net/smc/smc_rx.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Shared Memory Communications over RDMA (SMC-R) and RoCE
   4  *
   5  * Manage RMBE
   6  * copy new RMBE data into user space
   7  *
   8  * Copyright IBM Corp. 2016
   9  *
  10  * Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
  11  */
  12
  13 #include <linux/net.h>
  14 #include <linux/rcupdate.h>
  15 #include <linux/sched/signal.h>
  16
  17 #include <net/sock.h>
  18
  19 #include "smc.h"
  20 #include "smc_core.h"
  21 #include "smc_cdc.h"
  22 #include "smc_tx.h" /* smc_tx_consumer_update() */
  23 #include "smc_rx.h"
  24 #include "smc_stats.h"
  25 #include "smc_tracepoint.h"
  26
  27 /* callback implementation to wakeup consumers blocked with smc_rx_wait().
  28  * indirectly called by smc_cdc_msg_recv_action().
  29  */
  30 static void smc_rx_wake_up(struct sock *sk)
  31 {
  32         struct socket_wq *wq;
  33
  34         /* derived from sock_def_readable() */
  35         /* called already in smc_listen_work() */
  36         rcu_read_lock();
  37         wq = rcu_dereference(sk->sk_wq);
  38         if (skwq_has_sleeper(wq))
  39                 wake_up_interruptible_sync_poll(&wq->wait, EPOLLIN | EPOLLPRI |
  40                                                 EPOLLRDNORM | EPOLLRDBAND);
  41         sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
  42         if ((sk->sk_shutdown == SHUTDOWN_MASK) ||
  43             (sk->sk_state == SMC_CLOSED))
  44                 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
  45         rcu_read_unlock();
  46 }
  47
  48 /* Update consumer cursor
  49  *   @conn   connection to update
  50  *   @cons   consumer cursor
  51  *   @len    number of Bytes consumed
  52  *   Returns:
  53  *   1 if we should end our receive, 0 otherwise
  54  */
  55 static int smc_rx_update_consumer(struct smc_sock *smc,
  56                                   union smc_host_cursor cons, size_t len)
  57 {
  58         struct smc_connection *conn = &smc->conn;
  59         struct sock *sk = &smc->sk;
  60         bool force = false;
  61         int diff, rc = 0;
  62
  63         smc_curs_add(conn->rmb_desc->len, &cons, len);
  64
  65         /* did we process urgent data? */
  66         if (conn->urg_state == SMC_URG_VALID || conn->urg_rx_skip_pend) {
  67                 diff = smc_curs_comp(conn->rmb_desc->len, &cons,
  68                                      &conn->urg_curs);
  69                 if (sock_flag(sk, SOCK_URGINLINE)) {
  70                         if (diff == 0) {
  71                                 force = true;
  72                                 rc = 1;
  73                                 conn->urg_state = SMC_URG_READ;
  74                         }
  75                 } else {
  76                         if (diff == 1) {
  77                                 /* skip urgent byte */
  78                                 force = true;
  79                                 smc_curs_add(conn->rmb_desc->len, &cons, 1);
  80                                 conn->urg_rx_skip_pend = false;
  81                         } else if (diff < -1)
  82                                 /* we read past urgent byte */
  83                                 conn->urg_state = SMC_URG_READ;
  84                 }
  85         }
  86
  87         smc_curs_copy(&conn->local_tx_ctrl.cons, &cons, conn);
  88
  89         /* send consumer cursor update if required */
  90         /* similar to advertising new TCP rcv_wnd if required */
  91         smc_tx_consumer_update(conn, force);
  92
  93         return rc;
  94 }
  95
  96 static void smc_rx_update_cons(struct smc_sock *smc, size_t len)
  97 {
  98         struct smc_connection *conn = &smc->conn;
  99         union smc_host_cursor cons;
 100
 101         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 102         smc_rx_update_consumer(smc, cons, len);
 103 }
 104
 105 struct smc_spd_priv {
 106         struct smc_sock *smc;
 107         size_t           len;
 108 };
 109
 110 static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,
 111                                     struct pipe_buffer *buf)
 112 {
 113         struct smc_spd_priv *priv = (struct smc_spd_priv *)buf->private;
 114         struct smc_sock *smc = priv->smc;
 115         struct smc_connection *conn;
 116         struct sock *sk = &smc->sk;
 117
