net: Optimize hard_start_xmit() return checking
[linux-2.6.git] / net / core / stream.c
1 /*
2  *     SUCS NET3:
3  *
4  *     Generic stream handling routines. These are generic for most
5  *     protocols. Even IP. Tonight 8-).
6  *     This is used because TCP, LLC (others too) layer all have mostly
7  *     identical sendmsg() and recvmsg() code.
8  *     So we (will) share it here.
9  *
10  *     Authors:        Arnaldo Carvalho de Melo <acme@conectiva.com.br>
11  *                     (from old tcp.c code)
12  *                     Alan Cox <alan@lxorguk.ukuu.org.uk> (Borrowed comments 8-))
13  */
14
15 #include <linux/module.h>
16 #include <linux/net.h>
17 #include <linux/signal.h>
18 #include <linux/tcp.h>
19 #include <linux/wait.h>
20 #include <net/sock.h>
21
22 /**
23  * sk_stream_write_space - stream socket write_space callback.
24  * @sk: socket
25  *
26  * FIXME: write proper description
27  */
28 void sk_stream_write_space(struct sock *sk)
29 {
30         struct socket *sock = sk->sk_socket;
31
32         if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk) && sock) {
33                 clear_bit(SOCK_NOSPACE, &sock->flags);
34
35                 if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
36                         wake_up_interruptible_poll(sk->sk_sleep, POLLOUT |
37                                                 POLLWRNORM | POLLWRBAND);
38                 if (sock->fasync_list && !(sk->sk_shutdown & SEND_SHUTDOWN))
39                         sock_wake_async(sock, SOCK_WAKE_SPACE, POLL_OUT);
40         }
41 }
42
43 EXPORT_SYMBOL(sk_stream_write_space);
44
45 /**
46  * sk_stream_wait_connect - Wait for a socket to get into the connected state
47  * @sk: sock to wait on
48  * @timeo_p: for how long to wait
49  *
50  * Must be called with the socket locked.
51  */
52 int sk_stream_wait_connect(struct sock *sk, long *timeo_p)
53 {
54         struct task_struct *tsk = current;
55         DEFINE_WAIT(wait);
56         int done;
57
58         do {
59                 int err = sock_error(sk);
60                 if (err)
61                         return err;
62                 if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV))
63                         return -EPIPE;
64                 if (!*timeo_p)
65                         return -EAGAIN;
66                 if (signal_pending(tsk))
67                         return sock_intr_errno(*timeo_p);
68
69                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
70                 sk->sk_write_pending++;
71                 done = sk_wait_event(sk, timeo_p,
72                                      !sk->sk_err &&
73                                      !((1 << sk->sk_state) &
74                                        ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)));
75                 finish_wait(sk->sk_sleep, &wait);
76                 sk->sk_write_pending--;
77         } while (!done);
78         return 0;
79 }
80
81 EXPORT_SYMBOL(sk_stream_wait_connect);
82
83 /**
84  * sk_stream_closing - Return 1 if we still have things to send in our buffers.
85  * @sk: socket to verify
86  */
87 static inline int sk_stream_closing(struct sock *sk)
88 {
89         return (1 << sk->sk_state) &
90                (TCPF_FIN_WAIT1 | TCPF_CLOSING | TCPF_LAST_ACK);
91 }
92
93 void sk_stream_wait_close(struct sock *sk, long timeout)
94 {
95         if (timeout) {
96                 DEFINE_WAIT(wait);
97
98                 do {
99                         prepare_to_wait(sk->sk_sleep, &wait,
100                                         TASK_INTERRUPTIBLE);
101                         if (sk_wait_event(sk, &timeout, !sk_stream_closing(sk)))
102                                 break;
103                 } while (!signal_pending(current) && timeout);
104
105                 finish_wait(sk->sk_sleep, &wait);
106         }
107 }
108
109 EXPORT_SYMBOL(sk_stream_wait_close);
110
111 /**
112  * sk_stream_wait_memory - Wait for more memory for a socket
113  * @sk: socket to wait for memory
114  * @timeo_p: for how long
115  */
116 int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
117 {
118         int err = 0;
119         long vm_wait = 0;
120         long current_timeo = *timeo_p;
121         DEFINE_WAIT(wait);
122
123         if (sk_stream_memory_free(sk))
124                 current_timeo = vm_wait = (net_random() % (HZ / 5)) + 2;
125
126         while (1) {
127                 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
128
129                 prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
130
131                 if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
132                         goto do_error;
133                 if (!*timeo_p)
134                         goto do_nonblock;
135                 if (signal_pending(current))
136                         goto do_interrupted;
137                 clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
138                 if (sk_stream_memory_free(sk) && !vm_wait)
139                         break;
140
141                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
142                 sk->sk_write_pending++;
143                 sk_wait_event(sk, &current_timeo, !sk->sk_err &&
144                                                   !(sk->sk_shutdown & SEND_SHUTDOWN) &&
145                                                   sk_stream_memory_free(sk) &&
146                                                   vm_wait);
147                 sk->sk_write_pending--;
148
149                 if (vm_wait) {
150                         vm_wait -= current_timeo;
151                         current_timeo = *timeo_p;
152                         if (current_timeo != MAX_SCHEDULE_TIMEOUT &&
153                             (current_timeo -= vm_wait) < 0)
154                                 current_timeo = 0;
155                         vm_wait = 0;
156                 }
157                 *timeo_p = current_timeo;
158         }
159 out:
160         finish_wait(sk->sk_sleep, &wait);
161         return err;
162
163 do_error:
164         err = -EPIPE;
165         goto out;
166 do_nonblock:
167         err = -EAGAIN;
168         goto out;
169 do_interrupted:
170         err = sock_intr_errno(*timeo_p);
171         goto out;
172 }
173
174 EXPORT_SYMBOL(sk_stream_wait_memory);
175
176 int sk_stream_error(struct sock *sk, int flags, int err)
177 {
178         if (err == -EPIPE)
179                 err = sock_error(sk) ? : -EPIPE;
180         if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
181                 send_sig(SIGPIPE, current, 0);
182         return err;
183 }
184
185 EXPORT_SYMBOL(sk_stream_error);
186
187 void sk_stream_kill_queues(struct sock *sk)
188 {
189         /* First the read buffer. */
190         __skb_queue_purge(&sk->sk_receive_queue);
191
192         /* Next, the error queue. */
193         __skb_queue_purge(&sk->sk_error_queue);
194
195         /* Next, the write queue. */
196         WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
197
198         /* Account for returned memory. */
199         sk_mem_reclaim(sk);
200
201         WARN_ON(sk->sk_wmem_queued);
202         WARN_ON(sk->sk_forward_alloc);
203
204         /* It is _impossible_ for the backlog to contain anything
205          * when we get here.  All user references to this socket
206          * have gone away, only the net layer knows can touch it.
207          */
208 }
209
210 EXPORT_SYMBOL(sk_stream_kill_queues);