root/net/smc/smc_tx.c

DEFINITIONS

1. smc_tx_write_space
2. smc_tx_sndbuf_nonfull
3. smc_tx_wait
4. smc_tx_is_corked
5. smc_tx_sendmsg
6. smcd_tx_ism_write
7. smc_tx_rdma_write
8. smc_tx_advance_cursors
9. smcr_tx_rdma_writes
10. smcd_tx_rdma_writes
11. smc_tx_rdma_writes
12. smcr_tx_sndbuf_nonempty
13. smcd_tx_sndbuf_nonempty
14. smc_tx_sndbuf_nonempty
15. smc_tx_work
16. smc_tx_consumer_update
17. smc_tx_init

   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->local_tx_ctrl.conn_state_flags.peer_done_writing) {
  90                         rc = -EPIPE;
  91                         break;
  92                 }
  93                 if (smc_cdc_rxed_any_close(conn)) {
  94                         rc = -ECONNRESET;
  95                         break;
  96                 }
  97                 if (!timeo) {
  98                         /* ensure EPOLLOUT is subsequently generated */
  99                         set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 100                         rc = -EAGAIN;
 101                         break;
 102                 }
 103                 if (signal_pending(current)) {
 104                         rc = sock_intr_errno(timeo);
 105                         break;
 106                 }
 107                 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 108                 if (atomic_read(&conn->sndbuf_space) && !conn->urg_tx_pend)
 109                         break; /* at least 1 byte of free & no urgent data */
 110                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 111                 sk_wait_event(sk, &timeo,
 112                               sk->sk_err ||
 113                               (sk->sk_shutdown & SEND_SHUTDOWN) ||
 114                               smc_cdc_rxed_any_close(conn) ||
 115                               (atomic_read(&conn->sndbuf_space) &&
 116                                !conn->urg_tx_pend),
 117                               &wait);
 118         }
 119         remove_wait_queue(sk_sleep(sk), &wait);
 120         return rc;
 121 }
 122 
 123 static bool smc_tx_is_corked(struct smc_sock *smc)
 124 {
 125         struct tcp_sock *tp = tcp_sk(smc->clcsock->sk);
 126 
 127         return (tp->nonagle & TCP_NAGLE_CORK) ? true : false;
 128 }
 129 
 130 /* sndbuf producer: main API called by socket layer.
 131  * called under sock lock.
 132  */
 133 int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
 134 {
 135         size_t copylen, send_done = 0, send_remaining = len;
 136         size_t chunk_len, chunk_off, chunk_len_sum;
 137         struct smc_connection *conn = &smc->conn;
 138         union smc_host_cursor prep;
 139         struct sock *sk = &smc->sk;
 140         char *sndbuf_base;
 141         int tx_cnt_prep;
 142         int writespace;
 143         int rc, chunk;
 144 
 145         /* This should be in poll */
 146         sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 147 
 148         if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
 149                 rc = -EPIPE;
 150                 goto out_err;
 151         }
 152 
 153         while (msg_data_left(msg)) {
 154                 if (sk->sk_state == SMC_INIT)
 155                         return -ENOTCONN;
 156                 if (smc->sk.sk_shutdown & SEND_SHUTDOWN ||
 157                     (smc->sk.sk_err == ECONNABORTED) ||
 158                     conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
 159                         return -EPIPE;
 160                 if (smc_cdc_rxed_any_close(conn))
 161                         return send_done ?: -ECONNRESET;
 162 
 163                 if (msg->msg_flags & MSG_OOB)
 164                         conn->local_tx_ctrl.prod_flags.urg_data_pending = 1;
 165 
 166                 if (!atomic_read(&conn->sndbuf_space) || conn->urg_tx_pend) {
 167                         if (send_done)
 168                                 return send_done;
 169                         rc = smc_tx_wait(smc, msg->msg_flags);
 170                         if (rc)
 171                                 goto out_err;
 172                         continue;
 173                 }
 174 
 175                 /* initialize variables for 1st iteration of subsequent loop */
 176                 /* could be just 1 byte, even after smc_tx_wait above */
 177                 writespace = atomic_read(&conn->sndbuf_space);
 178                 /* not more than what user space asked for */
 179                 copylen = min_t(size_t, send_remaining, writespace);
 180                 /* determine start of sndbuf */
 181                 sndbuf_base = conn->sndbuf_desc->cpu_addr;
 182                 smc_curs_copy(&prep, &conn->tx_curs_prep, conn);
 183                 tx_cnt_prep = prep.count;
 184                 /* determine chunks where to write into sndbuf */
 185                 /* either unwrapped case, or 1st chunk of wrapped case */
 186                 chunk_len = min_t(size_t, copylen, conn->sndbuf_desc->len -
