net/rds/tcp_recv.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 <net/tcp.h>
  35
  36 #include "rds.h"
  37 #include "tcp.h"
  38
  39 static struct kmem_cache *rds_tcp_incoming_slab;
  40
  41 void rds_tcp_inc_purge(struct rds_incoming *inc)
  42 {
  43         struct rds_tcp_incoming *tinc;
  44         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
  45         rdsdebug("purging tinc %p inc %p\n", tinc, inc);
  46         skb_queue_purge(&tinc->ti_skb_list);
  47 }
  48
  49 void rds_tcp_inc_free(struct rds_incoming *inc)
  50 {
  51         struct rds_tcp_incoming *tinc;
  52         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
  53         rds_tcp_inc_purge(inc);
  54         rdsdebug("freeing tinc %p inc %p\n", tinc, inc);
  55         kmem_cache_free(rds_tcp_incoming_slab, tinc);
  56 }
  57
  58 /*
  59  * this is pretty lame, but, whatever.
  60  */
  61 int rds_tcp_inc_copy_to_user(struct rds_incoming *inc, struct iovec *first_iov,
  62                              size_t size)
  63 {
  64         struct rds_tcp_incoming *tinc;
  65         struct iovec *iov, tmp;
  66         struct sk_buff *skb;
  67         unsigned long to_copy, skb_off;
  68         int ret = 0;
  69
  70         if (size == 0)
  71                 goto out;
  72
  73         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
  74         iov = first_iov;
  75         tmp = *iov;
  76
  77         skb_queue_walk(&tinc->ti_skb_list, skb) {
  78                 skb_off = 0;
  79                 while (skb_off < skb->len) {
  80                         while (tmp.iov_len == 0) {
  81                                 iov++;
  82                                 tmp = *iov;
  83                         }
  84
  85                         to_copy = min(tmp.iov_len, size);
  86                         to_copy = min(to_copy, skb->len - skb_off);
  87
  88                         rdsdebug("ret %d size %zu skb %p skb_off %lu "
  89                                  "skblen %d iov_base %p iov_len %zu cpy %lu\n",
  90                                  ret, size, skb, skb_off, skb->len,
  91                                  tmp.iov_base, tmp.iov_len, to_copy);
  92
  93                         /* modifies tmp as it copies */
  94                         if (skb_copy_datagram_iovec(skb, skb_off, &tmp,
  95                                                     to_copy)) {
  96                                 ret = -EFAULT;
  97                                 goto out;
  98                         }
  99
 100                         size -= to_copy;
 101                         ret += to_copy;
 102                         skb_off += to_copy;
 103                         if (size == 0)
 104                                 goto out;
 105                 }
 106         }
 107 out:
 108         return ret;
 109 }
 110
 111 /*
 112  * We have a series of skbs that have fragmented pieces of the congestion
 113  * bitmap.  They must add up to the exact size of the congestion bitmap.  We
 114  * use the skb helpers to copy those into the pages that make up the in-memory
 115  * congestion bitmap for the remote address of this connection.  We then tell
 116  * the congestion core that the bitmap has been changed so that it can wake up
 117  * sleepers.
 118  *
 119  * This is racing with sending paths which are using test_bit to see if the
 120  * bitmap indicates that their recipient is congested.
