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_ism.h"
  28 #include "smc_tx.h"
  29
  30 #define SMC_TX_WORK_DELAY       HZ
  31 #define SMC_TX_CORK_DELAY       (HZ >> 2)       /* 250 ms */
  32
  33 /***************************** sndbuf producer *******************************/
  34
  35 /* callback implementation for sk.sk_write_space()
  36  * to wakeup sndbuf producers that blocked with smc_tx_wait().
  37  * called under sk_socket lock.
  38  */
  39 static void smc_tx_write_space(struct sock *sk)
  40 {
  41         struct socket *sock = sk->sk_socket;
  42         struct smc_sock *smc = smc_sk(sk);
  43         struct socket_wq *wq;
  44
  45         /* similar to sk_stream_write_space */
  46         if (atomic_read(&smc->conn.sndbuf_space) && sock) {
  47                 clear_bit(SOCK_NOSPACE, &sock->flags);
  48                 rcu_read_lock();
  49                 wq = rcu_dereference(sk->sk_wq);
  50                 if (skwq_has_sleeper(wq))
  51                         wake_up_interruptible_poll(&wq->wait,
  52                                                    EPOLLOUT | EPOLLWRNORM |
  53                                                    EPOLLWRBAND);
  54                 if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
  55                         sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT);
  56                 rcu_read_unlock();
  57         }
  58 }
  59
  60 /* Wakeup sndbuf producers that blocked with smc_tx_wait().
  61  * Cf. tcp_data_snd_check()=>tcp_check_space()=>tcp_new_space().
  62  */
  63 void smc_tx_sndbuf_nonfull(struct smc_sock *smc)
  64 {
  65         if (smc->sk.sk_socket &&
  66             test_bit(SOCK_NOSPACE, &smc->sk.sk_socket->flags))
  67                 smc->sk.sk_write_space(&smc->sk);
  68 }
  69
  70 /* blocks sndbuf producer until at least one byte of free space available
  71  * or urgent Byte was consumed
  72  */
  73 static int smc_tx_wait(struct smc_sock *smc, int flags)
  74 {
  75         DEFINE_WAIT_FUNC(wait, woken_wake_function);
  76         struct smc_connection *conn = &smc->conn;
  77         struct sock *sk = &smc->sk;
  78         long timeo;
  79         int rc = 0;
  80
  81         /* similar to sk_stream_wait_memory */
  82         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
  83         add_wait_queue(sk_sleep(sk), &wait);
  84         while (1) {
  85                 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
  86                 if (sk->sk_err ||
  87                     (sk->sk_shutdown & SEND_SHUTDOWN) ||
  88                     conn->local_tx_ctrl.conn_state_flags.peer_done_writing) {
  89                         rc = -EPIPE;
  90                         break;
  91                 }
  92                 if (smc_cdc_rxed_any_close(conn)) {
  93                         rc = -ECONNRESET;
  94                         break;
  95                 }
  96                 if (!timeo) {
  97                         /* ensure EPOLLOUT is subsequently generated */
  98                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
  99                         rc = -EAGAIN;
 100                         break;
 101                 }
 102                 if (signal_pending(current)) {
 103                         rc = sock_intr_errno(timeo);
 104                         break;
 105                 }
 106                 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 107                 if (atomic_read(&conn->sndbuf_space) && !conn->urg_tx_pend)
 108                         break; /* at least 1 byte of free & no urgent data */
 109                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 110                 sk_wait_event(sk, &timeo,
 111                               sk->sk_err ||
 112                               (sk->sk_shutdown & SEND_SHUTDOWN) ||
 113                               smc_cdc_rxed_any_close(conn) ||
 114                               (atomic_read(&conn->sndbuf_space) &&
 115                                !conn->urg_tx_pend),
 116                               &wait);
 117         }
 118         remove_wait_queue(sk_sleep(sk), &wait);
 119         return rc;
 120 }
 121
 122 static bool smc_tx_is_corked(struct smc_sock *smc)
 123 {
 124         struct tcp_sock *tp = tcp_sk(smc->clcsock->sk);
 125
 126         return (tp->nonagle & TCP_NAGLE_CORK) ? true : false;
 127 }
 128
 129 /* sndbuf producer: main API called by socket layer.
