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 #include <linux/splice.h>
  17
  18 #include <net/sock.h>
  19 #include <trace/events/sock.h>
  20
  21 #include "smc.h"
  22 #include "smc_core.h"
  23 #include "smc_cdc.h"
  24 #include "smc_tx.h" /* smc_tx_consumer_update() */
  25 #include "smc_rx.h"
  26 #include "smc_stats.h"
  27 #include "smc_tracepoint.h"
  28
  29 /* callback implementation to wakeup consumers blocked with smc_rx_wait().
  30  * indirectly called by smc_cdc_msg_recv_action().
  31  */
  32 static void smc_rx_wake_up(struct sock *sk)
  33 {
  34         struct socket_wq *wq;
  35
  36         trace_sk_data_ready(sk);
  37
  38         /* derived from sock_def_readable() */
  39         /* called already in smc_listen_work() */
  40         rcu_read_lock();
  41         wq = rcu_dereference(sk->sk_wq);
  42         if (skwq_has_sleeper(wq))
  43                 wake_up_interruptible_sync_poll(&wq->wait, EPOLLIN | EPOLLPRI |
  44                                                 EPOLLRDNORM | EPOLLRDBAND);
  45         sk_wake_async_rcu(sk, SOCK_WAKE_WAITD, POLL_IN);
  46         if ((sk->sk_shutdown == SHUTDOWN_MASK) ||
  47             (sk->sk_state == SMC_CLOSED))
  48                 sk_wake_async_rcu(sk, SOCK_WAKE_WAITD, POLL_HUP);
  49         rcu_read_unlock();
  50 }
  51
  52 /* Update consumer cursor
  53  *   @conn   connection to update
  54  *   @cons   consumer cursor
  55  *   @len    number of Bytes consumed
  56  *   Returns:
  57  *   1 if we should end our receive, 0 otherwise
  58  */
  59 static int smc_rx_update_consumer(struct smc_sock *smc,
  60                                   union smc_host_cursor cons, size_t len)
  61 {
  62         struct smc_connection *conn = &smc->conn;
  63         struct sock *sk = &smc->sk;
  64         bool force = false;
  65         int diff, rc = 0;
  66
  67         smc_curs_add(conn->rmb_desc->len, &cons, len);
  68
  69         /* did we process urgent data? */
  70         if (conn->urg_state == SMC_URG_VALID || conn->urg_rx_skip_pend) {
  71                 diff = smc_curs_comp(conn->rmb_desc->len, &cons,
  72                                      &conn->urg_curs);
  73                 if (sock_flag(sk, SOCK_URGINLINE)) {
  74                         if (diff == 0) {
  75                                 force = true;
  76                                 rc = 1;
  77                                 conn->urg_state = SMC_URG_READ;
  78                         }
  79                 } else {
  80                         if (diff == 1) {
  81                                 /* skip urgent byte */
  82                                 force = true;
  83                                 smc_curs_add(conn->rmb_desc->len, &cons, 1);
  84                                 conn->urg_rx_skip_pend = false;
  85                         } else if (diff < -1)
  86                                 /* we read past urgent byte */
  87                                 conn->urg_state = SMC_URG_READ;
  88                 }
  89         }
  90
  91         smc_curs_copy(&conn->local_tx_ctrl.cons, &cons, conn);
  92
  93         /* send consumer cursor update if required */
  94         /* similar to advertising new TCP rcv_wnd if required */
  95         smc_tx_consumer_update(conn, force);
  96
  97         return rc;
  98 }
  99
 100 static void smc_rx_update_cons(struct smc_sock *smc, size_t len)
 101 {
 102         struct smc_connection *conn = &smc->conn;
 103         union smc_host_cursor cons;
 104
 105         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 106         smc_rx_update_consumer(smc, cons, len);
 107 }
 108
 109 struct smc_spd_priv {
 110         struct smc_sock *smc;
 111         size_t           len;
 112 };
 113
 114 static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,
 115                                     struct pipe_buffer *buf)
 116 {
 117         struct smc_spd_priv *priv = (struct smc_spd_priv *)buf->private;
 118         struct smc_sock *smc = priv->smc;
 119         struct smc_connection *conn;
 120         struct sock *sk = &smc->sk;
 121
 122         if (sk->sk_state == SMC_CLOSED ||
 123             sk->sk_state == SMC_PEERFINCLOSEWAIT ||
 124             sk->sk_state == SMC_APPFINCLOSEWAIT)
 125                 goto out;