 121  */
 122
 123 static void rds_tcp_cong_recv(struct rds_connection *conn,
 124                               struct rds_tcp_incoming *tinc)
 125 {
 126         struct sk_buff *skb;
 127         unsigned int to_copy, skb_off;
 128         unsigned int map_off;
 129         unsigned int map_page;
 130         struct rds_cong_map *map;
 131         int ret;
 132
 133         /* catch completely corrupt packets */
 134         if (be32_to_cpu(tinc->ti_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
 135                 return;
 136
 137         map_page = 0;
 138         map_off = 0;
 139         map = conn->c_fcong;
 140
 141         skb_queue_walk(&tinc->ti_skb_list, skb) {
 142                 skb_off = 0;
 143                 while (skb_off < skb->len) {
 144                         to_copy = min_t(unsigned int, PAGE_SIZE - map_off,
 145                                         skb->len - skb_off);
 146
 147                         BUG_ON(map_page >= RDS_CONG_MAP_PAGES);
 148
 149                         /* only returns 0 or -error */
 150                         ret = skb_copy_bits(skb, skb_off,
 151                                 (void *)map->m_page_addrs[map_page] + map_off,
 152                                 to_copy);
 153                         BUG_ON(ret != 0);
 154
 155                         skb_off += to_copy;
 156                         map_off += to_copy;
 157                         if (map_off == PAGE_SIZE) {
 158                                 map_off = 0;
 159                                 map_page++;
 160                         }
 161                 }
 162         }
 163
 164         rds_cong_map_updated(map, ~(u64) 0);
 165 }
 166
 167 struct rds_tcp_desc_arg {
 168         struct rds_connection *conn;
 169         gfp_t gfp;
 170         enum km_type km;
 171 };
 172
 173 static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
 174                              unsigned int offset, size_t len)
 175 {
 176         struct rds_tcp_desc_arg *arg = desc->arg.data;
 177         struct rds_connection *conn = arg->conn;
 178         struct rds_tcp_connection *tc = conn->c_transport_data;
 179         struct rds_tcp_incoming *tinc = tc->t_tinc;
 180         struct sk_buff *clone;
 181         size_t left = len, to_copy;
 182
 183         rdsdebug("tcp data tc %p skb %p offset %u len %zu\n", tc, skb, offset,
 184                  len);
 185
 186         /*
 187          * tcp_read_sock() interprets partial progress as an indication to stop
 188          * processing.
 189          */
 190         while (left) {
 191                 if (tinc == NULL) {
 192                         tinc = kmem_cache_alloc(rds_tcp_incoming_slab,
 193                                                 arg->gfp);
 194                         if (tinc == NULL) {
 195                                 desc->error = -ENOMEM;
 196                                 goto out;
 197                         }
 198                         tc->t_tinc = tinc;
 199                         rdsdebug("alloced tinc %p\n", tinc);
 200                         rds_inc_init(&tinc->ti_inc, conn, conn->c_faddr);
 201                         /*
 202                          * XXX * we might be able to use the __ variants when
 203                          * we've already serialized at a higher level.
 204                          */
 205                         skb_queue_head_init(&tinc->ti_skb_list);
 206                 }
 207
 208                 if (left && tc->t_tinc_hdr_rem) {
 209                         to_copy = min(tc->t_tinc_hdr_rem, left);
 210                         rdsdebug("copying %zu header from skb %p\n", to_copy,
 211                                  skb);
 212                         skb_copy_bits(skb, offset,
 213                                       (char *)&tinc->ti_inc.i_hdr +
 214                                                 sizeof(struct rds_header) -
 215                                                 tc->t_tinc_hdr_rem,
 216                                       to_copy);
 217                         tc->t_tinc_hdr_rem -= to_copy;
 218                         left -= to_copy;
 219                         offset += to_copy;
 220
 221                         if (tc->t_tinc_hdr_rem == 0) {
 222                                 /* could be 0 for a 0 len message */
 223                                 tc->t_tinc_data_rem =
 224                                         be32_to_cpu(tinc->ti_inc.i_hdr.h_len);
 225                         }
 226                 }
 227
 228                 if (left && tc->t_tinc_data_rem) {
 229                         clone = skb_clone(skb, arg->gfp);
 230                         if (clone == NULL) {
 231                                 desc->error = -ENOMEM;
 232                                 goto out;
 233                         }
