net/smc/smc_rx.c

   1 /*
   2  * Shared Memory Communications over RDMA (SMC-R) and RoCE
   3  *
   4  * Manage RMBE
   5  * copy new RMBE data into user space
   6  *
   7  * Copyright IBM Corp. 2016
   8  *
   9  * Author(s):  Ursula Braun <[email protected]>
  10  */
  11
  12 #include <linux/net.h>
  13 #include <linux/rcupdate.h>
  14 #include <net/sock.h>
  15
  16 #include "smc.h"
  17 #include "smc_core.h"
  18 #include "smc_cdc.h"
  19 #include "smc_tx.h" /* smc_tx_consumer_update() */
  20 #include "smc_rx.h"
  21
  22 /* callback implementation for sk.sk_data_ready()
  23  * to wakeup rcvbuf consumers that blocked with smc_rx_wait_data().
  24  * indirectly called by smc_cdc_msg_recv_action().
  25  */
  26 static void smc_rx_data_ready(struct sock *sk)
  27 {
  28         struct socket_wq *wq;
  29
  30         /* derived from sock_def_readable() */
  31         /* called already in smc_listen_work() */
  32         rcu_read_lock();
  33         wq = rcu_dereference(sk->sk_wq);
  34         if (skwq_has_sleeper(wq))
  35                 wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLPRI |
  36                                                 POLLRDNORM | POLLRDBAND);
  37         if ((sk->sk_shutdown == SHUTDOWN_MASK) ||
  38             (sk->sk_state == SMC_CLOSED))
  39                 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
  40         else
  41                 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN);
  42         rcu_read_unlock();
  43 }
  44
  45 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted
  46  *   @smc    smc socket
  47  *   @timeo  pointer to max seconds to wait, pointer to value 0 for no timeout
  48  * Returns:
  49  * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
  50  * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
  51  */
  52 static int smc_rx_wait_data(struct smc_sock *smc, long *timeo)
  53 {
  54         DEFINE_WAIT_FUNC(wait, woken_wake_function);
  55         struct smc_connection *conn = &smc->conn;
  56         struct sock *sk = &smc->sk;
  57         int rc;
  58
  59         if (atomic_read(&conn->bytes_to_rcv))
  60                 return 1;
  61         sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
  62         add_wait_queue(sk_sleep(sk), &wait);
  63         rc = sk_wait_event(sk, timeo,
  64                            sk->sk_err ||
  65                            sk->sk_shutdown & RCV_SHUTDOWN ||
  66                            sock_flag(sk, SOCK_DONE) ||
  67                            atomic_read(&conn->bytes_to_rcv) ||
  68                            smc_cdc_rxed_any_close_or_senddone(conn),
  69                            &wait);
  70         remove_wait_queue(sk_sleep(sk), &wait);
  71         sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
  72         return rc;
  73 }
  74
  75 /* rcvbuf consumer: main API called by socket layer.
  76  * called under sk lock.
  77  */
  78 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len,
  79                    int flags)
  80 {
  81         size_t copylen, read_done = 0, read_remaining = len;
  82         size_t chunk_len, chunk_off, chunk_len_sum;
  83         struct smc_connection *conn = &smc->conn;
  84         union smc_host_cursor cons;
  85         int readable, chunk;
  86         char *rcvbuf_base;
  87         struct sock *sk;
  88         long timeo;
  89         int target;             /* Read at least these many bytes */
  90         int rc;
  91
  92         if (unlikely(flags & MSG_ERRQUEUE))
  93                 return -EINVAL; /* future work for sk.sk_family == AF_SMC */
  94         if (flags & MSG_OOB)
  95                 return -EINVAL; /* future work */
  96
  97         sk = &smc->sk;
  98         if (sk->sk_state == SMC_LISTEN)
  99                 return -ENOTCONN;
 100         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
 101         target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
 102
 103         msg->msg_namelen = 0;
 104         /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */
 105         rcvbuf_base = conn->rmb_desc->cpu_addr;
 106
 107         do { /* while (read_remaining) */
 108                 if (read_done >= target)
 109                         break;
 110
 111                 if (atomic_read(&conn->bytes_to_rcv))
 112                         goto copy;
 113
 114                 if (read_done) {
 115                         if (sk->sk_err ||
 116                             sk->sk_state == SMC_CLOSED ||
 117                             (sk->sk_shutdown & RCV_SHUTDOWN) ||
 118                             !timeo ||
 119                             signal_pending(current) ||
 120                             smc_cdc_rxed_any_close_or_senddone(conn) ||
 121                             conn->local_tx_ctrl.conn_state_flags.
