LXR linux/net/smc/smc

   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 */
  36static 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                                                   EPOLLOUT | EPOLLWRNORM |
  50                                                   EPOLLWRBAND);
  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 */
  60void 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 */
  68static 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 (smc_cdc_rxed_any_close(conn)) {
  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_wait_event(sk, &timeo,
 108                              sk->sk_err ||
 109                              (sk->sk_shutdown & SEND_SHUTDOWN) ||
 110                              smc_cdc_rxed_any_close(conn) ||
 111                              atomic_read(&conn->sndbuf_space),
 112                              &wait);
 113        }
 114        remove_wait_queue(sk_sleep(sk), &wait);
 115        return rc;
 116}
 117
 118/* sndbuf producer: main API called by socket layer.
 119 * called under sock lock.
 120 */
 121int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
 122{
 123        size_t copylen, send_done = 0, send_remaining = len;
 124        size_t chunk_len, chunk_off, chunk_len_sum;
 125        struct smc_connection *conn = &smc->conn;
 126        union smc_host_cursor prep;
 127        struct sock *sk = &smc->sk;
 128        char *sndbuf_base;
 129        int tx_cnt_prep;
 130        int writespace;
 131        int rc, chunk;
 132
 133        /* This should be in poll */
 134        sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 135
 136        if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
 137                rc = -EPIPE;
 138                goto out_err;
 139        }
 140
 141        while (msg_data_left(msg)) {
 142                if (sk->sk_state == SMC_INIT)
 143                        return -ENOTCONN;
 144                if (smc->sk.sk_shutdown & SEND_SHUTDOWN ||
 145                    (smc->sk.sk_err == ECONNABORTED) ||
 146                    conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
 147                        return -EPIPE;
 148                if (smc_cdc_rxed_any_close(conn))
 149                        return send_done ?: -ECONNRESET;
 150
 151                if (!atomic_read(&conn->sndbuf_space)) {
 152                        rc = smc_tx_wait_memory(smc, msg->msg_flags);
 153                        if (rc) {
 154                                if (send_done)
 155                                        return send_done;
 156                                goto out_err;
 157                        }
 158                        continue;
 159                }
 160
 161                /* initialize variables for 1st iteration of subsequent loop */
 162                /* could be just 1 byte, even after smc_tx_wait_memory above */
 163                writespace = atomic_read(&conn->sndbuf_space);
 164                /* not more than what user space asked for */
 165                copylen = min_t(size_t, send_remaining, writespace);
 166                /* determine start of sndbuf */
 167                sndbuf_base = conn->sndbuf_desc->cpu_addr;
 168                smc_curs_write(&prep,
 169                               smc_curs_read(&conn->tx_curs_prep, conn),
 170                               conn);
 171                tx_cnt_prep = prep.count;
 172                /* determine chunks where to write into sndbuf */
 173                /* either unwrapped case, or 1st chunk of wrapped case */
 174                chunk_len = min_t(size_t,
 175                                  copylen, conn->sndbuf_size - tx_cnt_prep);
 176                chunk_len_sum = chunk_len;
 177                chunk_off = tx_cnt_prep;
 178                smc_sndbuf_sync_sg_for_cpu(conn);
 179                for (chunk = 0; chunk < 2; chunk++) {
 180                        rc = memcpy_from_msg(sndbuf_base + chunk_off,
 181                                             msg, chunk_len);
 182                        if (rc) {
 183                                smc_sndbuf_sync_sg_for_device(conn);
 184                                if (send_done)
 185                                        return send_done;
 186                                goto out_err;
 187                        }
 188                        send_done += chunk_len;
 189                        send_remaining -= chunk_len;
 190
 191                        if (chunk_len_sum == copylen)
 192                                break; /* either on 1st or 2nd iteration */
 193                        /* prepare next (== 2nd) iteration */
 194                        chunk_len = copylen - chunk_len; /* remainder */
 195                        chunk_len_sum += chunk_len;
 196                        chunk_off = 0; /* modulo offset in send ring buffer */
 197                }
 198                smc_sndbuf_sync_sg_for_device(conn);
 199                /* update cursors */
 200                smc_curs_add(conn->sndbuf_size, &prep, copylen);
 201                smc_curs_write(&conn->tx_curs_prep,
 202                               smc_curs_read(&prep, conn),
 203                               conn);
 204                /* increased in send tasklet smc_cdc_tx_handler() */
 205                smp_mb__before_atomic();
 206                atomic_sub(copylen, &conn->sndbuf_space);
 207                /* guarantee 0 <= sndbuf_space <= sndbuf_size */
 208                smp_mb__after_atomic();
 209                /* since we just produced more new data into sndbuf,
 210                 * trigger sndbuf consumer: RDMA write into peer RMBE and CDC
 211                 */
 212                smc_tx_sndbuf_nonempty(conn);
