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