root/net/smc/smc_rx.c

DEFINITIONS

1. smc_rx_wake_up
2. smc_rx_update_consumer
3. smc_rx_update_cons
4. smc_rx_pipe_buf_release
5. smc_rx_pipe_buf_nosteal
6. smc_rx_spd_release
7. smc_rx_splice
8. smc_rx_data_available_and_no_splice_pend
9. smc_rx_wait
10. smc_rx_recv_urg
11. smc_rx_recvmsg_data_available
12. smc_rx_recvmsg
13. smc_rx_init

   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         .confirm = generic_pipe_buf_confirm,
 140         .release = smc_rx_pipe_buf_release,
 141         .steal = smc_rx_pipe_buf_nosteal,
 142         .get = generic_pipe_buf_get
 143 };
 144 
 145 static void smc_rx_spd_release(struct splice_pipe_desc *spd,
 146                                unsigned int i)
 147 {
 148         put_page(spd->pages[i]);
 149 }
 150 
 151 static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
 152                          struct smc_sock *smc)
 153 {
 154         struct splice_pipe_desc spd;
 155         struct partial_page partial;
 156         struct smc_spd_priv *priv;
 157         int bytes;
 158 
 159         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 160         if (!priv)
 161                 return -ENOMEM;
 162         priv->len = len;
 163         priv->smc = smc;
 164         partial.offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
 165         partial.len = len;
 166         partial.private = (unsigned long)priv;
 167 
 168         spd.nr_pages_max = 1;
 169         spd.nr_pages = 1;
 170         spd.pages = &smc->conn.rmb_desc->pages;
 171         spd.partial = &partial;
 172         spd.ops = &smc_pipe_ops;
 173         spd.spd_release = smc_rx_spd_release;
 174 
 175         bytes = splice_to_pipe(pipe, &spd);
 176         if (bytes > 0) {
 177                 sock_hold(&smc->sk);
 178                 get_page(smc->conn.rmb_desc->pages);
 179                 atomic_add(bytes, &smc->conn.splice_pending);
 180         }
 181 
 182         return bytes;
 183 }
 184 
 185 static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
 186 {
 187         return atomic_read(&conn->bytes_to_rcv) &&
 188                !atomic_read(&conn->splice_pending);
 189 }
 190 
 191 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
 192  *   @smc    smc socket
 193  *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
 194  *   @fcrit  add'l criterion to evaluate as function pointer
 195  * Returns:
 196  * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
 197  * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
 198  */
 199 int smc_rx_wait(struct smc_sock *smc, long *timeo,
 200                 int (*fcrit)(struct smc_connection *conn))
 201 {
 202         DEFINE_WAIT_FUNC(wait, woken_wake_function);
 203         struct smc_connection *conn = &smc->conn;
 204         struct sock *sk = &smc->sk;
 205         int rc;
 206 
 207         if (fcrit(conn))
 208                 return 1;
 209         sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 210         add_wait_queue(sk_sleep(sk), &wait);
 211         rc = sk_wait_event(sk, timeo,
 212                            sk->sk_err ||
 213                            sk->sk_shutdown & RCV_SHUTDOWN ||
 214                            fcrit(conn),
 215                            &wait);
 216         remove_wait_queue(sk_sleep(sk), &wait);
 217         sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 218         return rc;
 219 }
 220 
 221 static int smc_rx_recv_urg(struct smc_sock *smc, struct msghdr *msg, int len,
 222                            int flags)
 223 {
 224         struct smc_connection *conn = &smc->conn;
 225         union smc_host_cursor cons;
 226         struct sock *sk = &smc->sk;
 227         int rc = 0;
 228 
 229         if (sock_flag(sk, SOCK_URGINLINE) ||
 230             !(conn->urg_state == SMC_URG_VALID) ||
 231             conn->urg_state == SMC_URG_READ)
 232                 return -EINVAL;
 233 
 234         if (conn->urg_state == SMC_URG_VALID) {
 235                 if (!(flags & MSG_PEEK))
 236                         smc->conn.urg_state = SMC_URG_READ;
 237                 msg->msg_flags |= MSG_OOB;
 238                 if (len > 0) {
 239                         if (!(flags & MSG_TRUNC))
 240                                 rc = memcpy_to_msg(msg, &conn->urg_rx_byte, 1);
 241                         len = 1;
 242                         smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 243                         if (smc_curs_diff(conn->rmb_desc->len, &cons,
