net/smc/smc_tx.c

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