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 <ubraun@linux.vnet.ibm.com> 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 } 218