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 #include <net/tcp.h>
  23
  24 #include "smc.h"
  25 #include "smc_wr.h"
  26 #include "smc_cdc.h"
  27 #include "smc_tx.h"
  28
  29 #define SMC_TX_WORK_DELAY       HZ
  30 #define SMC_TX_CORK_DELAY       (HZ >> 2)       /* 250 ms */
  31
  32 /***************************** sndbuf producer *******************************/
  33
  34 /* callback implementation for sk.sk_write_space()
  35  * to wakeup sndbuf producers that blocked with smc_tx_wait().
  36  * called under sk_socket lock.
  37  */
  38 static void smc_tx_write_space(struct sock *sk)
  39 {
  40         struct socket *sock = sk->sk_socket;
  41         struct smc_sock *smc = smc_sk(sk);
  42         struct socket_wq *wq;
  43
  44         /* similar to sk_stream_write_space */
  45         if (atomic_read(&smc->conn.sndbuf_space) && sock) {
  46                 clear_bit(SOCK_NOSPACE, &sock->flags);
  47                 rcu_read_lock();
  48                 wq = rcu_dereference(sk->sk_wq);
  49                 if (skwq_has_sleeper(wq))
  50                         wake_up_interruptible_poll(&wq->wait,
  51                                                    EPOLLOUT | EPOLLWRNORM |
  52                                                    EPOLLWRBAND);
  53                 if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  54                         sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
  55                 rcu_read_unlock();
  56         }
  57 }
  58
  59 /* Wakeup sndbuf producers that blocked with smc_tx_wait().
  60  * Cf. tcp_data_snd_check()=>tcp_check_space()=>tcp_new_space().
  61  */
  62 void smc_tx_sndbuf_nonfull(struct smc_sock *smc)
  63 {
  64         if (smc->sk.sk_socket &&
  65             test_bit(SOCK_NOSPACE, &smc->sk.sk_socket->flags))
  66                 smc->sk.sk_write_space(&smc->sk);
  67 }
  68
  69 /* blocks sndbuf producer until at least one byte of free space available
  70  * or urgent Byte was consumed
  71  */
  72 static int smc_tx_wait(struct smc_sock *smc, int flags)
  73 {
  74         DEFINE_WAIT_FUNC(wait, woken_wake_function);
  75         struct smc_connection *conn = &smc->conn;
  76         struct sock *sk = &smc->sk;
  77         bool noblock;
  78         long timeo;
  79         int rc = 0;
  80
  81         /* similar to sk_stream_wait_memory */
  82         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
  83         noblock = timeo ? false : true;
  84         add_wait_queue(sk_sleep(sk), &wait);
  85         while (1) {
  86                 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
  87                 if (sk->sk_err ||
  88                     (sk->sk_shutdown & SEND_SHUTDOWN) ||
  89                     conn->local_tx_ctrl.conn_state_flags.peer_done_writing) {
  90                         rc = -EPIPE;
  91                         break;
  92                 }
  93                 if (smc_cdc_rxed_any_close(conn)) {
  94                         rc = -ECONNRESET;
  95                         break;
  96                 }
  97                 if (!timeo) {
  98                         if (noblock)
  99                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 100                         rc = -EAGAIN;
 101                         break;
 102                 }
 103                 if (signal_pending(current)) {
 104                         rc = sock_intr_errno(timeo);
 105                         break;
 106                 }
 107                 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 108                 if (atomic_read(&conn->sndbuf_space) && !conn->urg_tx_pend)
 109                         break; /* at least 1 byte of free & no urgent data */
 110                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 111                 sk_wait_event(sk, &timeo,
 112                               sk->sk_err ||
 113                               (sk->sk_shutdown & SEND_SHUTDOWN) ||
 114                               smc_cdc_rxed_any_close(conn) ||
 115                               (atomic_read(&conn->sndbuf_space) &&
 116                                !conn->urg_tx_pend),
 117                               &wait);
 118         }
 119         remove_wait_queue(sk_sleep(sk), &wait);
 120         return rc;
 121 }
 122
 123 static bool smc_tx_is_corked(struct smc_sock *smc)
 124 {
 125         struct tcp_sock *tp = tcp_sk(smc->clcsock->sk);
 126
 127         return (tp->nonagle & TCP_NAGLE_CORK) ? true : false;
 128 }
 129
 130 /* sndbuf producer: main API called by socket layer.
 131  * called under sock lock.