 187                                   tx_cnt_prep);
 188                 chunk_len_sum = chunk_len;
 189                 chunk_off = tx_cnt_prep;
 190                 smc_sndbuf_sync_sg_for_cpu(conn);
 191                 for (chunk = 0; chunk < 2; chunk++) {
 192                         rc = memcpy_from_msg(sndbuf_base + chunk_off,
 193                                              msg, chunk_len);
 194                         if (rc) {
 195                                 smc_sndbuf_sync_sg_for_device(conn);
 196                                 if (send_done)
 197                                         return send_done;
 198                                 goto out_err;
 199                         }
 200                         send_done += chunk_len;
 201                         send_remaining -= chunk_len;
 202 
 203                         if (chunk_len_sum == copylen)
 204                                 break; /* either on 1st or 2nd iteration */
 205                         /* prepare next (== 2nd) iteration */
 206                         chunk_len = copylen - chunk_len; /* remainder */
 207                         chunk_len_sum += chunk_len;
 208                         chunk_off = 0; /* modulo offset in send ring buffer */
 209                 }
 210                 smc_sndbuf_sync_sg_for_device(conn);
 211                 /* update cursors */
 212                 smc_curs_add(conn->sndbuf_desc->len, &prep, copylen);
 213                 smc_curs_copy(&conn->tx_curs_prep, &prep, conn);
 214                 /* increased in send tasklet smc_cdc_tx_handler() */
 215                 smp_mb__before_atomic();
 216                 atomic_sub(copylen, &conn->sndbuf_space);
 217                 /* guarantee 0 <= sndbuf_space <= sndbuf_desc->len */
 218                 smp_mb__after_atomic();
 219                 /* since we just produced more new data into sndbuf,
 220                  * trigger sndbuf consumer: RDMA write into peer RMBE and CDC
 221                  */
 222                 if ((msg->msg_flags & MSG_OOB) && !send_remaining)
 223                         conn->urg_tx_pend = true;
 224                 if ((msg->msg_flags & MSG_MORE || smc_tx_is_corked(smc)) &&
 225                     (atomic_read(&conn->sndbuf_space) >
 226                                                 (conn->sndbuf_desc->len >> 1)))
 227                         /* for a corked socket defer the RDMA writes if there
 228                          * is still sufficient sndbuf_space available
 229                          */
 230                         schedule_delayed_work(&conn->tx_work,
 231                                               SMC_TX_CORK_DELAY);
 232                 else
 233                         smc_tx_sndbuf_nonempty(conn);
 234         } /* while (msg_data_left(msg)) */
 235 
 236         return send_done;
 237 
 238 out_err:
 239         rc = sk_stream_error(sk, msg->msg_flags, rc);
 240         /* make sure we wake any epoll edge trigger waiter */
 241         if (unlikely(rc == -EAGAIN))
 242                 sk->sk_write_space(sk);
 243         return rc;
 244 }
 245 
 246 /***************************** sndbuf consumer *******************************/
 247 
 248 /* sndbuf consumer: actual data transfer of one target chunk with ISM write */
 249 int smcd_tx_ism_write(struct smc_connection *conn, void *data, size_t len,
 250                       u32 offset, int signal)
 251 {
 252         struct smc_ism_position pos;
 253         int rc;
 254 
 255         memset(&pos, 0, sizeof(pos));
 256         pos.token = conn->peer_token;
 257         pos.index = conn->peer_rmbe_idx;
 258         pos.offset = conn->tx_off + offset;
 259         pos.signal = signal;
 260         rc = smc_ism_write(conn->lgr->smcd, &pos, data, len);
 261         if (rc)
 262                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 263         return rc;
 264 }
 265 
 266 /* sndbuf consumer: actual data transfer of one target chunk with RDMA write */
 267 static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset,
 268                              int num_sges, struct ib_rdma_wr *rdma_wr)
 269 {
 270         struct smc_link_group *lgr = conn->lgr;
 271         struct smc_link *link;
 272         int rc;
 273 
 274         link = &lgr->lnk[SMC_SINGLE_LINK];
 275         rdma_wr->wr.wr_id = smc_wr_tx_get_next_wr_id(link);
 276         rdma_wr->wr.num_sge = num_sges;
 277         rdma_wr->remote_addr =
 278                 lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr +
 279                 /* RMBE within RMB */
 280                 conn->tx_off +
 281                 /* offset within RMBE */
 282                 peer_rmbe_offset;
 283         rdma_wr->rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey;
 284         rc = ib_post_send(link->roce_qp, &rdma_wr->wr, NULL);
 285         if (rc) {
 286                 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1;
 287                 smc_lgr_terminate(lgr);
 288         }
