net/rds/tcp_send.c

   1 /*
   2  * Copyright (c) 2006, 2017 Oracle and/or its affiliates. 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 void rds_tcp_xmit_path_prepare(struct rds_conn_path *cp)
  42 {
  43         struct rds_tcp_connection *tc = cp->cp_transport_data;
  44
  45         tcp_sock_set_cork(tc->t_sock->sk, true);
  46 }
  47
  48 void rds_tcp_xmit_path_complete(struct rds_conn_path *cp)
  49 {
  50         struct rds_tcp_connection *tc = cp->cp_transport_data;
  51
  52         tcp_sock_set_cork(tc->t_sock->sk, false);
  53 }
  54
  55 /* the core send_sem serializes this with other xmit and shutdown */
  56 static int rds_tcp_sendmsg(struct socket *sock, void *data, unsigned int len)
  57 {
  58         struct kvec vec = {
  59                 .iov_base = data,
  60                 .iov_len = len,
  61         };
  62         struct msghdr msg = {
  63                 .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL,
  64         };
  65
  66         return kernel_sendmsg(sock, &msg, &vec, 1, vec.iov_len);
  67 }
  68
  69 /* the core send_sem serializes this with other xmit and shutdown */
  70 int rds_tcp_xmit(struct rds_connection *conn, struct rds_message *rm,
  71                  unsigned int hdr_off, unsigned int sg, unsigned int off)
  72 {
  73         struct rds_conn_path *cp = rm->m_inc.i_conn_path;
  74         struct rds_tcp_connection *tc = cp->cp_transport_data;
  75         struct msghdr msg = {};
  76         struct bio_vec bvec;
  77         int done = 0;
  78         int ret = 0;
  79
  80         if (hdr_off == 0) {
  81                 /*
  82                  * m_ack_seq is set to the sequence number of the last byte of
  83                  * header and data.  see rds_tcp_is_acked().
  84                  */
  85                 tc->t_last_sent_nxt = rds_tcp_write_seq(tc);
  86                 rm->m_ack_seq = tc->t_last_sent_nxt +
  87                                 sizeof(struct rds_header) +
  88                                 be32_to_cpu(rm->m_inc.i_hdr.h_len) - 1;
  89                 smp_mb__before_atomic();
  90                 set_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags);
  91                 tc->t_last_expected_una = rm->m_ack_seq + 1;
  92
  93                 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
  94                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
  95
  96                 rdsdebug("rm %p tcp nxt %u ack_seq %llu\n",
  97                          rm, rds_tcp_write_seq(tc),
  98                          (unsigned long long)rm->m_ack_seq);
  99         }
 100
 101         if (hdr_off < sizeof(struct rds_header)) {
 102                 /* see rds_tcp_write_space() */
 103                 set_bit(SOCK_NOSPACE, &tc->t_sock->sk->sk_socket->flags);
 104
 105                 ret = rds_tcp_sendmsg(tc->t_sock,
 106                                       (void *)&rm->m_inc.i_hdr + hdr_off,
 107                                       sizeof(rm->m_inc.i_hdr) - hdr_off);
 108                 if (ret < 0)
 109                         goto out;
 110                 done += ret;
 111                 if (hdr_off + done != sizeof(struct rds_header))
 112                         goto out;
 113         }
 114
 115         while (sg < rm->data.op_nents) {
 116                 msg.msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT | MSG_NOSIGNAL;
 117                 if (sg + 1 < rm->data.op_nents)
 118                         msg.msg_flags |= MSG_MORE;
 119
 120                 bvec_set_page(&bvec, sg_page(&rm->data.op_sg[sg]),
 121                               rm->data.op_sg[sg].length - off,
 122                               rm->data.op_sg[sg].offset + off);
 123                 iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1,
 124                               rm->data.op_sg[sg].length - off);
 125                 ret = sock_sendmsg(tc->t_sock, &msg);
 126                 rdsdebug("tcp sendpage %p:%u:%u ret %d\n", (void *)sg_page(&rm->data.op_sg[sg]),
 127                          rm->data.op_sg[sg].offset + off, rm->data.op_sg[sg].length - off,
 128                          ret);
 129                 if (ret <= 0)
 130                         break;
 131
 132                 off += ret;
 133                 done += ret;
 134                 if (off == rm->data.op_sg[sg].length) {
 135                         off = 0;
 136                         sg++;
 137                 }
 138         }
 139
 140 out:
 141         if (ret <= 0) {
 142                 /* write_space will hit after EAGAIN, all else fatal */
 143                 if (ret == -EAGAIN) {
 144                         rds_tcp_stats_inc(s_tcp_sndbuf_full);
 145                         ret = 0;
 146                 } else {
 147                         /* No need to disconnect/reconnect if path_drop
 148                          * has already been triggered, because, e.g., of
 149                          * an incoming RST.
