net/rds/tcp_recv.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/slab.h>
  35 #include <net/tcp.h>
  36 #include <trace/events/sock.h>
  37
  38 #include "rds.h"
  39 #include "tcp.h"
  40
  41 static struct kmem_cache *rds_tcp_incoming_slab;
  42
  43 static void rds_tcp_inc_purge(struct rds_incoming *inc)
  44 {
  45         struct rds_tcp_incoming *tinc;
  46         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
  47         rdsdebug("purging tinc %p inc %p\n", tinc, inc);
  48         skb_queue_purge(&tinc->ti_skb_list);
  49 }
  50
  51 void rds_tcp_inc_free(struct rds_incoming *inc)
  52 {
  53         struct rds_tcp_incoming *tinc;
  54         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
  55         rds_tcp_inc_purge(inc);
  56         rdsdebug("freeing tinc %p inc %p\n", tinc, inc);
  57         kmem_cache_free(rds_tcp_incoming_slab, tinc);
  58 }
  59
  60 /*
  61  * this is pretty lame, but, whatever.
  62  */
  63 int rds_tcp_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to)
  64 {
  65         struct rds_tcp_incoming *tinc;
  66         struct sk_buff *skb;
  67         int ret = 0;
  68
  69         if (!iov_iter_count(to))
  70                 goto out;
  71
  72         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
  73
  74         skb_queue_walk(&tinc->ti_skb_list, skb) {
  75                 unsigned long to_copy, skb_off;
  76                 for (skb_off = 0; skb_off < skb->len; skb_off += to_copy) {
  77                         to_copy = iov_iter_count(to);
  78                         to_copy = min(to_copy, skb->len - skb_off);
  79
  80                         if (skb_copy_datagram_iter(skb, skb_off, to, to_copy))
  81                                 return -EFAULT;
  82
  83                         rds_stats_add(s_copy_to_user, to_copy);
  84                         ret += to_copy;
  85
  86                         if (!iov_iter_count(to))
  87                                 goto out;
  88                 }
  89         }
  90 out:
  91         return ret;
  92 }
  93
  94 /*
  95  * We have a series of skbs that have fragmented pieces of the congestion
  96  * bitmap.  They must add up to the exact size of the congestion bitmap.  We
  97  * use the skb helpers to copy those into the pages that make up the in-memory
  98  * congestion bitmap for the remote address of this connection.  We then tell
  99  * the congestion core that the bitmap has been changed so that it can wake up
 100  * sleepers.
 101  *
 102  * This is racing with sending paths which are using test_bit to see if the
 103  * bitmap indicates that their recipient is congested.
 104  */
 105
 106 static void rds_tcp_cong_recv(struct rds_connection *conn,
 107                               struct rds_tcp_incoming *tinc)
 108 {
 109         struct sk_buff *skb;
 110         unsigned int to_copy, skb_off;
 111         unsigned int map_off;
 112         unsigned int map_page;
 113         struct rds_cong_map *map;
 114         int ret;
 115
 116         /* catch completely corrupt packets */
 117         if (be32_to_cpu(tinc->ti_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
 118                 return;
 119
 120         map_page = 0;
 121         map_off = 0;
 122         map = conn->c_fcong;
 123
 124         skb_queue_walk(&tinc->ti_skb_list, skb) {
 125                 skb_off = 0;
 126                 while (skb_off < skb->len) {
 127                         to_copy = min_t(unsigned int, PAGE_SIZE - map_off,
 128                                         skb->len - skb_off);
 129
 130                         BUG_ON(map_page >= RDS_CONG_MAP_PAGES);
 131
 132                         /* only returns 0 or -error */
 133                         ret = skb_copy_bits(skb, skb_off,
 134                                 (void *)map->m_page_addrs[map_page] + map_off,
 135                                 to_copy);
 136                         BUG_ON(ret != 0);
 137
 138                         skb_off += to_copy;
 139                         map_off += to_copy;
 140                         if (map_off == PAGE_SIZE) {
 141                                 map_off = 0;
 142                                 map_page++;
 143                         }
 144                 }
 145         }
 146
 147         rds_cong_map_updated(map, ~(u64) 0);
 148 }
 149
 150 struct rds_tcp_desc_arg {
 151         struct rds_conn_path *conn_path;
 152         gfp_t gfp;
 153 };
 154
 155 static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
 156                              unsigned int offset, size_t len)
 157 {
 158         struct rds_tcp_desc_arg *arg = desc->arg.data;
 159         struct rds_conn_path *cp = arg->conn_path;
 160         struct rds_tcp_connection *tc = cp->cp_transport_data;
 161         struct rds_tcp_incoming *tinc = tc->t_tinc;
 162         struct sk_buff *clone;
 163         size_t left = len, to_copy;
 164
 165         rdsdebug("tcp data tc %p skb %p offset %u len %zu\n", tc, skb, offset,
 166                  len);
 167
 168         /*
 169          * tcp_read_sock() interprets partial progress as an indication to stop
 170          * processing.
