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 <[email protected]>
  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  */
  51 static void smc_rx_update_consumer(struct smc_connection *conn,
  52                                    union smc_host_cursor cons, size_t len)
  53 {
  54         smc_curs_add(conn->rmbe_size, &cons, len);
  55         smc_curs_write(&conn->local_tx_ctrl.cons, smc_curs_read(&cons, conn),
  56                        conn);
  57         /* send consumer cursor update if required */
  58         /* similar to advertising new TCP rcv_wnd if required */
  59         smc_tx_consumer_update(conn);
  60 }
  61
  62 struct smc_spd_priv {
  63         struct smc_sock *smc;
  64         size_t           len;
  65 };
  66
  67 static void smc_rx_pipe_buf_release(struct pipe_inode_info *pipe,
  68                                     struct pipe_buffer *buf)
  69 {
  70         struct smc_spd_priv *priv = (struct smc_spd_priv *)buf->private;
  71         struct smc_sock *smc = priv->smc;
  72         struct smc_connection *conn;
  73         union smc_host_cursor cons;
  74         struct sock *sk = &smc->sk;
  75
  76         if (sk->sk_state == SMC_CLOSED ||
  77             sk->sk_state == SMC_PEERFINCLOSEWAIT ||
  78             sk->sk_state == SMC_APPFINCLOSEWAIT)
  79                 goto out;
  80         conn = &smc->conn;
  81         lock_sock(sk);
  82         smc_curs_write(&cons, smc_curs_read(&conn->local_tx_ctrl.cons, conn),
  83                        conn);
  84         smc_rx_update_consumer(conn, cons, priv->len);
  85         release_sock(sk);
  86         if (atomic_sub_and_test(priv->len, &conn->splice_pending))
  87                 smc_rx_wake_up(sk);
  88 out:
  89         kfree(priv);
  90         put_page(buf->page);
  91         sock_put(sk);
  92 }
  93
  94 static int smc_rx_pipe_buf_nosteal(struct pipe_inode_info *pipe,
  95                                    struct pipe_buffer *buf)
  96 {
  97         return 1;
  98 }
  99
 100 static const struct pipe_buf_operations smc_pipe_ops = {
 101         .can_merge = 0,
 102         .confirm = generic_pipe_buf_confirm,
 103         .release = smc_rx_pipe_buf_release,
 104         .steal = smc_rx_pipe_buf_nosteal,
 105         .get = generic_pipe_buf_get
 106 };
 107
 108 static void smc_rx_spd_release(struct splice_pipe_desc *spd,
 109                                unsigned int i)
 110 {
 111         put_page(spd->pages[i]);
 112 }
 113
 114 static int smc_rx_splice(struct pipe_inode_info *pipe, char *src, size_t len,
 115                          struct smc_sock *smc)
 116 {
 117         struct splice_pipe_desc spd;
 118         struct partial_page partial;
 119         struct smc_spd_priv *priv;
 120         struct page *page;
 121         int bytes;
 122
 123         page = virt_to_page(smc->conn.rmb_desc->cpu_addr);
 124         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 125         if (!priv)
 126                 return -ENOMEM;
 127         priv->len = len;
 128         priv->smc = smc;
 129         partial.offset = src - (char *)smc->conn.rmb_desc->cpu_addr;
 130         partial.len = len;
 131         partial.private = (unsigned long)priv;
 132
 133         spd.nr_pages_max = 1;
 134         spd.nr_pages = 1;
 135         spd.pages = &page;
 136         spd.partial = &partial;
 137         spd.ops = &smc_pipe_ops;
 138         spd.spd_release = smc_rx_spd_release;
 139
 140         bytes = splice_to_pipe(pipe, &spd);
 141         if (bytes > 0) {
 142                 sock_hold(&smc->sk);
 143                 get_page(smc->conn.rmb_desc->pages);
 144                 atomic_add(bytes, &smc->conn.splice_pending);
 145         }
 146
 147         return bytes;
 148 }
 149
 150 static int smc_rx_data_available_and_no_splice_pend(struct smc_connection *conn)
 151 {
 152         return atomic_read(&conn->bytes_to_rcv) &&
 153                !atomic_read(&conn->splice_pending);
 154 }
 155
 156 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
 157  *   @smc    smc socket
