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 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 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 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 */ 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 */ 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_atomic(); 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 */ 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 } 170 171 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(&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(&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