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 splice_pipe_desc spd;
 149         struct partial_page partial;
 150         struct smc_spd_priv *priv;
 151         int bytes;
 152
 153         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 154         if (!priv)
 155                 return -ENOMEM;
 156         priv->len = len;
 157         priv->smc = smc;
 158         partial.offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
 159         partial.len = len;
 160         partial.private = (unsigned long)priv;
 161
 162         spd.nr_pages_max = 1;
 163         spd.nr_pages = 1;
 164         spd.pages = &smc->conn.rmb_desc->pages;
 165         spd.partial = &partial;
 166         spd.ops = &smc_pipe_ops;
 167         spd.spd_release = smc_rx_spd_release;
 168
 169         bytes = splice_to_pipe(pipe, &spd);
 170         if (bytes > 0) {
 171                 sock_hold(&smc->sk);
 172                 get_page(smc->conn.rmb_desc->pages);
 173                 atomic_add(bytes, &smc->conn.splice_pending);
 174         }
 175
 176         return bytes;
 177 }
 178
 179 static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
 180 {
 181         return atomic_read(&conn->bytes_to_rcv) &&
 182                !atomic_read(&conn->splice_pending);
 183 }
 184
 185 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
 186  *   @smc    smc socket
 187  *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
 188  *   @fcrit  add'l criterion to evaluate as function pointer
 189  * Returns:
 190  * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
 191  * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
 192  */
 193 int smc_rx_wait(struct smc_sock *smc, long *timeo,
 194                 int (*fcrit)(struct smc_connection *conn))
 195 {
 196         DEFINE_WAIT_FUNC(wait, woken_wake_function);
 197         struct smc_connection *conn = &smc->conn;
 198         struct smc_cdc_conn_state_flags *cflags =
 199                                         &conn->local_tx_ctrl.conn_state_flags;
 200         struct sock *sk = &smc->sk;
 201         int rc;
 202
 203         if (fcrit(conn))
 204                 return 1;
 205         sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 206         add_wait_queue(sk_sleep(sk), &wait);
 207         rc = sk_wait_event(sk, timeo,
 208                            sk->sk_err ||
 209                            cflags->peer_conn_abort ||
 210                            sk->sk_shutdown & RCV_SHUTDOWN ||
 211                            conn->killed ||
 212                            fcrit(conn),
 213                            &wait);
 214         remove_wait_queue(sk_sleep(sk), &wait);
 215         sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 216         return rc;
 217 }
 218
 219 static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
 220                            int flags)
 221 {
 222         struct smc_connection *conn = &smc->conn;
 223         union smc_host_cursor cons;
 224         struct sock *sk = &smc->sk;
 225         int rc = 0;
 226
 227         if (sock_flag(sk, SOCK_URGINLINE) ||
 228             !(conn->urg_state == SMC_URG_VALID) ||
 229             conn->urg_state == SMC_URG_READ)
 230                 return -EINVAL;
 231
 232         SMC_STAT_INC(smc, urg_data_cnt);
 233         if (conn->urg_state == SMC_URG_VALID) {
 234                 if (!(flags & MSG_PEEK))
 235                         smc->conn.urg_state = SMC_URG_READ;
 236                 msg->msg_flags |= MSG_OOB;
 237                 if (len > 0) {
 238                         if (!(flags & MSG_TRUNC))
 239                                 rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
 240                         len = 1;
 241                         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 242                         if (smc_curs_diff(conn->rmb_desc->len, &cons,
 243                                           &conn->urg_curs) > 1)
 244                                 conn->urg_rx_skip_pend = true;
 245                         /* Urgent Byte was already accounted for, but trigger
 246                          * skipping the urgent byte in non-inline case
 247                          */
 248                         if (!(flags & MSG_PEEK))
 249                                 smc_rx_update_consumer(smc, cons, 0);
 250                 } else {
 251                         msg->msg_flags |= MSG_TRUNC;
 252                 }
 253
 254                 return rc ? -EFAULT : len;
 255         }
 256
 257         if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
 258                 return 0;
 259
 260         return -EAGAIN;
 261 }
 262
 263 static bool smc_rx_recvmsg_data_available(struct smc_sock *smc)
 264 {
 265         struct smc_connection *conn = &smc->conn;
 266
 267         if (smc_rx_data_available(conn))
 268                 return true;
 269         else if (conn->urg_state == SMC_URG_VALID)
 270                 /* we received a single urgent Byte - skip */
 271                 smc_rx_update_cons(smc, 0);
 272         return false;
 273 }
 274
 275 /* smc_rx_recvmsg - receive data from RMBE
 276  * @msg:        copy data to receive buffer
 277  * @pipe:       copy data to pipe if set - indicates splice() call
 278  *
 279  * rcvbuf consumer: main API called by socket layer.