 158  *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
 159  *   @fcrit  add'l criterion to evaluate as function pointer
 160  * Returns:
 161  * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
 162  * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
 163  */
 164 int smc_rx_wait(struct smc_sock *smc, long *timeo,
 165                 int (*fcrit)(struct smc_connection *conn))
 166 {
 167         DEFINE_WAIT_FUNC(wait, woken_wake_function);
 168         struct smc_connection *conn = &smc->conn;
 169         struct sock *sk = &smc->sk;
 170         int rc;
 171
 172         if (fcrit(conn))
 173                 return 1;
 174         sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 175         add_wait_queue(sk_sleep(sk), &wait);
 176         rc = sk_wait_event(sk, timeo,
 177                            sk->sk_err ||
 178                            sk->sk_shutdown & RCV_SHUTDOWN ||
 179                            fcrit(conn) ||
 180                            smc_cdc_rxed_any_close_or_senddone(conn),
 181                            &wait);
 182         remove_wait_queue(sk_sleep(sk), &wait);
 183         sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
 184         return rc;
 185 }
 186
 187 /* smc_rx_recvmsg - receive data from RMBE
 188  * @msg:        copy data to receive buffer
 189  * @pipe:       copy data to pipe if set - indicates splice() call
 190  *
 191  * rcvbuf consumer: main API called by socket layer.
 192  * Called under sk lock.
 193  */
 194 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg,
 195                    struct pipe_inode_info *pipe, size_t len, int flags)
 196 {
 197         size_t copylen, read_done = 0, read_remaining = len;
 198         size_t chunk_len, chunk_off, chunk_len_sum;
 199         struct smc_connection *conn = &smc->conn;
 200         int (*func)(struct smc_connection *conn);
 201         union smc_host_cursor cons;
 202         int readable, chunk;
 203         char *rcvbuf_base;
 204         struct sock *sk;
 205         int splbytes;
 206         long timeo;
 207         int target;             /* Read at least these many bytes */
 208         int rc;
 209
 210         if (unlikely(flags & MSG_ERRQUEUE))
 211                 return -EINVAL; /* future work for sk.sk_family == AF_SMC */
 212         if (flags & MSG_OOB)
 213                 return -EINVAL; /* future work */
 214
 215         sk = &smc->sk;
 216         if (sk->sk_state == SMC_LISTEN)
 217                 return -ENOTCONN;
 218         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 219         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
 220
 221         /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
 222         rcvbuf_base = conn->rmb_desc->cpu_addr;
 223
 224         do { /* while (read_remaining) */
 225                 if (read_done >= target || (pipe && read_done))
 226                         break;
 227
 228                 if (atomic_read(&conn->bytes_to_rcv))
 229                         goto copy;
 230
 231                 if (sk->sk_shutdown & RCV_SHUTDOWN ||
 232                     smc_cdc_rxed_any_close_or_senddone(conn) ||
 233                     conn->local_tx_ctrl.conn_state_flags.peer_conn_abort)
 234                         break;
 235
 236                 if (read_done) {
 237                         if (sk->sk_err ||
 238                             sk->sk_state == SMC_CLOSED ||
 239                             !timeo ||
 240                             signal_pending(current))
 241                                 break;
 242                 } else {
 243                         if (sk->sk_err) {
 244                                 read_done = sock_error(sk);
 245                                 break;
 246                         }
 247                         if (sk->sk_state == SMC_CLOSED) {
 248                                 if (!sock_flag(sk, SOCK_DONE)) {
 249                                         /* This occurs when user tries to read
 250                                          * from never connected socket.
