LXR linux/net/sctp/inqueue.c

   1/* SCTP kernel implementation
   2 * Copyright (c) 1999-2000 Cisco, Inc.
   3 * Copyright (c) 1999-2001 Motorola, Inc.
   4 * Copyright (c) 2002 International Business Machines, Corp.
   5 *
   6 * This file is part of the SCTP kernel implementation
   7 *
   8 * These functions are the methods for accessing the SCTP inqueue.
   9 *
  10 * An SCTP inqueue is a queue into which you push SCTP packets
  11 * (which might be bundles or fragments of chunks) and out of which you
  12 * pop SCTP whole chunks.
  13 *
  14 * This SCTP implementation is free software;
  15 * you can redistribute it and/or modify it under the terms of
  16 * the GNU General Public License as published by
  17 * the Free Software Foundation; either version 2, or (at your option)
  18 * any later version.
  19 *
  20 * This SCTP implementation is distributed in the hope that it
  21 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  22 *                 ************************
  23 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  24 * See the GNU General Public License for more details.
  25 *
  26 * You should have received a copy of the GNU General Public License
  27 * along with GNU CC; see the file COPYING.  If not, see
  28 * <http://www.gnu.org/licenses/>.
  29 *
  30 * Please send any bug reports or fixes you make to the
  31 * email address(es):
  32 *    lksctp developers <linux-sctp@vger.kernel.org>
  33 *
  34 * Written or modified by:
  35 *    La Monte H.P. Yarroll <piggy@acm.org>
  36 *    Karl Knutson <karl@athena.chicago.il.us>
  37 */
  38
  39#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  40
  41#include <net/sctp/sctp.h>
  42#include <net/sctp/sm.h>
  43#include <linux/interrupt.h>
  44#include <linux/slab.h>
  45
  46/* Initialize an SCTP inqueue.  */
  47void sctp_inq_init(struct sctp_inq *queue)
  48{
  49        INIT_LIST_HEAD(&queue->in_chunk_list);
  50        queue->in_progress = NULL;
  51
  52        /* Create a task for delivering data.  */
  53        INIT_WORK(&queue->immediate, NULL);
  54}
  55
  56/* Release the memory associated with an SCTP inqueue.  */
  57void sctp_inq_free(struct sctp_inq *queue)
  58{
  59        struct sctp_chunk *chunk, *tmp;
  60
  61        /* Empty the queue.  */
  62        list_for_each_entry_safe(chunk, tmp, &queue->in_chunk_list, list) {
  63                list_del_init(&chunk->list);
  64                sctp_chunk_free(chunk);
  65        }
  66
  67        /* If there is a packet which is currently being worked on,
  68         * free it as well.
  69         */
  70        if (queue->in_progress) {
  71                sctp_chunk_free(queue->in_progress);
  72                queue->in_progress = NULL;
  73        }
  74}
  75
  76/* Put a new packet in an SCTP inqueue.
  77 * We assume that packet->sctp_hdr is set and in host byte order.
  78 */
  79void sctp_inq_push(struct sctp_inq *q, struct sctp_chunk *chunk)
  80{
  81        /* Directly call the packet handling routine. */
  82        if (chunk->rcvr->dead) {
  83                sctp_chunk_free(chunk);
  84                return;
  85        }
  86
  87        /* We are now calling this either from the soft interrupt
  88         * or from the backlog processing.
  89         * Eventually, we should clean up inqueue to not rely
  90         * on the BH related data structures.
  91         */
  92        list_add_tail(&chunk->list, &q->in_chunk_list);
  93        if (chunk->asoc)
  94                chunk->asoc->stats.ipackets++;
  95        q->immediate.func(&q->immediate);
  96}
  97
  98/* Peek at the next chunk on the inqeue. */
  99struct sctp_chunkhdr *sctp_inq_peek(struct sctp_inq *queue)
 100{
 101        struct sctp_chunk *chunk;
 102        sctp_chunkhdr_t *ch = NULL;
 103
 104        chunk = queue->in_progress;
 105        /* If there is no more chunks in this packet, say so */
 106        if (chunk->singleton ||
 107            chunk->end_of_packet ||
 108            chunk->pdiscard)
 109                    return NULL;
 110
 111        ch = (sctp_chunkhdr_t *)chunk->chunk_end;
 112
 113        return ch;
 114}
 115
 116
 117/* Extract a chunk from an SCTP inqueue.
