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