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_tx.h" 28 29 #define SMC_TX_WORK_DELAY HZ 30 #define SMC_TX_CORK_DELAY (HZ >> 2) /* 250 ms */ 31 32 /***************************** sndbuf producer *******************************/ 33 34 /* callback implementation for sk.sk_write_space() 35 * to wakeup sndbuf producers that blocked with smc_tx_wait_memory(). 36 * called under sk_socket lock. 37 */ 38 static void smc_tx_write_space(struct sock *sk) 39 { 40 struct socket *sock = sk->sk_socket; 41 struct smc_sock *smc = smc_sk(sk); 42 struct socket_wq *wq; 43 44 /* similar to sk_stream_write_space */ 45 if (atomic_read(&smc->conn.sndbuf_space) && sock) { 46 clear_bit(SOCK_NOSPACE, &sock->flags); 47 rcu_read_lock(); 48 wq = rcu_dereference(sk->sk_wq); 49 if (skwq_has_sleeper(wq)) 50 wake_up_interruptible_poll(&wq->wait, 51 EPOLLOUT | EPOLLWRNORM | 52 EPOLLWRBAND); 53 if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN)) 54 sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT); 55 rcu_read_unlock(); 56 } 57 } 58 59 /* Wakeup sndbuf producers that blocked with smc_tx_wait_memory(). 60 * Cf. tcp_data_snd_check()=>tcp_check_space()=>tcp_new_space(). 61 */ 62 void smc_tx_sndbuf_nonfull(struct smc_sock *smc) 63 { 64 if (smc->sk.sk_socket && 65 test_bit(SOCK_NOSPACE, &smc->sk.sk_socket->flags)) 66 smc->sk.sk_write_space(&smc->sk); 67 } 68 69 /* blocks sndbuf producer until at least one byte of free space available */ 70 static int smc_tx_wait_memory(struct smc_sock *smc, int flags) 71 { 72 DEFINE_WAIT_FUNC(wait, woken_wake_function); 73 struct smc_connection *conn = &smc->conn; 74 struct sock *sk = &smc->sk; 75 bool noblock; 76 long timeo; 77 int rc = 0; 78 79 /* similar to sk_stream_wait_memory */ 80 timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT); 81 noblock = timeo ? false : true; 82 add_wait_queue(sk_sleep(sk), &wait); 83 while (1) { 84 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); 85 if (sk->sk_err || 86 (sk->sk_shutdown & SEND_SHUTDOWN) || 87 conn->local_tx_ctrl.conn_state_flags.peer_done_writing) { 88 rc = -EPIPE; 89 break; 90 } 91 if (smc_cdc_rxed_any_close(conn)) { 92 rc = -ECONNRESET; 93 break; 94 } 95 if (!timeo) { 96 if (noblock) 97 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 98 rc = -EAGAIN; 99 break; 100 } 101 if (signal_pending(current)) { 102 rc = sock_intr_errno(timeo); 103 break; 104 } 105 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); 106 if (atomic_read(&conn->sndbuf_space)) 107 break; /* at least 1 byte of free space available */ 108 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 109 sk_wait_event(sk, &timeo, 110 sk->sk_err || 111 (sk->sk_shutdown & SEND_SHUTDOWN) || 112 smc_cdc_rxed_any_close(conn) || 113 atomic_read(&conn->sndbuf_space), 114 &wait); 115 } 116 remove_wait_queue(sk_sleep(sk), &wait); 117 return rc; 118 } 119 120 static bool smc_tx_is_corked(struct smc_sock *smc) 121 { 122 struct tcp_sock *tp = tcp_sk(smc->clcsock->sk); 123 124 return (tp->nonagle & TCP_NAGLE_CORK) ? true : false; 125 } 126 127 /* sndbuf producer: main API called by socket layer. 