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 <linux/slab.h>
  35 #include <net/tcp.h>
  36
  37 #include "rds.h"
  38 #include "tcp.h"
  39
  40 static struct kmem_cache *rds_tcp_incoming_slab;
  41
  42 static void rds_tcp_inc_purge(struct rds_incoming *inc)
  43 {
  44         struct rds_tcp_incoming *tinc;
  45         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
  46         rdsdebug("purging tinc %p inc %p\n", tinc, inc);
  47         skb_queue_purge(&tinc->ti_skb_list);
  48 }
  49
  50 void rds_tcp_inc_free(struct rds_incoming *inc)
  51 {
  52         struct rds_tcp_incoming *tinc;
  53         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
  54         rds_tcp_inc_purge(inc);
  55         rdsdebug("freeing tinc %p inc %p\n", tinc, inc);
  56         kmem_cache_free(rds_tcp_incoming_slab, tinc);
  57 }
  58
  59 /*
  60  * this is pretty lame, but, whatever.
  61  */
  62 int rds_tcp_inc_copy_to_user(struct rds_incoming *inc, struct iovec *first_iov,
  63                              size_t size)
  64 {
  65         struct rds_tcp_incoming *tinc;
  66         struct iovec *iov, tmp;
  67         struct sk_buff *skb;
  68         unsigned long to_copy, skb_off;
  69         int ret = 0;
  70
  71         if (size == 0)
  72                 goto out;
  73
  74         tinc = container_of(inc, struct rds_tcp_incoming, ti_inc);
  75         iov = first_iov;
  76         tmp = *iov;
  77
  78         skb_queue_walk(&tinc->ti_skb_list, skb) {
  79                 skb_off = 0;
  80                 while (skb_off < skb->len) {
  81                         while (tmp.iov_len == 0) {
  82                                 iov++;
  83                                 tmp = *iov;
  84                         }
  85
  86                         to_copy = min(tmp.iov_len, size);
  87                         to_copy = min(to_copy, skb->len - skb_off);
  88
  89                         rdsdebug("ret %d size %zu skb %p skb_off %lu "
  90                                  "skblen %d iov_base %p iov_len %zu cpy %lu\n",
  91                                  ret, size, skb, skb_off, skb->len,
  92                                  tmp.iov_base, tmp.iov_len, to_copy);
  93
  94                         /* modifies tmp as it copies */
  95                         if (skb_copy_datagram_iovec(skb, skb_off, &tmp,
  96                                                     to_copy)) {
  97                                 ret = -EFAULT;
  98                                 goto out;
  99                         }
 100
 101                         rds_stats_add(s_copy_to_user, to_copy);
 102                         size -= to_copy;
 103                         ret += to_copy;
 104                         skb_off += to_copy;
 105                         if (size == 0)
 106                                 goto out;
 107                 }
 108         }
 109 out:
 110         return ret;
 111 }
 112
 113 /*
 114  * We have a series of skbs that have fragmented pieces of the congestion
 115  * bitmap.  They must add up to the exact size of the congestion bitmap.  We
 116  * use the skb helpers to copy those into the pages that make up the in-memory
 117  * congestion bitmap for the remote address of this connection.  We then tell
 118  * the congestion core that the bitmap has been changed so that it can wake up
 119  * sleepers.
 120  *
 121  * This is racing with sending paths which are using test_bit to see if the
 122  * bitmap indicates that their recipient is congested.