 244                                           &conn->urg_curs) > 1)
 245                                 conn->urg_rx_skip_pend = true;
 246                         /* Urgent Byte was already accounted for, but trigger
 247                          * skipping the urgent byte in non-inline case
 248                          */
 249                         if (!(flags & MSG_PEEK))
 250                                 smc_rx_update_consumer(smc, cons, 0);
 251                 } else {
 252                         msg->msg_flags |= MSG_TRUNC;
 253                 }
 254 
 255                 return rc ? -EFAULT : len;
 256         }
 257 
 258         if (sk->sk_state == SMC_CLOSED || sk->sk_shutdown & RCV_SHUTDOWN)
 259                 return 0;
 260 
 261         return -EAGAIN;
 262 }
 263 
 264 static bool smc_rx_recvmsg_data_available(struct smc_sock *smc)
 265 {
 266         struct smc_connection *conn = &smc->conn;
 267 
 268         if (smc_rx_data_available(conn))
 269                 return true;
 270         else if (conn->urg_state == SMC_URG_VALID)
 271                 /* we received a single urgent Byte - skip */
 272                 smc_rx_update_cons(smc, 0);
 273         return false;
 274 }
 275 
 276 /* smc_rx_recvmsg - receive data from RMBE
 277  * @msg:        copy data to receive buffer
 278  * @pipe:       copy data to pipe if set - indicates splice() call
 279  *
 280  * rcvbuf consumer: main API called by socket layer.
 281  * Called under sk lock.
 282  */
 283 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
 284                    struct pipe_inode_info *pipe, size_t len, int flags)
 285 {
 286         size_t copylen, read_done = 0, read_remaining = len;
 287         size_t chunk_len, chunk_off, chunk_len_sum;
 288         struct smc_connection *conn = &smc->conn;
 289         int (*func)(struct smc_connection *conn);
 290         union smc_host_cursor cons;
 291         int readable, chunk;
 292         char *rcvbuf_base;
 293         struct sock *sk;
 294         int splbytes;
 295         long timeo;
 296         int target;             /* Read at least these many bytes */
 297         int rc;
 298 
 299         if (unlikely(flags & MSG_ERRQUEUE))
 300                 return -EINVAL; /* future work for sk.sk_family == AF_SMC */
 301 
 302         sk = &smc->sk;
 303         if (sk->sk_state == SMC_LISTEN)
 304                 return -ENOTCONN;
 305         if (flags & MSG_OOB)
 306                 return smc_rx_recv_urg(smc, msg, len, flags);
 307         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 308         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
 309 
 310         /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
 311         rcvbuf_base = conn->rx_off + conn->rmb_desc->cpu_addr;
 312 
 313         do { /* while (read_remaining) */
 314                 if (read_done >= target || (pipe && read_done))
 315                         break;
 316 
 317                 if (smc_rx_recvmsg_data_available(smc))
 318                         goto copy;
 319 
 320                 if (sk->sk_shutdown & RCV_SHUTDOWN ||
 321                     conn->local_tx_ctrl.conn_state_flags.peer_conn_abort) {
 322                         /* smc_cdc_msg_recv_action() could have run after
 323                          * above smc_rx_recvmsg_data_available()
 324                          */
 325                         if (smc_rx_recvmsg_data_available(smc))
 326                                 goto copy;
 327                         break;
 328                 }
 329 
 330                 if (read_done) {
 331                         if (sk->sk_err ||
 332                             sk->sk_state == SMC_CLOSED ||
 333                             !timeo ||
 334                             signal_pending(current))
 335                                 break;
 336                 } else {
 337                         if (sk->sk_err) {
 338                                 read_done = sock_error(sk);
 339                                 break;
 340                         }
 341                         if (sk->sk_state == SMC_CLOSED) {
 342                                 if (!sock_flag(sk, SOCK_DONE)) {
 343                                         /* This occurs when user tries to read
 344                                          * from never connected socket.