 280  * Called under sk lock.
 281  */
 282 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
 283                    struct pipe_inode_info *pipe, size_t len, int flags)
 284 {
 285         size_t copylen, read_done = 0, read_remaining = len;
 286         size_t chunk_len, chunk_off, chunk_len_sum;
 287         struct smc_connection *conn = &smc->conn;
 288         int (*func)(struct smc_connection *conn);
 289         union smc_host_cursor cons;
 290         int readable, chunk;
 291         char *rcvbuf_base;
 292         struct sock *sk;
 293         int splbytes;
 294         long timeo;
 295         int target;             /* Read at least these many bytes */
 296         int rc;
 297
 298         if (unlikely(flags & MSG_ERRQUEUE))
 299                 return -EINVAL; /* future work for sk.sk_family == AF_SMC */
 300
 301         sk = &smc->sk;
 302         if (sk->sk_state == SMC_LISTEN)
 303                 return -ENOTCONN;
 304         if (flags & MSG_OOB)
 305                 return smc_rx_recv_urg(smc, msg, len, flags);
 306         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 307         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
 308
 309         readable = atomic_read(&conn->bytes_to_rcv);
 310         if (readable >= conn->rmb_desc->len)
 311                 SMC_STAT_RMB_RX_FULL(smc, !conn->lnk);
 312
 313         if (len < readable)
 314                 SMC_STAT_RMB_RX_SIZE_SMALL(smc, !conn->lnk);
 315         /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
 316         rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
 317
 318         do { /* while (read_remaining) */
 319                 if (read_done >= target || (pipe && read_done))
 320                         break;
 321
 322                 if (conn->killed)
 323                         break;
 324
 325                 if (smc_rx_recvmsg_data_available(smc))
 326                         goto copy;
 327
 328                 if (sk->sk_shutdown & RCV_SHUTDOWN) {
 329                         /* smc_cdc_msg_recv_action() could have run after
 330                          * above smc_rx_recvmsg_data_available()
 331                          */
 332                         if (smc_rx_recvmsg_data_available(smc))
 333                                 goto copy;
 334                         break;
 335                 }
 336
 337                 if (read_done) {
 338                         if (sk->sk_err ||
 339                             sk->sk_state == SMC_CLOSED ||
 340                             !timeo ||
 341                             signal_pending(current))
 342                                 break;
 343                 } else {
 344                         if (sk->sk_err) {
 345                                 read_done = sock_error(sk);
 346                                 break;
 347                         }
 348                         if (sk->sk_state == SMC_CLOSED) {
 349                                 if (!sock_flag(sk, SOCK_DONE)) {
 350                                         /* This occurs when user tries to read
 351                                          * from never connected socket.
