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 */ 30void 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, 1) && 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 */ 56int 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 !READ_ONCE(sk->sk_err) && 77 !((1 << READ_ONCE(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} 84EXPORT_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 */ 90static int sk_stream_closing(const struct sock *sk) 91{ 92 return (1 << READ_ONCE(sk->sk_state)) & 93 (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK); 94} 95 96void 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} 111EXPORT_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 */ 118int 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 DEFINE_WAIT_FUNC(wait, woken_wake_function); 124 125 if (sk_stream_memory_free(sk)) 126 current_timeo = vm_wait = (prandom_u32() % (HZ / 5)) + 2; 127 128 add_wait_queue(sk_sleep(sk), &wait); 129 130 while (1) { 131 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk); 132 133 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) 134 goto do_error; 135 if (!*timeo_p) 136 goto do_eagain; 137 if (signal_pending(current)) 138 goto do_interrupted; 139 sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); 140 if (sk_stream_memory_free(sk) && !vm_wait) 141 break; 142 143 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 144 sk->sk_write_pending++; 145 sk_wait_event(sk, ¤t_timeo, READ_ONCE(sk->sk_err) || 146 (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN) || 147 (sk_stream_memory_free(sk) && 148 !vm_wait), &wait); 149 sk->sk_write_pending--; 150 151 if (vm_wait) { 152 vm_wait -= current_timeo; 153 current_timeo = *timeo_p; 154 if (current_timeo != MAX_SCHEDULE_TIMEOUT && 155 (current_timeo -= vm_wait) < 0) 156 current_timeo = 0; 157 vm_wait = 0; 158 } 159 *timeo_p = current_timeo; 160 } 161out: 162 if (!sock_flag(sk, SOCK_DEAD)) 163 remove_wait_queue(sk_sleep(sk), &wait); 164 return err; 165 166do_error: 167 err = -EPIPE; 168 goto out; 169do_eagain: 170 /* Make sure that whenever EAGAIN is returned, EPOLLOUT event can 171 * be generated later. 172 * When TCP receives ACK packets that make room, tcp_check_space() 173 * only calls tcp_new_space() if SOCK_NOSPACE is set. 174 */ 175 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); 176 err = -EAGAIN; 177 goto out; 178do_interrupted: 179 err = sock_intr_errno(*timeo_p); 180 goto out; 181} 182EXPORT_SYMBOL(sk_stream_wait_memory); 183 184int sk_stream_error(struct sock *sk, int flags, int err) 185{ 186 if (err == -EPIPE) 187 err = sock_error(sk) ? : -EPIPE; 188 if (err == -EPIPE && !(flags & MSG_NOSIGNAL)) 189 send_sig(SIGPIPE, current, 0); 190 return err; 191} 192EXPORT_SYMBOL(sk_stream_error); 193 194void sk_stream_kill_queues(struct sock *sk) 195{ 196 /* First the read buffer. */ 197 __skb_queue_purge(&sk->sk_receive_queue); 198 199 /* Next, the error queue. 200 * We need to use queue lock, because other threads might 201 * add packets to the queue without socket lock being held. 202 */ 203 skb_queue_purge(&sk->sk_error_queue); 204 205 /* Next, the write queue. */ 206 WARN_ON(!skb_queue_empty(&sk->sk_write_queue)); 207 208 /* Account for returned memory. */ 209 sk_mem_reclaim(sk); 210 211 WARN_ON(sk->sk_wmem_queued); 212 213 /* It is _impossible_ for the backlog to contain anything 214 * when we get here. All user references to this socket 215 * have gone away, only the net layer knows can touch it. 216 */ 217} 218EXPORT_SYMBOL(sk_stream_kill_queues); 219