Root/net/rds/tcp_send.c

1/*
2 * Copyright (c) 2006 Oracle. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33#include <linux/kernel.h>
34#include <linux/in.h>
35#include <net/tcp.h>
36
37#include "rds.h"
38#include "tcp.h"
39
40static void rds_tcp_cork(struct socket *sock, int val)
41{
42    mm_segment_t oldfs;
43
44    oldfs = get_fs();
45    set_fs(KERNEL_DS);
46    sock->ops->setsockopt(sock, SOL_TCP, TCP_CORK, (char __user *)&val,
47                  sizeof(val));
48    set_fs(oldfs);
49}
50
51void rds_tcp_xmit_prepare(struct rds_connection *conn)
52{
53    struct rds_tcp_connection *tc = conn->c_transport_data;
54
55    rds_tcp_cork(tc->t_sock, 1);
56}
57
58void rds_tcp_xmit_complete(struct rds_connection *conn)
59{
60    struct rds_tcp_connection *tc = conn->c_transport_data;
61
62    rds_tcp_cork(tc->t_sock, 0);
63}
64
65/* the core send_sem serializes this with other xmit and shutdown */
66int rds_tcp_sendmsg(struct socket *sock, void *data, unsigned int len)
67{
68    struct kvec vec = {
69                .iov_base = data,
70                .iov_len = len,
71    };
72        struct msghdr msg = {
73                .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL,
74        };
75
76    return kernel_sendmsg(sock, &msg, &vec, 1, vec.iov_len);
77}
78
79/* the core send_sem serializes this with other xmit and shutdown */
80int rds_tcp_xmit_cong_map(struct rds_connection *conn,
81              struct rds_cong_map *map, unsigned long offset)
82{
83    static struct rds_header rds_tcp_map_header = {
84        .h_flags = RDS_FLAG_CONG_BITMAP,
85    };
86    struct rds_tcp_connection *tc = conn->c_transport_data;
87    unsigned long i;
88    int ret;
89    int copied = 0;
90
91    /* Some problem claims cpu_to_be32(constant) isn't a constant. */
92    rds_tcp_map_header.h_len = cpu_to_be32(RDS_CONG_MAP_BYTES);
93
94    if (offset < sizeof(struct rds_header)) {
95        ret = rds_tcp_sendmsg(tc->t_sock,
96                      (void *)&rds_tcp_map_header + offset,
97                      sizeof(struct rds_header) - offset);
98        if (ret <= 0)
99            return ret;
100        offset += ret;
101        copied = ret;
102        if (offset < sizeof(struct rds_header))
103            return ret;
104    }
105
106    offset -= sizeof(struct rds_header);
107    i = offset / PAGE_SIZE;
108    offset = offset % PAGE_SIZE;
109    BUG_ON(i >= RDS_CONG_MAP_PAGES);
110
111    do {
112        ret = tc->t_sock->ops->sendpage(tc->t_sock,
113                    virt_to_page(map->m_page_addrs[i]),
114                    offset, PAGE_SIZE - offset,
115                    MSG_DONTWAIT);
116        if (ret <= 0)
117            break;
118        copied += ret;
119        offset += ret;
120        if (offset == PAGE_SIZE) {
121            offset = 0;
122            i++;
123        }
124    } while (i < RDS_CONG_MAP_PAGES);
125
126        return copied ? copied : ret;
127}
128
129/* the core send_sem serializes this with other xmit and shutdown */
130int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
131             unsigned int hdr_off, unsigned int sg, unsigned int off)
132{
133    struct rds_tcp_connection *tc = conn->c_transport_data;
134    int done = 0;
135    int ret = 0;
136
137    if (hdr_off == 0) {
138        /*
139         * m_ack_seq is set to the sequence number of the last byte of
140         * header and data. see rds_tcp_is_acked().