 171          */
 172         while (left) {
 173                 if (!tinc) {
 174                         tinc = kmem_cache_alloc(rds_tcp_incoming_slab,
 175                                                 arg->gfp);
 176                         if (!tinc) {
 177                                 desc->error = -ENOMEM;
 178                                 goto out;
 179                         }
 180                         tc->t_tinc = tinc;
 181                         rdsdebug("allocated tinc %p\n", tinc);
 182                         rds_inc_path_init(&tinc->ti_inc, cp,
 183                                           &cp->cp_conn->c_faddr);
 184                         tinc->ti_inc.i_rx_lat_trace[RDS_MSG_RX_HDR] =
 185                                         local_clock();
 186
 187                         /*
 188                          * XXX * we might be able to use the __ variants when
 189                          * we've already serialized at a higher level.
 190                          */
 191                         skb_queue_head_init(&tinc->ti_skb_list);
 192                 }
 193
 194                 if (left && tc->t_tinc_hdr_rem) {
 195                         to_copy = min(tc->t_tinc_hdr_rem, left);
 196                         rdsdebug("copying %zu header from skb %p\n", to_copy,
 197                                  skb);
 198                         skb_copy_bits(skb, offset,
 199                                       (char *)&tinc->ti_inc.i_hdr +
 200                                                 sizeof(struct rds_header) -
 201                                                 tc->t_tinc_hdr_rem,
 202                                       to_copy);
 203                         tc->t_tinc_hdr_rem -= to_copy;
 204                         left -= to_copy;
 205                         offset += to_copy;
 206
 207                         if (tc->t_tinc_hdr_rem == 0) {
 208                                 /* could be 0 for a 0 len message */
 209                                 tc->t_tinc_data_rem =
 210                                         be32_to_cpu(tinc->ti_inc.i_hdr.h_len);
 211                                 tinc->ti_inc.i_rx_lat_trace[RDS_MSG_RX_START] =
 212                                         local_clock();
 213                         }
 214                 }
 215
 216                 if (left && tc->t_tinc_data_rem) {
 217                         to_copy = min(tc->t_tinc_data_rem, left);
 218
 219                         clone = pskb_extract(skb, offset, to_copy, arg->gfp);
 220                         if (!clone) {
 221                                 desc->error = -ENOMEM;
 222                                 goto out;
 223                         }
 224
 225                         skb_queue_tail(&tinc->ti_skb_list, clone);
 226
 227                         rdsdebug("skb %p data %p len %d off %u to_copy %zu -> "
 228                                  "clone %p data %p len %d\n",
 229                                  skb, skb->data, skb->len, offset, to_copy,
 230                                  clone, clone->data, clone->len);
 231
 232                         tc->t_tinc_data_rem -= to_copy;
 233                         left -= to_copy;
 234                         offset += to_copy;
 235                 }
 236
 237                 if (tc->t_tinc_hdr_rem == 0 && tc->t_tinc_data_rem == 0) {
 238                         struct rds_connection *conn = cp->cp_conn;
 239
 240                         if (tinc->ti_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
 241                                 rds_tcp_cong_recv(conn, tinc);
 242                         else
 243                                 rds_recv_incoming(conn, &conn->c_faddr,
 244                                                   &conn->c_laddr,
