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         mm_segment_t oldfs;
  44
  45         oldfs = get_fs();
  46         set_fs(KERNEL_DS);
  47         sock->ops->setsockopt(sock, SOL_TCP, TCP_CORK, (char __user *)&val,
  48                               sizeof(val));
  49         set_fs(oldfs);
  50 }
  51
  52 void rds_tcp_xmit_prepare(struct rds_connection *conn)
  53 {
  54         struct rds_tcp_connection *tc = conn->c_transport_data;
  55
  56         rds_tcp_cork(tc->t_sock, 1);
  57 }
  58
  59 void rds_tcp_xmit_complete(struct rds_connection *conn)
  60 {
  61         struct rds_tcp_connection *tc = conn->c_transport_data;
  62
  63         rds_tcp_cork(tc->t_sock, 0);
  64 }
  65
  66 /* the core send_sem serializes this with other xmit and shutdown */
  67 static int rds_tcp_sendmsg(struct socket *sock, void *data, unsigned int len)
  68 {
  69         struct kvec vec = {
  70                 .iov_base = data,
  71                 .iov_len = len,
  72         };
  73         struct msghdr msg = {
  74                 .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL,
  75         };
  76
  77         return kernel_sendmsg(sock, &msg, &vec, 1, vec.iov_len);
  78 }
  79
  80 /* the core send_sem serializes this with other xmit and shutdown */
  81 int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
  82                  unsigned int hdr_off, unsigned int sg, unsigned int off)
  83 {
  84         struct rds_tcp_connection *tc = conn->c_transport_data;
  85         int done = 0;
  86         int ret = 0;
  87         int more;
  88
  89         if (hdr_off == 0) {
  90                 /*
  91                  * m_ack_seq is set to the sequence number of the last byte of
  92                  * header and data.  see rds_tcp_is_acked().
  93                  */
  94                 tc->t_last_sent_nxt = rds_tcp_snd_nxt(tc);
  95                 rm->m_ack_seq = tc->t_last_sent_nxt +
  96                                 sizeof(struct rds_header) +
  97                                 be32_to_cpu(rm->m_inc.i_hdr.h_len) - 1;
  98                 smp_mb__before_atomic();
  99                 set_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags);
 100                 tc->t_last_expected_una = rm->m_ack_seq + 1;
 101
 102                 rdsdebug("rm %p tcp nxt %u ack_seq %llu\n",
 103                          rm, rds_tcp_snd_nxt(tc),
 104                          (unsigned long long)rm->m_ack_seq);
 105         }
 106
 107         if (hdr_off < sizeof(struct rds_header)) {
 108                 /* see rds_tcp_write_space() */
 109                 set_bit(SOCK_NOSPACE, &tc->t_sock->sk->sk_socket->flags);
 110
 111                 ret = rds_tcp_sendmsg(tc->t_sock,
 112                                       (void *)&rm->m_inc.i_hdr + hdr_off,
 113                                       sizeof(rm->m_inc.i_hdr) - hdr_off);
 114                 if (ret < 0)
 115                         goto out;
 116                 done += ret;
 117                 if (hdr_off + done != sizeof(struct rds_header))
 118                         goto out;
 119         }
 120
 121         more = rm->data.op_nents > 1 ? (MSG_MORE | MSG_SENDPAGE_NOTLAST) : 0;
 122         while (sg < rm->data.op_nents) {
 123                 int flags = MSG_DONTWAIT | MSG_NOSIGNAL | more;
 124
 125                 ret = tc->t_sock->ops->sendpage(tc->t_sock,
 126                                                 sg_page(&rm->data.op_sg[sg]),
 127                                                 rm->data.op_sg[sg].offset + off,
 128                                                 rm->data.op_sg[sg].length - off,
 129                                                 flags);
 130                 rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->data.op_sg[sg]),
 131                          rm->data.op_sg[sg].offset + off, rm->data.op_sg[sg].length - off,
 132                          ret);
 133                 if (ret <= 0)
 134                         break;
 135
 136                 off += ret;
 137                 done += ret;
 138                 if (off == rm->data.op_sg[sg].length) {
 139                         off = 0;
 140                         sg++;
 141                 }
 142                 if (sg == rm->data.op_nents - 1)
 143                         more = 0;
 144         }
 145
 146 out:
 147         if (ret <= 0) {
 148                 /* write_space will hit after EAGAIN, all else fatal */
 149                 if (ret == -EAGAIN) {
 150                         rds_tcp_stats_inc(s_tcp_sndbuf_full);
 151                         ret = 0;
 152                 } else {
 153                         printk(KERN_WARNING "RDS/tcp: send to %pI4 "
 154                                "returned %d, disconnecting and reconnecting\n",
 155                                &conn->c_faddr, ret);
 156                         rds_conn_drop(conn);
 157                 }
 158         }
 159         if (done == 0)
 160                 done = ret;
 161         return done;
 162 }
 163
 164 /*
 165  * rm->m_ack_seq is set to the tcp sequence number that corresponds to the
 166  * last byte of the message, including the header.  This means that the
 167  * entire message has been received if rm->m_ack_seq is "before" the next
 168  * unacked byte of the TCP sequence space.  We have to do very careful
 169  * wrapping 32bit comparisons here.
 170  */
 171 static int rds_tcp_is_acked(struct rds_message *rm, uint64_t ack)
 172 {
 173         if (!test_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags))
 174                 return 0;
 175         return (__s32)((u32)rm->m_ack_seq - (u32)ack) < 0;
 176 }
 177
 178 void rds_tcp_write_space(struct sock *sk)
 179 {
 180         void (*write_space)(struct sock *sk);
 181         struct rds_connection *conn;
 182         struct rds_tcp_connection *tc;
 183
 184         read_lock_bh(&sk->sk_callback_lock);
 185         conn = sk->sk_user_data;
 186         if (!conn) {
 187                 write_space = sk->sk_write_space;
 188                 goto out;
 189         }
 190
 191         tc = conn->c_transport_data;
 192         rdsdebug("write_space for tc %p\n", tc);
 193         write_space = tc->t_orig_write_space;
 194         rds_tcp_stats_inc(s_tcp_write_space_calls);
 195
 196         rdsdebug("tcp una %u\n", rds_tcp_snd_una(tc));
 197         tc->t_last_seen_una = rds_tcp_snd_una(tc);
 198         rds_send_drop_acked(conn, rds_tcp_snd_una(tc), rds_tcp_is_acked);
 199
 200         if ((atomic_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf)
 201                 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
 202
 203 out:
 204         read_unlock_bh(&sk->sk_callback_lock);
 205
 206         /*
 207          * write_space is only called when data leaves tcp's send queue if
 208          * SOCK_NOSPACE is set.  We set SOCK_NOSPACE every time we put
 209          * data in tcp's send queue because we use write_space to parse the
 210          * sequence numbers and notice that rds messages have been fully
 211          * received.
 212          *
 213          * tcp's write_space clears SOCK_NOSPACE if the send queue has more
 214          * than a certain amount of space. So we need to set it again *after*
 215          * we call tcp's write_space or else we might only get called on the
 216          * first of a series of incoming tcp acks.
 217          */
 218         write_space(sk);
 219
 220         if (sk->sk_socket)
 221                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 222 }