 126         conn = &smc->conn;
 127         lock_sock(sk);
 128         smc_rx_update_cons(smc, priv->len);
 129         release_sock(sk);
 130         if (atomic_sub_and_test(priv->len, &conn->splice_pending))
 131                 smc_rx_wake_up(sk);
 132 out:
 133         kfree(priv);
 134         put_page(buf->page);
 135         sock_put(sk);
 136 }
 137
 138 static const struct pipe_buf_operations smc_pipe_ops = {
 139         .release = smc_rx_pipe_buf_release,
 140         .get = generic_pipe_buf_get
 141 };
 142
 143 static void smc_rx_spd_release(struct splice_pipe_desc *spd,
 144                                unsigned int i)
 145 {
 146         put_page(spd->pages[i]);
 147 }
 148
 149 static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
 150                          struct smc_sock *smc)
 151 {
 152         struct smc_link_group *lgr = smc->conn.lgr;
 153         int offset = offset_in_page(src);
 154         struct partial_page *partial;
 155         struct splice_pipe_desc spd;
 156         struct smc_spd_priv **priv;
 157         struct page **pages;
 158         int bytes, nr_pages;
 159         int i;
 160
 161         nr_pages = !lgr->is_smcd && smc->conn.rmb_desc->is_vm ?
 162                    PAGE_ALIGN(len + offset) / PAGE_SIZE : 1;
 163
 164         pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
 165         if (!pages)
 166                 goto out;
 167         partial = kcalloc(nr_pages, sizeof(*partial), GFP_KERNEL);
 168         if (!partial)
 169                 goto out_page;
 170         priv = kcalloc(nr_pages, sizeof(*priv), GFP_KERNEL);
 171         if (!priv)
 172                 goto out_part;
 173         for (i = 0; i < nr_pages; i++) {
 174                 priv[i] = kzalloc(sizeof(**priv), GFP_KERNEL);
 175                 if (!priv[i])
 176                         goto out_priv;
 177         }
 178
 179         if (lgr->is_smcd ||
 180             (!lgr->is_smcd && !smc->conn.rmb_desc->is_vm)) {
 181                 /* smcd or smcr that uses physically contiguous RMBs */
 182                 priv[0]->len = len;
 183                 priv[0]->smc = smc;
 184                 partial[0].offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
 185                 partial[0].len = len;
 186                 partial[0].private = (unsigned long)priv[0];
 187                 pages[0] = smc->conn.rmb_desc->pages;
 188         } else {
 189                 int size, left = len;
 190                 void *buf = src;
 191                 /* smcr that uses virtually contiguous RMBs*/
 192                 for (i = 0; i < nr_pages; i++) {
 193                         size = min_t(int, PAGE_SIZE - offset, left);
 194                         priv[i]->len = size;
 195                         priv[i]->smc = smc;
 196                         pages[i] = vmalloc_to_page(buf);
 197                         partial[i].offset = offset;
 198                         partial[i].len = size;
 199                         partial[i].private = (unsigned long)priv[i];
 200                         buf += size / sizeof(*buf);
 201                         left -= size;
 202                         offset = 0;
 203                 }
 204         }
 205         spd.nr_pages_max = nr_pages;
 206         spd.nr_pages = nr_pages;
 207         spd.pages = pages;
 208         spd.partial = partial;
 209         spd.ops = &smc_pipe_ops;
 210         spd.spd_release = smc_rx_spd_release;
 211
 212         bytes = splice_to_pipe(pipe, &spd);
 213         if (bytes > 0) {
 214                 sock_hold(&smc->sk);
 215                 if (!lgr->is_smcd && smc->conn.rmb_desc->is_vm) {
 216                         for (i = 0; i < PAGE_ALIGN(bytes + offset) / PAGE_SIZE; i++)
 217                                 get_page(pages[i]);
 218                 } else {
 219                         get_page(smc->conn.rmb_desc->pages);
 220                 }
 221                 atomic_add(bytes, &smc->conn.splice_pending);
 222         }
 223         kfree(priv);
 224         kfree(partial);
 225         kfree(pages);
 226
 227         return bytes;
 228
 229 out_priv:
 230         for (i = (i - 1); i >= 0; i--)
 231                 kfree(priv[i]);
 232         kfree(priv);
 233 out_part:
 234         kfree(partial);
 235 out_page:
 236         kfree(pages);