 130  * called under sock lock.
 131  */
 132 int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
 133 {
 134         size_t copylen, send_done = 0, send_remaining = len;
 135         size_t chunk_len, chunk_off, chunk_len_sum;
 136         struct smc_connection *conn = &smc->conn;
 137         union smc_host_cursor prep;
 138         struct sock *sk = &smc->sk;
 139         char *sndbuf_base;
 140         int tx_cnt_prep;
 141         int writespace;
 142         int rc, chunk;
 143
 144         /* This should be in poll */
 145         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 146
 147         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
 148                 rc = -EPIPE;
 149                 goto out_err;
 150         }
 151
 152         while (msg_data_left(msg)) {
 153                 if (sk->sk_state == SMC_INIT)
 154                         return -ENOTCONN;
 155                 if (smc->sk.sk_shutdown & SEND_SHUTDOWN ||
 156                     (smc->sk.sk_err == ECONNABORTED) ||
 157                     conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
 158                         return -EPIPE;
 159                 if (smc_cdc_rxed_any_close(conn))
 160                         return send_done ?: -ECONNRESET;
 161
 162                 if (msg->msg_flags & MSG_OOB)
 163                         conn->local_tx_ctrl.prod_flags.urg_data_pending = 1;
 164
 165                 if (!atomic_read(&conn->sndbuf_space) || conn->urg_tx_pend) {
 166                         if (send_done)
 167                                 return send_done;
 168                         rc = smc_tx_wait(smc, msg->msg_flags);
 169                         if (rc)
 170                                 goto out_err;
 171                         continue;
 172                 }
 173
 174                 /* initialize variables for 1st iteration of subsequent loop */
 175                 /* could be just 1 byte, even after smc_tx_wait above */
 176                 writespace = atomic_read(&conn->sndbuf_space);
 177                 /* not more than what user space asked for */
 178                 copylen = min_t(size_t, send_remaining, writespace);
 179                 /* determine start of sndbuf */
 180                 sndbuf_base = conn->sndbuf_desc->cpu_addr;
 181                 smc_curs_copy(&prep, &conn->tx_curs_prep, conn);
 182                 tx_cnt_prep = prep.count;
 183                 /* determine chunks where to write into sndbuf */
 184                 /* either unwrapped case, or 1st chunk of wrapped case */
 185                 chunk_len = min_t(size_t, copylen, conn->sndbuf_desc->len -
 186                                   tx_cnt_prep);
 187                 chunk_len_sum = chunk_len;
 188                 chunk_off = tx_cnt_prep;
 189                 smc_sndbuf_sync_sg_for_cpu(conn);
 190                 for (chunk = 0; chunk < 2; chunk++) {
 191                         rc = memcpy_from_msg(sndbuf_base + chunk_off,
 192                                              msg, chunk_len);
 193                         if (rc) {
 194                                 smc_sndbuf_sync_sg_for_device(conn);
 195                                 if (send_done)
 196                                         return send_done;
 197                                 goto out_err;
 198                         }
 199                         send_done += chunk_len;
 200                         send_remaining -= chunk_len;
 201
 202                         if (chunk_len_sum == copylen)
 203                                 break; /* either on 1st or 2nd iteration */
 204                         /* prepare next (== 2nd) iteration */
 205                         chunk_len = copylen - chunk_len; /* remainder */
 206                         chunk_len_sum += chunk_len;
 207                         chunk_off = 0; /* modulo offset in send ring buffer */
 208                 }
 209                 smc_sndbuf_sync_sg_for_device(conn);
 210                 /* update cursors */
 211                 smc_curs_add(conn->sndbuf_desc->len, &prep, copylen);
 212                 smc_curs_copy(&conn->tx_curs_prep, &prep, conn);
 213                 /* increased in send tasklet smc_cdc_tx_handler() */
 214                 smp_mb__before_atomic();
