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_close.h"
  28 #include "smc_ism.h"
  29 #include "smc_tx.h"
  30
  31 #define SMC_TX_WORK_DELAY       0
  32 #define SMC_TX_CORK_DELAY       (HZ >> 2)       /* 250 ms */
  33
  34 /***************************** sndbuf producer *******************************/
  35
  36 /* callback implementation for sk.sk_write_space()
  37  * to wakeup sndbuf producers that blocked with smc_tx_wait().
  38  * called under sk_socket lock.
  39  */
  40 static void smc_tx_write_space(struct sock *sk)
  41 {
  42         struct socket *sock = sk->sk_socket;
  43         struct smc_sock *smc = smc_sk(sk);
  44         struct socket_wq *wq;
  45
  46         /* similar to sk_stream_write_space */
  47         if (atomic_read(&smc->conn.sndbuf_space) && sock) {
  48                 clear_bit(SOCK_NOSPACE, &sock->flags);
  49                 rcu_read_lock();
  50                 wq = rcu_dereference(sk->sk_wq);
  51                 if (skwq_has_sleeper(wq))
  52                         wake_up_interruptible_poll(&wq->wait,
  53                                                    EPOLLOUT | EPOLLWRNORM |
  54                                                    EPOLLWRBAND);
  55                 if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  56                         sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
  57                 rcu_read_unlock();
  58         }
  59 }
  60
  61 /* Wakeup sndbuf producers that blocked with smc_tx_wait().
  62  * Cf. tcp_data_snd_check()=>tcp_check_space()=>tcp_new_space().
  63  */
  64 void smc_tx_sndbuf_nonfull(struct smc_sock *smc)
  65 {
  66         if (smc->sk.sk_socket &&
  67             test_bit(SOCK_NOSPACE, &smc->sk.sk_socket->flags))
  68                 smc->sk.sk_write_space(&smc->sk);
  69 }
  70
  71 /* blocks sndbuf producer until at least one byte of free space available
  72  * or urgent Byte was consumed
  73  */
  74 static int smc_tx_wait(struct smc_sock *smc, int flags)
  75 {
  76         DEFINE_WAIT_FUNC(wait, woken_wake_function);
  77         struct smc_connection *conn = &smc->conn;
  78         struct sock *sk = &smc->sk;
  79         long timeo;
  80         int rc = 0;
  81
  82         /* similar to sk_stream_wait_memory */
  83         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
  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->killed ||
  90                     conn->local_tx_ctrl.conn_state_flags.peer_done_writing) {
  91                         rc = -EPIPE;
  92                         break;
  93                 }
  94                 if (smc_cdc_rxed_any_close(conn)) {
  95                         rc = -ECONNRESET;
  96                         break;
  97                 }
  98                 if (!timeo) {
  99                         /* ensure EPOLLOUT is subsequently generated */
 100                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 101                         rc = -EAGAIN;
 102                         break;
 103                 }
 104                 if (signal_pending(current)) {
 105                         rc = sock_intr_errno(timeo);
 106                         break;
 107                 }
 108                 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 109                 if (atomic_read(&conn->sndbuf_space) && !conn->urg_tx_pend)
 110                         break; /* at least 1 byte of free & no urgent data */
 111                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 112                 sk_wait_event(sk, &timeo,
 113                               sk->sk_err ||
 114                               (sk->sk_shutdown & SEND_SHUTDOWN) ||
 115                               smc_cdc_rxed_any_close(conn) ||
 116                               (atomic_read(&conn->sndbuf_space) &&
 117                                !conn->urg_tx_pend),
 118                               &wait);
 119         }
 120         remove_wait_queue(sk_sleep(sk), &wait);
 121         return rc;
 122 }
 123
 124 static bool smc_tx_is_corked(struct smc_sock *smc)
 125 {
 126         struct tcp_sock *tp = tcp_sk(smc->clcsock->sk);
 127
 128         return (tp->nonagle & TCP_NAGLE_CORK) ? true : false;
 129 }
 130
 131 /* sndbuf producer: main API called by socket layer.
 132  * called under sock lock.
