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         bool noblock;
  80         long timeo;
  81         int rc = 0;
  82
  83         /* similar to sk_stream_wait_memory */
  84         timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
  85         noblock = timeo ? false : true;
  86         add_wait_queue(sk_sleep(sk), &wait);
  87         while (1) {
  88                 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
  89                 if (sk->sk_err ||
  90                     (sk->sk_shutdown & SEND_SHUTDOWN) ||
  91                     conn->local_tx_ctrl.conn_state_flags.peer_done_writing) {
  92                         rc = -EPIPE;
  93                         break;
  94                 }
  95                 if (smc_cdc_rxed_any_close(conn)) {
  96                         rc = -ECONNRESET;
  97                         break;
  98                 }
  99                 if (!timeo) {
 100                         if (noblock)
 101                                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 102                         rc = -EAGAIN;
 103                         break;
 104                 }
 105                 if (signal_pending(current)) {
 106                         rc = sock_intr_errno(timeo);
 107                         break;
 108                 }
 109                 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 110                 if (atomic_read(&conn->sndbuf_space) && !conn->urg_tx_pend)
 111                         break; /* at least 1 byte of free & no urgent data */
 112                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 113                 sk_wait_event(sk, &timeo,
 114                               sk->sk_err ||
 115                               (sk->sk_shutdown & SEND_SHUTDOWN) ||
 116                               smc_cdc_rxed_any_close(conn) ||
 117                               (atomic_read(&conn->sndbuf_space) &&
 118                                !conn->urg_tx_pend),
 119                               &wait);
 120         }
 121         remove_wait_queue(sk_sleep(sk), &wait);
 122         return rc;
 123 }
 124
 125 static bool smc_tx_is_corked(struct smc_sock *smc)
 126 {
 127         struct tcp_sock *tp = tcp_sk(smc->clcsock->sk);
 128
 129         return (tp->nonagle & TCP_NAGLE_CORK) ? true : false;
 130 }
 131
 132 /* sndbuf producer: main API called by socket layer.
 133  * called under sock lock.
 134  */
 135 int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
 136 {
 137         size_t copylen, send_done = 0, send_remaining = len;
 138         size_t chunk_len, chunk_off, chunk_len_sum;
 139         struct smc_connection *conn = &smc->conn;
 140         union smc_host_cursor prep;
 141         struct sock *sk = &smc->sk;
 142         char *sndbuf_base;
 143         int tx_cnt_prep;
 144         int writespace;
 145         int rc, chunk;
 146
 147         /* This should be in poll */
 148         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 149
 150         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
 151                 rc = -EPIPE;
 152                 goto out_err;
 153         }
 154
 155         while (msg_data_left(msg)) {
 156                 if (sk->sk_state == SMC_INIT)
 157                         return -ENOTCONN;
 158                 if (smc->sk.sk_shutdown & SEND_SHUTDOWN ||
 159                     (smc->sk.sk_err == ECONNABORTED) ||
 160                     conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
 161                         return -EPIPE;
 162                 if (smc_cdc_rxed_any_close(conn))
 163                         return send_done ?: -ECONNRESET;
 164
 165                 if (msg->msg_flags & MSG_OOB)
 166                         conn->local_tx_ctrl.prod_flags.urg_data_pending = 1;
 167
 168                 if (!atomic_read(&conn->sndbuf_space) || conn->urg_tx_pend) {
 169                         if (send_done)
 170                                 return send_done;
 171                         rc = smc_tx_wait(smc, msg->msg_flags);
 172                         if (rc)
 173                                 goto out_err;
 174                         continue;
 175                 }
 176
 177                 /* initialize variables for 1st iteration of subsequent loop */
 178                 /* could be just 1 byte, even after smc_tx_wait above */
 179                 writespace = atomic_read(&conn->sndbuf_space);
 180                 /* not more than what user space asked for */
 181                 copylen = min_t(size_t, send_remaining, writespace);
 182                 /* determine start of sndbuf */
 183                 sndbuf_base = conn->sndbuf_desc->cpu_addr;
 184                 smc_curs_copy(&prep, &conn->tx_curs_prep, conn);
 185                 tx_cnt_prep = prep.count;
 186                 /* determine chunks where to write into sndbuf */
 187                 /* either unwrapped case, or 1st chunk of wrapped case */
