LXR linux/net/smc/smc

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