128 * called under sock lock. 129 */ 130 int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len) 131 { 132 size_t copylen, send_done = 0, send_remaining = len; 133 size_t chunk_len, chunk_off, chunk_len_sum; 134 struct smc_connection *conn = &smc->conn; 135 union smc_host_cursor prep; 136 struct sock *sk = &smc->sk; 137 char *sndbuf_base; 138 int tx_cnt_prep; 139 int writespace; 140 int rc, chunk; 141 142 /* This should be in poll */ 143 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); 144 145 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) { 146 rc = -EPIPE; 147 goto out_err; 148 } 149 150 while (msg_data_left(msg)) { 151 if (sk->sk_state == SMC_INIT) 152 return -ENOTCONN; 153 if (smc->sk.sk_shutdown & SEND_SHUTDOWN || 154 (smc->sk.sk_err == ECONNABORTED) || 155 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort) 156 return -EPIPE; 157 if (smc_cdc_rxed_any_close(conn)) 158 return send_done ?: -ECONNRESET; 159 160 if (!atomic_read(&conn->sndbuf_space)) { 161 rc = smc_tx_wait_memory(smc, msg->msg_flags); 162 if (rc) { 163 if (send_done) 164 return send_done; 165 goto out_err; 166 } 167 continue; 168 } 169 170 /* initialize variables for 1st iteration of subsequent loop */ 171 /* could be just 1 byte, even after smc_tx_wait_memory above */ 172 writespace = atomic_read(&conn->sndbuf_space); 173 /* not more than what user space asked for */ 174 copylen = min_t(size_t, send_remaining, writespace); 175 /* determine start of sndbuf */ 176 sndbuf_base = conn->sndbuf_desc->cpu_addr; 177 smc_curs_write(&prep, 178 smc_curs_read(&conn->tx_curs_prep, conn), 179 conn); 180 tx_cnt_prep = prep.count; 181 /* determine chunks where to write into sndbuf */ 182 /* either unwrapped case, or 1st chunk of wrapped case */ 183 chunk_len = min_t(size_t, copylen, conn->sndbuf_desc->len - 184 tx_cnt_prep); 185 chunk_len_sum = chunk_len; 186 chunk_off = tx_cnt_prep; 187 smc_sndbuf_sync_sg_for_cpu(conn); 188 for (chunk = 0; chunk < 2; chunk++) { 189 rc = memcpy_from_msg(sndbuf_base + chunk_off, 190 msg, chunk_len); 191 if (rc) { 192 smc_sndbuf_sync_sg_for_device(conn); 193 if (send_done) 194 return send_done; 195 goto out_err; 196 } 197 send_done += chunk_len; 198 send_remaining -= chunk_len; 199 200 if (chunk_len_sum == copylen) 201 break; /* either on 1st or 2nd iteration */ 202 /* prepare next (== 2nd) iteration */ 203 chunk_len = copylen - chunk_len; /* remainder */ 204 chunk_len_sum += chunk_len; 205 chunk_off = 0; /* modulo offset in send ring buffer */ 206 } 207 smc_sndbuf_sync_sg_for_device(conn); 208 /* update cursors */ 209 smc_curs_add(conn->sndbuf_desc->len, &prep, copylen); 210 smc_curs_write(&conn->tx_curs_prep, 211 smc_curs_read(&prep, conn), 212 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_MORE || smc_tx_is_corked(smc)) && 222 (atomic_read(&conn->sndbuf_space) > 223 (conn->sndbuf_desc->len >> 1))) 224 /* for a corked socket defer the RDMA writes if there 225 * is still sufficient sndbuf_space available 226 */ 227 schedule_delayed_work(&conn->tx_work, 228 SMC_TX_CORK_DELAY); 229 else 230 smc_tx_sndbuf_nonempty(conn); 231 } /* while (msg_data_left(msg)) */ 232 233 return send_done; 234 235 out_err: 236 rc = sk_stream_error(sk, msg->msg_flags, rc); 237 /* make sure we wake any epoll edge trigger waiter */ 238 if (unlikely(rc == -EAGAIN)) 239 sk->sk_write_space(sk); 240 return rc; 241 } 242 243 /***************************** sndbuf consumer *******************************/ 244 245 /* sndbuf consumer: actual data transfer of one target chunk with RDMA write */ 246 static int smc_tx_rdma_write(struct smc_connection *conn, int peer_rmbe_offset, 247 int num_sges, struct ib_sge sges[]) 248 { 249 struct smc_link_group *lgr = conn->lgr; 250 struct ib_send_wr *failed_wr = NULL; 251 struct ib_rdma_wr rdma_wr; 252 struct smc_link *link; 253 int rc; 254 255 memset(&rdma_wr, 0, sizeof(rdma_wr)); 256 link = &lgr->lnk[SMC_SINGLE_LINK]; 257 rdma_wr.wr.wr_id = smc_wr_tx_get_next_wr_id(link); 258 rdma_wr.wr.sg_list = sges; 259 rdma_wr.wr.num_sge = num_sges; 260 rdma_wr.wr.opcode = IB_WR_RDMA_WRITE; 261 rdma_wr.remote_addr = 262 lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].dma_addr + 263 /* RMBE within RMB */ 264 conn->tx_off + 265 /* offset within RMBE */ 266 peer_rmbe_offset; 267 rdma_wr.rkey = lgr->rtokens[conn->rtoken_idx][SMC_SINGLE_LINK].rkey; 268 rc = ib_post_send(link->roce_qp, &rdma_wr.wr, &failed_wr); 269 if (rc) { 270 conn->local_tx_ctrl.conn_state_flags.peer_conn_abort = 1; 271 smc_lgr_terminate(lgr); 272 } 273 return rc; 274 } 275 276 /* sndbuf consumer */ 277 static inline void smc_tx_advance_cursors(struct smc_connection *conn, 278 union smc_host_cursor *prod, 279 union smc_host_cursor *sent, 280 size_t len) 281 { 282 smc_curs_add(conn->peer_rmbe_size, prod, len); 283 /* increased in recv tasklet smc_cdc_msg_rcv() */ 284 smp_mb__before_atomic(); 285 /* data in flight reduces usable snd_wnd */ 286 atomic_sub(len, &conn->peer_rmbe_space); 287 /* guarantee 0 <= peer_rmbe_space <= peer_rmbe_size */ 288 smp_mb__after_atomic(); 289 smc_curs_add(conn->sndbuf_desc->len, sent, len); 290 } 291 292 /* sndbuf consumer: prepare all necessary (src&dst) chunks of data transmit; 293 * usable snd_wnd as max transmit 294 */ 295 static int smc_tx_rdma_writes(struct smc_connection *conn) 296 { 297 size_t src_off, src_len, dst_off, dst_len; /* current chunk values */ 298 size_t len, dst_len_sum, src_len_sum, dstchunk, srcchunk; 299 union smc_host_cursor sent, prep, prod, cons; 300 struct ib_sge sges[SMC_IB_MAX_SEND_SGE]; 301 struct smc_link_group *lgr = conn->lgr; 302 int to_send, rmbespace; 303 struct smc_link *link; 304 dma_addr_t dma_addr; 305 int num_sges; 306 int rc; 307 308 /* source: sndbuf */ 309 smc_curs_write(&sent, smc_curs_read(&conn->tx_curs_sent, conn), conn); 310 smc_curs_write(&prep, smc_curs_read(&conn->tx_curs_prep, conn), conn); 311 /* cf. wmem_alloc - (snd_max - snd_una) */ 312 to_send = smc_curs_diff(conn->sndbuf_desc->len, &sent, &prep); 313 if (to_send <= 0) 314 return 0; 315 316 /* destination: RMBE */ 317 /* cf. snd_wnd */ 318 rmbespace = atomic_read(&conn->peer_rmbe_space); 319 if (rmbespace <= 0) 320 return 0; 321 smc_curs_write(&prod, 322 smc_curs_read(&conn->local_tx_ctrl.prod, conn), 