1 /*
2 * Copyright (c) 2006, 2017 Oracle and/or its affiliates. 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_single_path.h"
38 #include "rds.h"
39 #include "tcp.h"
40
41 static void rds_tcp_cork(struct socket *sock, int val)
42 {
43 kernel_setsockopt(sock, SOL_TCP, TCP_CORK, (void *)&val, sizeof(val));
44 }
45
46 void rds_tcp_xmit_path_prepare(struct rds_conn_path *cp)
47 {
48 struct rds_tcp_connection *tc = cp->cp_transport_data;
49
50 rds_tcp_cork(tc->t_sock, 1);
51 }
52
53 void rds_tcp_xmit_path_complete(struct rds_conn_path *cp)
54 {
55 struct rds_tcp_connection *tc = cp->cp_transport_data;
56
57 rds_tcp_cork(tc->t_sock, 0);
58 }
59
60 /* the core send_sem serializes this with other xmit and shutdown */
61 static int rds_tcp_sendmsg(struct socket *sock, void *data, unsigned int len)
62 {
63 struct kvec vec = {
64 .iov_base = data,
65 .iov_len = len,
66 };
67 struct msghdr msg = {
68 .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL,
69 };
70
71 return kernel_sendmsg(sock, &msg, &vec, 1, vec.iov_len);
72 }
73
74 /* the core send_sem serializes this with other xmit and shutdown */
75 int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
76 unsigned int hdr_off, unsigned int sg, unsigned int off)
77 {
78 struct rds_conn_path *cp = rm->m_inc.i_conn_path;
79 struct rds_tcp_connection *tc = cp->cp_transport_data;
80 int done = 0;
81 int ret = 0;
82 int more;
83
84 if (hdr_off == 0) {
85 /*
86 * m_ack_seq is set to the sequence number of the last byte of
87 * header and data. see rds_tcp_is_acked().
88 */
89 tc->t_last_sent_nxt = rds_tcp_write_seq(tc);
90 rm->m_ack_seq = tc->t_last_sent_nxt +
91 sizeof(struct rds_header) +
92 be32_to_cpu(rm->m_inc.i_hdr.h_len) - 1;
93 smp_mb__before_atomic();
94 set_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags);
95 tc->t_last_expected_una = rm->m_ack_seq + 1;
96
97 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
98 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
99
100 rdsdebug("rm %p tcp nxt %u ack_seq %llu\n",
101 rm, rds_tcp_write_seq(tc),
102 (unsigned long long)rm->m_ack_seq);
103 }
104
105 if (hdr_off < sizeof(struct rds_header)) {
106 /* see rds_tcp_write_space() */
107 set_bit(SOCK_NOSPACE, &tc->t_sock->sk->sk_socket->flags);
108
109 ret = rds_tcp_sendmsg(tc->t_sock,
110 (void *)&rm->m_inc.i_hdr + hdr_off,
111 sizeof(rm->m_inc.i_hdr) - hdr_off);
112 if (ret < 0)
113 goto out;
114 done += ret;
115 if (hdr_off + done != sizeof(struct rds_header))
116 goto out;
117 }
118
119 more = rm->data.op_nents > 1 ? (MSG_MORE | MSG_SENDPAGE_NOTLAST) : 0;
120 while (sg < rm->data.op_nents) {
121 int flags = MSG_DONTWAIT | MSG_NOSIGNAL | more;
122
123 ret = tc->t_sock->ops->sendpage(tc->t_sock,
124 sg_page(&rm->data.op_sg[sg]),
125 rm->data.op_sg[sg].offset + off,
126 rm->data.op_sg[sg].length - off,
127 flags);
128 rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->data.op_sg[sg]),
129 rm->data.op_sg[sg].offset + off, rm->data.op_sg[sg].length - off,
130 ret);
131 if (ret <= 0)
132 break;
133
134 off += ret;
135 done += ret;
136 if (off == rm->data.op_sg[sg].length) {
137 off = 0;
138 sg++;
139 }
140 if (sg == rm->data.op_nents - 1)
141 more = 0;
142 }
143
144 out:
145 if (ret <= 0) {
146 /* write_space will hit after EAGAIN, all else fatal */
147 if (ret == -EAGAIN) {
148 rds_tcp_stats_inc(s_tcp_sndbuf_full);
149 ret = 0;
150 } else {
151 /* No need to disconnect/reconnect if path_drop
152 * has already been triggered, because, e.g., of
153 * an incoming RST.
154 */
155 if (rds_conn_path_up(cp)) {
156 pr_warn("RDS/tcp: send to %pI6c on cp [%d]"
157 "returned %d, "
158 "disconnecting and reconnecting\n",
159 &conn->c_faddr, cp->cp_index, ret);
160 rds_conn_path_drop(cp, false);
161 }
162 }
163 }
164 if (done == 0)
165 done = ret;
166 return done;
167 }
168
169 /*
170 * rm->m_ack_seq is set to the tcp sequence number that corresponds to the
171 * last byte of the message, including the header. This means that the
172 * entire message has been received if rm->m_ack_seq is "before" the next
173 * unacked byte of the TCP sequence space. We have to do very careful
174 * wrapping 32bit comparisons here.
175 */
176 static int rds_tcp_is_acked(struct rds_message *rm, uint64_t ack)
177 {
178 if (!test_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags))
179 return 0;
180 return (__s32)((u32)rm->m_ack_seq - (u32)ack) < 0;
181 }
182
183 void rds_tcp_write_space(struct sock *sk)
184 {
185 void (*write_space)(struct sock *sk);
186 struct rds_conn_path *cp;
187 struct rds_tcp_connection *tc;
188
189 read_lock_bh(&sk->sk_callback_lock);
190 cp = sk->sk_user_data;
191 if (!cp) {
192 write_space = sk->sk_write_space;
193 goto out;
194 }
195
196 tc = cp->cp_transport_data;
197 rdsdebug("write_space for tc %p\n", tc);
198 write_space = tc->t_orig_write_space;
199 rds_tcp_stats_inc(s_tcp_write_space_calls);
200
201 rdsdebug("tcp una %u\n", rds_tcp_snd_una(tc));
202 tc->t_last_seen_una = rds_tcp_snd_una(tc);
203 rds_send_path_drop_acked(cp, rds_tcp_snd_una(tc), rds_tcp_is_acked);
204
205 rcu_read_lock();
206 if ((refcount_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf &&
207 !rds_destroy_pending(cp->cp_conn))
208 queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
209 rcu_read_unlock();
210
211 out:
212 read_unlock_bh(&sk->sk_callback_lock);
213
214 /*
215 * write_space is only called when data leaves tcp's send queue if
216 * SOCK_NOSPACE is set. We set SOCK_NOSPACE every time we put
217 * data in tcp's send queue because we use write_space to parse the
218 * sequence numbers and notice that rds messages have been fully
219 * received.
220 *
221 * tcp's write_space clears SOCK_NOSPACE if the send queue has more
222 * than a certain amount of space. So we need to set it again *after*
223 * we call tcp's write_space or else we might only get called on the
224 * first of a series of incoming tcp acks.
225 */
226 write_space(sk);
227
228 if (sk->sk_socket)
229 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
230 }