 188                 chunk_len = min_t(size_t, copylen, conn->sndbuf_desc->len -
 189                                   tx_cnt_prep);
 190                 chunk_len_sum = chunk_len;
 191                 chunk_off = tx_cnt_prep;
 192                 smc_sndbuf_sync_sg_for_cpu(conn);
 193                 for (chunk = 0; chunk < 2; chunk++) {
 194                         rc = memcpy_from_msg(sndbuf_base + chunk_off,
 195                                              msg, chunk_len);
 196                         if (rc) {
 197                                 smc_sndbuf_sync_sg_for_device(conn);
 198                                 if (send_done)
 199                                         return send_done;
 200                                 goto out_err;
 201                         }
 202                         send_done += chunk_len;
 203                         send_remaining -= chunk_len;
 204
 205                         if (chunk_len_sum == copylen)
 206                                 break; /* either on 1st or 2nd iteration */
 207                         /* prepare next (== 2nd) iteration */
 208                         chunk_len = copylen - chunk_len; /* remainder */
 209                         chunk_len_sum += chunk_len;
 210                         chunk_off = 0; /* modulo offset in send ring buffer */
 211                 }
 212                 smc_sndbuf_sync_sg_for_device(conn);
 213                 /* update cursors */
 214                 smc_curs_add(conn->sndbuf_desc->len, &prep, copylen);
 215                 smc_curs_copy(&conn->tx_curs_prep, &prep, conn);
 216                 /* increased in send tasklet smc_cdc_tx_handler() */
 217                 smp_mb__before_atomic();
 218                 atomic_sub(copylen, &conn->sndbuf_space);
 219                 /* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
 220                 smp_mb__after_atomic();
 221                 /* since we just produced more new data into sndbuf,
 222                  * trigger sndbuf consumer: RDMA write into peer RMBE and CDC
 223                  */
 224                 if ((msg->msg_flags & MSG_OOB) && !send_remaining)
 225                         conn->urg_tx_pend = true;
 226                 if ((msg->msg_flags & MSG_MORE || smc_tx_is_corked(smc)) &&
 227                     (atomic_read(&conn->sndbuf_space) >
 228                                                 (conn->sndbuf_desc->len >> 1)))
 229                         /* for a corked socket defer the RDMA writes if there
 230                          * is still sufficient sndbuf_space available
 231                          */
 232                         schedule_delayed_work(&conn->tx_work,
 233                                               SMC_TX_CORK_DELAY);
 234                 else
 235                         smc_tx_sndbuf_nonempty(conn);
 236         } /* while (msg_data_left(msg)) */
 237
 238         return send_done;
 239
 240 out_err:
 241         rc = sk_stream_error(sk, msg->msg_flags, rc);
 242         /* make sure we wake any epoll edge trigger waiter */
 243         if (unlikely(rc == -EAGAIN))
 244                 sk->sk_write_space(sk);
 245         return rc;
 246 }
 247
 248 /***************************** sndbuf consumer *******************************/
 249
 250 /* sndbuf consumer: actual data transfer of one target chunk with ISM write */
 251 int smcd_tx_ism_write(struct smc_connection *conn, void *data, size_t len,
 252                       u32 offset, int signal)
 253 {
 254         struct smc_ism_position pos;
 255         int rc;
 256
 257         memset(&pos, 0, sizeof(pos));
 258         pos.token = conn->peer_token;
 259         pos.index = conn->peer_rmbe_idx;
 260         pos.offset = conn->tx_off + offset;
 261         pos.signal = signal;
 262         rc = smc_ism_write(conn->lgr->smcd, &pos, data, len);
 263         if (rc)
 264                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 265         return rc;
 266 }
 267
 268 /* sndbuf consumer: actual data transfer of one target chunk with RDMA write */
 269 static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
 270                              int num_sges, struct ib_rdma_wr *rdma_wr)
 271 {
 272         struct smc_link_group *lgr = conn->lgr;
 273         struct smc_link *link;
 274         int rc;
 275
 276         link = &lgr->lnk[SMC_SINGLE_LINK];
 277         rdma_wr->wr.wr_id = smc_wr_tx_get_next_wr_id(link);
 278         rdma_wr->wr.num_sge = num_sges;
 279         rdma_wr->remote_addr =
 280                 lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr +
 281                 /* RMBE within RMB */
 282                 conn->tx_off +
 283                 /* offset within RMBE */
 284                 peer_rmbe_offset;
 285         rdma_wr->rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey;
 286         rc = ib_post_send(link->roce_qp, &rdma_wr->wr, NULL);