323 conn); 324 smc_curs_write(&cons, 325 smc_curs_read(&conn->local_rx_ctrl.cons, conn), 326 conn); 327 328 /* if usable snd_wnd closes ask peer to advertise once it opens again */ 329 conn->local_tx_ctrl.prod_flags.write_blocked = (to_send >= rmbespace); 330 /* cf. usable snd_wnd */ 331 len = min(to_send, rmbespace); 332 333 /* initialize variables for first iteration of subsequent nested loop */ 334 link = &lgr->lnk[SMC_SINGLE_LINK]; 335 dst_off = prod.count; 336 if (prod.wrap == cons.wrap) { 337 /* the filled destination area is unwrapped, 338 * hence the available free destination space is wrapped 339 * and we need 2 destination chunks of sum len; start with 1st 340 * which is limited by what's available in sndbuf 341 */ 342 dst_len = min_t(size_t, 343 conn->peer_rmbe_size - prod.count, len); 344 } else { 345 /* the filled destination area is wrapped, 346 * hence the available free destination space is unwrapped 347 * and we need a single destination chunk of entire len 348 */ 349 dst_len = len; 350 } 351 dst_len_sum = dst_len; 352 src_off = sent.count; 353 /* dst_len determines the maximum src_len */ 354 if (sent.count + dst_len <= conn->sndbuf_desc->len) { 355 /* unwrapped src case: single chunk of entire dst_len */ 356 src_len = dst_len; 357 } else { 358 /* wrapped src case: 2 chunks of sum dst_len; start with 1st: */ 359 src_len = conn->sndbuf_desc->len - sent.count; 360 } 361 src_len_sum = src_len; 362 dma_addr = sg_dma_address(conn->sndbuf_desc->sgt[SMC_SINGLE_LINK].sgl); 363 for (dstchunk = 0; dstchunk < 2; dstchunk++) { 364 num_sges = 0; 365 for (srcchunk = 0; srcchunk < 2; srcchunk++) { 366 sges[srcchunk].addr = dma_addr + src_off; 367 sges[srcchunk].length = src_len; 368 sges[srcchunk].lkey = link->roce_pd->local_dma_lkey; 369 num_sges++; 370 src_off += src_len; 371 if (src_off >= conn->sndbuf_desc->len) 372 src_off -= conn->sndbuf_desc->len; 373 /* modulo in send ring */ 374 if (src_len_sum == dst_len) 375 break; /* either on 1st or 2nd iteration */ 376 /* prepare next (== 2nd) iteration */ 377 src_len = dst_len - src_len; /* remainder */ 378 src_len_sum += src_len; 379 } 380 rc = smc_tx_rdma_write(conn, dst_off, num_sges, sges); 381 if (rc) 382 return rc; 383 if (dst_len_sum == len) 384 break; /* either on 1st or 2nd iteration */ 385 /* prepare next (== 2nd) iteration */ 386 dst_off = 0; /* modulo offset in RMBE ring buffer */ 387 dst_len = len - dst_len; /* remainder */ 388 dst_len_sum += dst_len; 389 src_len = min_t(int, 390 dst_len, conn->sndbuf_desc->len - sent.count); 391 src_len_sum = src_len; 392 } 393 394 smc_tx_advance_cursors(conn, &prod, &sent, len); 395 /* update connection's cursors with advanced local cursors */ 396 smc_curs_write(&conn->local_tx_ctrl.prod, 397 smc_curs_read(&prod, conn), 398 conn); 399 /* dst: peer RMBE */ 400 smc_curs_write(&conn->tx_curs_sent, 401 smc_curs_read(&sent, conn), 402 conn); 403 /* src: local sndbuf */ 404 405 return 0; 406 } 407 408 /* Wakeup sndbuf consumers from any context (IRQ or process) 409 * since there is more data to transmit; usable snd_wnd as max transmit 