 289         return rc;
 290 }
 291 
 292 /* sndbuf consumer */
 293 static inline void smc_tx_advance_cursors(struct smc_connection *conn,
 294                                           union smc_host_cursor *prod,
 295                                           union smc_host_cursor *sent,
 296                                           size_t len)
 297 {
 298         smc_curs_add(conn->peer_rmbe_size, prod, len);
 299         /* increased in recv tasklet smc_cdc_msg_rcv() */
 300         smp_mb__before_atomic();
 301         /* data in flight reduces usable snd_wnd */
 302         atomic_sub(len, &conn->peer_rmbe_space);
 303         /* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */
 304         smp_mb__after_atomic();
 305         smc_curs_add(conn->sndbuf_desc->len, sent, len);
 306 }
 307 
 308 /* SMC-R helper for smc_tx_rdma_writes() */
 309 static int smcr_tx_rdma_writes(struct smc_connection *conn, size_t len,
 310                                size_t src_off, size_t src_len,
 311                                size_t dst_off, size_t dst_len,
 312                                struct smc_rdma_wr *wr_rdma_buf)
 313 {
 314         dma_addr_t dma_addr =
 315                 sg_dma_address(conn->sndbuf_desc->sgt[SMC_SINGLE_LINK].sgl);
 316         int src_len_sum = src_len, dst_len_sum = dst_len;
 317         int sent_count = src_off;
 318         int srcchunk, dstchunk;
 319         int num_sges;
 320         int rc;
 321 
 322         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 323                 struct ib_sge *sge =
 324                         wr_rdma_buf->wr_tx_rdma[dstchunk].wr.sg_list;
 325 
 326                 num_sges = 0;
 327                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 328                         sge[srcchunk].addr = dma_addr + src_off;
 329                         sge[srcchunk].length = src_len;
 330                         num_sges++;
 331 
 332                         src_off += src_len;
 333                         if (src_off >= conn->sndbuf_desc->len)
 334                                 src_off -= conn->sndbuf_desc->len;
 335                                                 /* modulo in send ring */
 336                         if (src_len_sum == dst_len)
 337                                 break; /* either on 1st or 2nd iteration */
 338                         /* prepare next (== 2nd) iteration */
 339                         src_len = dst_len - src_len; /* remainder */
 340                         src_len_sum += src_len;
 341                 }
 342                 rc = smc_tx_rdma_write(conn, dst_off, num_sges,
 343                                        &wr_rdma_buf->wr_tx_rdma[dstchunk]);
 344                 if (rc)
 345                         return rc;
 346                 if (dst_len_sum == len)
 347                         break; /* either on 1st or 2nd iteration */
 348                 /* prepare next (== 2nd) iteration */
 349                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 350                 dst_len = len - dst_len; /* remainder */
 351                 dst_len_sum += dst_len;
 352                 src_len = min_t(int, dst_len, conn->sndbuf_desc->len -
 353                                 sent_count);
 354                 src_len_sum = src_len;
 355         }
 356         return 0;
 357 }
 358 
 359 /* SMC-D helper for smc_tx_rdma_writes() */
 360 static int smcd_tx_rdma_writes(struct smc_connection *conn, size_t len,
 361                                size_t src_off, size_t src_len,
 362                                size_t dst_off, size_t dst_len)
 363 {
 364         int src_len_sum = src_len, dst_len_sum = dst_len;
 365         int srcchunk, dstchunk;
 366         int rc;
 367 
 368         for (dstchunk = 0; dstchunk < 2; dstchunk++) {
 369                 for (srcchunk = 0; srcchunk < 2; srcchunk++) {
 370                         void *data = conn->sndbuf_desc->cpu_addr + src_off;
 371 
 372                         rc = smcd_tx_ism_write(conn, data, src_len, dst_off +
 373                                                sizeof(struct smcd_cdc_msg), 0);
 374                         if (rc)
 375                                 return rc;
 376                         dst_off += src_len;
 377                         src_off += src_len;
 378                         if (src_off >= conn->sndbuf_desc->len)
 379                                 src_off -= conn->sndbuf_desc->len;
 380                                                 /* modulo in send ring */
 381                         if (src_len_sum == dst_len)
 382                                 break; /* either on 1st or 2nd iteration */
 383                         /* prepare next (== 2nd) iteration */
 384                         src_len = dst_len - src_len; /* remainder */
 385                         src_len_sum += src_len;
 386                 }
 387                 if (dst_len_sum == len)
 388                         break; /* either on 1st or 2nd iteration */
