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 
rds_tcp_cork(struct socket * sock,int val)40 static 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 
rds_tcp_xmit_prepare(struct rds_connection * conn)51 void 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 
rds_tcp_xmit_complete(struct rds_connection * conn)58 void 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 */
rds_tcp_sendmsg(struct socket * sock,void * data,unsigned int len)66 static int 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 */
rds_tcp_xmit(struct rds_connection * conn,struct rds_message * rm,unsigned int hdr_off,unsigned int sg,unsigned int off)80 int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
81 	         unsigned int hdr_off, unsigned int sg, unsigned int off)
82 {
83 	struct rds_tcp_connection *tc = conn->c_transport_data;
84 	int done = 0;
85 	int ret = 0;
86 
87 	if (hdr_off == 0) {
88 		/*
89 		 * m_ack_seq is set to the sequence number of the last byte of
90 		 * header and data.  see rds_tcp_is_acked().
91 		 */
92 		tc->t_last_sent_nxt = rds_tcp_snd_nxt(tc);
93 		rm->m_ack_seq = tc->t_last_sent_nxt +
94 				sizeof(struct rds_header) +
95 				be32_to_cpu(rm->m_inc.i_hdr.h_len) - 1;
96 		smp_mb__before_clear_bit();
97 		set_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags);
98 		tc->t_last_expected_una = rm->m_ack_seq + 1;
99 
100 		rdsdebug("rm %p tcp nxt %u ack_seq %llu\n",
101 			 rm, rds_tcp_snd_nxt(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 	while (sg < rm->data.op_nents) {
120 		ret = tc->t_sock->ops->sendpage(tc->t_sock,
121 						sg_page(&rm->data.op_sg[sg]),
122 						rm->data.op_sg[sg].offset + off,
123 						rm->data.op_sg[sg].length - off,
124 						MSG_DONTWAIT|MSG_NOSIGNAL);
125 		rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->data.op_sg[sg]),
126 			 rm->data.op_sg[sg].offset + off, rm->data.op_sg[sg].length - off,
127 			 ret);
128 		if (ret <= 0)
129 			break;
130 
131 		off += ret;
132 		done += ret;
133 		if (off == rm->data.op_sg[sg].length) {
134 			off = 0;
135 			sg++;
136 		}
137 	}
138 
139 out:
140 	if (ret <= 0) {
141 		/* write_space will hit after EAGAIN, all else fatal */
142 		if (ret == -EAGAIN) {
143 			rds_tcp_stats_inc(s_tcp_sndbuf_full);
144 			ret = 0;
145 		} else {
146 			printk(KERN_WARNING "RDS/tcp: send to %pI4 "
147 			       "returned %d, disconnecting and reconnecting\n",
148 			       &conn->c_faddr, ret);
149 			rds_conn_drop(conn);
150 		}
151 	}
152 	if (done == 0)
153 		done = ret;
154 	return done;
155 }
156 
157 /*
158  * rm->m_ack_seq is set to the tcp sequence number that corresponds to the
159  * last byte of the message, including the header.  This means that the
160  * entire message has been received if rm->m_ack_seq is "before" the next
161  * unacked byte of the TCP sequence space.  We have to do very careful
162  * wrapping 32bit comparisons here.
163  */
rds_tcp_is_acked(struct rds_message * rm,uint64_t ack)164 static int rds_tcp_is_acked(struct rds_message *rm, uint64_t ack)
165 {
166 	if (!test_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags))
167 		return 0;
168 	return (__s32)((u32)rm->m_ack_seq - (u32)ack) < 0;
169 }
170 
rds_tcp_write_space(struct sock * sk)171 void rds_tcp_write_space(struct sock *sk)
172 {
173 	void (*write_space)(struct sock *sk);
174 	struct rds_connection *conn;
175 	struct rds_tcp_connection *tc;
176 
177 	read_lock_bh(&sk->sk_callback_lock);
178 	conn = sk->sk_user_data;
179 	if (!conn) {
180 		write_space = sk->sk_write_space;
181 		goto out;
182 	}
183 
184 	tc = conn->c_transport_data;
185 	rdsdebug("write_space for tc %p\n", tc);
186 	write_space = tc->t_orig_write_space;
187 	rds_tcp_stats_inc(s_tcp_write_space_calls);
188 
189 	rdsdebug("tcp una %u\n", rds_tcp_snd_una(tc));
190 	tc->t_last_seen_una = rds_tcp_snd_una(tc);
191 	rds_send_drop_acked(conn, rds_tcp_snd_una(tc), rds_tcp_is_acked);
192 
193         if ((atomic_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf)
194 		queue_delayed_work(rds_wq, &conn->c_send_w, 0);
195 
196 out:
197 	read_unlock_bh(&sk->sk_callback_lock);
198 
199 	/*
200 	 * write_space is only called when data leaves tcp's send queue if
201 	 * SOCK_NOSPACE is set.  We set SOCK_NOSPACE every time we put
202 	 * data in tcp's send queue because we use write_space to parse the
203 	 * sequence numbers and notice that rds messages have been fully
204 	 * received.
205 	 *
206 	 * tcp's write_space clears SOCK_NOSPACE if the send queue has more
207 	 * than a certain amount of space. So we need to set it again *after*
208 	 * we call tcp's write_space or else we might only get called on the
209 	 * first of a series of incoming tcp acks.
210 	 */
211 	write_space(sk);
212 
213 	if (sk->sk_socket)
214 		set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
215 }
216