 133  */
 134 int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
 135 {
 136         size_t copylen, send_done = 0, send_remaining = len;
 137         size_t chunk_len, chunk_off, chunk_len_sum;
 138         struct smc_connection *conn = &smc->conn;
 139         union smc_host_cursor prep;
 140         struct sock *sk = &smc->sk;
 141         char *sndbuf_base;
 142         int tx_cnt_prep;
 143         int writespace;
 144         int rc, chunk;
 145
 146         /* This should be in poll */
 147         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 148
 149         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
 150                 rc = -EPIPE;
 151                 goto out_err;
 152         }
 153
 154         while (msg_data_left(msg)) {
 155                 if (sk->sk_state == SMC_INIT)
 156                         return -ENOTCONN;
 157                 if (smc->sk.sk_shutdown & SEND_SHUTDOWN ||
 158                     (smc->sk.sk_err == ECONNABORTED) ||
 159                     conn->killed)
 160                         return -EPIPE;
 161                 if (smc_cdc_rxed_any_close(conn))
 162                         return send_done ?: -ECONNRESET;
 163
 164                 if (msg->msg_flags & MSG_OOB)
 165                         conn->local_tx_ctrl.prod_flags.urg_data_pending = 1;
 166
 167                 if (!atomic_read(&conn->sndbuf_space) || conn->urg_tx_pend) {
 168                         if (send_done)
 169                                 return send_done;
 170                         rc = smc_tx_wait(smc, msg->msg_flags);
 171                         if (rc)
 172                                 goto out_err;
 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_copy(&prep, &conn->tx_curs_prep, conn);
 184                 tx_cnt_prep = prep.count;
 185                 /* determine chunks where to write into sndbuf */
 186                 /* either unwrapped case, or 1st chunk of wrapped case */
 187                 chunk_len = min_t(size_t, copylen, conn->sndbuf_desc->len -
 188                                   tx_cnt_prep);
 189                 chunk_len_sum = chunk_len;
 190                 chunk_off = tx_cnt_prep;
 191                 smc_sndbuf_sync_sg_for_cpu(conn);
 192                 for (chunk = 0; chunk < 2; chunk++) {
 193                         rc = memcpy_from_msg(sndbuf_base + chunk_off,
 194                                              msg, chunk_len);
 195                         if (rc) {
 196                                 smc_sndbuf_sync_sg_for_device(conn);
 197                                 if (send_done)
 198                                         return send_done;
 199                                 goto out_err;
 200                         }
 201                         send_done += chunk_len;
 202                         send_remaining -= chunk_len;
 203
 204                         if (chunk_len_sum == copylen)
 205                                 break; /* either on 1st or 2nd iteration */
 206                         /* prepare next (== 2nd) iteration */
 207                         chunk_len = copylen - chunk_len; /* remainder */
 208                         chunk_len_sum += chunk_len;
 209                         chunk_off = 0; /* modulo offset in send ring buffer */
 210                 }
 211                 smc_sndbuf_sync_sg_for_device(conn);
 212                 /* update cursors */
 213                 smc_curs_add(conn->sndbuf_desc->len, &prep, copylen);
 214                 smc_curs_copy(&conn->tx_curs_prep, &prep, conn);
 215                 /* increased in send tasklet smc_cdc_tx_handler() */
 216                 smp_mb__before_atomic();
 217                 atomic_sub(copylen, &conn->sndbuf_space);
 218                 /* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
 219                 smp_mb__after_atomic();
 220                 /* since we just produced more new data into sndbuf,
 221                  * trigger sndbuf consumer: RDMA write into peer RMBE and CDC
 222                  */
 223                 if ((msg->msg_flags & MSG_OOB) && !send_remaining)
 224                         conn->urg_tx_pend = true;
 225                 if ((msg->msg_flags & MSG_MORE || smc_tx_is_corked(smc)) &&
 226                     (atomic_read(&conn->sndbuf_space) >
 227                                                 (conn->sndbuf_desc->len >> 1)))
 228                         /* for a corked socket defer the RDMA writes if there