 215                 atomic_sub(copylen, &conn->sndbuf_space);
 216                 /* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
 217                 smp_mb__after_atomic();
 218                 /* since we just produced more new data into sndbuf,
 219                  * trigger sndbuf consumer: RDMA write into peer RMBE and CDC
 220                  */
 221                 if ((msg->msg_flags & MSG_OOB) && !send_remaining)
 222                         conn->urg_tx_pend = true;
 223                 if ((msg->msg_flags & MSG_MORE || smc_tx_is_corked(smc)) &&
 224                     (atomic_read(&conn->sndbuf_space) >
 225                                                 (conn->sndbuf_desc->len >> 1)))
 226                         /* for a corked socket defer the RDMA writes if there
 227                          * is still sufficient sndbuf_space available
 228                          */
 229                         schedule_delayed_work(&conn->tx_work,
 230                                               SMC_TX_CORK_DELAY);
 231                 else
 232                         smc_tx_sndbuf_nonempty(conn);
 233         } /* while (msg_data_left(msg)) */
 234
 235         return send_done;
 236
 237 out_err:
 238         rc = sk_stream_error(sk, msg->msg_flags, rc);
 239         /* make sure we wake any epoll edge trigger waiter */
 240         if (unlikely(rc == -EAGAIN))
 241                 sk->sk_write_space(sk);
 242         return rc;
 243 }
 244
 245 /***************************** sndbuf consumer *******************************/
 246
 247 /* sndbuf consumer: actual data transfer of one target chunk with ISM write */
 248 int smcd_tx_ism_write(struct smc_connection *conn, void *data, size_t len,
 249                       u32 offset, int signal)
 250 {
 251         struct smc_ism_position pos;
 252         int rc;
 253
 254         memset(&pos, 0, sizeof(pos));
 255         pos.token = conn->peer_token;
 256         pos.index = conn->peer_rmbe_idx;
 257         pos.offset = conn->tx_off + offset;
 258         pos.signal = signal;
 259         rc = smc_ism_write(conn->lgr->smcd, &pos, data, len);
 260         if (rc)
 261                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 262         return rc;
 263 }
 264
 265 /* sndbuf consumer: actual data transfer of one target chunk with RDMA write */
 266 static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
 267                              int num_sges, struct ib_sge sges[])
 268 {
 269         struct smc_link_group *lgr = conn->lgr;
 270         struct ib_rdma_wr rdma_wr;
 271         struct smc_link *link;
 272         int rc;
 273
 274         memset(&rdma_wr, 0, sizeof(rdma_wr));
 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.sg_list = sges;
 278         rdma_wr.wr.num_sge = num_sges;
 279         rdma_wr.wr.opcode = IB_WR_RDMA_WRITE;
 280         rdma_wr.remote_addr =
 281                 lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr +
 282                 /* RMBE within RMB */
 283                 conn->tx_off +
 284                 /* offset within RMBE */
 285                 peer_rmbe_offset;
 286         rdma_wr.rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey;
 287         rc = ib_post_send(link->roce_qp, &rdma_wr.wr, NULL);
 288         if (rc) {
 289                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 290                 smc_lgr_terminate(lgr);
 291         }
 292         return rc;
 293 }
 294
 295 /* sndbuf consumer */
 296 static inline void smc_tx_advance_cursors(struct smc_connection *conn,
 297                                           union smc_host_cursor *prod,
 298                                           union smc_host_cursor *sent,
 299                                           size_t len)
 300 {
 301         smc_curs_add(conn->peer_rmbe_size, prod, len);
 302         /* increased in recv tasklet smc_cdc_msg_rcv() */
 303         smp_mb__before_atomic();
 304         /* data in flight reduces usable snd_wnd */
 305         atomic_sub(len, &conn->peer_rmbe_space);
 306         /* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
 307         smp_mb__after_atomic();
 308         smc_curs_add(conn->sndbuf_desc->len, sent, len);
 309 }
 310
 311 /* SMC-R helper for smc_tx_rdma_writes() */