141         */
142        tc->t_last_sent_nxt = rds_tcp_snd_nxt(tc);
143        rm->m_ack_seq = tc->t_last_sent_nxt +
144                sizeof(struct rds_header) +
145                be32_to_cpu(rm->m_inc.i_hdr.h_len) - 1;
146        smp_mb__before_clear_bit();
147        set_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags);
148        tc->t_last_expected_una = rm->m_ack_seq + 1;
149
150        rdsdebug("rm %p tcp nxt %u ack_seq %llu\n",
151             rm, rds_tcp_snd_nxt(tc),
152             (unsigned long long)rm->m_ack_seq);
153    }
154
155    if (hdr_off < sizeof(struct rds_header)) {
156        /* see rds_tcp_write_space() */
157        set_bit(SOCK_NOSPACE, &tc->t_sock->sk->sk_socket->flags);
158
159        ret = rds_tcp_sendmsg(tc->t_sock,
160                      (void *)&rm->m_inc.i_hdr + hdr_off,
161                      sizeof(rm->m_inc.i_hdr) - hdr_off);
162        if (ret < 0)
163            goto out;
164        done += ret;
165        if (hdr_off + done != sizeof(struct rds_header))
166            goto out;
167    }
168
169    while (sg < rm->m_nents) {
170        ret = tc->t_sock->ops->sendpage(tc->t_sock,
171                        sg_page(&rm->m_sg[sg]),
172                        rm->m_sg[sg].offset + off,
173                        rm->m_sg[sg].length - off,
174                        MSG_DONTWAIT|MSG_NOSIGNAL);
175        rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->m_sg[sg]),
176             rm->m_sg[sg].offset + off, rm->m_sg[sg].length - off,
177             ret);
178        if (ret <= 0)
179            break;
180
181        off += ret;
182        done += ret;
183        if (off == rm->m_sg[sg].length) {
184            off = 0;
185            sg++;
186        }
187    }
188
189out:
190    if (ret <= 0) {
191        /* write_space will hit after EAGAIN, all else fatal */
192        if (ret == -EAGAIN) {
193            rds_tcp_stats_inc(s_tcp_sndbuf_full);
194            ret = 0;
195        } else {
196            printk(KERN_WARNING "RDS/tcp: send to %pI4 "
197                   "returned %d, disconnecting and reconnecting\n",
198                   &conn->c_faddr, ret);
199            rds_conn_drop(conn);
200        }
201    }
202    if (done == 0)
203        done = ret;
204    return done;
205}
206
207/*
208 * rm->m_ack_seq is set to the tcp sequence number that corresponds to the
209 * last byte of the message, including the header. This means that the
210 * entire message has been received if rm->m_ack_seq is "before" the next
211 * unacked byte of the TCP sequence space. We have to do very careful
212 * wrapping 32bit comparisons here.
213 */
214static int rds_tcp_is_acked(struct rds_message *rm, uint64_t ack)
215{
216    if (!test_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags))
217        return 0;
218    return (__s32)((u32)rm->m_ack_seq - (u32)ack) < 0;
219}
220
221void rds_tcp_write_space(struct sock *sk)
222{
223    void (*write_space)(struct sock *sk);
224    struct rds_connection *conn;
225    struct rds_tcp_connection *tc;
226
227    read_lock(&sk->sk_callback_lock);
228    conn = sk->sk_user_data;
229    if (conn == NULL) {
230        write_space = sk->sk_write_space;
231        goto out;
232    }
233
234    tc = conn->c_transport_data;
235    rdsdebug("write_space for tc %p\n", tc);
236    write_space = tc->t_orig_write_space;
237    rds_tcp_stats_inc(s_tcp_write_space_calls);
238
239    rdsdebug("tcp una %u\n", rds_tcp_snd_una(tc));
240    tc->t_last_seen_una = rds_tcp_snd_una(tc);
241    rds_send_drop_acked(conn, rds_tcp_snd_una(tc), rds_tcp_is_acked);
242
243    queue_delayed_work(rds_wq, &conn->c_send_w, 0);
244out:
245    read_unlock(&sk->sk_callback_lock);
246
247    /*
248     * write_space is only called when data leaves tcp's send queue if
249     * SOCK_NOSPACE is set. We set SOCK_NOSPACE every time we put
250     * data in tcp's send queue because we use write_space to parse the
251     * sequence numbers and notice that rds messages have been fully
252     * received.
253     *
254     * tcp's write_space clears SOCK_NOSPACE if the send queue has more
255     * than a certain amount of space. So we need to set it again *after*
256     * we call tcp's write_space or else we might only get called on the
257     * first of a series of incoming tcp acks.
258     */
259    write_space(sk);
260
261    if (sk->sk_socket)
262        set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
263}
264

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