 229                          * is still sufficient sndbuf_space available
 230                          */
 231                         schedule_delayed_work(&conn->tx_work,
 232                                               SMC_TX_CORK_DELAY);
 233                 else
 234                         smc_tx_sndbuf_nonempty(conn);
 235         } /* while (msg_data_left(msg)) */
 236
 237         return send_done;
 238
 239 out_err:
 240         rc = sk_stream_error(sk, msg->msg_flags, rc);
 241         /* make sure we wake any epoll edge trigger waiter */
 242         if (unlikely(rc == -EAGAIN))
 243                 sk->sk_write_space(sk);
 244         return rc;
 245 }
 246
 247 /***************************** sndbuf consumer *******************************/
 248
 249 /* sndbuf consumer: actual data transfer of one target chunk with ISM write */
 250 int smcd_tx_ism_write(struct smc_connection *conn, void *data, size_t len,
 251                       u32 offset, int signal)
 252 {
 253         struct smc_ism_position pos;
 254         int rc;
 255
 256         memset(&pos, 0, sizeof(pos));
 257         pos.token = conn->peer_token;
 258         pos.index = conn->peer_rmbe_idx;
 259         pos.offset = conn->tx_off + offset;
 260         pos.signal = signal;
 261         rc = smc_ism_write(conn->lgr->smcd, &pos, data, len);
 262         if (rc)
 263                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 264         return rc;
 265 }
 266
 267 /* sndbuf consumer: actual data transfer of one target chunk with RDMA write */
 268 static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
 269                              int num_sges, struct ib_rdma_wr *rdma_wr)
 270 {
 271         struct smc_link_group *lgr = conn->lgr;
 272         struct smc_link *link;
 273         int rc;
 274
 275         link = &lgr->lnk[SMC_SINGLE_LINK];
 276         rdma_wr->wr.wr_id = smc_wr_tx_get_next_wr_id(link);
 277         rdma_wr->wr.num_sge = num_sges;
 278         rdma_wr->remote_addr =
 279                 lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr +
 280                 /* RMBE within RMB */
 281                 conn->tx_off +
 282                 /* offset within RMBE */
 283                 peer_rmbe_offset;
 284         rdma_wr->rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey;
 285         rc = ib_post_send(link->roce_qp, &rdma_wr->wr, NULL);
 286         if (rc)
 287                 smc_lgr_terminate(lgr, true);
 288         return rc;
 289 }
 290
 291 /* sndbuf consumer */
 292 static inline void smc_tx_advance_cursors(struct smc_connection *conn,
 293                                           union smc_host_cursor *prod,
 294                                           union smc_host_cursor *sent,
 295                                           size_t len)
 296 {
 297         smc_curs_add(conn->peer_rmbe_size, prod, len);
 298         /* increased in recv tasklet smc_cdc_msg_rcv() */
 299         smp_mb__before_atomic();
 300         /* data in flight reduces usable snd_wnd */
 301         atomic_sub(len, &conn->peer_rmbe_space);
 302         /* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
 303         smp_mb__after_atomic();
 304         smc_curs_add(conn->sndbuf_desc->len, sent, len);
 305 }
 306
 307 /* SMC-R helper for smc_tx_rdma_writes() */
 308 static int smcr_tx_rdma_writes(struct smc_connection *conn, size_t len,
 309                                size_t src_off, size_t src_len,
 310                                size_t dst_off, size_t dst_len,
 311                                struct smc_rdma_wr *wr_rdma_buf)
 312 {
 313         dma_addr_t dma_addr =
 314                 sg_dma_address(conn->sndbuf_desc->sgt[SMC_SINGLE_LINK].sgl);
 315         int src_len_sum = src_len, dst_len_sum = dst_len;
 316         int sent_count = src_off;
 317         int srcchunk, dstchunk;
 318         int num_sges;
 319         int rc;
 320
 321         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 322                 struct ib_sge *sge =
 323                         wr_rdma_buf->wr_tx_rdma[dstchunk].wr.sg_list;
 324
 325                 num_sges = 0;
 326                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 327                         sge[srcchunk].addr = dma_addr + src_off;
 328                         sge[srcchunk].length = src_len;
 329                         num_sges++;
 330
 331                         src_off += src_len;
 332                         if (src_off >= conn->sndbuf_desc->len)