 132  */
 133 int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
 134 {
 135         size_t copylen, send_done = 0, send_remaining = len;
 136         size_t chunk_len, chunk_off, chunk_len_sum;
 137         struct smc_connection *conn = &smc->conn;
 138         union smc_host_cursor prep;
 139         struct sock *sk = &smc->sk;
 140         char *sndbuf_base;
 141         int tx_cnt_prep;
 142         int writespace;
 143         int rc, chunk;
 144
 145         /* This should be in poll */
 146         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 147
 148         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
 149                 rc = -EPIPE;
 150                 goto out_err;
 151         }
 152
 153         while (msg_data_left(msg)) {
 154                 if (sk->sk_state == SMC_INIT)
 155                         return -ENOTCONN;
 156                 if (smc->sk.sk_shutdown & SEND_SHUTDOWN ||
 157                     (smc->sk.sk_err == ECONNABORTED) ||
 158                     conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
 159                         return -EPIPE;
 160                 if (smc_cdc_rxed_any_close(conn))
 161                         return send_done ?: -ECONNRESET;
 162
 163                 if (msg->msg_flags & MSG_OOB)
 164                         conn->local_tx_ctrl.prod_flags.urg_data_pending = 1;
 165
 166                 if (!atomic_read(&conn->sndbuf_space) || conn->urg_tx_pend) {
 167                         rc = smc_tx_wait(smc, msg->msg_flags);
 168                         if (rc) {
 169                                 if (send_done)
 170                                         return send_done;
 171                                 goto out_err;
 172                         }
 173                         continue;
 174                 }
 175
 176                 /* initialize variables for 1st iteration of subsequent loop */
 177                 /* could be just 1 byte, even after smc_tx_wait above */
 178                 writespace = atomic_read(&conn->sndbuf_space);
 179                 /* not more than what user space asked for */
 180                 copylen = min_t(size_t, send_remaining, writespace);
 181                 /* determine start of sndbuf */
 182                 sndbuf_base = conn->sndbuf_desc->cpu_addr;
 183                 smc_curs_write(&prep,
 184                                smc_curs_read(&conn->tx_curs_prep, conn),
 185                                conn);
 186                 tx_cnt_prep = prep.count;
 187                 /* determine chunks where to write into sndbuf */
 188                 /* either unwrapped case, or 1st chunk of wrapped case */
 189                 chunk_len = min_t(size_t, copylen, conn->sndbuf_desc->len -
 190                                   tx_cnt_prep);
 191                 chunk_len_sum = chunk_len;
 192                 chunk_off = tx_cnt_prep;
 193                 smc_sndbuf_sync_sg_for_cpu(conn);
 194                 for (chunk = 0; chunk < 2; chunk++) {
 195                         rc = memcpy_from_msg(sndbuf_base + chunk_off,
 196                                              msg, chunk_len);
 197                         if (rc) {
 198                                 smc_sndbuf_sync_sg_for_device(conn);
 199                                 if (send_done)
 200                                         return send_done;
 201                                 goto out_err;
 202                         }
 203                         send_done += chunk_len;
 204                         send_remaining -= chunk_len;
 205
 206                         if (chunk_len_sum == copylen)
 207                                 break; /* either on 1st or 2nd iteration */
 208                         /* prepare next (== 2nd) iteration */
 209                         chunk_len = copylen - chunk_len; /* remainder */
 210                         chunk_len_sum += chunk_len;
 211                         chunk_off = 0; /* modulo offset in send ring buffer */
 212                 }
 213                 smc_sndbuf_sync_sg_for_device(conn);
 214                 /* update cursors */
 215                 smc_curs_add(conn->sndbuf_desc->len, &prep, copylen);
 216                 smc_curs_write(&conn->tx_curs_prep,
 217                                smc_curs_read(&prep, conn),
 218                                conn);
 219                 /* increased in send tasklet smc_cdc_tx_handler() */
 220                 smp_mb__before_atomic();
 221                 atomic_sub(copylen, &conn->sndbuf_space);
 222                 /* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
 223                 smp_mb__after_atomic();
 224                 /* since we just produced more new data into sndbuf,
 225                  * trigger sndbuf consumer: RDMA write into peer RMBE and CDC
 226                  */
 227                 if ((msg->msg_flags & MSG_OOB) && !send_remaining)