 389                 /* prepare next (== 2nd) iteration */
 390                 dst_off = 0; /* modulo offset in RMBE ring buffer */
 391                 dst_len = len - dst_len; /* remainder */
 392                 dst_len_sum += dst_len;
 393                 src_len = min_t(int, dst_len, conn->sndbuf_desc->len - src_off);
 394                 src_len_sum = src_len;
 395         }
 396         return 0;
 397 }
 398 
 399 /* sndbuf consumer: prepare all necessary (src&dst) chunks of data transmit;
 400  * usable snd_wnd as max transmit
 401  */
 402 static int smc_tx_rdma_writes(struct smc_connection *conn,
 403                               struct smc_rdma_wr *wr_rdma_buf)
 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, wr_rdma_buf);
 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 = &conn->local_tx_ctrl.prod_flags;
 485         struct smc_rdma_wr *wr_rdma_buf;
 486         struct smc_cdc_tx_pend *pend;
 487         struct smc_wr_buf *wr_buf;
 488         int rc;
 489 
 490         rc = smc_cdc_get_free_slot(conn, &wr_buf, &wr_rdma_buf, &pend);
 491         if (rc < 0) {
 492                 if (rc == -EBUSY) {
 493                         struct smc_sock *smc =
 494                                 container_of(conn, struct smc_sock, conn);
 495 
 496                         if (smc->sk.sk_err == ECONNABORTED)
 497                                 return sock_error(&smc->sk);
 498                         rc = 0;
 499                         if (conn->alert_token_local) /* connection healthy */
 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->lgr->is_smcd)
 551                 rc = smcd_tx_sndbuf_nonempty(conn);
 552         else
 553                 rc = smcr_tx_sndbuf_nonempty(conn);
 554 
 555         if (!rc) {
 556                 /* trigger socket release if connection is closing */
 557                 struct smc_sock *smc = container_of(conn, struct smc_sock,
 558                                                     conn);
 559                 smc_close_wake_tx_prepared(smc);
 560         }
 561         return rc;
 562 }
 563 
 564 /* Wakeup sndbuf consumers from process context
 565  * since there is more data to transmit
 566  */
 567 void smc_tx_work(struct work_struct *work)
 568 {
 569         struct smc_connection *conn = container_of(to_delayed_work(work),
 570                                                    struct smc_connection,
 571                                                    tx_work);
 572         struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
 573         int rc;
 574 
 575         lock_sock(&smc->sk);
 576         if (smc->sk.sk_err ||
 577             !conn->alert_token_local ||
 578             conn->local_rx_ctrl.conn_state_flags.peer_conn_abort)
 579                 goto out;
 580 
 581         rc = smc_tx_sndbuf_nonempty(conn);
 582         if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked &&
 583             !atomic_read(&conn->bytes_to_rcv))
 584                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 585 
 586 out:
 587         release_sock(&smc->sk);
 588 }
 589 
 590 void smc_tx_consumer_update(struct smc_connection *conn, bool force)
 591 {
 592         union smc_host_cursor cfed, cons, prod;
 593         int sender_free = conn->rmb_desc->len;
 594         int to_confirm;
 595 
 596         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 597         smc_curs_copy(&cfed, &conn->rx_curs_confirmed, conn);
 598         to_confirm = smc_curs_diff(conn->rmb_desc->len, &cfed, &cons);
 599         if (to_confirm > conn->rmbe_update_limit) {
 600                 smc_curs_copy(&prod, &conn->local_rx_ctrl.prod, conn);
 601                 sender_free = conn->rmb_desc->len -
 602                               smc_curs_diff_large(conn->rmb_desc->len,
 603                                                   &cfed, &prod);
 604         }
 605 
 606         if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req ||
 607             force ||
 608             ((to_confirm > conn->rmbe_update_limit) &&
 609              ((sender_free <= (conn->rmb_desc->len / 2)) ||
 610               conn->local_rx_ctrl.prod_flags.write_blocked))) {
 611                 if ((smc_cdc_get_slot_and_msg_send(conn) < 0) &&
 612                     conn->alert_token_local) { /* connection healthy */
 613                         schedule_delayed_work(&conn->tx_work,
 614                                               SMC_TX_WORK_DELAY);
 615                         return;
 616                 }
 617         }
 618         if (conn->local_rx_ctrl.prod_flags.write_blocked &&
 619             !atomic_read(&conn->bytes_to_rcv))
 620                 conn->local_rx_ctrl.prod_flags.write_blocked = 0;
 621 }
 622 
 623 /***************************** send initialize *******************************/
 624 
 625 /* Initialize send properties on connection establishment. NB: not __init! */
 626 void smc_tx_init(struct smc_sock *smc)
 627 {
 628         smc->sk.sk_write_space = smc_tx_write_space;
 629 }