 122                             peer_conn_abort)
 123                                 break;
 124                 } else {
 125                         if (sock_flag(sk, SOCK_DONE))
 126                                 break;
 127                         if (sk->sk_err) {
 128                                 read_done = sock_error(sk);
 129                                 break;
 130                         }
 131                         if (sk->sk_shutdown & RCV_SHUTDOWN ||
 132                             smc_cdc_rxed_any_close_or_senddone(conn) ||
 133                             conn->local_tx_ctrl.conn_state_flags.
 134                             peer_conn_abort)
 135                                 break;
 136                         if (sk->sk_state == SMC_CLOSED) {
 137                                 if (!sock_flag(sk, SOCK_DONE)) {
 138                                         /* This occurs when user tries to read
 139                                          * from never connected socket.
 140                                          */
 141                                         read_done = -ENOTCONN;
 142                                         break;
 143                                 }
 144                                 break;
 145                         }
 146                         if (signal_pending(current)) {
 147                                 read_done = sock_intr_errno(timeo);
 148                                 break;
 149                         }
 150                 }
 151
 152                 if (!atomic_read(&conn->bytes_to_rcv)) {
 153                         smc_rx_wait_data(smc, &timeo);
 154                         continue;
 155                 }
 156
 157 copy:
 158                 /* initialize variables for 1st iteration of subsequent loop */
 159                 /* could be just 1 byte, even after smc_rx_wait_data above */
 160                 readable = atomic_read(&conn->bytes_to_rcv);
 161                 /* not more than what user space asked for */
 162                 copylen = min_t(size_t, read_remaining, readable);
 163                 smc_curs_write(&cons,
 164                                smc_curs_read(&conn->local_tx_ctrl.cons, conn),
 165                                conn);
 166                 /* determine chunks where to read from rcvbuf */
 167                 /* either unwrapped case, or 1st chunk of wrapped case */
 168                 chunk_len = min_t(size_t,
 169                                   copylen, conn->rmbe_size - cons.count);
 170                 chunk_len_sum = chunk_len;
 171                 chunk_off = cons.count;
 172                 for (chunk = 0; chunk < 2; chunk++) {
 173                         if (!(flags & MSG_TRUNC)) {
 174                                 rc = memcpy_to_msg(msg, rcvbuf_base + chunk_off,
 175                                                    chunk_len);
 176                                 if (rc) {
 177                                         if (!read_done)
 178                                                 read_done = -EFAULT;
 179                                         goto out;
 180                                 }
 181                         }
 182                         read_remaining -= chunk_len;
 183                         read_done += chunk_len;
 184
 185                         if (chunk_len_sum == copylen)
 186                                 break; /* either on 1st or 2nd iteration */
 187                         /* prepare next (== 2nd) iteration */
 188                         chunk_len = copylen - chunk_len; /* remainder */
 189                         chunk_len_sum += chunk_len;
 190                         chunk_off = 0; /* modulo offset in recv ring buffer */
 191                 }
 192
 193                 /* update cursors */
 194                 if (!(flags & MSG_PEEK)) {
 195                         smc_curs_add(conn->rmbe_size, &cons, copylen);
 196                         /* increased in recv tasklet smc_cdc_msg_rcv() */
 197                         smp_mb__before_atomic();
 198                         atomic_sub(copylen, &conn->bytes_to_rcv);
 199                         /* guarantee 0 <= bytes_to_rcv <= rmbe_size */
 200                         smp_mb__after_atomic();
 201                         smc_curs_write(&conn->local_tx_ctrl.cons,
 202                                        smc_curs_read(&cons, conn),
 203                                        conn);
 204                         /* send consumer cursor update if required */
 205                         /* similar to advertising new TCP rcv_wnd if required */
 206                         smc_tx_consumer_update(conn);
 207                 }
 208         } while (read_remaining);
 209 out:
 210         return read_done;
 211 }
 212
 213 /* Initialize receive properties on connection establishment. NB: not __init! */
 214 void smc_rx_init(struct smc_sock *smc)
 215 {
 216         smc->sk.sk_data_ready = smc_rx_data_ready;
 217 }