 123  */
 124
 125 static void rds_tcp_cong_recv(struct rds_connection *conn,
 126                               struct rds_tcp_incoming *tinc)
 127 {
 128         struct sk_buff *skb;
 129         unsigned int to_copy, skb_off;
 130         unsigned int map_off;
 131         unsigned int map_page;
 132         struct rds_cong_map *map;
 133         int ret;
 134
 135         /* catch completely corrupt packets */
 136         if (be32_to_cpu(tinc->ti_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
 137                 return;
 138
 139         map_page = 0;
 140         map_off = 0;
 141         map = conn->c_fcong;
 142
 143         skb_queue_walk(&tinc->ti_skb_list, skb) {
 144                 skb_off = 0;
 145                 while (skb_off < skb->len) {
 146                         to_copy = min_t(unsigned int, PAGE_SIZE - map_off,
 147                                         skb->len - skb_off);
 148
 149                         BUG_ON(map_page >= RDS_CONG_MAP_PAGES);
 150
 151                         /* only returns 0 or -error */
 152                         ret = skb_copy_bits(skb, skb_off,
 153                                 (void *)map->m_page_addrs[map_page] + map_off,
 154                                 to_copy);
 155                         BUG_ON(ret != 0);
 156
 157                         skb_off += to_copy;
 158                         map_off += to_copy;
 159                         if (map_off == PAGE_SIZE) {
 160                                 map_off = 0;
 161                                 map_page++;
 162                         }
 163                 }
 164         }
 165
 166         rds_cong_map_updated(map, ~(u64) 0);
 167 }
 168
 169 struct rds_tcp_desc_arg {
 170         struct rds_connection *conn;
 171         gfp_t gfp;
 172         enum km_type km;
 173 };
 174
 175 static int rds_tcp_data_recv(read_descriptor_t *desc, struct sk_buff *skb,
 176                              unsigned int offset, size_t len)
 177 {
 178         struct rds_tcp_desc_arg *arg = desc->arg.data;
 179         struct rds_connection *conn = arg->conn;
 180         struct rds_tcp_connection *tc = conn->c_transport_data;
 181         struct rds_tcp_incoming *tinc = tc->t_tinc;
 182         struct sk_buff *clone;
 183         size_t left = len, to_copy;
 184
 185         rdsdebug("tcp data tc %p skb %p offset %u len %zu\n", tc, skb, offset,
 186                  len);
 187
 188         /*
 189          * tcp_read_sock() interprets partial progress as an indication to stop
 190          * processing.
 191          */
 192         while (left) {
 193                 if (!tinc) {
 194                         tinc = kmem_cache_alloc(rds_tcp_incoming_slab,
 195                                                 arg->gfp);
 196                         if (!tinc) {
 197                                 desc->error = -ENOMEM;
 198                                 goto out;
 199                         }
 200                         tc->t_tinc = tinc;
 201                         rdsdebug("alloced tinc %p\n", tinc);
 202                         rds_inc_init(&tinc->ti_inc, conn, conn->c_faddr);
 203                         /*
 204                          * XXX * we might be able to use the __ variants when
 205                          * we've already serialized at a higher level.
 206                          */
 207                         skb_queue_head_init(&tinc->ti_skb_list);
 208                 }
 209
 210                 if (left && tc->t_tinc_hdr_rem) {
 211                         to_copy = min(tc->t_tinc_hdr_rem, left);
 212                         rdsdebug("copying %zu header from skb %p\n", to_copy,
 213                                  skb);
 214                         skb_copy_bits(skb, offset,
 215                                       (char *)&tinc->ti_inc.i_hdr +
 216                                                 sizeof(struct rds_header) -
 217                                                 tc->t_tinc_hdr_rem,
 218                                       to_copy);
 219                         tc->t_tinc_hdr_rem -= to_copy;
 220                         left -= to_copy;
 221                         offset += to_copy;
 222
 223                         if (tc->t_tinc_hdr_rem == 0) {
 224                                 /* could be 0 for a 0 len message */
 225                                 tc->t_tinc_data_rem =
 226                                         be32_to_cpu(tinc->ti_inc.i_hdr.h_len);
 227                         }
 228                 }
 229
 230                 if (left && tc->t_tinc_data_rem) {
 231                         clone = skb_clone(skb, arg->gfp);
 232                         if (!clone) {
 233                                 desc->error = -ENOMEM;
 234                                 goto out;
 235                         }
 236