 287         if (rc) {
 288                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 289                 smc_lgr_terminate(lgr);
 290         }
 291         return rc;
 292 }
 293
 294 /* sndbuf consumer */
 295 static inline void smc_tx_advance_cursors(struct smc_connection *conn,
 296                                           union smc_host_cursor *prod,
 297                                           union smc_host_cursor *sent,
 298                                           size_t len)
 299 {
 300         smc_curs_add(conn->peer_rmbe_size, prod, len);
 301         /* increased in recv tasklet smc_cdc_msg_rcv() */
 302         smp_mb__before_atomic();
 303         /* data in flight reduces usable snd_wnd */
 304         atomic_sub(len, &conn->peer_rmbe_space);
 305         /* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
 306         smp_mb__after_atomic();
 307         smc_curs_add(conn->sndbuf_desc->len, sent, len);
 308 }
 309
 310 /* SMC-R helper for smc_tx_rdma_writes() */
 311 static int smcr_tx_rdma_writes(struct smc_connection *conn, size_t len,
 312                                size_t src_off, size_t src_len,
 313                                size_t dst_off, size_t dst_len,
 314                                struct smc_rdma_wr *wr_rdma_buf)
 315 {
 316         dma_addr_t dma_addr =
 317                 sg_dma_address(conn->sndbuf_desc->sgt[SMC_SINGLE_LINK].sgl);
 318         int src_len_sum = src_len, dst_len_sum = dst_len;
 319         int sent_count = src_off;
 320         int srcchunk, dstchunk;
 321         int num_sges;
 322         int rc;
 323
 324         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 325                 struct ib_sge *sge =
 326                         wr_rdma_buf->wr_tx_rdma[dstchunk].wr.sg_list;
 327
 328                 num_sges = 0;
 329                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 330                         sge[srcchunk].addr = dma_addr + src_off;
 331                         sge[srcchunk].length = src_len;
 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,
 345                                        &wr_rdma_buf->wr_tx_rdma[dstchunk]);
 346                 if (rc)
 347                         return rc;
 348                 if (dst_len_sum == len)
 349                         break; /* either on 1st or 2nd iteration */
 350                 /* prepare next (== 2nd) iteration */
 351                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 352                 dst_len = len - dst_len; /* remainder */
 353                 dst_len_sum += dst_len;
 354                 src_len = min_t(int, dst_len, conn->sndbuf_desc->len -
 355                                 sent_count);
 356                 src_len_sum = src_len;
 357         }
 358         return 0;
 359 }
 360
 361 /* SMC-D helper for smc_tx_rdma_writes() */
 362 static int smcd_tx_rdma_writes(struct smc_connection *conn, size_t len,
 363                                size_t src_off, size_t src_len,
 364                                size_t dst_off, size_t dst_len)
 365 {
 366         int src_len_sum = src_len, dst_len_sum = dst_len;
 367         int srcchunk, dstchunk;
 368         int rc;
 369
 370         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 371                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 372                         void *data = conn->sndbuf_desc->cpu_addr + src_off;
 373
 374                         rc = smcd_tx_ism_write(conn, data, src_len, dst_off +
 375                                                sizeof(struct smcd_cdc_msg), 0);
 376                         if (rc)
 377                                 return rc;
 378                         dst_off += src_len;
 379                         src_off += src_len;
 380                         if (src_off >= conn->sndbuf_desc->len)
 381                                 src_off -= conn->sndbuf_desc->len;
 382                                                 /* modulo in send ring */
 383                         if (src_len_sum == dst_len)
 384                                 break; /* either on 1st or 2nd iteration */
 385                         /* prepare next (== 2nd) iteration */
 386                         src_len = dst_len - src_len; /* remainder */
 387                         src_len_sum += src_len;
 388                 }
 389                 if (dst_len_sum == len)
 390                         break; /* either on 1st or 2nd iteration */
 391                 /* prepare next (== 2nd) iteration */
 392                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 393                 dst_len = len - dst_len; /* remainder */
 394                 dst_len_sum += dst_len;
 395                 src_len = min_t(int, dst_len, conn->sndbuf_desc->len - src_off);
 396                 src_len_sum = src_len;
 397         }
 398         return 0;
 399 }
 400
 401 /* sndbuf consumer: prepare all necessary (src&dst) chunks of data transmit;