410 */ 411 int smc_tx_sndbuf_nonempty(struct smc_connection *conn) 412 { 413 struct smc_cdc_tx_pend *pend; 414 struct smc_wr_buf *wr_buf; 415 int rc; 416 417 spin_lock_bh(&conn->send_lock); 418 rc = smc_cdc_get_free_slot(conn, &wr_buf, &pend); 419 if (rc < 0) { 420 if (rc == -EBUSY) { 421 struct smc_sock *smc = 422 container_of(conn, struct smc_sock, conn); 423 424 if (smc->sk.sk_err == ECONNABORTED) { 425 rc = sock_error(&smc->sk); 426 goto out_unlock; 427 } 428 rc = 0; 429 if (conn->alert_token_local) /* connection healthy */ 430 mod_delayed_work(system_wq, &conn->tx_work, 431 SMC_TX_WORK_DELAY); 432 } 433 goto out_unlock; 434 } 435 436 rc = smc_tx_rdma_writes(conn); 437 if (rc) { 438 smc_wr_tx_put_slot(&conn->lgr->lnk[SMC_SINGLE_LINK], 439 (struct smc_wr_tx_pend_priv *)pend); 440 goto out_unlock; 441 } 442 443 rc = smc_cdc_msg_send(conn, wr_buf, pend); 444 445 out_unlock: 446 spin_unlock_bh(&conn->send_lock); 447 return rc; 448 } 449 450 /* Wakeup sndbuf consumers from process context 451 * since there is more data to transmit 452 */ 453 void smc_tx_work(struct work_struct *work) 454 { 455 struct smc_connection *conn = container_of(to_delayed_work(work), 456 struct smc_connection, 457 tx_work); 458 struct smc_sock *smc = container_of(conn, struct smc_sock, conn); 459 int rc; 460 461 lock_sock(&smc->sk); 462 if (smc->sk.sk_err || 463 !conn->alert_token_local || 464 conn->local_rx_ctrl.conn_state_flags.peer_conn_abort) 465 goto out; 466 467 rc = smc_tx_sndbuf_nonempty(conn); 468 if (!rc && conn->local_rx_ctrl.prod_flags.write_blocked && 469 !atomic_read(&conn->bytes_to_rcv)) 470 conn->local_rx_ctrl.prod_flags.write_blocked = 0; 471 472 out: 473 release_sock(&smc->sk); 474 } 475 476 void smc_tx_consumer_update(struct smc_connection *conn) 477 { 478 union smc_host_cursor cfed, cons; 479 int to_confirm; 480 481 smc_curs_write(&cons, 482 smc_curs_read(&conn->local_tx_ctrl.cons, conn), 483 conn); 484 smc_curs_write(&cfed, 485 smc_curs_read(&conn->rx_curs_confirmed, conn), 486 conn); 487 to_confirm = smc_curs_diff(conn->rmb_desc->len, &cfed, &cons); 488 489 if (conn->local_rx_ctrl.prod_flags.cons_curs_upd_req || 490 ((to_confirm > conn->rmbe_update_limit) && 491 ((to_confirm > (conn->rmb_desc->len / 2)) || 492 conn->local_rx_ctrl.prod_flags.write_blocked))) { 493 if ((smc_cdc_get_slot_and_msg_send(conn) < 0) && 494 conn->alert_token_local) { /* connection healthy */ 495 schedule_delayed_work(&conn->tx_work, 496 SMC_TX_WORK_DELAY); 497 return; 498 } 499 smc_curs_write(&conn->rx_curs_confirmed, 500 smc_curs_read(&conn->local_tx_ctrl.cons, conn), 501 conn); 502 conn->local_rx_ctrl.prod_flags.cons_curs_upd_req = 0; 503 } 504 if (conn->local_rx_ctrl.prod_flags.write_blocked && 505 !atomic_read(&conn->bytes_to_rcv)) 506 conn->local_rx_ctrl.prod_flags.write_blocked = 0; 507 } 508 509 /***************************** send initialize *******************************/ 510 511 /* Initialize send properties on connection establishment. NB: not __init! */ 512 void smc_tx_init(struct smc_sock *smc) 513 { 514 smc->sk.sk_write_space = smc_tx_write_space; 515 } 516