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