 228                         conn->urg_tx_pend = true;
 229                 if ((msg->msg_flags & MSG_MORE || smc_tx_is_corked(smc)) &&
 230                     (atomic_read(&conn->sndbuf_space) >
 231                                                 (conn->sndbuf_desc->len >> 1)))
 232                         /* for a corked socket defer the RDMA writes if there
 233                          * is still sufficient sndbuf_space available
 234                          */
 235                         schedule_delayed_work(&conn->tx_work,
 236                                               SMC_TX_CORK_DELAY);
 237                 else
 238                         smc_tx_sndbuf_nonempty(conn);
 239         } /* while (msg_data_left(msg)) */
 240
 241         return send_done;
 242
 243 out_err:
 244         rc = sk_stream_error(sk, msg->msg_flags, rc);
 245         /* make sure we wake any epoll edge trigger waiter */
 246         if (unlikely(rc == -EAGAIN))
 247                 sk->sk_write_space(sk);
 248         return rc;
 249 }
 250
 251 /***************************** sndbuf consumer *******************************/
 252
 253 /* sndbuf consumer: actual data transfer of one target chunk with RDMA write */
 254 static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
 255                              int num_sges, struct ib_sge sges[])
 256 {
 257         struct smc_link_group *lgr = conn->lgr;
 258         struct ib_send_wr *failed_wr = NULL;
 259         struct ib_rdma_wr rdma_wr;
 260         struct smc_link *link;
 261         int rc;
 262
 263         memset(&rdma_wr, 0, sizeof(rdma_wr));
 264         link = &lgr->lnk[SMC_SINGLE_LINK];
 265         rdma_wr.wr.wr_id = smc_wr_tx_get_next_wr_id(link);
 266         rdma_wr.wr.sg_list = sges;
 267         rdma_wr.wr.num_sge = num_sges;
 268         rdma_wr.wr.opcode = IB_WR_RDMA_WRITE;
 269         rdma_wr.remote_addr =
 270                 lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr +
 271                 /* RMBE within RMB */
 272                 conn->tx_off +
 273                 /* offset within RMBE */
 274                 peer_rmbe_offset;
 275         rdma_wr.rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey;
 276         rc = ib_post_send(link->roce_qp, &rdma_wr.wr, &failed_wr);
 277         if (rc) {
 278                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 279                 smc_lgr_terminate(lgr);
 280         }
 281         return rc;
 282 }
 283
 284 /* sndbuf consumer */
 285 static inline void smc_tx_advance_cursors(struct smc_connection *conn,
 286                                           union smc_host_cursor *prod,
 287                                           union smc_host_cursor *sent,
 288                                           size_t len)
 289 {
 290         smc_curs_add(conn->peer_rmbe_size, prod, len);
 291         /* increased in recv tasklet smc_cdc_msg_rcv() */
 292         smp_mb__before_atomic();
 293         /* data in flight reduces usable snd_wnd */
 294         atomic_sub(len, &conn->peer_rmbe_space);
 295         /* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
 296         smp_mb__after_atomic();
 297         smc_curs_add(conn->sndbuf_desc->len, sent, len);
 298 }
 299
 300 /* sndbuf consumer: prepare all necessary (src&dst) chunks of data transmit;
 301  * usable snd_wnd as max transmit
 302  */
 303 static int smc_tx_rdma_writes(struct smc_connection *conn)
 304 {
 305         size_t src_off, src_len, dst_off, dst_len; /* current chunk values */
 306         size_t len, dst_len_sum, src_len_sum, dstchunk, srcchunk;
 307         union smc_host_cursor sent, prep, prod, cons;
 308         struct ib_sge sges[SMC_IB_MAX_SEND_SGE];
 309         struct smc_link_group *lgr = conn->lgr;
 310         struct smc_cdc_producer_flags *pflags;
 311         int to_send, rmbespace;
 312         struct smc_link *link;
 313         dma_addr_t dma_addr;
 314         int num_sges;
 315         int rc;
 316
 317         /* source: sndbuf */
 318         smc_curs_write(&sent, smc_curs_read(&conn->tx_curs_sent, conn), conn);
 319         smc_curs_write(&prep, smc_curs_read(&conn->tx_curs_prep, conn), conn);
 320         /* cf. wmem_alloc - (snd_max - snd_una) */
 321         to_send = smc_curs_diff(conn->sndbuf_desc->len, &sent, &prep);
 322         if (to_send <= 0)
 323                 return 0;
 324
 325         /* destination: RMBE */
 326         /* cf. snd_wnd */
 327         rmbespace = atomic_read(&conn->peer_rmbe_space);
 328         if (rmbespace <= 0)
 329                 return 0;
 330         smc_curs_write(&prod,
 331                        smc_curs_read(&conn->local_tx_ctrl.prod, conn),
 332                        conn);
 333         smc_curs_write(&cons,
 334                        smc_curs_read(&conn->local_rx_ctrl.cons, conn),
 335                        conn);
 336