 312 static int smcr_tx_rdma_writes(struct smc_connection *conn, size_t len,
 313                                size_t src_off, size_t src_len,
 314                                size_t dst_off, size_t dst_len)
 315 {
 316         dma_addr_t dma_addr =
 317                 sg_dma_address(conn->sndbuf_desc->sgt[SMC_SINGLE_LINK].sgl);
 318         struct smc_link *link = &conn->lgr->lnk[SMC_SINGLE_LINK];
 319         int src_len_sum = src_len, dst_len_sum = dst_len;
 320         struct ib_sge sges[SMC_IB_MAX_SEND_SGE];
 321         int sent_count = src_off;
 322         int srcchunk, dstchunk;
 323         int num_sges;
 324         int rc;
 325
 326         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 327                 num_sges = 0;
 328                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 329                         sges[srcchunk].addr = dma_addr + src_off;
 330                         sges[srcchunk].length = src_len;
 331                         sges[srcchunk].lkey = link->roce_pd->local_dma_lkey;
 332                         num_sges++;
 333
 334                         src_off += src_len;
 335                         if (src_off >= conn->sndbuf_desc->len)
 336                                 src_off -= conn->sndbuf_desc->len;
 337                                                 /* modulo in send ring */
 338                         if (src_len_sum == dst_len)
 339                                 break; /* either on 1st or 2nd iteration */
 340                         /* prepare next (== 2nd) iteration */
 341                         src_len = dst_len - src_len; /* remainder */
 342                         src_len_sum += src_len;
 343                 }
 344                 rc = smc_tx_rdma_write(conn, dst_off, num_sges, sges);
 345                 if (rc)
 346                         return rc;
 347                 if (dst_len_sum == len)
 348                         break; /* either on 1st or 2nd iteration */
 349                 /* prepare next (== 2nd) iteration */
 350                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 351                 dst_len = len - dst_len; /* remainder */
 352                 dst_len_sum += dst_len;
 353                 src_len = min_t(int, dst_len, conn->sndbuf_desc->len -
 354                                 sent_count);
 355                 src_len_sum = src_len;
 356         }
 357         return 0;
 358 }
 359
 360 /* SMC-D helper for smc_tx_rdma_writes() */
 361 static int smcd_tx_rdma_writes(struct smc_connection *conn, size_t len,
 362                                size_t src_off, size_t src_len,
 363                                size_t dst_off, size_t dst_len)
 364 {
 365         int src_len_sum = src_len, dst_len_sum = dst_len;
 366         int srcchunk, dstchunk;
 367         int rc;
 368
 369         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 370                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 371                         void *data = conn->sndbuf_desc->cpu_addr + src_off;
 372
 373                         rc = smcd_tx_ism_write(conn, data, src_len, dst_off +
 374                                                sizeof(struct smcd_cdc_msg), 0);
 375                         if (rc)
 376                                 return rc;
 377                         dst_off += src_len;
 378                         src_off += src_len;
 379                         if (src_off >= conn->sndbuf_desc->len)
 380                                 src_off -= conn->sndbuf_desc->len;
 381                                                 /* modulo in send ring */
 382                         if (src_len_sum == dst_len)
 383                                 break; /* either on 1st or 2nd iteration */
 384                         /* prepare next (== 2nd) iteration */
 385                         src_len = dst_len - src_len; /* remainder */
 386                         src_len_sum += src_len;
 387                 }
 388                 if (dst_len_sum == len)
 389                         break; /* either on 1st or 2nd iteration */
 390                 /* prepare next (== 2nd) iteration */
 391                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 392                 dst_len = len - dst_len; /* remainder */
 393                 dst_len_sum += dst_len;
