net/rds/tcp_send.c

   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_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 %pI4 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 }