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