 251                                          */
 252                                         read_done = -ENOTCONN;
 253                                         break;
 254                                 }
 255                                 break;
 256                         }
 257                         if (signal_pending(current)) {
 258                                 read_done = sock_intr_errno(timeo);
 259                                 break;
 260                         }
 261                         if (!timeo)
 262                                 return -EAGAIN;
 263                 }
 264
 265                 if (!smc_rx_data_available(conn)) {
 266                         smc_rx_wait(smc, &timeo, smc_rx_data_available);
 267                         continue;
 268                 }
 269
 270 copy:
 271                 /* initialize variables for 1st iteration of subsequent loop */
 272                 /* could be just 1 byte, even after waiting on data above */
 273                 readable = atomic_read(&conn->bytes_to_rcv);
 274                 splbytes = atomic_read(&conn->splice_pending);
 275                 if (!readable || (msg && splbytes)) {
 276                         if (splbytes)
 277                                 func = smc_rx_data_available_and_no_splice_pend;
 278                         else
 279                                 func = smc_rx_data_available;
 280                         smc_rx_wait(smc, &timeo, func);
 281                         continue;
 282                 }
 283
 284                 /* not more than what user space asked for */
 285                 copylen = min_t(size_t, read_remaining, readable);
 286                 smc_curs_write(&cons,
 287                                smc_curs_read(&conn->local_tx_ctrl.cons, conn),
 288                                conn);
 289                 /* subsequent splice() calls pick up where previous left */
 290                 if (splbytes)
 291                         smc_curs_add(conn->rmbe_size, &cons, splbytes);
 292                 /* determine chunks where to read from rcvbuf */
 293                 /* either unwrapped case, or 1st chunk of wrapped case */
 294                 chunk_len = min_t(size_t,
 295                                   copylen, conn->rmbe_size - cons.count);
 296                 chunk_len_sum = chunk_len;
 297                 chunk_off = cons.count;
 298                 smc_rmb_sync_sg_for_cpu(conn);
 299                 for (chunk = 0; chunk < 2; chunk++) {
 300                         if (!(flags & MSG_TRUNC)) {
 301                                 if (msg) {
 302                                         rc = memcpy_to_msg(msg, rcvbuf_base +
 303                                                            chunk_off,
 304                                                            chunk_len);
 305                                 } else {
 306                                         rc = smc_rx_splice(pipe, rcvbuf_base +
 307                                                         chunk_off, chunk_len,
 308                                                         smc);
 309                                 }
 310                                 if (rc < 0) {
 311                                         if (!read_done)
 312                                                 read_done = -EFAULT;
 313                                         smc_rmb_sync_sg_for_device(conn);
 314                                         goto out;
 315                                 }
 316                         }
 317                         read_remaining -= chunk_len;
 318                         read_done += chunk_len;
 319
 320                         if (chunk_len_sum == copylen)
 321                                 break; /* either on 1st or 2nd iteration */
 322                         /* prepare next (== 2nd) iteration */
 323                         chunk_len = copylen - chunk_len; /* remainder */
 324                         chunk_len_sum += chunk_len;
 325                         chunk_off = 0; /* modulo offset in recv ring buffer */
 326                 }
 327                 smc_rmb_sync_sg_for_device(conn);
 328
 329                 /* update cursors */
 330                 if (!(flags & MSG_PEEK)) {
 331                         /* increased in recv tasklet smc_cdc_msg_rcv() */
 332                         smp_mb__before_atomic();
 333                         atomic_sub(copylen, &conn->bytes_to_rcv);
 334                         /* guarantee 0 <= bytes_to_rcv <= rmbe_size */
 335                         smp_mb__after_atomic();
 336                         if (msg)
 337                                 smc_rx_update_consumer(conn, cons, copylen);
 338                 }
 339         } while (read_remaining);
 340 out:
 341         return read_done;
 342 }
 343
 344 /* Initialize receive properties on connection establishment. NB: not __init! */
 345 void smc_rx_init(struct smc_sock *smc)
 346 {
 347         smc->sk.sk_data_ready = smc_rx_wake_up;
 348         atomic_set(&smc->conn.splice_pending, 0);
 349 }