 333                                 src_off -= conn->sndbuf_desc->len;
 334                                                 /* modulo in send ring */
 335                         if (src_len_sum == dst_len)
 336                                 break; /* either on 1st or 2nd iteration */
 337                         /* prepare next (== 2nd) iteration */
 338                         src_len = dst_len - src_len; /* remainder */
 339                         src_len_sum += src_len;
 340                 }
 341                 rc = smc_tx_rdma_write(conn, dst_off, num_sges,
 342                                        &wr_rdma_buf->wr_tx_rdma[dstchunk]);
 343                 if (rc)
 344                         return rc;
 345                 if (dst_len_sum == len)
 346                         break; /* either on 1st or 2nd iteration */
 347                 /* prepare next (== 2nd) iteration */
 348                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 349                 dst_len = len - dst_len; /* remainder */
 350                 dst_len_sum += dst_len;
 351                 src_len = min_t(int, dst_len, conn->sndbuf_desc->len -
 352                                 sent_count);
 353                 src_len_sum = src_len;
 354         }
 355         return 0;
 356 }
 357
 358 /* SMC-D helper for smc_tx_rdma_writes() */
 359 static int smcd_tx_rdma_writes(struct smc_connection *conn, size_t len,
 360                                size_t src_off, size_t src_len,
 361                                size_t dst_off, size_t dst_len)
 362 {
 363         int src_len_sum = src_len, dst_len_sum = dst_len;
 364         int srcchunk, dstchunk;
 365         int rc;
 366
 367         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 368                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 369                         void *data = conn->sndbuf_desc->cpu_addr + src_off;
 370
 371                         rc = smcd_tx_ism_write(conn, data, src_len, dst_off +
 372                                                sizeof(struct smcd_cdc_msg), 0);
 373                         if (rc)
 374                                 return rc;
 375                         dst_off += src_len;
 376                         src_off += src_len;
 377                         if (src_off >= conn->sndbuf_desc->len)
 378                                 src_off -= conn->sndbuf_desc->len;
 379                                                 /* modulo in send ring */
 380                         if (src_len_sum == dst_len)
 381                                 break; /* either on 1st or 2nd iteration */
 382                         /* prepare next (== 2nd) iteration */
 383                         src_len = dst_len - src_len; /* remainder */
 384                         src_len_sum += src_len;
 385                 }
 386                 if (dst_len_sum == len)
 387                         break; /* either on 1st or 2nd iteration */
 388                 /* prepare next (== 2nd) iteration */
 389                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 390                 dst_len = len - dst_len; /* remainder */
 391                 dst_len_sum += dst_len;
 392                 src_len = min_t(int, dst_len, conn->sndbuf_desc->len - src_off);
 393                 src_len_sum = src_len;
 394         }
 395         return 0;
 396 }
 397
 398 /* sndbuf consumer: prepare all necessary (src&dst) chunks of data transmit;
 399  * usable snd_wnd as max transmit
 400  */
 401 static int smc_tx_rdma_writes(struct smc_connection *conn,
 402                               struct smc_rdma_wr *wr_rdma_buf)
 403 {
 404         size_t len, src_len, dst_off, dst_len; /* current chunk values */
 405         union smc_host_cursor sent, prep, prod, cons;
 406         struct smc_cdc_producer_flags *pflags;
 407         int to_send, rmbespace;
 408         int rc;
 409
 410         /* source: sndbuf */
 411         smc_curs_copy(&sent, &conn->tx_curs_sent, conn);
 412         smc_curs_copy(&prep, &conn->tx_curs_prep, conn);
 413         /* cf. wmem_alloc - (snd_max - snd_una) */
 414         to_send = smc_curs_diff(conn->sndbuf_desc->len, &sent, &prep);
 415         if (to_send <= 0)
 416                 return 0;
 417
 418         /* destination: RMBE */
 419         /* cf. snd_wnd */
 420         rmbespace = atomic_read(&conn->peer_rmbe_space);
 421         if (rmbespace <= 0)
 422                 return 0;
 423         smc_curs_copy(&prod, &conn->local_tx_ctrl.prod, conn);