 118         if (sk->sk_state == SMC_CLOSED ||
 119             sk->sk_state == SMC_PEERFINCLOSEWAIT ||
 120             sk->sk_state == SMC_APPFINCLOSEWAIT)
 121                 goto out;
 122         conn = &smc->conn;
 123         lock_sock(sk);
 124         smc_rx_update_cons(smc, priv->len);
 125         release_sock(sk);
 126         if (atomic_sub_and_test(priv->len, &conn->splice_pending))
 127                 smc_rx_wake_up(sk);
 128 out:
 129         kfree(priv);
 130         put_page(buf->page);
 131         sock_put(sk);
 132 }
 133
 134 static const struct pipe_buf_operations smc_pipe_ops = {
 135         .release = smc_rx_pipe_buf_release,
 136         .get = generic_pipe_buf_get
 137 };
 138
 139 static void smc_rx_spd_release(struct splice_pipe_desc *spd,
 140                                unsigned int i)
 141 {
 142         put_page(spd->pages[i]);
 143 }
 144
 145 static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
 146                          struct smc_sock *smc)
 147 {
 148         struct smc_link_group *lgr = smc->conn.lgr;
 149         int offset = offset_in_page(src);
 150         struct partial_page *partial;
 151         struct splice_pipe_desc spd;
 152         struct smc_spd_priv **priv;
 153         struct page **pages;
 154         int bytes, nr_pages;
 155         int i;
 156
 157         nr_pages = !lgr->is_smcd && smc->conn.rmb_desc->is_vm ?
 158                    PAGE_ALIGN(len + offset) / PAGE_SIZE : 1;
 159
 160         pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
 161         if (!pages)
 162                 goto out;
 163         partial = kcalloc(nr_pages, sizeof(*partial), GFP_KERNEL);
 164         if (!partial)
 165                 goto out_page;
 166         priv = kcalloc(nr_pages, sizeof(*priv), GFP_KERNEL);
 167         if (!priv)
 168                 goto out_part;
 169         for (i = 0; i < nr_pages; i++) {
 170                 priv[i] = kzalloc(sizeof(**priv), GFP_KERNEL);
 171                 if (!priv[i])
 172                         goto out_priv;
 173         }
 174
 175         if (lgr->is_smcd ||
 176             (!lgr->is_smcd && !smc->conn.rmb_desc->is_vm)) {
 177                 /* smcd or smcr that uses physically contiguous RMBs */
 178                 priv[0]->len = len;
 179                 priv[0]->smc = smc;
 180                 partial[0].offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
 181                 partial[0].len = len;
 182                 partial[0].private = (unsigned long)priv[0];
 183                 pages[0] = smc->conn.rmb_desc->pages;
 184         } else {
 185                 int size, left = len;
 186                 void *buf = src;
 187                 /* smcr that uses virtually contiguous RMBs*/
 188                 for (i = 0; i < nr_pages; i++) {
 189                         size = min_t(int, PAGE_SIZE - offset, left);
 190                         priv[i]->len = size;
 191                         priv[i]->smc = smc;
 192                         pages[i] = vmalloc_to_page(buf);
 193                         partial[i].offset = offset;
 194                         partial[i].len = size;
 195                         partial[i].private = (unsigned long)priv[i];
 196                         buf += size / sizeof(*buf);
 197                         left -= size;
 198                         offset = 0;
 199                 }
 200         }
 201         spd.nr_pages_max = nr_pages;
 202         spd.nr_pages = nr_pages;
 203         spd.pages = pages;
 204         spd.partial = partial;
 205         spd.ops = &smc_pipe_ops;
 206         spd.spd_release = smc_rx_spd_release;
 207
 208         bytes = splice_to_pipe(pipe, &spd);
 209         if (bytes > 0) {
 210                 sock_hold(&smc->sk);
 211                 if (!lgr->is_smcd && smc->conn.rmb_desc->is_vm) {
 212                         for (i = 0; i < PAGE_ALIGN(bytes + offset) / PAGE_SIZE; i++)
 213                                 get_page(pages[i]);
 214                 } else {
 215                         get_page(smc->conn.rmb_desc->pages);
 216                 }
 217                 atomic_add(bytes, &smc->conn.splice_pending);
 218         }
 219         kfree(priv);
 220         kfree(partial);
 221         kfree(pages);
 222
 223         return bytes;
 224
 225 out_priv:
 226         for (i = (i - 1); i >= 0; i--)
 227                 kfree(priv[i]);
 228         kfree(priv);