 402  * usable snd_wnd as max transmit
 403  */
 404 static int smc_tx_rdma_writes(struct smc_connection *conn,
 405                               struct smc_rdma_wr *wr_rdma_buf)
 406 {
 407         size_t len, src_len, dst_off, dst_len; /* current chunk values */
 408         union smc_host_cursor sent, prep, prod, cons;
 409         struct smc_cdc_producer_flags *pflags;
 410         int to_send, rmbespace;
 411         int rc;
 412
 413         /* source: sndbuf */
 414         smc_curs_copy(&sent, &conn->tx_curs_sent, conn);
 415         smc_curs_copy(&prep, &conn->tx_curs_prep, conn);
 416         /* cf. wmem_alloc - (snd_max - snd_una) */
 417         to_send = smc_curs_diff(conn->sndbuf_desc->len, &sent, &prep);
 418         if (to_send <= 0)
 419                 return 0;
 420
 421         /* destination: RMBE */
 422         /* cf. snd_wnd */
 423         rmbespace = atomic_read(&conn->peer_rmbe_space);
 424         if (rmbespace <= 0)
 425                 return 0;
 426         smc_curs_copy(&prod, &conn->local_tx_ctrl.prod, conn);
 427         smc_curs_copy(&cons, &conn->local_rx_ctrl.cons, conn);
 428
 429         /* if usable snd_wnd closes ask peer to advertise once it opens again */
 430         pflags = &conn->local_tx_ctrl.prod_flags;
 431         pflags->write_blocked = (to_send >= rmbespace);
 432         /* cf. usable snd_wnd */
 433         len = min(to_send, rmbespace);
 434
 435         /* initialize variables for first iteration of subsequent nested loop */
 436         dst_off = prod.count;
 437         if (prod.wrap == cons.wrap) {
 438                 /* the filled destination area is unwrapped,
 439                  * hence the available free destination space is wrapped
 440                  * and we need 2 destination chunks of sum len; start with 1st
 441                  * which is limited by what's available in sndbuf
 442                  */
 443                 dst_len = min_t(size_t,
 444                                 conn->peer_rmbe_size - prod.count, len);
 445         } else {
 446                 /* the filled destination area is wrapped,
 447                  * hence the available free destination space is unwrapped
 448                  * and we need a single destination chunk of entire len
 449                  */
 450                 dst_len = len;
 451         }
 452         /* dst_len determines the maximum src_len */
 453         if (sent.count + dst_len <= conn->sndbuf_desc->len) {
 454                 /* unwrapped src case: single chunk of entire dst_len */
 455                 src_len = dst_len;
 456         } else {
 457                 /* wrapped src case: 2 chunks of sum dst_len; start with 1st: */
 458                 src_len = conn->sndbuf_desc->len - sent.count;
 459         }
 460
 461         if (conn->lgr->is_smcd)
 462                 rc = smcd_tx_rdma_writes(conn, len, sent.count, src_len,
 463                                          dst_off, dst_len);
 464         else
 465                 rc = smcr_tx_rdma_writes(conn, len, sent.count, src_len,
 466                                          dst_off, dst_len, wr_rdma_buf);
 467         if (rc)
 468                 return rc;
 469
 470         if (conn->urg_tx_pend && len == to_send)
 471                 pflags->urg_data_present = 1;
 472         smc_tx_advance_cursors(conn, &prod, &sent, len);
 473         /* update connection's cursors with advanced local cursors */
 474         smc_curs_copy(&conn->local_tx_ctrl.prod, &prod, conn);
 475                                                         /* dst: peer RMBE */
 476         smc_curs_copy(&conn->tx_curs_sent, &sent, conn);/* src: local sndbuf */
 477
 478         return 0;
 479 }
 480
 481 /* Wakeup sndbuf consumers from any context (IRQ or process)
 482  * since there is more data to transmit; usable snd_wnd as max transmit
 483  */
 484 static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
 485 {
 486         struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags;
 487         struct smc_rdma_wr *wr_rdma_buf;
 488         struct smc_cdc_tx_pend *pend;
 489         struct smc_wr_buf *wr_buf;
 490         int rc;
 491
 492         rc = smc_cdc_get_free_slot(conn, &wr_buf, &wr_rdma_buf, &pend);
 493         if (rc < 0) {
 494                 if (rc == -EBUSY) {
 495                         struct smc_sock *smc =
 496                                 container_of(conn, struct smc_sock, conn);
 497
 498                         if (smc->sk.sk_err == ECONNABORTED)
 499                                 return sock_error(&smc->sk);
 500                         rc = 0;
 501                         if (conn->alert_token_local) /* connection healthy */
 502                                 mod_delayed_work(system_wq, &conn->tx_work,
 503                                                  SMC_TX_WORK_DELAY);
 504                 }
 505                 return rc;
 506         }
 507