 237                         to_copy = min(tc->t_tinc_data_rem, left);
 238                         pskb_pull(clone, offset);
 239                         pskb_trim(clone, to_copy);
 240                         skb_queue_tail(&tinc->ti_skb_list, clone);
 241
 242                         rdsdebug("skb %p data %p len %d off %u to_copy %zu -> "
 243                                  "clone %p data %p len %d\n",
 244                                  skb, skb->data, skb->len, offset, to_copy,
 245                                  clone, clone->data, clone->len);
 246
 247                         tc->t_tinc_data_rem -= to_copy;
 248                         left -= to_copy;
 249                         offset += to_copy;
 250                 }
 251
 252                 if (tc->t_tinc_hdr_rem == 0 && tc->t_tinc_data_rem == 0) {
 253                         if (tinc->ti_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
 254                                 rds_tcp_cong_recv(conn, tinc);
 255                         else
 256                                 rds_recv_incoming(conn, conn->c_faddr,
 257                                                   conn->c_laddr, &tinc->ti_inc,
 258                                                   arg->gfp, arg->km);
 259
 260                         tc->t_tinc_hdr_rem = sizeof(struct rds_header);
 261                         tc->t_tinc_data_rem = 0;
 262                         tc->t_tinc = NULL;
 263                         rds_inc_put(&tinc->ti_inc);
 264                         tinc = NULL;
 265                 }
 266         }
 267 out:
 268         rdsdebug("returning len %zu left %zu skb len %d rx queue depth %d\n",
 269                  len, left, skb->len,
 270                  skb_queue_len(&tc->t_sock->sk->sk_receive_queue));
 271         return len - left;
 272 }
 273
 274 /* the caller has to hold the sock lock */
 275 static int rds_tcp_read_sock(struct rds_connection *conn, gfp_t gfp,
 276                              enum km_type km)
 277 {
 278         struct rds_tcp_connection *tc = conn->c_transport_data;
 279         struct socket *sock = tc->t_sock;
 280         read_descriptor_t desc;
 281         struct rds_tcp_desc_arg arg;
 282
 283         /* It's like glib in the kernel! */
 284         arg.conn = conn;
 285         arg.gfp = gfp;
 286         arg.km = km;
 287         desc.arg.data = &arg;
 288         desc.error = 0;
 289         desc.count = 1; /* give more than one skb per call */
 290
 291         tcp_read_sock(sock->sk, &desc, rds_tcp_data_recv);
 292         rdsdebug("tcp_read_sock for tc %p gfp 0x%x returned %d\n", tc, gfp,
 293                  desc.error);
 294
 295         return desc.error;
 296 }
 297
 298 /*
 299  * We hold the sock lock to serialize our rds_tcp_recv->tcp_read_sock from
 300  * data_ready.
 301  *
 302  * if we fail to allocate we're in trouble.. blindly wait some time before
 303  * trying again to see if the VM can free up something for us.
 304  */
 305 int rds_tcp_recv(struct rds_connection *conn)
 306 {
 307         struct rds_tcp_connection *tc = conn->c_transport_data;
 308         struct socket *sock = tc->t_sock;
 309         int ret = 0;
 310
 311         rdsdebug("recv worker conn %p tc %p sock %p\n", conn, tc, sock);
 312
 313         lock_sock(sock->sk);
 314         ret = rds_tcp_read_sock(conn, GFP_KERNEL, KM_USER0);
 315         release_sock(sock->sk);
 316
 317         return ret;
 318 }
 319
 320 void rds_tcp_data_ready(struct sock *sk, int bytes)
 321 {
 322         void (*ready)(struct sock *sk, int bytes);
 323         struct rds_connection *conn;
 324         struct rds_tcp_connection *tc;
 325
 326         rdsdebug("data ready sk %p bytes %d\n", sk, bytes);
 327
 328         read_lock_bh(&sk->sk_callback_lock);
 329         conn = sk->sk_user_data;
 330         if (!conn) { /* check for teardown race */
 331                 ready = sk->sk_data_ready;
 332                 goto out;
 333         }
 334
 335         tc = conn->c_transport_data;
 336         ready = tc->t_orig_data_ready;
 337         rds_tcp_stats_inc(s_tcp_data_ready_calls);
 338
 339         if (rds_tcp_read_sock(conn, GFP_ATOMIC, KM_SOFTIRQ0) == -ENOMEM)
 340                 queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
 341 out:
 342         read_unlock_bh(&sk->sk_callback_lock);
 343         ready(sk, bytes);
 344 }
 345
 346 int rds_tcp_recv_init(void)
 347 {
 348         rds_tcp_incoming_slab = kmem_cache_create("rds_tcp_incoming",
 349                                         sizeof(struct rds_tcp_incoming),
 350                                         0, 0, NULL);
 351         if (!rds_tcp_incoming_slab)
 352                 return -ENOMEM;
 353         return 0;
 354 }
 355
 356 void rds_tcp_recv_exit(void)
 357 {
 358         kmem_cache_destroy(rds_tcp_incoming_slab);
 359 }