 237 out:
 238         return -ENOMEM;
 239 }
 240
 241 static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
 242 {
 243         return atomic_read(&conn->bytes_to_rcv) &&
 244                !atomic_read(&conn->splice_pending);
 245 }
 246
 247 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
 248  *   @smc    smc socket
 249  *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
 250  *   @fcrit  add'l criterion to evaluate as function pointer
 251  * Returns:
 252  * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
 253  * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
 254  */
 255 int smc_rx_wait(struct smc_sock *smc, long *timeo,
 256                 int (*fcrit)(struct smc_connection *conn))
 257 {
 258         DEFINE_WAIT_FUNC(wait, woken_wake_function);
 259         struct smc_connection *conn = &smc->conn;
 260         struct smc_cdc_conn_state_flags *cflags =
 261                                         &conn->local_tx_ctrl.conn_state_flags;
 262         struct sock *sk = &smc->sk;
 263         int rc;
 264
 265         if (fcrit(conn))
 266                 return 1;
 267         sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 268         add_wait_queue(sk_sleep(sk), &wait);
 269         rc = sk_wait_event(sk, timeo,
 270                            READ_ONCE(sk->sk_err) ||
 271                            cflags->peer_conn_abort ||
 272                            READ_ONCE(sk->sk_shutdown) & RCV_SHUTDOWN ||
 273                            conn->killed ||
 274                            fcrit(conn),
 275                            &wait);
 276         remove_wait_queue(sk_sleep(sk), &wait);
 277         sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 278         return rc;
 279 }
 280
 281 static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
 282                            int flags)
 283 {
 284         struct smc_connection *conn = &smc->conn;
 285         union smc_host_cursor cons;
 286         struct sock *sk = &smc->sk;
 287         int rc = 0;
 288
 289         if (sock_flag(sk, SOCK_URGINLINE) ||
 290             !(conn->urg_state == SMC_URG_VALID) ||
 291             conn->urg_state == SMC_URG_READ)
 292                 return -EINVAL;
 293
 294         SMC_STAT_INC(smc, urg_data_cnt);
 295         if (conn->urg_state == SMC_URG_VALID) {
 296                 if (!(flags & MSG_PEEK))
 297                         smc->conn.urg_state = SMC_URG_READ;
 298                 msg->msg_flags |= MSG_OOB;
 299                 if (len > 0) {
 300                         if (!(flags & MSG_TRUNC))
 301                                 rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
 302                         len = 1;
 303                         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 304                         if (smc_curs_diff(conn->rmb_desc->len, &cons,
 305                                           &conn->urg_curs) > 1)
 306                                 conn->urg_rx_skip_pend = true;
 307                         /* Urgent Byte was already accounted for, but trigger
 308                          * skipping the urgent byte in non-inline case
 309                          */
 310                         if (!(flags & MSG_PEEK))
 311                                 smc_rx_update_consumer(smc, cons, 0);
 312                 } else {
 313                         msg->msg_flags |= MSG_TRUNC;
 314                 }
 315
 316                 return rc ? -EFAULT : len;
 317         }
 318
 319         if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
 320                 return 0;
 321
 322         return -EAGAIN;
 323 }
 324
 325 static bool smc_rx_recvmsg_data_available(struct smc_sock *smc)
 326 {
 327         struct smc_connection *conn = &smc->conn;
 328
 329         if (smc_rx_data_available(conn))
 330                 return true;
 331         else if (conn->urg_state == SMC_URG_VALID)
 332                 /* we received a single urgent Byte - skip */
 333                 smc_rx_update_cons(smc, 0);
 334         return false;
 335 }
 336
 337 /* smc_rx_recvmsg - receive data from RMBE
 338  * @msg:        copy data to receive buffer
 339  * @pipe:       copy data to pipe if set - indicates splice() call
 340  *
 341  * rcvbuf consumer: main API called by socket layer.
