linux/net/rds/tcp_send.c
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   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
  40static 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
  51void 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
  58void 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 */
  66int 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 */
  80int rds_tcp_xmit_cong_map(struct rds_connection *conn,
  81                          struct rds_cong_map *map, unsigned long offset)
  82{
  83        static struct rds_header rds_tcp_map_header = {
  84                .h_flags = RDS_FLAG_CONG_BITMAP,
  85        };
  86        struct rds_tcp_connection *tc = conn->c_transport_data;
  87        unsigned long i;
  88        int ret;
  89        int copied = 0;
  90
  91        /* Some problem claims cpu_to_be32(constant) isn't a constant. */
  92        rds_tcp_map_header.h_len = cpu_to_be32(RDS_CONG_MAP_BYTES);
  93
  94        if (offset < sizeof(struct rds_header)) {
  95                ret = rds_tcp_sendmsg(tc->t_sock,
  96                                      (void *)&rds_tcp_map_header + offset,
  97                                      sizeof(struct rds_header) - offset);
  98                if (ret <= 0)
  99                        return ret;
 100                offset += ret;
 101                copied = ret;
 102                if (offset < sizeof(struct rds_header))
 103                        return ret;
 104        }
 105
 106        offset -= sizeof(struct rds_header);
 107        i = offset / PAGE_SIZE;
 108        offset = offset % PAGE_SIZE;
 109        BUG_ON(i >= RDS_CONG_MAP_PAGES);
 110
 111        do {
 112                ret = tc->t_sock->ops->sendpage(tc->t_sock,
 113                                        virt_to_page(map->m_page_addrs[i]),
 114                                        offset, PAGE_SIZE - offset,
 115                                        MSG_DONTWAIT);
 116                if (ret <= 0)
 117                        break;
 118                copied += ret;
 119                offset += ret;
 120                if (offset == PAGE_SIZE) {
 121                        offset = 0;
 122                        i++;
 123                }
 124        } while (i < RDS_CONG_MAP_PAGES);
 125
 126        return copied ? copied : ret;
 127}
 128
 129/* the core send_sem serializes this with other xmit and shutdown */
 130int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
 131                 unsigned int hdr_off, unsigned int sg, unsigned int off)
 132{
 133        struct rds_tcp_connection *tc = conn->c_transport_data;
 134        int done = 0;
 135        int ret = 0;
 136
 137        if (hdr_off == 0) {
 138                /*
 139                 * m_ack_seq is set to the sequence number of the last byte of
 140                 * header and data.  see rds_tcp_is_acked().
 141                 */
 142                tc->t_last_sent_nxt = rds_tcp_snd_nxt(tc);
 143                rm->m_ack_seq = tc->t_last_sent_nxt +
 144                                sizeof(struct rds_header) +
 145                                be32_to_cpu(rm->m_inc.i_hdr.h_len) - 1;
 146                smp_mb__before_clear_bit();
 147                set_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags);
 148                tc->t_last_expected_una = rm->m_ack_seq + 1;
 149
 150                rdsdebug("rm %p tcp nxt %u ack_seq %llu\n",
 151                         rm, rds_tcp_snd_nxt(tc),
 152                         (unsigned long long)rm->m_ack_seq);
 153        }
 154
 155        if (hdr_off < sizeof(struct rds_header)) {
 156                /* see rds_tcp_write_space() */
 157                set_bit(SOCK_NOSPACE, &tc->t_sock->sk->sk_socket->flags);
 158
 159                ret = rds_tcp_sendmsg(tc->t_sock,
 160                                      (void *)&rm->m_inc.i_hdr + hdr_off,
 161                                      sizeof(rm->m_inc.i_hdr) - hdr_off);
 162                if (ret < 0)
 163                        goto out;
 164                done += ret;
 165                if (hdr_off + done != sizeof(struct rds_header))
 166                        goto out;
 167        }
 168
 169        while (sg < rm->m_nents) {
 170                ret = tc->t_sock->ops->sendpage(tc->t_sock,
 171                                                sg_page(&rm->m_sg[sg]),
 172                                                rm->m_sg[sg].offset + off,
 173                                                rm->m_sg[sg].length - off,
 174                                                MSG_DONTWAIT|MSG_NOSIGNAL);
 175                rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->m_sg[sg]),
 176                         rm->m_sg[sg].offset + off, rm->m_sg[sg].length - off,
 177                         ret);
 178                if (ret <= 0)
 179                        break;
 180
 181                off += ret;
 182                done += ret;
 183                if (off == rm->m_sg[sg].length) {
 184                        off = 0;
 185                        sg++;
 186                }
 187        }
 188
 189out:
 190        if (ret <= 0) {
 191                /* write_space will hit after EAGAIN, all else fatal */
 192                if (ret == -EAGAIN) {
 193                        rds_tcp_stats_inc(s_tcp_sndbuf_full);
 194                        ret = 0;
 195                } else {
 196                        printk(KERN_WARNING "RDS/tcp: send to %pI4 "
 197                               "returned %d, disconnecting and reconnecting\n",
 198                               &conn->c_faddr, ret);
 199                        rds_conn_drop(conn);
 200                }
 201        }
 202        if (done == 0)
 203                done = ret;
 204        return done;
 205}
 206
 207/*
 208 * rm->m_ack_seq is set to the tcp sequence number that corresponds to the
 209 * last byte of the message, including the header.  This means that the
 210 * entire message has been received if rm->m_ack_seq is "before" the next
 211 * unacked byte of the TCP sequence space.  We have to do very careful
 212 * wrapping 32bit comparisons here.
 213 */
 214static int rds_tcp_is_acked(struct rds_message *rm, uint64_t ack)
 215{
 216        if (!test_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags))
 217                return 0;
 218        return (__s32)((u32)rm->m_ack_seq - (u32)ack) < 0;
 219}
 220
 221void rds_tcp_write_space(struct sock *sk)
 222{
 223        void (*write_space)(struct sock *sk);
 224        struct rds_connection *conn;
 225        struct rds_tcp_connection *tc;
 226
 227        read_lock(&sk->sk_callback_lock);
 228        conn = sk->sk_user_data;
 229        if (conn == NULL) {
 230                write_space = sk->sk_write_space;
 231                goto out;
 232        }
 233
 234        tc = conn->c_transport_data;
 235        rdsdebug("write_space for tc %p\n", tc);
 236        write_space = tc->t_orig_write_space;
 237        rds_tcp_stats_inc(s_tcp_write_space_calls);
 238
 239        rdsdebug("tcp una %u\n", rds_tcp_snd_una(tc));
 240        tc->t_last_seen_una = rds_tcp_snd_una(tc);
 241        rds_send_drop_acked(conn, rds_tcp_snd_una(tc), rds_tcp_is_acked);
 242
 243        if ((atomic_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf)
 244                queue_delayed_work(rds_wq, &conn->c_send_w, 0);
 245
 246out:
 247        read_unlock(&sk->sk_callback_lock);
 248
 249        /*
 250         * write_space is only called when data leaves tcp's send queue if
 251         * SOCK_NOSPACE is set.  We set SOCK_NOSPACE every time we put
 252         * data in tcp's send queue because we use write_space to parse the
 253         * sequence numbers and notice that rds messages have been fully
 254         * received.
 255         *
 256         * tcp's write_space clears SOCK_NOSPACE if the send queue has more
 257         * than a certain amount of space. So we need to set it again *after*
 258         * we call tcp's write_space or else we might only get called on the
 259         * first of a series of incoming tcp acks.
 260         */
 261        write_space(sk);
 262
 263        if (sk->sk_socket)
 264                set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 265}
 266