 229 out_part:
 230         kfree(partial);
 231 out_page:
 232         kfree(pages);
 233 out:
 234         return -ENOMEM;
 235 }
 236
 237 static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
 238 {
 239         return atomic_read(&conn->bytes_to_rcv) &&
 240                !atomic_read(&conn->splice_pending);
 241 }
 242
 243 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
 244  *   @smc    smc socket
 245  *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
 246  *   @fcrit  add'l criterion to evaluate as function pointer
 247  * Returns:
 248  * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
 249  * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
 250  */
 251 int smc_rx_wait(struct smc_sock *smc, long *timeo,
 252                 int (*fcrit)(struct smc_connection *conn))
 253 {
 254         DEFINE_WAIT_FUNC(wait, woken_wake_function);
 255         struct smc_connection *conn = &smc->conn;
 256         struct smc_cdc_conn_state_flags *cflags =
 257                                         &conn->local_tx_ctrl.conn_state_flags;
 258         struct sock *sk = &smc->sk;
 259         int rc;
 260
 261         if (fcrit(conn))
 262                 return 1;
 263         sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 264         add_wait_queue(sk_sleep(sk), &wait);
 265         rc = sk_wait_event(sk, timeo,
 266                            READ_ONCE(sk->sk_err) ||
 267                            cflags->peer_conn_abort ||
 268                            READ_ONCE(sk->sk_shutdown) & RCV_SHUTDOWN ||
 269                            conn->killed ||
 270                            fcrit(conn),
 271                            &wait);
 272         remove_wait_queue(sk_sleep(sk), &wait);
 273         sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 274         return rc;
 275 }
 276
 277 static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
 278                            int flags)
 279 {
 280         struct smc_connection *conn = &smc->conn;
 281         union smc_host_cursor cons;
 282         struct sock *sk = &smc->sk;
 283         int rc = 0;
 284
 285         if (sock_flag(sk, SOCK_URGINLINE) ||
 286             !(conn->urg_state == SMC_URG_VALID) ||
 287             conn->urg_state == SMC_URG_READ)
 288                 return -EINVAL;
 289
 290         SMC_STAT_INC(smc, urg_data_cnt);
 291         if (conn->urg_state == SMC_URG_VALID) {
 292                 if (!(flags & MSG_PEEK))
 293                         smc->conn.urg_state = SMC_URG_READ;
 294                 msg->msg_flags |= MSG_OOB;
 295                 if (len > 0) {
 296                         if (!(flags & MSG_TRUNC))
 297                                 rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
 298                         len = 1;
 299                         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 300                         if (smc_curs_diff(conn->rmb_desc->len, &cons,
 301                                           &conn->urg_curs) > 1)
 302                                 conn->urg_rx_skip_pend = true;
 303                         /* Urgent Byte was already accounted for, but trigger
 304                          * skipping the urgent byte in non-inline case
 305                          */
 306                         if (!(flags & MSG_PEEK))
 307                                 smc_rx_update_consumer(smc, cons, 0);
 308                 } else {
 309                         msg->msg_flags |= MSG_TRUNC;
 310                 }
 311
 312                 return rc ? -EFAULT : len;
 313         }
 314
 315         if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
 316                 return 0;
 317
 318         return -EAGAIN;
 319 }
 320
 321 static bool smc_rx_recvmsg_data_available(struct smc_sock *smc)
 322 {
 323         struct smc_connection *conn = &smc->conn;
 324
 325         if (smc_rx_data_available(conn))
 326                 return true;
 327         else if (conn->urg_state == SMC_URG_VALID)
 328                 /* we received a single urgent Byte - skip */
 329                 smc_rx_update_cons(smc, 0);
 330         return false;
 331 }
 332
 333 /* smc_rx_recvmsg - receive data from RMBE
 334  * @msg:        copy data to receive buffer
 335  * @pipe:       copy data to pipe if set - indicates splice() call
 336  *
 337  * rcvbuf consumer: main API called by socket layer.
