1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * SUCS NET3: 4 * 5 * Generic stream handling routines. These are generic for most 6 * protocols. Even IP. Tonight 8-). 7 * This is used because TCP, LLC (others too) layer all have mostly 8 * identical sendmsg() and recvmsg() code. 9 * So we (will) share it here. 10 * 11 * Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br> 12 * (from old tcp.c code) 13 * Alan Cox <alan@lxorguk.ukuu.org.uk> (Borrowed comments 8-)) 14 */ 15 16 #include <linux/module.h> 17 #include <linux/sched/signal.h> 18 #include <linux/net.h> 19 #include <linux/signal.h> 20 #include <linux/tcp.h> 21 #include <linux/wait.h> 22 #include <net/sock.h> 23 24 /** 25 * sk_stream_write_space - stream socket write_space callback. 26 * @sk: socket 27 * 28 * FIXME: write proper description 29 */ 30 void sk_stream_write_space(struct sock *sk) 31 { 32 struct socket *sock = sk->sk_socket; 33 struct socket_wq *wq; 34 35 if (sk_stream_is_writeable(sk) && sock) { 36 clear_bit(SOCK_NOSPACE, &sock->flags); 37 38 rcu_read_lock(); 39 wq = rcu_dereference(sk->sk_wq); 40 if (skwq_has_sleeper(wq)) 41 wake_up_interruptible_poll(&wq->wait, EPOLLOUT | 42 EPOLLWRNORM | EPOLLWRBAND); 43 if (wq && wq->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN)) 44 sock_wake_async(wq, SOCK_WAKE_SPACE, POLL_OUT); 45 rcu_read_unlock(); 46 } 47 } 48 49 /** 50 * sk_stream_wait_connect - Wait for a socket to get into the connected state 51 * @sk: sock to wait on 52 * @timeo_p: for how long to wait 53 * 54 * Must be called with the socket locked. 55 */ 56 int sk_stream_wait_connect(struct sock *sk, long *timeo_p) 57 { 58 DEFINE_WAIT_FUNC(wait, woken_wake_function); 59 struct task_struct *tsk = current; 60 int done; 61 62 do { 63 int err = sock_error(sk); 64 if (err) 65 return err; 66 if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) 67 return -EPIPE; 68 if (!*timeo_p) 69 return -EAGAIN; 70 if (signal_pending(tsk)) 71 return sock_intr_errno(*timeo_p); 72 73 add_wait_queue(sk_sleep(sk), &wait); 74 sk->sk_write_pending++; 75 done = sk_wait_event(sk, timeo_p, 76 !sk->sk_err && 77 !((1 << sk->sk_state) & 78 ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)), &wait); 79 remove_wait_queue(sk_sleep(sk), &wait); 80 sk->sk_write_pending--; 81 } while (!done); 82 return 0; 83 } 84 EXPORT_SYMBOL(sk_stream_wait_connect); 85 86 /** 87 * sk_stream_closing - Return 1 if we still have things to send in our buffers. 88 * @sk: socket to verify 89 */ 90 static inline int sk_stream_closing(struct sock *sk) 91 { 92 return (1 << sk->sk_state) & 93 (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK); 94 } 95 96 void sk_stream_wait_close(struct sock *sk, long timeout) 97 { 98 if (timeout) { 99 DEFINE_WAIT_FUNC(wait, woken_wake_function); 100 101 add_wait_queue(sk_sleep(sk), &wait); 102 103 do { 104 if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk), &wait)) 105 break; 106 } while (!signal_pending(current) && timeout); 107 108 remove_wait_queue(sk_sleep(sk), &wait); 109 } 110 } 111 EXPORT_SYMBOL(sk_stream_wait_close); 112 113 /** 114 * sk_stream_wait_memory - Wait for more memory for a socket 115 * @sk: socket to wait for memory 116 * @timeo_p: for how long 117 */ 118 int sk_stream_wait_memory(struct sock *sk, long *timeo_p) 119 { 120 int err = 0; 121 long vm_wait = 0; 122 long current_timeo = *timeo_p; 123 bool noblock = (*timeo_p ? false : true); 124 DEFINE_WAIT_FUNC(wait, woken_wake_function); 125 126 if (sk_stream_memory_free(sk)) 127 current_timeo = vm_wait = (prandom_u32() % (HZ / 5)) + 2; 128 129 add_wait_queue(sk_sleep(sk), &wait); 130 131 while (1) { 132 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); 133 134 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) 135 goto do_error; 136 if (!*timeo_p) { 137 if (noblock) 138 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 139 goto do_nonblock; 140 } 141 if (signal_pending(current)) 142 goto do_interrupted; 143 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); 144 if (sk_stream_memory_free(sk) && !vm_wait) 145 break; 146 147 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 148 sk->sk_write_pending++; 149 sk_wait_event(sk, ¤t_timeo, sk->sk_err || 150 (sk->sk_shutdown & SEND_SHUTDOWN) || 151 (sk_stream_memory_free(sk) && 152 !vm_wait), &wait); 153 sk->sk_write_pending--; 154 155 if (vm_wait) { 156 vm_wait -= current_timeo; 157 current_timeo = *timeo_p; 158 if (current_timeo != MAX_SCHEDULE_TIMEOUT && 159 (current_timeo -= vm_wait) < 0) 160 current_timeo = 0; 161 vm_wait = 0; 162 } 163 *timeo_p = current_timeo; 164 } 165 out: 166 remove_wait_queue(sk_sleep(sk), &wait); 167 return err; 168 169 do_error: 170 err = -EPIPE; 171 goto out; 172 do_nonblock: 173 err = -EAGAIN; 174 goto out; 175 do_interrupted: 176 err = sock_intr_errno(*timeo_p); 177 goto out; 178 } 179 EXPORT_SYMBOL(sk_stream_wait_memory); 180 181 int sk_stream_error(struct sock *sk, int flags, int err) 182 { 183 if (err == -EPIPE) 184 err = sock_error(sk) ? : -EPIPE; 185 if (err == -EPIPE && !(flags & MSG_NOSIGNAL)) 186 send_sig(SIGPIPE, current, 0); 187 return err; 188 } 189 EXPORT_SYMBOL(sk_stream_error); 190 191 void sk_stream_kill_queues(struct sock *sk) 192 { 193 /* First the read buffer. */ 194 __skb_queue_purge(&sk->sk_receive_queue); 195 196 /* Next, the error queue. */ 197 __skb_queue_purge(&sk->sk_error_queue); 198 199 /* Next, the write queue. */ 200 WARN_ON(!skb_queue_empty(&sk->sk_write_queue)); 201 202 /* Account for returned memory. */ 203 sk_mem_reclaim(sk); 204 205 WARN_ON(sk->sk_wmem_queued); 206 WARN_ON(sk->sk_forward_alloc); 207 208 /* It is _impossible_ for the backlog to contain anything 209 * when we get here. All user references to this socket 210 * have gone away, only the net layer knows can touch it. 211 */ 212 } 213 EXPORT_SYMBOL(sk_stream_kill_queues); 214