctrl.cons, conn),
 308                        conn);
 309
 310         /* if usable snd_wnd closes ask peer to advertise once it opens again */
 311         conn->local_tx_ctrl.prod_flags.write_blocked = (to_send >= rmbespace);
 312         /* cf. usable snd_wnd */
 313         len = min(to_send, rmbespace);
 314
 315         /* initialize variables for first iteration of subsequent nested loop */
 316         link = &lgr->lnk[SMC_SINGLE_LINK];
 317         dst_off = prod.count;
 318         if (prod.wrap == cons.wrap) {
 319                 /* the filled destination area is unwrapped,
 320                  * hence the available free destination space is wrapped
 321                  * and we need 2 destination chunks of sum len; start with 1st
 322                  * which is limited by what's available in sndbuf
 323                  */
 324                 dst_len = min_t(size_t,
 325                                 conn->peer_rmbe_size - prod.count, len);
 326         } else {
 327                 /* the filled destination area is wrapped,
 328                  * hence the available free destination space is unwrapped
 329                  * and we need a single destination chunk of entire len
 330                  */
 331                 dst_len = len;
 332         }
 333         dst_len_sum = dst_len;
 334         src_off = sent.count;
 335         /* dst_len determines the maximum src_len */
 336         if (sent.count + dst_len <= conn->sndbuf_size) {
 337                 /* unwrapped src case: single chunk of entire dst_len */
 338                 src_len = dst_len;
 339         } else {
 340                 /* wrapped src case: 2 chunks of sum dst_len; start with 1st: */
 341                 src_len = conn->sndbuf_size - sent.count;
 342         }
 343         src_len_sum = src_len;
 344         dma_addr = sg_dma_address(conn->sndbuf_desc->sgt[SMC_SINGLE_LINK].sgl);
 345         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 346                 num_sges = 0;
 347                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 348                         sges[srcchunk].addr = dma_addr + src_off;
 349                         sges[srcchunk].length = src_len;
 350                         sges[srcchunk].lkey = link->roce_pd->local_dma_lkey;
 351                         num_sges++;
 352                         src_off += src_len;
 353                         if (src_off >= conn->sndbuf_size)
 354                                 src_off -= conn->sndbuf_size;
 355                                                 /* modulo in send ring */
 356                         if (src_len_sum == dst_len)
 357                                 break; /* either on 1st or 2nd iteration */
 358                         /* prepare next (== 2nd) iteration */
 359                         src_len = dst_len - src_len; /* remainder */
 360                         src_len_sum += src_len;
 361                 }
 362                 rc = smc_tx_rdma_write(conn, dst_off, num_sges, sges);
 363                 if (rc)
 364                         return rc;
 365                 if (dst_len_sum == len)
 366                         break; /* either on 1st or 2nd iteration */
 367                 /* prepare next (== 2nd) iteration */
 368                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 369                 dst_len = len - dst_len; /* remainder */
 370                 dst_len_sum += dst_len;
 371                 src_len = min_t(int,
 372                                 dst_len, conn->sndbuf_size - sent.count);
 373                 src_len_sum = src_len;
 374         }
 375
 376         smc_tx_advance_cursors(conn, &prod, &sent, len);
 377         /* update connection's cursors with advanced local cursors */
 378         smc_curs_write(&conn->local_tx_ctrl.prod,
 379                        smc_curs_read(&prod, conn),
 380                        conn);
 381                                                         /* dst: peer RMBE */
 382         smc_curs_write(&conn->tx_curs_sent,
 383                        smc_curs_read(&sent, conn),
 384                        conn);
 385                                                         /* src: local sndbuf */
 386
 387         return 0;
 388 }
 389
 390 /* Wakeup sndbuf consumers from any context (IRQ or process)
 391  * since there is more data to transmit; usable snd_wnd as max transmit
