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
41void 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
48void 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 */
56static 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 */
70int 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
140out:
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 */
172static 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
179void 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
207out:
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