 342  * Called under sk lock.
 343  */
 344 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
 345                    struct pipe_inode_info *pipe, size_t len, int flags)
 346 {
 347         size_t copylen, read_done = 0, read_remaining = len;
 348         size_t chunk_len, chunk_off, chunk_len_sum;
 349         struct smc_connection *conn = &smc->conn;
 350         int (*func)(struct smc_connection *conn);
 351         union smc_host_cursor cons;
 352         int readable, chunk;
 353         char *rcvbuf_base;
 354         struct sock *sk;
 355         int splbytes;
 356         long timeo;
 357         int target;             /* Read at least these many bytes */
 358         int rc;
 359
 360         if (unlikely(flags & MSG_ERRQUEUE))
 361                 return -EINVAL; /* future work for sk.sk_family == AF_SMC */
 362
 363         sk = &smc->sk;
 364         if (sk->sk_state == SMC_LISTEN)
 365                 return -ENOTCONN;
 366         if (flags & MSG_OOB)
 367                 return smc_rx_recv_urg(smc, msg, len, flags);
 368         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 369         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
 370
 371         readable = atomic_read(&conn->bytes_to_rcv);
 372         if (readable >= conn->rmb_desc->len)
 373                 SMC_STAT_RMB_RX_FULL(smc, !conn->lnk);
 374
 375         if (len < readable)
 376                 SMC_STAT_RMB_RX_SIZE_SMALL(smc, !conn->lnk);
 377         /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
 378         rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
 379
 380         do { /* while (read_remaining) */
 381                 if (read_done >= target || (pipe && read_done))
 382                         break;
 383
 384                 if (conn->killed)
 385                         break;
 386
 387                 if (smc_rx_recvmsg_data_available(smc))
 388                         goto copy;
 389
 390                 if (sk->sk_shutdown & RCV_SHUTDOWN) {
 391                         /* smc_cdc_msg_recv_action() could have run after
 392                          * above smc_rx_recvmsg_data_available()
 393                          */
 394                         if (smc_rx_recvmsg_data_available(smc))
 395                                 goto copy;
 396                         break;
 397                 }
 398
 399                 if (read_done) {
 400                         if (sk->sk_err ||
 401                             sk->sk_state == SMC_CLOSED ||
 402                             !timeo ||
 403                             signal_pending(current))
 404                                 break;
 405                 } else {
 406                         if (sk->sk_err) {
 407                                 read_done = sock_error(sk);
 408                                 break;
 409                         }
 410                         if (sk->sk_state == SMC_CLOSED) {
 411                                 if (!sock_flag(sk, SOCK_DONE)) {
 412                                         /* This occurs when user tries to read
 413                                          * from never connected socket.
