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.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 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_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 */
 130 int 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
 189 out:
 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  */
 214 static 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
 221 void 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
 246 out:
 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 }