 345                                          */
 346                                         read_done = -ENOTCONN;
 347                                         break;
 348                                 }
 349                                 break;
 350                         }
 351                         if (signal_pending(current)) {
 352                                 read_done = sock_intr_errno(timeo);
 353                                 break;
 354                         }
 355                         if (!timeo)
 356                                 return -EAGAIN;
 357                 }
 358 
 359                 if (!smc_rx_data_available(conn)) {
 360                         smc_rx_wait(smc, &timeo, smc_rx_data_available);
 361                         continue;
 362                 }
 363 
 364 copy:
 365                 /* initialize variables for 1st iteration of subsequent loop */
 366                 /* could be just 1 byte, even after waiting on data above */
 367                 readable = atomic_read(&conn->bytes_to_rcv);
 368                 splbytes = atomic_read(&conn->splice_pending);
 369                 if (!readable || (msg && splbytes)) {
 370                         if (splbytes)
 371                                 func = smc_rx_data_available_and_no_splice_pend;
 372                         else
 373                                 func = smc_rx_data_available;
 374                         smc_rx_wait(smc, &timeo, func);
 375                         continue;
 376                 }
 377 
 378                 smc_curs_copy(&cons, &conn->local_tx_ctrl.cons, conn);
 379                 /* subsequent splice() calls pick up where previous left */
 380                 if (splbytes)
 381                         smc_curs_add(conn->rmb_desc->len, &cons, splbytes);
 382                 if (conn->urg_state == SMC_URG_VALID &&
 383                     sock_flag(&smc->sk, SOCK_URGINLINE) &&
 384                     readable > 1)
 385                         readable--;     /* always stop at urgent Byte */
 386                 /* not more than what user space asked for */
 387                 copylen = min_t(size_t, read_remaining, readable);
 388                 /* determine chunks where to read from rcvbuf */
 389                 /* either unwrapped case, or 1st chunk of wrapped case */
 390                 chunk_len = min_t(size_t, copylen, conn->rmb_desc->len -
 391                                   cons.count);
 392                 chunk_len_sum = chunk_len;
 393                 chunk_off = cons.count;
 394                 smc_rmb_sync_sg_for_cpu(conn);
 395                 for (chunk = 0; chunk < 2; chunk++) {
 396                         if (!(flags & MSG_TRUNC)) {
 397                                 if (msg) {
 398                                         rc = memcpy_to_msg(msg, rcvbuf_base +
 399                                                            chunk_off,
 400                                                            chunk_len);
 401                                 } else {
 402                                         rc = smc_rx_splice(pipe, rcvbuf_base +
 403                                                         chunk_off, chunk_len,
 404                                                         smc);
 405                                 }
 406                                 if (rc < 0) {
 407                                         if (!read_done)
 408                                                 read_done = -EFAULT;
 409                                         smc_rmb_sync_sg_for_device(conn);
 410                                         goto out;
 411                                 }
 412                         }
 413                         read_remaining -= chunk_len;
 414                         read_done += chunk_len;
 415 
 416                         if (chunk_len_sum == copylen)
 417                                 break; /* either on 1st or 2nd iteration */
 418                         /* prepare next (== 2nd) iteration */
 419                         chunk_len = copylen - chunk_len; /* remainder */
 420                         chunk_len_sum += chunk_len;
 421                         chunk_off = 0; /* modulo offset in recv ring buffer */
 422                 }
 423                 smc_rmb_sync_sg_for_device(conn);
 424 
 425                 /* update cursors */
 426                 if (!(flags & MSG_PEEK)) {
 427                         /* increased in recv tasklet smc_cdc_msg_rcv() */
 428                         smp_mb__before_atomic();
 429                         atomic_sub(copylen, &conn->bytes_to_rcv);
 430                         /* guarantee 0 <= bytes_to_rcv <= rmb_desc->len */
 431                         smp_mb__after_atomic();
 432                         if (msg && smc_rx_update_consumer(smc, cons, copylen))
 433                                 goto out;
 434                 }
 435         } while (read_remaining);
 436 out:
 437         return read_done;
 438 }
 439 
 440 /* Initialize receive properties on connection establishment. NB: not __init! */
 441 void smc_rx_init(struct smc_sock *smc)
 442 {
 443         smc->sk.sk_data_ready = smc_rx_wake_up;
 444         atomic_set(&smc->conn.splice_pending, 0);
 445         smc->conn.urg_state = SMC_URG_READ;
 446 }