 414                                          */
 415                                         read_done = -ENOTCONN;
 416                                         break;
 417                                 }
 418                                 break;
 419                         }
 420                         if (!timeo)
 421                                 return -EAGAIN;
 422                         if (signal_pending(current)) {
 423                                 read_done = sock_intr_errno(timeo);
 424                                 break;
 425                         }
 426                 }
 427
 428                 if (!smc_rx_data_available(conn)) {
 429                         smc_rx_wait(smc, &timeo, smc_rx_data_available);
 430                         continue;
 431                 }
 432
 433 copy:
 434                 /* initialize variables for 1st iteration of subsequent loop */
 435                 /* could be just 1 byte, even after waiting on data above */
 436                 readable = atomic_read(&conn->bytes_to_rcv);
 437                 splbytes = atomic_read(&conn->splice_pending);
 438                 if (!readable || (msg && splbytes)) {
 439                         if (splbytes)
 440                                 func = smc_rx_data_available_and_no_splice_pend;
 441                         else
 442                                 func = smc_rx_data_available;
 443                         smc_rx_wait(smc, &timeo, func);
 444                         continue;
 445                 }
 446
 447                 smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 448                 /* subsequent splice() calls pick up where previous left */
 449                 if (splbytes)
 450                         smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
 451                 if (conn->urg_state == SMC_URG_VALID &&
 452                     sock_flag(&smc->sk, SOCK_URGINLINE) &&
 453                     readable > 1)
 454                         readable--;     /* always stop at urgent Byte */
 455                 /* not more than what user space asked for */
 456                 copylen = min_t(size_t, read_remaining, readable);
 457                 /* determine chunks where to read from rcvbuf */
 458                 /* either unwrapped case, or 1st chunk of wrapped case */
 459                 chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
 460                                   cons.count);
 461                 chunk_len_sum = chunk_len;
 462                 chunk_off = cons.count;
 463                 smc_rmb_sync_sg_for_cpu(conn);
 464                 for (chunk = 0; chunk < 2; chunk++) {
 465                         if (!(flags & MSG_TRUNC)) {
 466                                 if (msg) {
 467                                         rc = memcpy_to_msg(msg, rcvbuf_base +
 468                                                            chunk_off,
 469                                                            chunk_len);
 470                                 } else {
 471                                         rc = smc_rx_splice(pipe, rcvbuf_base +
 472                                                         chunk_off, chunk_len,
 473                                                         smc);
 474                                 }
 475                                 if (rc < 0) {
 476                                         if (!read_done)
 477                                                 read_done = -EFAULT;
 478                                         goto out;
 479                                 }
 480                         }
 481                         read_remaining -= chunk_len;
 482                         read_done += chunk_len;
 483
 484                         if (chunk_len_sum == copylen)
 485                                 break; /* either on 1st or 2nd iteration */
 486                         /* prepare next (== 2nd) iteration */
 487                         chunk_len = copylen - chunk_len; /* remainder */
 488                         chunk_len_sum += chunk_len;
 489                         chunk_off = 0; /* modulo offset in recv ring buffer */
 490                 }
 491
 492                 /* update cursors */
 493                 if (!(flags & MSG_PEEK)) {
 494                         /* increased in recv tasklet smc_cdc_msg_rcv() */
 495                         smp_mb__before_atomic();
 496                         atomic_sub(copylen, &conn->bytes_to_rcv);
 497                         /* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
 498                         smp_mb__after_atomic();
 499                         if (msg && smc_rx_update_consumer(smc, cons, copylen))
 500                                 goto out;
 501                 }
 502
 503                 trace_smc_rx_recvmsg(smc, copylen);
 504         } while (read_remaining);
 505 out:
 506         return read_done;
 507 }
 508
 509 /* Initialize receive properties on connection establishment. NB: not __init! */
 510 void smc_rx_init(struct smc_sock *smc)
 511 {
 512         smc->sk.sk_data_ready = smc_rx_wake_up;
 513         atomic_set(&smc->conn.splice_pending, 0);
 514         smc->conn.urg_state = SMC_URG_READ;
 515 }