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 for sk.sk_data_ready() 26 * to wakeup rcvbuf consumers that blocked with smc_rx_wait_data(). 27 * indirectly called by smc_cdc_msg_recv_action(). 28 */ 29 static void smc_rx_data_ready(struct sock *sk) 30 { 31 struct socket_wq *wq; 32 33 /* derived from sock_def_readable() */ 34 /* called already in smc_listen_work() */ 35 rcu_read_lock(); 36 wq = rcu_dereference(sk->sk_wq); 37 if (skwq_has_sleeper(wq)) 38 wake_up_interruptible_sync_poll(&wq->wait, POLLIN | POLLPRI | 39 POLLRDNORM | POLLRDBAND); 40 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_IN); 41 if ((sk->sk_shutdown == SHUTDOWN_MASK) || 42 (sk->sk_state == SMC_CLOSED)) 43 sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP); 44 rcu_read_unlock(); 45 } 46 47 /* blocks rcvbuf consumer until >=len bytes available or timeout or interrupted 48 * @smc smc socket 49 * @timeo pointer to max seconds to wait, pointer to value 0 for no timeout 50 * Returns: 51 * 1 if at least 1 byte available in rcvbuf or if socket error/shutdown. 52 * 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted). 53 */ 54 static int smc_rx_wait_data(struct smc_sock *smc, long *timeo) 55 { 56 DEFINE_WAIT_FUNC(wait, woken_wake_function); 57 struct smc_connection *conn = &smc->conn; 58 struct sock *sk = &smc->sk; 59 int rc; 60 61 if (atomic_read(&conn->bytes_to_rcv)) 62 return 1; 63 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk); 64 add_wait_queue(sk_sleep(sk), &wait); 65 rc = sk_wait_event(sk, timeo, 66 sk->sk_err || 67 sk->sk_shutdown & RCV_SHUTDOWN || 68 sock_flag(sk, SOCK_DONE) || 69 atomic_read(&conn->bytes_to_rcv) || 70 smc_cdc_rxed_any_close_or_senddone(conn), 71 &wait); 72 remove_wait_queue(sk_sleep(sk), &wait); 73 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk); 74 return rc; 75 } 76 77 /* rcvbuf consumer: main API called by socket layer. 78 * called under sk lock. 79 */ 80 int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len, 81 int flags) 82 { 83 size_t copylen, read_done = 0, read_remaining = len; 84 size_t chunk_len, chunk_off, chunk_len_sum; 85 struct smc_connection *conn = &smc->conn; 86 union smc_host_cursor cons; 87 int readable, chunk; 88 char *rcvbuf_base; 89 struct sock *sk; 90 long timeo; 91 int target; /* Read at least these many bytes */ 92 int rc; 93 94 if (unlikely(flags & MSG_ERRQUEUE)) 95 return -EINVAL; /* future work for sk.sk_family == AF_SMC */ 96 if (flags & MSG_OOB) 97 return -EINVAL; /* future work */ 98 99 sk = &smc->sk; 100 if (sk->sk_state == SMC_LISTEN) 101 return -ENOTCONN; 102 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT); 103 target = sock_rcvlowat(sk, flags & MSG_WAITALL, len); 104 105 msg->msg_namelen = 0; 106 /* we currently use 1 RMBE per RMB, so RMBE == RMB base addr */ 107 rcvbuf_base = conn->rmb_desc->cpu_addr; 108 109 do { /* while (read_remaining) */ 110 if (read_done >= target) 111 break; 112 113 if (atomic_read(&conn->bytes_to_rcv)) 114 goto copy; 115 116 if (read_done) { 117 if (sk->sk_err || 118 sk->sk_state == SMC_CLOSED || 119 (sk->sk_shutdown & RCV_SHUTDOWN) || 120 !timeo || 121 signal_pending(current) || 122 smc_cdc_rxed_any_close_or_senddone(conn) || 123 conn->local_tx_ctrl.conn_state_flags. 