linux/net/rds/tcp_recv.c
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   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
  40static struct kmem_cache *rds_tcp_incoming_slab;
  41
  42static 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
  50void 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 */
  62int 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        }
 109out:
 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
 125static 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
 169struct rds_tcp_desc_arg {
 170        struct rds_connection *conn;
 171        gfp_t gfp;
 172        enum km_type km;
 173};
 174
 175static 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        }
 267out:
 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 */
 275static 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 */
 305int 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
 320void 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);
 341out:
 342        read_unlock_bh(&sk->sk_callback_lock);
 343        ready(sk, bytes);
 344}
 345
 346int 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
 356void rds_tcp_recv_exit(void)
 357{
 358        kmem_cache_destroy(rds_tcp_incoming_slab);
 359}
 360