 392  */
 393 int smc_tx_sndbuf_nonempty(struct smc_connection *conn)
 394 {
 395         struct smc_cdc_tx_pend *pend;
 396         struct smc_wr_buf *wr_buf;
 397         int rc;
 398
 399         spin_lock_bh(&conn->send_lock);
 400         rc = smc_cdc_get_free_slot(conn, &wr_buf, &pend);
 401         if (rc < 0) {
 402                 if (rc == -EBUSY) {
 403                         struct smc_sock *smc =
 404                                 container_of(conn, struct smc_sock, conn);
 405
 406                         if (smc->sk.sk_err == ECONNABORTED) {
 407                                 rc = sock_error(&smc->sk);
 408                                 goto out_unlock;
 409                         }
 410                         rc = 0;
 411                         schedule_delayed_work(&conn->tx_work,
 412                                               SMC_TX_WORK_DELAY);
 413                 }
 414                 goto out_unlock;
 415         }
 416
 417         rc = smc_tx_rdma_writes(conn);
 418         if (rc) {
 419                 smc_wr_tx_put_slot(&conn->lgr->lnk[SMC_SINGLE_LINK],
 420                                    (struct smc_wr_tx_pend_priv *)pend);
 421                 goto out_unlock;
 422         }
 423
 424         rc = smc_cdc_msg_send(conn, wr_buf, pend);
 425
 426 out_unlock:
 427         spin_unlock_bh(&conn->send_lock);
 428         return rc;
 429 }
 430
 431 /* Wakeup sndbuf consumers from process context
 432  * since there is more data to transmit
 433  */
 434 static void smc_tx_work(struct work_struct *work)
 435 {
 436         struct smc_connection *conn = container_of(to_delayed_work(work),
 437                                                    struct smc_connection,
 438                                                    tx_work);
 439         struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
 440         int rc;
 441
 442         lock_sock(&smc->sk);
 443         rc = smc_tx_sndbuf_nonempty(conn);
 444         if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked &&
 445             !atomic_read(&conn->bytes_to_rcv))
 446                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 447         release_sock(&smc->sk);
 448 }
 449
 450 void smc_tx_consumer_update(struct smc_connection *conn)
 451 {
 452         union smc_host_cursor cfed, cons;
 453         struct smc_cdc_tx_pend *pend;
 454         struct smc_wr_buf *wr_buf;
 455         int to_confirm, rc;
 456
 457         smc_curs_write(&cons,
 458                        smc_curs_read(&conn->local_tx_ctrl.cons, conn),
 459                        conn);
 460         smc_curs_write(&cfed,
 461                        smc_curs_read(&conn->rx_curs_confirmed, conn),
 462                        conn);
 463         to_confirm = smc_curs_diff(conn->rmbe_size, &cfed, &cons);
 464
 465         if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
 466             ((to_confirm > conn->rmbe_update_limit) &&
 467              ((to_confirm > (conn->rmbe_size / 2)) ||
 468               conn->local_rx_ctrl.prod_flags.write_blocked))) {
 469                 rc = smc_cdc_get_free_slot(conn, &wr_buf, &pend);
 470                 if (!rc)
 471                         rc = smc_cdc_msg_send(conn, wr_buf, pend);
 472                 if (rc < 0) {
 473                         schedule_delayed_work(&conn->tx_work,
 474                                               SMC_TX_WORK_DELAY);
 475                         return;
 476                 }
 477                 smc_curs_write(&conn->rx_curs_confirmed,
 478                                smc_curs_read(&conn->local_tx_ctrl.cons, conn),
 479                                conn);
 480                 conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0;
 481         }
 482         if (conn->local_rx_ctrl.prod_flags.write_blocked &&
 483             !atomic_read(&conn->bytes_to_rcv))
 484                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 485 }
 486
 487 /***************************** send initialize *******************************/
 488
 489 /* Initialize send properties on connection establishment. NB: not __init! */
 490 void smc_tx_init(struct smc_sock *smc)
 491 {
 492         smc->sk.sk_write_space = smc_tx_write_space;
 493         INIT_DELAYED_WORK(&smc->conn.tx_work, smc_tx_work);
 494         spin_lock_init(&smc->conn.send_lock);
 495 }