 245                                                   &tinc->ti_inc,
 246                                                   arg->gfp);
 247
 248                         tc->t_tinc_hdr_rem = sizeof(struct rds_header);
 249                         tc->t_tinc_data_rem = 0;
 250                         tc->t_tinc = NULL;
 251                         rds_inc_put(&tinc->ti_inc);
 252                         tinc = NULL;
 253                 }
 254         }
 255 out:
 256         rdsdebug("returning len %zu left %zu skb len %d rx queue depth %d\n",
 257                  len, left, skb->len,
 258                  skb_queue_len(&tc->t_sock->sk->sk_receive_queue));
 259         return len - left;
 260 }
 261
 262 /* the caller has to hold the sock lock */
 263 static int rds_tcp_read_sock(struct rds_conn_path *cp, gfp_t gfp)
 264 {
 265         struct rds_tcp_connection *tc = cp->cp_transport_data;
 266         struct socket *sock = tc->t_sock;
 267         read_descriptor_t desc;
 268         struct rds_tcp_desc_arg arg;
 269
 270         /* It's like glib in the kernel! */
 271         arg.conn_path = cp;
 272         arg.gfp = gfp;
 273         desc.arg.data = &arg;
 274         desc.error = 0;
 275         desc.count = 1; /* give more than one skb per call */
 276
 277         tcp_read_sock(sock->sk, &desc, rds_tcp_data_recv);
 278         rdsdebug("tcp_read_sock for tc %p gfp 0x%x returned %d\n", tc, gfp,
 279                  desc.error);
 280
 281         return desc.error;
 282 }
 283
 284 /*
 285  * We hold the sock lock to serialize our rds_tcp_recv->tcp_read_sock from
 286  * data_ready.
 287  *
 288  * if we fail to allocate we're in trouble.. blindly wait some time before
 289  * trying again to see if the VM can free up something for us.
 290  */
 291 int rds_tcp_recv_path(struct rds_conn_path *cp)
 292 {
 293         struct rds_tcp_connection *tc = cp->cp_transport_data;
 294         struct socket *sock = tc->t_sock;
 295         int ret = 0;
 296
 297         rdsdebug("recv worker path [%d] tc %p sock %p\n",
 298                  cp->cp_index, tc, sock);
 299
 300         lock_sock(sock->sk);
 301         ret = rds_tcp_read_sock(cp, GFP_KERNEL);
 302         release_sock(sock->sk);
 303
 304         return ret;
 305 }
 306
 307 void rds_tcp_data_ready(struct sock *sk)
 308 {
 309         void (*ready)(struct sock *sk);
 310         struct rds_conn_path *cp;
 311         struct rds_tcp_connection *tc;
 312
 313         trace_sk_data_ready(sk);
 314         rdsdebug("data ready sk %p\n", sk);
 315
 316         read_lock_bh(&sk->sk_callback_lock);
 317         cp = sk->sk_user_data;
 318         if (!cp) { /* check for teardown race */
 319                 ready = sk->sk_data_ready;
 320                 goto out;
 321         }
 322
 323         tc = cp->cp_transport_data;
 324         ready = tc->t_orig_data_ready;
 325         rds_tcp_stats_inc(s_tcp_data_ready_calls);
 326
 327         if (rds_tcp_read_sock(cp, GFP_ATOMIC) == -ENOMEM) {
 328                 rcu_read_lock();
 329                 if (!rds_destroy_pending(cp->cp_conn))
 330                         queue_delayed_work(rds_wq, &cp->cp_recv_w, 0);
 331                 rcu_read_unlock();
 332         }
 333 out:
 334         read_unlock_bh(&sk->sk_callback_lock);
 335         ready(sk);
 336 }
 337
 338 int rds_tcp_recv_init(void)
 339 {
 340         rds_tcp_incoming_slab = kmem_cache_create("rds_tcp_incoming",
 341                                         sizeof(struct rds_tcp_incoming),
 342                                         0, 0, NULL);
 343         if (!rds_tcp_incoming_slab)
 344                 return -ENOMEM;
 345         return 0;
 346 }
 347
 348 void rds_tcp_recv_exit(void)
 349 {
 350         kmem_cache_destroy(rds_tcp_incoming_slab);
 351 }