 337         /* if usable snd_wnd closes ask peer to advertise once it opens again */
 338         pflags = &conn->local_tx_ctrl.prod_flags;
 339         pflags->write_blocked = (to_send >= rmbespace);
 340         /* cf. usable snd_wnd */
 341         len = min(to_send, rmbespace);
 342
 343         /* initialize variables for first iteration of subsequent nested loop */
 344         link = &lgr->lnk[SMC_SINGLE_LINK];
 345         dst_off = prod.count;
 346         if (prod.wrap == cons.wrap) {
 347                 /* the filled destination area is unwrapped,
 348                  * hence the available free destination space is wrapped
 349                  * and we need 2 destination chunks of sum len; start with 1st
 350                  * which is limited by what's available in sndbuf
 351                  */
 352                 dst_len = min_t(size_t,
 353                                 conn->peer_rmbe_size - prod.count, len);
 354         } else {
 355                 /* the filled destination area is wrapped,
 356                  * hence the available free destination space is unwrapped
 357                  * and we need a single destination chunk of entire len
 358                  */
 359                 dst_len = len;
 360         }
 361         dst_len_sum = dst_len;
 362         src_off = sent.count;
 363         /* dst_len determines the maximum src_len */
 364         if (sent.count + dst_len <= conn->sndbuf_desc->len) {
 365                 /* unwrapped src case: single chunk of entire dst_len */
 366                 src_len = dst_len;
 367         } else {
 368                 /* wrapped src case: 2 chunks of sum dst_len; start with 1st: */
 369                 src_len = conn->sndbuf_desc->len - sent.count;
 370         }
 371         src_len_sum = src_len;
 372         dma_addr = sg_dma_address(conn->sndbuf_desc->sgt[SMC_SINGLE_LINK].sgl);
 373         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 374                 num_sges = 0;
 375                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 376                         sges[srcchunk].addr = dma_addr + src_off;
 377                         sges[srcchunk].length = src_len;
 378                         sges[srcchunk].lkey = link->roce_pd->local_dma_lkey;
 379                         num_sges++;
 380                         src_off += src_len;
 381                         if (src_off >= conn->sndbuf_desc->len)
 382                                 src_off -= conn->sndbuf_desc->len;
 383                                                 /* modulo in send ring */
 384                         if (src_len_sum == dst_len)
 385                                 break; /* either on 1st or 2nd iteration */
 386                         /* prepare next (== 2nd) iteration */
 387                         src_len = dst_len - src_len; /* remainder */
 388                         src_len_sum += src_len;
 389                 }
 390                 rc = smc_tx_rdma_write(conn, dst_off, num_sges, sges);
 391                 if (rc)
 392                         return rc;
 393                 if (dst_len_sum == len)
 394                         break; /* either on 1st or 2nd iteration */
 395                 /* prepare next (== 2nd) iteration */
 396                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 397                 dst_len = len - dst_len; /* remainder */
 398                 dst_len_sum += dst_len;
 399                 src_len = min_t(int,
 400                                 dst_len, conn->sndbuf_desc->len - sent.count);
 401                 src_len_sum = src_len;
 402         }
 403
 404         if (conn->urg_tx_pend && len == to_send)
 405                 pflags->urg_data_present = 1;
 406         smc_tx_advance_cursors(conn, &prod, &sent, len);
 407         /* update connection's cursors with advanced local cursors */
 408         smc_curs_write(&conn->local_tx_ctrl.prod,
 409                        smc_curs_read(&prod, conn),
 410                        conn);
 411                                                         /* dst: peer RMBE */
 412         smc_curs_write(&conn->tx_curs_sent,
 413                        smc_curs_read(&sent, conn),
 414                        conn);
 415                                                         /* src: local sndbuf */
 416
 417         return 0;
 418 }
 419
 420 /* Wakeup sndbuf consumers from any context (IRQ or process)
 421  * since there is more data to transmit; usable snd_wnd as max transmit
 422  */
 423 int smc_tx_sndbuf_nonempty(struct smc_connection *conn)
 424 {
 425         struct smc_cdc_producer_flags *pflags;
 426         struct smc_cdc_tx_pend *pend;
 427         struct smc_wr_buf *wr_buf;
 428         int rc;
 429
 430         spin_lock_bh(&conn->send_lock);
 431         rc = smc_cdc_get_free_slot(conn, &wr_buf, &pend);
 432         if (rc < 0) {
 433                 if (rc == -EBUSY) {