 150                          */
 151                         if (rds_conn_path_up(cp)) {
 152                                 pr_warn("RDS/tcp: send to %pI6c on cp [%d]"
 153                                         "returned %d, "
 154                                         "disconnecting and reconnecting\n",
 155                                         &conn->c_faddr, cp->cp_index, ret);
 156                                 rds_conn_path_drop(cp, false);
 157                         }
 158                 }
 159         }
 160         if (done == 0)
 161                 done = ret;
 162         return done;
 163 }
 164
 165 /*
 166  * rm->m_ack_seq is set to the tcp sequence number that corresponds to the
 167  * last byte of the message, including the header.  This means that the
 168  * entire message has been received if rm->m_ack_seq is "before" the next
 169  * unacked byte of the TCP sequence space.  We have to do very careful
 170  * wrapping 32bit comparisons here.
 171  */
 172 static int rds_tcp_is_acked(struct rds_message *rm, uint64_t ack)
 173 {
 174         if (!test_bit(RDS_MSG_HAS_ACK_SEQ, &rm->m_flags))
 175                 return 0;
 176         return (__s32)((u32)rm->m_ack_seq - (u32)ack) < 0;
 177 }
 178
 179 void rds_tcp_write_space(struct sock *sk)
 180 {
 181         void (*write_space)(struct sock *sk);
 182         struct rds_conn_path *cp;
 183         struct rds_tcp_connection *tc;
 184
 185         read_lock_bh(&sk->sk_callback_lock);
 186         cp = sk->sk_user_data;
 187         if (!cp) {
 188                 write_space = sk->sk_write_space;
 189                 goto out;
 190         }
 191
 192         tc = cp->cp_transport_data;
 193         rdsdebug("write_space for tc %p\n", tc);
 194         write_space = tc->t_orig_write_space;
 195         rds_tcp_stats_inc(s_tcp_write_space_calls);
 196
 197         rdsdebug("tcp una %u\n", rds_tcp_snd_una(tc));
 198         tc->t_last_seen_una = rds_tcp_snd_una(tc);
 199         rds_send_path_drop_acked(cp, rds_tcp_snd_una(tc), rds_tcp_is_acked);
 200
 201         rcu_read_lock();
 202         if ((refcount_read(&sk->sk_wmem_alloc) << 1) <= sk->sk_sndbuf &&
 203             !rds_destroy_pending(cp->cp_conn))
 204                 queue_delayed_work(rds_wq, &cp->cp_send_w, 0);
 205         rcu_read_unlock();
 206
 207 out:
 208         read_unlock_bh(&sk->sk_callback_lock);
 209
 210         /*
 211          * write_space is only called when data leaves tcp's send queue if
 212          * SOCK_NOSPACE is set.  We set SOCK_NOSPACE every time we put
 213          * data in tcp's send queue because we use write_space to parse the
 214          * sequence numbers and notice that rds messages have been fully
 215          * received.
 216          *
 217          * tcp's write_space clears SOCK_NOSPACE if the send queue has more
 218          * than a certain amount of space. So we need to set it again *after*
 219          * we call tcp's write_space or else we might only get called on the
 220          * first of a series of incoming tcp acks.
 221          */
 222         write_space(sk);
 223
 224         if (sk->sk_socket)
 225                 set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 226 }