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 <linux/sched/signal.h> 15 16 #include <net/sock.h> 17 18 #include "smc.h" 19 #include "smc_core.h" 20 #include "smc_cdc.h" 21 #include "smc_tx.h" /* smc_tx_consumer_update() */ 22 #include "smc_rx.h" 23 24 /* callback implementation for sk.sk_data_ready() 25 * to wakeup rcvbuf consumers that blocked with smc_rx_wait_data(). 26 * indirectly called by smc_cdc_msg_recv_action(). 27 */ 28 static void smc_rx_data_ready(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, POLLIN | POLLPRI | 38 POLLRDNORM | POLLRDBAND); 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 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted 47 * @smc smc socket 48 * @timeo pointer to max seconds to wait, pointer to value 0 for no timeout 49 * Returns: 50 * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown. 51 * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted). 52 */ 53 static int smc_rx_wait_data(struct smc_sock *smc, long *timeo) 54 { 55 DEFINE_WAIT_FUNC(wait, woken_wake_function); 56 struct smc_connection *conn = &smc->conn; 57 struct sock *sk = &smc->sk; 58 int rc; 59 60 if (atomic_read(&conn->bytes_to_rcv)) 61 return 1; 62 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); 63 add_wait_queue(sk_sleep(sk), &wait); 64 rc = sk_wait_event(sk, timeo, 65 sk->sk_err || 66 sk->sk_shutdown & RCV_SHUTDOWN || 67 sock_flag(sk, SOCK_DONE) || 68 atomic_read(&conn->bytes_to_rcv) || 69 smc_cdc_rxed_any_close_or_senddone(conn), 70 &wait); 71 remove_wait_queue(sk_sleep(sk), &wait); 72 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); 73 return rc; 74 } 75 76 /* rcvbuf consumer: main API called by socket layer. 77 * called under sk lock. 78 */ 79 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len, 80 int flags) 81 { 82 size_t copylen, read_done = 0, read_remaining = len; 83 size_t chunk_len, chunk_off, chunk_len_sum; 84 struct smc_connection *conn = &smc->conn; 85 union smc_host_cursor cons; 86 int readable, chunk; 87 char *rcvbuf_base; 88 struct sock *sk; 89 long timeo; 90 int target; /* Read at least these many bytes */ 91 int rc; 92 93 if (unlikely(flags & MSG_ERRQUEUE)) 94 return -EINVAL; /* future work for sk.sk_family == AF_SMC */ 95 if (flags & MSG_OOB) 96 return -EINVAL; /* future work */ 97 98 sk = &smc->sk; 99 if (sk->sk_state == SMC_LISTEN) 100 return -ENOTCONN; 101 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); 102 target = sock_rcvlowat(sk, flags & MSG_WAITALL, len); 103 104 msg->msg_namelen = 0; 105 /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */ 106 rcvbuf_base = conn->rmb_desc->cpu_addr; 107 108 do { /* while (read_remaining) */ 109 if (read_done >= target) 110 break; 111 112 if (atomic_read(&conn->bytes_to_rcv)) 113 goto copy; 114 115 if (read_done) { 116 if (sk->sk_err || 117 sk->sk_state == SMC_CLOSED || 118 (sk->sk_shutdown & RCV_SHUTDOWN) || 119 !timeo || 120 signal_pending(current) || 121 smc_cdc_rxed_any_close_or_senddone(conn) || 122 conn->local_tx_ctrl.conn_state_flags. 123 peer_conn_abort) 124 break; 125 } else { 126 if (sock_flag(sk, SOCK_DONE)) 127 break; 128 if (sk->sk_err) { 129 read_done = sock_error(sk); 130 break; 131 } 132 if (sk->sk_shutdown & RCV_SHUTDOWN || 133 smc_cdc_rxed_any_close_or_senddone(conn) || 134 conn->local_tx_ctrl.conn_state_flags. 135 peer_conn_abort) 136 break; 137 if (sk->sk_state == SMC_CLOSED) { 138 if (!sock_flag(sk, SOCK_DONE)) { 139 /* This occurs when user tries to read 140 * from never connected socket. 141 */ 142 read_done = -ENOTCONN; 143 break; 144 } 145 break; 146 } 147 if (signal_pending(current)) { 148 read_done = sock_intr_errno(timeo); 149 break; 150 } 151 if (!timeo) 152 return -EAGAIN; 153 } 154 155 if (!atomic_read(&conn->bytes_to_rcv)) { 156 smc_rx_wait_data(smc, &timeo); 157 continue; 158 } 159 160 copy: 161 /* initialize variables for 1st iteration of subsequent loop */ 162 /* could be just 1 byte, even after smc_rx_wait_data above */ 163 readable = atomic_read(&conn->bytes_to_rcv); 164 /* not more than what user space asked for */ 165 copylen = min_t(size_t, read_remaining, readable); 166 smc_curs_write(&cons, 167 smc_curs_read(&conn->local_tx_ctrl.cons, conn), 168 conn); 169 /* determine chunks where to read from rcvbuf */ 170 /* either unwrapped case, or 1st chunk of wrapped case */ 171 chunk_len = min_t(size_t, 172 copylen, conn->rmbe_size - cons.count); 173 chunk_len_sum = chunk_len; 174 chunk_off = cons.count; 175 smc_rmb_sync_sg_for_cpu(conn); 176 for (chunk = 0; chunk < 2; chunk++) { 177 if (!(flags & MSG_TRUNC)) { 178 rc = memcpy_to_msg(msg, rcvbuf_base + chunk_off, 179 chunk_len); 180 if (rc) { 181 if (!read_done) 182 read_done = -EFAULT; 183 smc_rmb_sync_sg_for_device(conn); 184 goto out; 185 } 186 } 187 read_remaining -= chunk_len; 188 read_done += chunk_len; 189 190 if (chunk_len_sum == copylen) 191 break; /* either on 1st or 2nd iteration */ 192 /* prepare next (== 2nd) iteration */ 193 chunk_len = copylen - chunk_len; /* remainder */ 194 chunk_len_sum += chunk_len; 195 chunk_off = 0; /* modulo offset in recv ring buffer */ 196 } 197 smc_rmb_sync_sg_for_device(conn); 198 199 /* update cursors */ 200 if (!(flags & MSG_PEEK)) { 201 smc_curs_add(conn->rmbe_size, &cons, copylen); 202 /* increased in recv tasklet smc_cdc_msg_rcv() */ 203 smp_mb__before_atomic(); 204 atomic_sub(copylen, &conn->bytes_to_rcv); 205 /* guarantee 0 <= bytes_to_rcv <= rmbe_size */ 206 smp_mb__after_atomic(); 207 smc_curs_write(&conn->local_tx_ctrl.cons, 208 smc_curs_read(&cons, conn), 209 conn); 210 /* send consumer cursor update if required */ 211 /* similar to advertising new TCP rcv_wnd if required */ 212 smc_tx_consumer_update(conn); 213 } 214 } while (read_remaining); 215 out: 216 return read_done; 217 } 218 219 /* Initialize receive properties on connection establishment. NB: not __init! */ 220 void smc_rx_init(struct smc_sock *smc) 221 { 222 smc->sk.sk_data_ready = smc_rx_data_ready; 223 } 224