 508         spin_lock_bh(&conn->send_lock);
 509         if (!pflags->urg_data_present) {
 510                 rc = smc_tx_rdma_writes(conn, wr_rdma_buf);
 511                 if (rc) {
 512                         smc_wr_tx_put_slot(&conn->lgr->lnk[SMC_SINGLE_LINK],
 513                                            (struct smc_wr_tx_pend_priv *)pend);
 514                         goto out_unlock;
 515                 }
 516         }
 517
 518         rc = smc_cdc_msg_send(conn, wr_buf, pend);
 519         if (!rc && pflags->urg_data_present) {
 520                 pflags->urg_data_pending = 0;
 521                 pflags->urg_data_present = 0;
 522         }
 523
 524 out_unlock:
 525         spin_unlock_bh(&conn->send_lock);
 526         return rc;
 527 }
 528
 529 static int smcd_tx_sndbuf_nonempty(struct smc_connection *conn)
 530 {
 531         struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags;
 532         int rc = 0;
 533
 534         spin_lock_bh(&conn->send_lock);
 535         if (!pflags->urg_data_present)
 536                 rc = smc_tx_rdma_writes(conn, NULL);
 537         if (!rc)
 538                 rc = smcd_cdc_msg_send(conn);
 539
 540         if (!rc && pflags->urg_data_present) {
 541                 pflags->urg_data_pending = 0;
 542                 pflags->urg_data_present = 0;
 543         }
 544         spin_unlock_bh(&conn->send_lock);
 545         return rc;
 546 }
 547
 548 int smc_tx_sndbuf_nonempty(struct smc_connection *conn)
 549 {
 550         int rc;
 551
 552         if (conn->lgr->is_smcd)
 553                 rc = smcd_tx_sndbuf_nonempty(conn);
 554         else
 555                 rc = smcr_tx_sndbuf_nonempty(conn);
 556
 557         if (!rc) {
 558                 /* trigger socket release if connection is closing */
 559                 struct smc_sock *smc = container_of(conn, struct smc_sock,
 560                                                     conn);
 561                 smc_close_wake_tx_prepared(smc);
 562         }
 563         return rc;
 564 }
 565
 566 /* Wakeup sndbuf consumers from process context
 567  * since there is more data to transmit
 568  */
 569 void smc_tx_work(struct work_struct *work)
 570 {
 571         struct smc_connection *conn = container_of(to_delayed_work(work),
 572                                                    struct smc_connection,
 573                                                    tx_work);
 574         struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
 575         int rc;
 576
 577         lock_sock(&smc->sk);
 578         if (smc->sk.sk_err ||
 579             !conn->alert_token_local ||
 580             conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
 581                 goto out;
 582
 583         rc = smc_tx_sndbuf_nonempty(conn);
 584         if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked &&
 585             !atomic_read(&conn->bytes_to_rcv))
 586                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 587
 588 out:
 589         release_sock(&smc->sk);
 590 }
 591
 592 void smc_tx_consumer_update(struct smc_connection *conn, bool force)
 593 {
 594         union smc_host_cursor cfed, cons, prod;
 595         int sender_free = conn->rmb_desc->len;
 596         int to_confirm;
 597
 598         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 599         smc_curs_copy(&cfed, &conn->rx_curs_confirmed, conn);
 600         to_confirm = smc_curs_diff(conn->rmb_desc->len, &cfed, &cons);
 601         if (to_confirm > conn->rmbe_update_limit) {
 602                 smc_curs_copy(&prod, &conn->local_rx_ctrl.prod, conn);
 603                 sender_free = conn->rmb_desc->len -
 604                               smc_curs_diff_large(conn->rmb_desc->len,
 605                                                   &cfed, &prod);
 606         }
 607
 608         if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
 609             force ||
 610             ((to_confirm > conn->rmbe_update_limit) &&
 611              ((sender_free <= (conn->rmb_desc->len / 2)) ||
 612               conn->local_rx_ctrl.prod_flags.write_blocked))) {
 613                 if ((smc_cdc_get_slot_and_msg_send(conn) < 0) &&
 614                     conn->alert_token_local) { /* connection healthy */
 615                         schedule_delayed_work(&conn->tx_work,
 616                                               SMC_TX_WORK_DELAY);
 617                         return;
 618                 }
 619         }
 620         if (conn->local_rx_ctrl.prod_flags.write_blocked &&
 621             !atomic_read(&conn->bytes_to_rcv))
 622                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 623 }
 624
 625 /***************************** send initialize *******************************/
 626
 627 /* Initialize send properties on connection establishment. NB: not __init! */
 628 void smc_tx_init(struct smc_sock *smc)
 629 {
 630         smc->sk.sk_write_space = smc_tx_write_space;
 631 }