net/rds/tcp_listen.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/gfp.h>
  35 #include <linux/in.h>
  36 #include <net/tcp.h>
  37
  38 #include "rds.h"
  39 #include "tcp.h"
  40
  41 int rds_tcp_keepalive(struct socket *sock)
  42 {
  43         /* values below based on xs_udp_default_timeout */
  44         int keepidle = 5; /* send a probe 'keepidle' secs after last data */
  45         int keepcnt = 5; /* number of unack'ed probes before declaring dead */
  46         int keepalive = 1;
  47         int ret = 0;
  48
  49         ret = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
  50                                 (char *)&keepalive, sizeof(keepalive));
  51         if (ret < 0)
  52                 goto bail;
  53
  54         ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPCNT,
  55                                 (char *)&keepcnt, sizeof(keepcnt));
  56         if (ret < 0)
  57                 goto bail;
  58
  59         ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPIDLE,
  60                                 (char *)&keepidle, sizeof(keepidle));
  61         if (ret < 0)
  62                 goto bail;
  63
  64         /* KEEPINTVL is the interval between successive probes. We follow
  65          * the model in xs_tcp_finish_connecting() and re-use keepidle.
  66          */
  67         ret = kernel_setsockopt(sock, IPPROTO_TCP, TCP_KEEPINTVL,
  68                                 (char *)&keepidle, sizeof(keepidle));
  69 bail:
  70         return ret;
  71 }
  72
  73 /* rds_tcp_accept_one_path(): if accepting on cp_index > 0, make sure the
  74  * client's ipaddr < server's ipaddr. Otherwise, close the accepted
  75  * socket and force a reconneect from smaller -> larger ip addr. The reason
  76  * we special case cp_index 0 is to allow the rds probe ping itself to itself
  77  * get through efficiently.
  78  * Since reconnects are only initiated from the node with the numerically
  79  * smaller ip address, we recycle conns in RDS_CONN_ERROR on the passive side
  80  * by moving them to CONNECTING in this function.
  81  */
  82 static
  83 struct rds_tcp_connection *rds_tcp_accept_one_path(struct rds_connection *conn)
  84 {
  85         int i;
  86         bool peer_is_smaller = (conn->c_faddr < conn->c_laddr);
  87         int npaths = max_t(int, 1, conn->c_npaths);
  88
  89         /* for mprds, all paths MUST be initiated by the peer
  90          * with the smaller address.
  91          */
  92         if (!peer_is_smaller) {
  93                 /* Make sure we initiate at least one path if this
  94                  * has not already been done; rds_start_mprds() will
  95                  * take care of additional paths, if necessary.
  96                  */
  97                 if (npaths == 1)
  98                         rds_conn_path_connect_if_down(&conn->c_path[0]);
  99                 return NULL;
 100         }
 101
 102         for (i = 0; i < npaths; i++) {
 103                 struct rds_conn_path *cp = &conn->c_path[i];
 104
 105                 if (rds_conn_path_transition(cp, RDS_CONN_DOWN,
 106                                              RDS_CONN_CONNECTING) ||
 107                     rds_conn_path_transition(cp, RDS_CONN_ERROR,
 108                                              RDS_CONN_CONNECTING)) {
 109                         return cp->cp_transport_data;
 110                 }
 111         }
 112         return NULL;
 113 }
 114
 115 int rds_tcp_accept_one(struct socket *sock)
 116 {
 117         struct socket *new_sock = NULL;
 118         struct rds_connection *conn;
 119         int ret;
 120         struct inet_sock *inet;
 121         struct rds_tcp_connection *rs_tcp = NULL;
 122         int conn_state;
 123         struct rds_conn_path *cp;
 124
 125         if (!sock) /* module unload or netns delete in progress */
 126                 return -ENETUNREACH;
 127
 128         ret = sock_create_kern(sock_net(sock->sk), sock->sk->sk_family,
 129                                sock->sk->sk_type, sock->sk->sk_protocol,
 130                                &new_sock);
 131         if (ret)
 132                 goto out;
 133
 134         new_sock->type = sock->type;
 135         new_sock->ops = sock->ops;
 136         ret = sock->ops->accept(sock, new_sock, O_NONBLOCK, true);
 137         if (ret < 0)
 138                 goto out;
 139
 140         ret = rds_tcp_keepalive(new_sock);
 141         if (ret < 0)
 142                 goto out;
 143
 144         rds_tcp_tune(new_sock);
 145
 146         inet = inet_sk(new_sock->sk);
 147
 148         rdsdebug("accepted tcp %pI4:%u -> %pI4:%u\n",
 149                  &inet->inet_saddr, ntohs(inet->inet_sport),
 150                  &inet->inet_daddr, ntohs(inet->inet_dport));
 151
 152         conn = rds_conn_create(sock_net(sock->sk),
 153                                inet->inet_saddr, inet->inet_daddr,
 154                                &rds_tcp_transport, GFP_KERNEL);
 155         if (IS_ERR(conn)) {
 156                 ret = PTR_ERR(conn);
 157                 goto out;
 158         }
 159         /* An incoming SYN request came in, and TCP just accepted it.
 160          *
 161          * If the client reboots, this conn will need to be cleaned up.