 424         smc_curs_copy(&cons, &conn->local_rx_ctrl.cons, conn);
 425
 426         /* if usable snd_wnd closes ask peer to advertise once it opens again */
 427         pflags = &conn->local_tx_ctrl.prod_flags;
 428         pflags->write_blocked = (to_send >= rmbespace);
 429         /* cf. usable snd_wnd */
 430         len = min(to_send, rmbespace);
 431
 432         /* initialize variables for first iteration of subsequent nested loop */
 433         dst_off = prod.count;
 434         if (prod.wrap == cons.wrap) {
 435                 /* the filled destination area is unwrapped,
 436                  * hence the available free destination space is wrapped
 437                  * and we need 2 destination chunks of sum len; start with 1st
 438                  * which is limited by what's available in sndbuf
 439                  */
 440                 dst_len = min_t(size_t,
 441                                 conn->peer_rmbe_size - prod.count, len);
 442         } else {
 443                 /* the filled destination area is wrapped,
 444                  * hence the available free destination space is unwrapped
 445                  * and we need a single destination chunk of entire len
 446                  */
 447                 dst_len = len;
 448         }
 449         /* dst_len determines the maximum src_len */
 450         if (sent.count + dst_len <= conn->sndbuf_desc->len) {
 451                 /* unwrapped src case: single chunk of entire dst_len */
 452                 src_len = dst_len;
 453         } else {
 454                 /* wrapped src case: 2 chunks of sum dst_len; start with 1st: */
 455                 src_len = conn->sndbuf_desc->len - sent.count;
 456         }
 457
 458         if (conn->lgr->is_smcd)
 459                 rc = smcd_tx_rdma_writes(conn, len, sent.count, src_len,
 460                                          dst_off, dst_len);
 461         else
 462                 rc = smcr_tx_rdma_writes(conn, len, sent.count, src_len,
 463                                          dst_off, dst_len, wr_rdma_buf);
 464         if (rc)
 465                 return rc;
 466
 467         if (conn->urg_tx_pend && len == to_send)
 468                 pflags->urg_data_present = 1;
 469         smc_tx_advance_cursors(conn, &prod, &sent, len);
 470         /* update connection's cursors with advanced local cursors */
 471         smc_curs_copy(&conn->local_tx_ctrl.prod, &prod, conn);
 472                                                         /* dst: peer RMBE */
 473         smc_curs_copy(&conn->tx_curs_sent, &sent, conn);/* src: local sndbuf */
 474
 475         return 0;
 476 }
 477
 478 /* Wakeup sndbuf consumers from any context (IRQ or process)
 479  * since there is more data to transmit; usable snd_wnd as max transmit
 480  */
 481 static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
 482 {
 483         struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags;
 484         struct smc_rdma_wr *wr_rdma_buf;
 485         struct smc_cdc_tx_pend *pend;
 486         struct smc_wr_buf *wr_buf;
 487         int rc;
 488
 489         rc = smc_cdc_get_free_slot(conn, &wr_buf, &wr_rdma_buf, &pend);
 490         if (rc < 0) {
 491                 if (rc == -EBUSY) {
 492                         struct smc_sock *smc =
 493                                 container_of(conn, struct smc_sock, conn);
 494
 495                         if (smc->sk.sk_err == ECONNABORTED)
 496                                 return sock_error(&smc->sk);
 497                         if (conn->killed)
 498                                 return -EPIPE;
 499                         rc = 0;
 500                         mod_delayed_work(system_wq, &conn->tx_work,
 501                                          SMC_TX_WORK_DELAY);
 502                 }
 503                 return rc;
 504         }
 505
 506         spin_lock_bh(&conn->send_lock);
 507         if (!pflags->urg_data_present) {
 508                 rc = smc_tx_rdma_writes(conn, wr_rdma_buf);
 509                 if (rc) {
 510                         smc_wr_tx_put_slot(&conn->lgr->lnk[SMC_SINGLE_LINK],
 511                                            (struct smc_wr_tx_pend_priv *)pend);
 512                         goto out_unlock;
 513                 }
 514         }
 515
 516         rc = smc_cdc_msg_send(conn, wr_buf, pend);
 517         if (!rc && pflags->urg_data_present) {
 518                 pflags->urg_data_pending = 0;
 519                 pflags->urg_data_present = 0;