 434                         struct smc_sock *smc =
 435                                 container_of(conn, struct smc_sock, conn);
 436
 437                         if (smc->sk.sk_err == ECONNABORTED) {
 438                                 rc = sock_error(&smc->sk);
 439                                 goto out_unlock;
 440                         }
 441                         rc = 0;
 442                         if (conn->alert_token_local) /* connection healthy */
 443                                 mod_delayed_work(system_wq, &conn->tx_work,
 444                                                  SMC_TX_WORK_DELAY);
 445                 }
 446                 goto out_unlock;
 447         }
 448
 449         if (!conn->local_tx_ctrl.prod_flags.urg_data_present) {
 450                 rc = smc_tx_rdma_writes(conn);
 451                 if (rc) {
 452                         smc_wr_tx_put_slot(&conn->lgr->lnk[SMC_SINGLE_LINK],
 453                                            (struct smc_wr_tx_pend_priv *)pend);
 454                         goto out_unlock;
 455                 }
 456         }
 457
 458         rc = smc_cdc_msg_send(conn, wr_buf, pend);
 459         pflags = &conn->local_tx_ctrl.prod_flags;
 460         if (!rc && pflags->urg_data_present) {
 461                 pflags->urg_data_pending = 0;
 462                 pflags->urg_data_present = 0;
 463         }
 464
 465 out_unlock:
 466         spin_unlock_bh(&conn->send_lock);
 467         return rc;
 468 }
 469
 470 /* Wakeup sndbuf consumers from process context
 471  * since there is more data to transmit
 472  */
 473 void smc_tx_work(struct work_struct *work)
 474 {
 475         struct smc_connection *conn = container_of(to_delayed_work(work),
 476                                                    struct smc_connection,
 477                                                    tx_work);
 478         struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
 479         int rc;
 480
 481         lock_sock(&smc->sk);
 482         if (smc->sk.sk_err ||
 483             !conn->alert_token_local ||
 484             conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
 485                 goto out;
 486
 487         rc = smc_tx_sndbuf_nonempty(conn);
 488         if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked &&
 489             !atomic_read(&conn->bytes_to_rcv))
 490                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 491
 492 out:
 493         release_sock(&smc->sk);
 494 }
 495
 496 void smc_tx_consumer_update(struct smc_connection *conn, bool force)
 497 {
 498         union smc_host_cursor cfed, cons, prod;
 499         int sender_free = conn->rmb_desc->len;
 500         int to_confirm;
 501
 502         smc_curs_write(&cons,
 503                        smc_curs_read(&conn->local_tx_ctrl.cons, conn),
 504                        conn);
 505         smc_curs_write(&cfed,
 506                        smc_curs_read(&conn->rx_curs_confirmed, conn),
 507                        conn);
 508         to_confirm = smc_curs_diff(conn->rmb_desc->len, &cfed, &cons);
 509         if (to_confirm > conn->rmbe_update_limit) {
 510                 smc_curs_write(&prod,
 511                                smc_curs_read(&conn->local_rx_ctrl.prod, conn),
 512                                conn);
 513                 sender_free = conn->rmb_desc->len -
 514                               smc_curs_diff(conn->rmb_desc->len, &prod, &cfed);
 515         }
 516
 517         if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
 518             force ||
 519             ((to_confirm > conn->rmbe_update_limit) &&
 520              ((sender_free <= (conn->rmb_desc->len / 2)) ||
 521               conn->local_rx_ctrl.prod_flags.write_blocked))) {
 522                 if ((smc_cdc_get_slot_and_msg_send(conn) < 0) &&
 523                     conn->alert_token_local) { /* connection healthy */
 524                         schedule_delayed_work(&conn->tx_work,
 525                                               SMC_TX_WORK_DELAY);
 526                         return;
 527                 }
 528                 smc_curs_write(&conn->rx_curs_confirmed,
 529                                smc_curs_read(&conn->local_tx_ctrl.cons, conn),
 530                                conn);
 531                 conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0;
 532         }
 533         if (conn->local_rx_ctrl.prod_flags.write_blocked &&
 534             !atomic_read(&conn->bytes_to_rcv))
 535                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 536 }
 537
 538 /***************************** send initialize *******************************/
 539
 540 /* Initialize send properties on connection establishment. NB: not __init! */
 541 void smc_tx_init(struct smc_sock *smc)
 542 {
 543         smc->sk.sk_write_space = smc_tx_write_space;
 544 }