 352                                          */
 353                                         read_done = -ENOTCONN;
 354                                         break;
 355                                 }
 356                                 break;
 357                         }
 358                         if (!timeo)
 359                                 return -EAGAIN;
 360                         if (signal_pending(current)) {
 361                                 read_done = sock_intr_errno(timeo);
 362                                 break;
 363                         }
 364                 }
 365
 366                 if (!smc_rx_data_available(conn)) {
 367                         smc_rx_wait(smc, &timeo, smc_rx_data_available);
 368                         continue;
 369                 }
 370
 371 copy:
 372                 /* initialize variables for 1st iteration of subsequent loop */
 373                 /* could be just 1 byte, even after waiting on data above */
 374                 readable = atomic_read(&conn->bytes_to_rcv);
 375                 splbytes = atomic_read(&conn->splice_pending);
 376                 if (!readable || (msg && splbytes)) {
 377                         if (splbytes)
 378                                 func = smc_rx_data_available_and_no_splice_pend;
 379                         else
 380                                 func = smc_rx_data_available;
 381                         smc_rx_wait(smc, &timeo, func);
 382                         continue;
 383                 }
 384
 385                 smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 386                 /* subsequent splice() calls pick up where previous left */
 387                 if (splbytes)
 388                         smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
 389                 if (conn->urg_state == SMC_URG_VALID &&
 390                     sock_flag(&smc->sk, SOCK_URGINLINE) &&
 391                     readable > 1)
 392                         readable--;     /* always stop at urgent Byte */
 393                 /* not more than what user space asked for */
 394                 copylen = min_t(size_t, read_remaining, readable);
 395                 /* determine chunks where to read from rcvbuf */
 396                 /* either unwrapped case, or 1st chunk of wrapped case */
 397                 chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
 398                                   cons.count);
 399                 chunk_len_sum = chunk_len;
 400                 chunk_off = cons.count;
 401                 smc_rmb_sync_sg_for_cpu(conn);
 402                 for (chunk = 0; chunk < 2; chunk++) {
 403                         if (!(flags & MSG_TRUNC)) {
 404                                 if (msg) {
 405                                         rc = memcpy_to_msg(msg, rcvbuf_base +
 406                                                            chunk_off,
 407                                                            chunk_len);
 408                                 } else {
 409                                         rc = smc_rx_splice(pipe, rcvbuf_base +
 410                                                         chunk_off, chunk_len,
 411                                                         smc);
 412                                 }
 413                                 if (rc < 0) {
 414                                         if (!read_done)
 415                                                 read_done = -EFAULT;
 416                                         smc_rmb_sync_sg_for_device(conn);
 417                                         goto out;
 418                                 }
 419                         }
 420                         read_remaining -= chunk_len;
 421                         read_done += chunk_len;
 422
 423                         if (chunk_len_sum == copylen)
 424                                 break; /* either on 1st or 2nd iteration */
 425                         /* prepare next (== 2nd) iteration */
 426                         chunk_len = copylen - chunk_len; /* remainder */
 427                         chunk_len_sum += chunk_len;
 428                         chunk_off = 0; /* modulo offset in recv ring buffer */
 429                 }
 430                 smc_rmb_sync_sg_for_device(conn);
 431
 432                 /* update cursors */
 433                 if (!(flags & MSG_PEEK)) {
 434                         /* increased in recv tasklet smc_cdc_msg_rcv() */
 435                         smp_mb__before_atomic();
 436                         atomic_sub(copylen, &conn->bytes_to_rcv);
 437                         /* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
 438                         smp_mb__after_atomic();
 439                         if (msg && smc_rx_update_consumer(smc, cons, copylen))
 440                                 goto out;
 441                 }
 442
 443                 trace_smc_rx_recvmsg(smc, copylen);
 444         } while (read_remaining);
 445 out:
 446         return read_done;
 447 }
 448
 449 /* Initialize receive properties on connection establishment. NB: not __init! */
 450 void smc_rx_init(struct smc_sock *smc)
 451 {
 452         smc->sk.sk_data_ready = smc_rx_wake_up;
 453         atomic_set(&smc->conn.splice_pending, 0);
 454         smc->conn.urg_state = SMC_URG_READ;
 455 }