 338  * Called under sk lock.
 339  */
 340 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
 341                    struct pipe_inode_info *pipe, size_t len, int flags)
 342 {
 343         size_t copylen, read_done = 0, read_remaining = len;
 344         size_t chunk_len, chunk_off, chunk_len_sum;
 345         struct smc_connection *conn = &smc->conn;
 346         int (*func)(struct smc_connection *conn);
 347         union smc_host_cursor cons;
 348         int readable, chunk;
 349         char *rcvbuf_base;
 350         struct sock *sk;
 351         int splbytes;
 352         long timeo;
 353         int target;             /* Read at least these many bytes */
 354         int rc;
 355
 356         if (unlikely(flags & MSG_ERRQUEUE))
 357                 return -EINVAL; /* future work for sk.sk_family == AF_SMC */
 358
 359         sk = &smc->sk;
 360         if (sk->sk_state == SMC_LISTEN)
 361                 return -ENOTCONN;
 362         if (flags & MSG_OOB)
 363                 return smc_rx_recv_urg(smc, msg, len, flags);
 364         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 365         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
 366
 367         readable = atomic_read(&conn->bytes_to_rcv);
 368         if (readable >= conn->rmb_desc->len)
 369                 SMC_STAT_RMB_RX_FULL(smc, !conn->lnk);
 370
 371         if (len < readable)
 372                 SMC_STAT_RMB_RX_SIZE_SMALL(smc, !conn->lnk);
 373         /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
 374         rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
 375
 376         do { /* while (read_remaining) */
 377                 if (read_done >= target || (pipe && read_done))
 378                         break;
 379
 380                 if (conn->killed)
 381                         break;
 382
 383                 if (smc_rx_recvmsg_data_available(smc))
 384                         goto copy;
 385
 386                 if (sk->sk_shutdown & RCV_SHUTDOWN) {
 387                         /* smc_cdc_msg_recv_action() could have run after
 388                          * above smc_rx_recvmsg_data_available()
 389                          */
 390                         if (smc_rx_recvmsg_data_available(smc))
 391                                 goto copy;
 392                         break;
 393                 }
 394
 395                 if (read_done) {
 396                         if (sk->sk_err ||
 397                             sk->sk_state == SMC_CLOSED ||
 398                             !timeo ||
 399                             signal_pending(current))
 400                                 break;
 401                 } else {
 402                         if (sk->sk_err) {
 403                                 read_done = sock_error(sk);
 404                                 break;
 405                         }
 406                         if (sk->sk_state == SMC_CLOSED) {
 407                                 if (!sock_flag(sk, SOCK_DONE)) {
 408                                         /* This occurs when user tries to read
 409                                          * from never connected socket.