 394                 src_len = min_t(int, dst_len, conn->sndbuf_desc->len - src_off);
 395                 src_len_sum = src_len;
 396         }
 397         return 0;
 398 }
 399
 400 /* sndbuf consumer: prepare all necessary (src&dst) chunks of data transmit;
 401  * usable snd_wnd as max transmit
 402  */
 403 static int smc_tx_rdma_writes(struct smc_connection *conn)
 404 {
 405         size_t len, src_len, dst_off, dst_len; /* current chunk values */
 406         union smc_host_cursor sent, prep, prod, cons;
 407         struct smc_cdc_producer_flags *pflags;
 408         int to_send, rmbespace;
 409         int rc;
 410
 411         /* source: sndbuf */
 412         smc_curs_copy(&sent, &conn->tx_curs_sent, conn);
 413         smc_curs_copy(&prep, &conn->tx_curs_prep, conn);
 414         /* cf. wmem_alloc - (snd_max - snd_una) */
 415         to_send = smc_curs_diff(conn->sndbuf_desc->len, &sent, &prep);
 416         if (to_send <= 0)
 417                 return 0;
 418
 419         /* destination: RMBE */
 420         /* cf. snd_wnd */
 421         rmbespace = atomic_read(&conn->peer_rmbe_space);
 422         if (rmbespace <= 0)
 423                 return 0;
 424         smc_curs_copy(&prod, &conn->local_tx_ctrl.prod, conn);
 425         smc_curs_copy(&cons, &conn->local_rx_ctrl.cons, conn);
 426
 427         /* if usable snd_wnd closes ask peer to advertise once it opens again */
 428         pflags = &conn->local_tx_ctrl.prod_flags;
 429         pflags->write_blocked = (to_send >= rmbespace);
 430         /* cf. usable snd_wnd */
 431         len = min(to_send, rmbespace);
 432
 433         /* initialize variables for first iteration of subsequent nested loop */
 434         dst_off = prod.count;
 435         if (prod.wrap == cons.wrap) {
 436                 /* the filled destination area is unwrapped,
 437                  * hence the available free destination space is wrapped
 438                  * and we need 2 destination chunks of sum len; start with 1st
 439                  * which is limited by what's available in sndbuf
 440                  */
 441                 dst_len = min_t(size_t,
 442                                 conn->peer_rmbe_size - prod.count, len);
 443         } else {
 444                 /* the filled destination area is wrapped,
 445                  * hence the available free destination space is unwrapped
 446                  * and we need a single destination chunk of entire len
 447                  */
 448                 dst_len = len;
 449         }
 450         /* dst_len determines the maximum src_len */
 451         if (sent.count + dst_len <= conn->sndbuf_desc->len) {
 452                 /* unwrapped src case: single chunk of entire dst_len */
 453                 src_len = dst_len;
 454         } else {
 455                 /* wrapped src case: 2 chunks of sum dst_len; start with 1st: */
 456                 src_len = conn->sndbuf_desc->len - sent.count;
 457         }
 458
 459         if (conn->lgr->is_smcd)
 460                 rc = smcd_tx_rdma_writes(conn, len, sent.count, src_len,
 461                                          dst_off, dst_len);
 462         else
 463                 rc = smcr_tx_rdma_writes(conn, len, sent.count, src_len,
 464                                          dst_off, dst_len);
 465         if (rc)
 466                 return rc;
 467
 468         if (conn->urg_tx_pend && len == to_send)
 469                 pflags->urg_data_present = 1;
 470         smc_tx_advance_cursors(conn, &prod, &sent, len);
 471         /* update connection's cursors with advanced local cursors */
 472         smc_curs_copy(&conn->local_tx_ctrl.prod, &prod, conn);
 473                                                         /* dst: peer RMBE */
 474         smc_curs_copy(&conn->tx_curs_sent, &sent, conn);/* src: local sndbuf */
 475
 476         return 0;
 477 }
 478
 479 /* Wakeup sndbuf consumers from any context (IRQ or process)
 480  * since there is more data to transmit; usable snd_wnd as max transmit
 481  */
 482 static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
 483 {
 484         struct smc_cdc_producer_flags *pflags;
 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, &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                         rc = 0;