124 peer_conn_abort) 125 break; 126 } else { 127 if (sock_flag(sk, SOCK_DONE)) 128 break; 129 if (sk->sk_err) { 130 read_done = sock_error(sk); 131 break; 132 } 133 if (sk->sk_shutdown & RCV_SHUTDOWN || 134 smc_cdc_rxed_any_close_or_senddone(conn) || 135 conn->local_tx_ctrl.conn_state_flags. 136 peer_conn_abort) 137 break; 138 if (sk->sk_state == SMC_CLOSED) { 139 if (!sock_flag(sk, SOCK_DONE)) { 140 /* This occurs when user tries to read 141 * from never connected socket. 142 */ 143 read_done = -ENOTCONN; 144 break; 145 } 146 break; 147 } 148 if (signal_pending(current)) { 149 read_done = sock_intr_errno(timeo); 150 break; 151 } 152 if (!timeo) 153 return -EAGAIN; 154 } 155 156 if (!atomic_read(&conn->bytes_to_rcv)) { 157 smc_rx_wait_data(smc, &timeo); 158 continue; 159 } 160 161 copy: 162 /* initialize variables for 1st iteration of subsequent loop */ 163 /* could be just 1 byte, even after smc_rx_wait_data above */ 164 readable = atomic_read(&conn->bytes_to_rcv); 165 /* not more than what user space asked for */ 166 copylen = min_t(size_t, read_remaining, readable); 167 smc_curs_write(&cons, 168 smc_curs_read(&conn->local_tx_ctrl.cons, conn), 169 conn); 170 /* determine chunks where to read from rcvbuf */ 171 /* either unwrapped case, or 1st chunk of wrapped case */ 172 chunk_len = min_t(size_t, 173 copylen, conn->rmbe_size - cons.count); 174 chunk_len_sum = chunk_len; 175 chunk_off = cons.count; 176 smc_rmb_sync_sg_for_cpu(conn); 177 for (chunk = 0; chunk < 2; chunk++) { 178 if (!(flags & MSG_TRUNC)) { 179 rc = memcpy_to_msg(msg, rcvbuf_base + chunk_off, 180 chunk_len); 181 if (rc) { 182 if (!read_done) 183 read_done = -EFAULT; 184 smc_rmb_sync_sg_for_device(conn); 185 goto out; 186 } 187 } 188 read_remaining -= chunk_len; 189 read_done += chunk_len; 190 191 if (chunk_len_sum == copylen) 192 break; /* either on 1st or 2nd iteration */ 193 /* prepare next (== 2nd) iteration */ 194 chunk_len = copylen - chunk_len; /* remainder */ 195 chunk_len_sum += chunk_len; 196 chunk_off = 0; /* modulo offset in recv ring buffer */ 197 } 198 smc_rmb_sync_sg_for_device(conn); 199 200 /* update cursors */ 201 if (!(flags & MSG_PEEK)) { 202 smc_curs_add(conn->rmbe_size, &cons, copylen); 203 /* increased in recv tasklet smc_cdc_msg_rcv() */ 204 smp_mb__before_atomic(); 205 atomic_sub(copylen, &conn->bytes_to_rcv); 206 /* guarantee 0 <= bytes_to_rcv <= rmbe_size */ 207 smp_mb__after_atomic(); 208 smc_curs_write(&conn->local_tx_ctrl.cons, 209 smc_curs_read(&cons, conn), 210 conn); 211 /* send consumer cursor update if required */ 212 /* similar to advertising new TCP rcv_wnd if required */ 213 smc_tx_consumer_update(conn); 214 } 215 } while (read_remaining); 216 out: 217 return read_done; 218 } 219 220 /* Initialize receive properties on connection establishment. NB: not __init! */ 221 void smc_rx_init(struct smc_sock *smc) 222 { 223 smc->sk.sk_data_ready = smc_rx_data_ready; 224 } 225