 162          * rds_tcp_state_change() will do that cleanup
 163          */
 164         rs_tcp = rds_tcp_accept_one_path(conn);
 165         if (!rs_tcp)
 166                 goto rst_nsk;
 167         mutex_lock(&rs_tcp->t_conn_path_lock);
 168         cp = rs_tcp->t_cpath;
 169         conn_state = rds_conn_path_state(cp);
 170         WARN_ON(conn_state == RDS_CONN_UP);
 171         if (conn_state != RDS_CONN_CONNECTING && conn_state != RDS_CONN_ERROR)
 172                 goto rst_nsk;
 173         if (rs_tcp->t_sock) {
 174                 /* Need to resolve a duelling SYN between peers.
 175                  * We have an outstanding SYN to this peer, which may
 176                  * potentially have transitioned to the RDS_CONN_UP state,
 177                  * so we must quiesce any send threads before resetting
 178                  * c_transport_data.
 179                  */
 180                 if (ntohl(inet->inet_saddr) < ntohl(inet->inet_daddr) ||
 181                     !cp->cp_outgoing) {
 182                         goto rst_nsk;
 183                 } else {
 184                         rds_tcp_reset_callbacks(new_sock, cp);
 185                         cp->cp_outgoing = 0;
 186                         /* rds_connect_path_complete() marks RDS_CONN_UP */
 187                         rds_connect_path_complete(cp, RDS_CONN_RESETTING);
 188                 }
 189         } else {
 190                 rds_tcp_set_callbacks(new_sock, cp);
 191                 rds_connect_path_complete(cp, RDS_CONN_CONNECTING);
 192         }
 193         new_sock = NULL;
 194         ret = 0;
 195         goto out;
 196 rst_nsk:
 197         /* reset the newly returned accept sock and bail */
 198         kernel_sock_shutdown(new_sock, SHUT_RDWR);
 199         ret = 0;
 200 out:
 201         if (rs_tcp)
 202                 mutex_unlock(&rs_tcp->t_conn_path_lock);
 203         if (new_sock)
 204                 sock_release(new_sock);
 205         return ret;
 206 }
 207
 208 void rds_tcp_listen_data_ready(struct sock *sk)
 209 {
 210         void (*ready)(struct sock *sk);
 211
 212         rdsdebug("listen data ready sk %p\n", sk);
 213
 214         read_lock_bh(&sk->sk_callback_lock);
 215         ready = sk->sk_user_data;
 216         if (!ready) { /* check for teardown race */
 217                 ready = sk->sk_data_ready;
 218                 goto out;
 219         }
 220
 221         /*
 222          * ->sk_data_ready is also called for a newly established child socket
 223          * before it has been accepted and the accepter has set up their
 224          * data_ready.. we only want to queue listen work for our listening
 225          * socket
 226          *
 227          * (*ready)() may be null if we are racing with netns delete, and
 228          * the listen socket is being torn down.
 229          */
 230         if (sk->sk_state == TCP_LISTEN)
 231                 rds_tcp_accept_work(sk);
 232         else
 233                 ready = rds_tcp_listen_sock_def_readable(sock_net(sk));
 234
 235 out:
 236         read_unlock_bh(&sk->sk_callback_lock);
 237         if (ready)
 238                 ready(sk);
 239 }
 240
 241 struct socket *rds_tcp_listen_init(struct net *net)
 242 {
 243         struct sockaddr_in sin;
 244         struct socket *sock = NULL;
 245         int ret;
 246
 247         ret = sock_create_kern(net, PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock);
 248         if (ret < 0)
 249                 goto out;
 250
 251         sock->sk->sk_reuse = SK_CAN_REUSE;
 252         rds_tcp_nonagle(sock);
 253
 254         write_lock_bh(&sock->sk->sk_callback_lock);
 255         sock->sk->sk_user_data = sock->sk->sk_data_ready;
 256         sock->sk->sk_data_ready = rds_tcp_listen_data_ready;
 257         write_unlock_bh(&sock->sk->sk_callback_lock);
 258
 259         sin.sin_family = PF_INET;
 260         sin.sin_addr.s_addr = (__force u32)htonl(INADDR_ANY);
 261         sin.sin_port = (__force u16)htons(RDS_TCP_PORT);
 262
 263         ret = sock->ops->bind(sock, (struct sockaddr *)&sin, sizeof(sin));
 264         if (ret < 0)
 265                 goto out;
 266
 267         ret = sock->ops->listen(sock, 64);
 268         if (ret < 0)
 269                 goto out;
 270
 271         return sock;
 272 out:
 273         if (sock)
 274                 sock_release(sock);
 275         return NULL;
 276 }
 277
 278 void rds_tcp_listen_stop(struct socket *sock, struct work_struct *acceptor)
 279 {
 280         struct sock *sk;
 281
 282         if (!sock)
 283                 return;
 284
 285         sk = sock->sk;
 286
 287         /* serialize with and prevent further callbacks */
 288         lock_sock(sk);
 289         write_lock_bh(&sk->sk_callback_lock);
 290         if (sk->sk_user_data) {
 291                 sk->sk_data_ready = sk->sk_user_data;
 292                 sk->sk_user_data = NULL;
 293         }
 294         write_unlock_bh(&sk->sk_callback_lock);
 295         release_sock(sk);
 296
 297         /* wait for accepts to stop and close the socket */
 298         flush_workqueue(rds_wq);
 299         flush_work(acceptor);
 300         sock_release(sock);
 301 }