 520         }
 521
 522 out_unlock:
 523         spin_unlock_bh(&conn->send_lock);
 524         return rc;
 525 }
 526
 527 static int smcd_tx_sndbuf_nonempty(struct smc_connection *conn)
 528 {
 529         struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags;
 530         int rc = 0;
 531
 532         spin_lock_bh(&conn->send_lock);
 533         if (!pflags->urg_data_present)
 534                 rc = smc_tx_rdma_writes(conn, NULL);
 535         if (!rc)
 536                 rc = smcd_cdc_msg_send(conn);
 537
 538         if (!rc && pflags->urg_data_present) {
 539                 pflags->urg_data_pending = 0;
 540                 pflags->urg_data_present = 0;
 541         }
 542         spin_unlock_bh(&conn->send_lock);
 543         return rc;
 544 }
 545
 546 int smc_tx_sndbuf_nonempty(struct smc_connection *conn)
 547 {
 548         int rc;
 549
 550         if (conn->killed ||
 551             conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
 552                 return -EPIPE;  /* connection being aborted */
 553         if (conn->lgr->is_smcd)
 554                 rc = smcd_tx_sndbuf_nonempty(conn);
 555         else
 556                 rc = smcr_tx_sndbuf_nonempty(conn);
 557
 558         if (!rc) {
 559                 /* trigger socket release if connection is closing */
 560                 struct smc_sock *smc = container_of(conn, struct smc_sock,
 561                                                     conn);
 562                 smc_close_wake_tx_prepared(smc);
 563         }
 564         return rc;
 565 }
 566
 567 /* Wakeup sndbuf consumers from process context
 568  * since there is more data to transmit
 569  */
 570 void smc_tx_work(struct work_struct *work)
 571 {
 572         struct smc_connection *conn = container_of(to_delayed_work(work),
 573                                                    struct smc_connection,
 574                                                    tx_work);
 575         struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
 576         int rc;
 577
 578         lock_sock(&smc->sk);
 579         if (smc->sk.sk_err)
 580                 goto out;
 581
 582         rc = smc_tx_sndbuf_nonempty(conn);
 583         if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked &&
 584             !atomic_read(&conn->bytes_to_rcv))
 585                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 586
 587 out:
 588         release_sock(&smc->sk);
 589 }
 590
 591 void smc_tx_consumer_update(struct smc_connection *conn, bool force)
 592 {
 593         union smc_host_cursor cfed, cons, prod;
 594         int sender_free = conn->rmb_desc->len;
 595         int to_confirm;
 596
 597         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 598         smc_curs_copy(&cfed, &conn->rx_curs_confirmed, conn);
 599         to_confirm = smc_curs_diff(conn->rmb_desc->len, &cfed, &cons);
 600         if (to_confirm > conn->rmbe_update_limit) {
 601                 smc_curs_copy(&prod, &conn->local_rx_ctrl.prod, conn);
 602                 sender_free = conn->rmb_desc->len -
 603                               smc_curs_diff_large(conn->rmb_desc->len,
 604                                                   &cfed, &prod);
 605         }
 606
 607         if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
 608             force ||
 609             ((to_confirm > conn->rmbe_update_limit) &&
 610              ((sender_free <= (conn->rmb_desc->len / 2)) ||
 611               conn->local_rx_ctrl.prod_flags.write_blocked))) {
 612                 if (conn->killed ||
 613                     conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
 614                         return;
 615                 if ((smc_cdc_get_slot_and_msg_send(conn) < 0) &&
 616                     !conn->killed) {
 617                         schedule_delayed_work(&conn->tx_work,
 618                                               SMC_TX_WORK_DELAY);
 619                         return;
 620                 }
 621         }
 622         if (conn->local_rx_ctrl.prod_flags.write_blocked &&
 623             !atomic_read(&conn->bytes_to_rcv))
 624                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 625 }
 626
 627 /***************************** send initialize *******************************/
 628
 629 /* Initialize send properties on connection establishment. NB: not __init! */
 630 void smc_tx_init(struct smc_sock *smc)
 631 {
 632         smc->sk.sk_write_space = smc_tx_write_space;
 633 }