 234
 235                         to_copy = min(tc->t_tinc_data_rem, left);
 236                         pskb_pull(clone, offset);
 237                         pskb_trim(clone, to_copy);
 238                         skb_queue_tail(&tinc->ti_skb_list, clone);
 239
 240                         rdsdebug("skb %p data %p len %d off %u to_copy %zu -> "
 241                                  "clone %p data %p len %d\n",
 242                                  skb, skb->data, skb->len, offset, to_copy,
 243                                  clone, clone->data, clone->len);
 244
 245                         tc->t_tinc_data_rem -= to_copy;
 246                         left -= to_copy;
 247                         offset += to_copy;
 248                 }
 249
 250                 if (tc->t_tinc_hdr_rem == 0 && tc->t_tinc_data_rem == 0) {
 251                         if (tinc->ti_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
 252                                 rds_tcp_cong_recv(conn, tinc);
 253                         else
 254                                 rds_recv_incoming(conn, conn->c_faddr,
 255                                                   conn->c_laddr, &tinc->ti_inc,
 256                                                   arg->gfp, arg->km);
 257
 258                         tc->t_tinc_hdr_rem = sizeof(struct rds_header);
 259                         tc->t_tinc_data_rem = 0;
 260                         tc->t_tinc = NULL;
 261                         rds_inc_put(&tinc->ti_inc);
 262                         tinc = NULL;
 263                 }
 264         }
 265 out:
 266         rdsdebug("returning len %zu left %zu skb len %d rx queue depth %d\n",
 267                  len, left, skb->len,
 268                  skb_queue_len(&tc->t_sock->sk->sk_receive_queue));
 269         return len - left;
 270 }
 271
 272 /* the caller has to hold the sock lock */
 273 int rds_tcp_read_sock(struct rds_connection *conn, gfp_t gfp, enum km_type km)
 274 {
 275         struct rds_tcp_connection *tc = conn->c_transport_data;
 276         struct socket *sock = tc->t_sock;
 277         read_descriptor_t desc;
 278         struct rds_tcp_desc_arg arg;
 279
 280         /* It's like glib in the kernel! */
 281         arg.conn = conn;
 282         arg.gfp = gfp;
 283         arg.km = km;
 284         desc.arg.data = &arg;
 285         desc.error = 0;
 286         desc.count = 1; /* give more than one skb per call */
 287
 288         tcp_read_sock(sock->sk, &desc, rds_tcp_data_recv);
 289         rdsdebug("tcp_read_sock for tc %p gfp 0x%x returned %d\n", tc, gfp,
 290                  desc.error);
 291
 292         return desc.error;
 293 }
 294
 295 /*
 296  * We hold the sock lock to serialize our rds_tcp_recv->tcp_read_sock from
 297  * data_ready.
 298  *
 299  * if we fail to allocate we're in trouble.. blindly wait some time before
 300  * trying again to see if the VM can free up something for us.
 301  */
 302 int rds_tcp_recv(struct rds_connection *conn)
 303 {
 304         struct rds_tcp_connection *tc = conn->c_transport_data;
 305         struct socket *sock = tc->t_sock;
 306         int ret = 0;
 307
 308         rdsdebug("recv worker conn %p tc %p sock %p\n", conn, tc, sock);
 309
 310         lock_sock(sock->sk);
 311         ret = rds_tcp_read_sock(conn, GFP_KERNEL, KM_USER0);
 312         release_sock(sock->sk);
 313
 314         return ret;
 315 }
 316
 317 void rds_tcp_data_ready(struct sock *sk, int bytes)
 318 {
 319         void (*ready)(struct sock *sk, int bytes);
 320         struct rds_connection *conn;
 321         struct rds_tcp_connection *tc;
 322
 323         rdsdebug("data ready sk %p bytes %d\n", sk, bytes);
 324
 325         read_lock(&sk->sk_callback_lock);
 326         conn = sk->sk_user_data;
 327         if (conn == NULL) { /* check for teardown race */
 328                 ready = sk->sk_data_ready;
 329                 goto out;
 330         }
 331
 332         tc = conn->c_transport_data;
 333         ready = tc->t_orig_data_ready;
 334         rds_tcp_stats_inc(s_tcp_data_ready_calls);
 335
 336         if (rds_tcp_read_sock(conn, GFP_ATOMIC, KM_SOFTIRQ0) == -ENOMEM)
 337                 queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
 338 out:
 339         read_unlock(&sk->sk_callback_lock);
 340         ready(sk, bytes);
 341 }
 342
 343 int __init rds_tcp_recv_init(void)
 344 {
 345         rds_tcp_incoming_slab = kmem_cache_create("rds_tcp_incoming",
 346                                         sizeof(struct rds_tcp_incoming),
 347                                         0, 0, NULL);
 348         if (rds_tcp_incoming_slab == NULL)
 349                 return -ENOMEM;
 350         return 0;
 351 }
 352
 353 void rds_tcp_recv_exit(void)
 354 {
 355         kmem_cache_destroy(rds_tcp_incoming_slab);
 356 }