 213        } /* while (msg_data_left(msg)) */
 214
 215        return send_done;
 216
 217out_err:
 218        rc = sk_stream_error(sk, msg->msg_flags, rc);
 219        /* make sure we wake any epoll edge trigger waiter */
 220        if (unlikely(rc == -EAGAIN))
 221                sk->sk_write_space(sk);
 222        return rc;
 223}
 224
 225/***************************** sndbuf consumer *******************************/
 226
 227/* sndbuf consumer: actual data transfer of one target chunk with RDMA write */
 228static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
 229                             int num_sges, struct ib_sge sges[])
 230{
 231        struct smc_link_group *lgr = conn->lgr;
 232        struct ib_send_wr *failed_wr = NULL;
 233        struct ib_rdma_wr rdma_wr;
 234        struct smc_link *link;
 235        int rc;
 236
 237        memset(&rdma_wr, 0, sizeof(rdma_wr));
 238        link = &lgr->lnk[SMC_SINGLE_LINK];
 239        rdma_wr.wr.wr_id = smc_wr_tx_get_next_wr_id(link);
 240        rdma_wr.wr.sg_list = sges;
 241        rdma_wr.wr.num_sge = num_sges;
 242        rdma_wr.wr.opcode = IB_WR_RDMA_WRITE;
 243        rdma_wr.remote_addr =
 244                lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr +
 245                /* RMBE within RMB */
 246                ((conn->peer_conn_idx - 1) * conn->peer_rmbe_size) +
 247                /* offset within RMBE */
 248                peer_rmbe_offset;
 249        rdma_wr.rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey;
 250        rc = ib_post_send(link->roce_qp, &rdma_wr.wr, &failed_wr);
 251        if (rc) {
 252                conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 253                smc_lgr_terminate(lgr);
 254        }
 255        return rc;
 256}
 257
 258/* sndbuf consumer */
 259static 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 */
 277static 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 */
 393int 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                        if (conn->alert_token_local) /* connection healthy */
 412                                schedule_delayed_work(&conn->tx_work,
 413                                                      SMC_TX_WORK_DELAY);
 414                }
 415                goto out_unlock;
 416        }
 417
 418        rc = smc_tx_rdma_writes(conn);
 419        if (rc) {
 420                smc_wr_tx_put_slot(&conn->lgr->lnk[SMC_SINGLE_LINK],
 421                                   (struct smc_wr_tx_pend_priv *)pend);
 422                goto out_unlock;
 423        }
 424
 425        rc = smc_cdc_msg_send(conn, wr_buf, pend);
 426
 427out_unlock:
 428        spin_unlock_bh(&conn->send_lock);
 429        return rc;
 430}
 431
 432/* Wakeup sndbuf consumers from process context
 433 * since there is more data to transmit
 434 */
 435static void smc_tx_work(struct work_struct *work)
 436{
 437        struct smc_connection *conn = container_of(to_delayed_work(work),
 438                                                   struct smc_connection,
 439                                                   tx_work);
 440        struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
 441        int rc;
 442
 443        lock_sock(&smc->sk);
 444        if (smc->sk.sk_err ||
 445            !conn->alert_token_local ||
 446            conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
 447                goto out;
 448
 449        rc = smc_tx_sndbuf_nonempty(conn);
 450        if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked &&
 451            !atomic_read(&conn->bytes_to_rcv))
 452                conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 453
 454out:
 455        release_sock(&smc->sk);
 456}
 457
 458void smc_tx_consumer_update(struct smc_connection *conn)
 459{
 460        union smc_host_cursor cfed, cons;
 461        int to_confirm;
 462
 463        smc_curs_write(&cons,
 464                       smc_curs_read(&conn->local_tx_ctrl.cons, conn),
 465                       conn);
 466        smc_curs_write(&cfed,
 467                       smc_curs_read(&conn->rx_curs_confirmed, conn),
 468                       conn);
 469        to_confirm = smc_curs_diff(conn->rmbe_size, &cfed, &cons);
 470
 471        if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
 472            ((to_confirm > conn->rmbe_update_limit) &&
 473             ((to_confirm > (conn->rmbe_size / 2)) ||
 474              conn->local_rx_ctrl.prod_flags.write_blocked))) {
 475                if ((smc_cdc_get_slot_and_msg_send(conn) < 0) &&
 476                    conn->alert_token_local) { /* connection healthy */
 477                        schedule_delayed_work(&conn->tx_work,
 478                                              SMC_TX_WORK_DELAY);
 479                        return;
 480                }
 481                smc_curs_write(&conn->rx_curs_confirmed,
 482                               smc_curs_read(&conn->local_tx_ctrl.cons, conn),
 483                               conn);
 484                conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0;
 485        }
 486        if (conn->local_rx_ctrl.prod_flags.write_blocked &&
 487            !atomic_read(&conn->bytes_to_rcv))
 488                conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 489}
 490
 491/***************************** send initialize *******************************/
 492
 493/* Initialize send properties on connection establishment. NB: not __init! */
 494void smc_tx_init(struct smc_sock *smc)
 495{
 496        smc->sk.sk_write_space = smc_tx_write_space;
 497        INIT_DELAYED_WORK(&smc->conn.tx_work, smc_tx_work);
 498        spin_lock_init(&smc->conn.send_lock);
 499}
 500