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