 118 *
 119 * WARNING:  If you need to put the chunk on another queue, you need to
 120 * make a shallow copy (clone) of it.
 121 */
 122struct sctp_chunk *sctp_inq_pop(struct sctp_inq *queue)
 123{
 124        struct sctp_chunk *chunk;
 125        sctp_chunkhdr_t *ch = NULL;
 126
 127        /* The assumption is that we are safe to process the chunks
 128         * at this time.
 129         */
 130
 131        if ((chunk = queue->in_progress)) {
 132                /* There is a packet that we have been working on.
 133                 * Any post processing work to do before we move on?
 134                 */
 135                if (chunk->singleton ||
 136                    chunk->end_of_packet ||
 137                    chunk->pdiscard) {
 138                        sctp_chunk_free(chunk);
 139                        chunk = queue->in_progress = NULL;
 140                } else {
 141                        /* Nothing to do. Next chunk in the packet, please. */
 142                        ch = (sctp_chunkhdr_t *) chunk->chunk_end;
 143                        /* Force chunk->skb->data to chunk->chunk_end.  */
 144                        skb_pull(chunk->skb, chunk->chunk_end - chunk->skb->data);
 145                        /* We are guaranteed to pull a SCTP header. */
 146                }
 147        }
 148
 149        /* Do we need to take the next packet out of the queue to process? */
 150        if (!chunk) {
 151                struct list_head *entry;
 152
 153                /* Is the queue empty?  */
 154                if (list_empty(&queue->in_chunk_list))
 155                        return NULL;
 156
 157                entry = queue->in_chunk_list.next;
 158                chunk = queue->in_progress =
 159                        list_entry(entry, struct sctp_chunk, list);
 160                list_del_init(entry);
 161
 162                /* This is the first chunk in the packet.  */
 163                chunk->singleton = 1;
 164                ch = (sctp_chunkhdr_t *) chunk->skb->data;
 165                chunk->data_accepted = 0;
 166        }
 167
 168        chunk->chunk_hdr = ch;
 169        chunk->chunk_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
 170        /* In the unlikely case of an IP reassembly, the skb could be
 171         * non-linear. If so, update chunk_end so that it doesn't go past
 172         * the skb->tail.
 173         */
 174        if (unlikely(skb_is_nonlinear(chunk->skb))) {
 175                if (chunk->chunk_end > skb_tail_pointer(chunk->skb))
 176                        chunk->chunk_end = skb_tail_pointer(chunk->skb);
 177        }
 178        skb_pull(chunk->skb, sizeof(sctp_chunkhdr_t));
 179        chunk->subh.v = NULL; /* Subheader is no longer valid.  */
 180
 181        if (chunk->chunk_end + sizeof(sctp_chunkhdr_t) <
 182            skb_tail_pointer(chunk->skb)) {
 183                /* This is not a singleton */
 184                chunk->singleton = 0;
 185        } else if (chunk->chunk_end > skb_tail_pointer(chunk->skb)) {
 186                /* Discard inside state machine. */
 187                chunk->pdiscard = 1;
 188                chunk->chunk_end = skb_tail_pointer(chunk->skb);
 189        } else {
 190                /* We are at the end of the packet, so mark the chunk
 191                 * in case we need to send a SACK.
 192                 */
 193                chunk->end_of_packet = 1;
 194        }
 195
 196        pr_debug("+++sctp_inq_pop+++ chunk:%p[%s], length:%d, skb->len:%d\n",
 197                 chunk, sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
 198                 ntohs(chunk->chunk_hdr->length), chunk->skb->len);
 199
 200        return chunk;
 201}
 202
 203/* Set a top-half handler.
 204 *
 205 * Originally, we the top-half handler was scheduled as a BH.  We now
 206 * call the handler directly in sctp_inq_push() at a time that
 207 * we know we are lock safe.
 208 * The intent is that this routine will pull stuff out of the
 209 * inqueue and process it.
 210 */
 211void sctp_inq_set_th_handler(struct sctp_inq *q, work_func_t callback)
 212{
 213        INIT_WORK(&q->immediate, callback);
 214}
 215