 498                         if (conn->alert_token_local) /* connection healthy */
 499                                 mod_delayed_work(system_wq, &conn->tx_work,
 500                                                  SMC_TX_WORK_DELAY);
 501                 }
 502                 return rc;
 503         }
 504
 505         spin_lock_bh(&conn->send_lock);
 506         if (!conn->local_tx_ctrl.prod_flags.urg_data_present) {
 507                 rc = smc_tx_rdma_writes(conn);
 508                 if (rc) {
 509                         smc_wr_tx_put_slot(&conn->lgr->lnk[SMC_SINGLE_LINK],
 510                                            (struct smc_wr_tx_pend_priv *)pend);
 511                         goto out_unlock;
 512                 }
 513         }
 514
 515         rc = smc_cdc_msg_send(conn, wr_buf, pend);
 516         pflags = &conn->local_tx_ctrl.prod_flags;
 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);
 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->lgr->is_smcd)
 551                 rc = smcd_tx_sndbuf_nonempty(conn);
 552         else
 553                 rc = smcr_tx_sndbuf_nonempty(conn);
 554
 555         return rc;
 556 }
 557
 558 /* Wakeup sndbuf consumers from process context
 559  * since there is more data to transmit
 560  */
 561 void smc_tx_work(struct work_struct *work)
 562 {
 563         struct smc_connection *conn = container_of(to_delayed_work(work),
 564                                                    struct smc_connection,
 565                                                    tx_work);
 566         struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
 567         int rc;
 568
 569         lock_sock(&smc->sk);
 570         if (smc->sk.sk_err ||
 571             !conn->alert_token_local ||
 572             conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
 573                 goto out;
 574
 575         rc = smc_tx_sndbuf_nonempty(conn);
 576         if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked &&
 577             !atomic_read(&conn->bytes_to_rcv))
 578                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 579
 580 out:
 581         release_sock(&smc->sk);
 582 }
 583
 584 void smc_tx_consumer_update(struct smc_connection *conn, bool force)
 585 {
 586         union smc_host_cursor cfed, cons, prod;
 587         int sender_free = conn->rmb_desc->len;
 588         int to_confirm;
 589
 590         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 591         smc_curs_copy(&cfed, &conn->rx_curs_confirmed, conn);
 592         to_confirm = smc_curs_diff(conn->rmb_desc->len, &cfed, &cons);
 593         if (to_confirm > conn->rmbe_update_limit) {
 594                 smc_curs_copy(&prod, &conn->local_rx_ctrl.prod, conn);
 595                 sender_free = conn->rmb_desc->len -
 596                               smc_curs_diff_large(conn->rmb_desc->len,
 597                                                   &cfed, &prod);
 598         }
 599
 600         if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
 601             force ||
 602             ((to_confirm > conn->rmbe_update_limit) &&
 603              ((sender_free <= (conn->rmb_desc->len / 2)) ||
 604               conn->local_rx_ctrl.prod_flags.write_blocked))) {
 605                 if ((smc_cdc_get_slot_and_msg_send(conn) < 0) &&
 606                     conn->alert_token_local) { /* connection healthy */
 607                         schedule_delayed_work(&conn->tx_work,
 608                                               SMC_TX_WORK_DELAY);
 609                         return;
 610                 }
 611                 smc_curs_copy(&conn->rx_curs_confirmed,
 612                               &conn->local_tx_ctrl.cons, conn);
 613                 conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0;
 614         }
 615         if (conn->local_rx_ctrl.prod_flags.write_blocked &&
 616             !atomic_read(&conn->bytes_to_rcv))
 617                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 618 }
 619
 620 /***************************** send initialize *******************************/
 621
 622 /* Initialize send properties on connection establishment. NB: not __init! */
 623 void smc_tx_init(struct smc_sock *smc)
 624 {
 625         smc->sk.sk_write_space = smc_tx_write_space;
 626 }