 410                                          */
 411                                         read_done = -ENOTCONN;
 412                                         break;
 413                                 }
 414                                 break;
 415                         }
 416                         if (!timeo)
 417                                 return -EAGAIN;
 418                         if (signal_pending(current)) {
 419                                 read_done = sock_intr_errno(timeo);
 420                                 break;
 421                         }
 422                 }
 423
 424                 if (!smc_rx_data_available(conn)) {
 425                         smc_rx_wait(smc, &timeo, smc_rx_data_available);
 426                         continue;
 427                 }
 428
 429 copy:
 430                 /* initialize variables for 1st iteration of subsequent loop */
 431                 /* could be just 1 byte, even after waiting on data above */
 432                 readable = atomic_read(&conn->bytes_to_rcv);
 433                 splbytes = atomic_read(&conn->splice_pending);
 434                 if (!readable || (msg && splbytes)) {
 435                         if (splbytes)
 436                                 func = smc_rx_data_available_and_no_splice_pend;
 437                         else
 438                                 func = smc_rx_data_available;
 439                         smc_rx_wait(smc, &timeo, func);
 440                         continue;
 441                 }
 442
 443                 smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 444                 /* subsequent splice() calls pick up where previous left */
 445                 if (splbytes)
 446                         smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
 447                 if (conn->urg_state == SMC_URG_VALID &&
 448                     sock_flag(&smc->sk, SOCK_URGINLINE) &&
 449                     readable > 1)
 450                         readable--;     /* always stop at urgent Byte */
 451                 /* not more than what user space asked for */
 452                 copylen = min_t(size_t, read_remaining, readable);
 453                 /* determine chunks where to read from rcvbuf */
 454                 /* either unwrapped case, or 1st chunk of wrapped case */
 455                 chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
 456                                   cons.count);
 457                 chunk_len_sum = chunk_len;
 458                 chunk_off = cons.count;
 459                 smc_rmb_sync_sg_for_cpu(conn);
 460                 for (chunk = 0; chunk < 2; chunk++) {
 461                         if (!(flags & MSG_TRUNC)) {
 462                                 if (msg) {
 463                                         rc = memcpy_to_msg(msg, rcvbuf_base +
 464                                                            chunk_off,
 465                                                            chunk_len);
 466                                 } else {
 467                                         rc = smc_rx_splice(pipe, rcvbuf_base +
 468                                                         chunk_off, chunk_len,
 469                                                         smc);
 470                                 }
 471                                 if (rc < 0) {
 472                                         if (!read_done)
 473                                                 read_done = -EFAULT;
 474                                         goto out;
 475                                 }
 476                         }
 477                         read_remaining -= chunk_len;
 478                         read_done += chunk_len;
 479
 480                         if (chunk_len_sum == copylen)
 481                                 break; /* either on 1st or 2nd iteration */
 482                         /* prepare next (== 2nd) iteration */
 483                         chunk_len = copylen - chunk_len; /* remainder */
 484                         chunk_len_sum += chunk_len;
 485                         chunk_off = 0; /* modulo offset in recv ring buffer */
 486                 }
 487
 488                 /* update cursors */
 489                 if (!(flags & MSG_PEEK)) {
 490                         /* increased in recv tasklet smc_cdc_msg_rcv() */
 491                         smp_mb__before_atomic();
 492                         atomic_sub(copylen, &conn->bytes_to_rcv);
 493                         /* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
 494                         smp_mb__after_atomic();
 495                         if (msg && smc_rx_update_consumer(smc, cons, copylen))
 496                                 goto out;
 497                 }
 498
 499                 trace_smc_rx_recvmsg(smc, copylen);
 500         } while (read_remaining);
 501 out:
 502         return read_done;
 503 }
 504
 505 /* Initialize receive properties on connection establishment. NB: not __init! */
 506 void smc_rx_init(struct smc_sock *smc)
 507 {
 508         smc->sk.sk_data_ready = smc_rx_wake_up;
 509         atomic_set(&smc->conn.splice_pending, 0);
 510         smc->conn.urg_state = SMC_URG_READ;
 511 }