linux/net/rxrpc/ar-skbuff.c
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   1/* ar-skbuff.c: socket buffer destruction handling
   2 *
   3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/net.h>
  14#include <linux/skbuff.h>
  15#include <net/sock.h>
  16#include <net/af_rxrpc.h>
  17#include "ar-internal.h"
  18
  19/*
  20 * set up for the ACK at the end of the receive phase when we discard the final
  21 * receive phase data packet
  22 * - called with softirqs disabled
  23 */
  24static void rxrpc_request_final_ACK(struct rxrpc_call *call)
  25{
  26        /* the call may be aborted before we have a chance to ACK it */
  27        write_lock(&call->state_lock);
  28
  29        switch (call->state) {
  30        case RXRPC_CALL_CLIENT_RECV_REPLY:
  31                call->state = RXRPC_CALL_CLIENT_FINAL_ACK;
  32                _debug("request final ACK");
  33
  34                /* get an extra ref on the call for the final-ACK generator to
  35                 * release */
  36                rxrpc_get_call(call);
  37                set_bit(RXRPC_CALL_ACK_FINAL, &call->events);
  38                if (try_to_del_timer_sync(&call->ack_timer) >= 0)
  39                        rxrpc_queue_call(call);
  40                break;
  41
  42        case RXRPC_CALL_SERVER_RECV_REQUEST:
  43                call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
  44        default:
  45                break;
  46        }
  47
  48        write_unlock(&call->state_lock);
  49}
  50
  51/*
  52 * drop the bottom ACK off of the call ACK window and advance the window
  53 */
  54static void rxrpc_hard_ACK_data(struct rxrpc_call *call,
  55                                struct rxrpc_skb_priv *sp)
  56{
  57        int loop;
  58        u32 seq;
  59
  60        spin_lock_bh(&call->lock);
  61
  62        _debug("hard ACK #%u", ntohl(sp->hdr.seq));
  63
  64        for (loop = 0; loop < RXRPC_ACKR_WINDOW_ASZ; loop++) {
  65                call->ackr_window[loop] >>= 1;
  66                call->ackr_window[loop] |=
  67                        call->ackr_window[loop + 1] << (BITS_PER_LONG - 1);
  68        }
  69
  70        seq = ntohl(sp->hdr.seq);
  71        ASSERTCMP(seq, ==, call->rx_data_eaten + 1);
  72        call->rx_data_eaten = seq;
  73
  74        if (call->ackr_win_top < UINT_MAX)
  75                call->ackr_win_top++;
  76
  77        ASSERTIFCMP(call->state <= RXRPC_CALL_COMPLETE,
  78                    call->rx_data_post, >=, call->rx_data_recv);
  79        ASSERTIFCMP(call->state <= RXRPC_CALL_COMPLETE,
  80                    call->rx_data_recv, >=, call->rx_data_eaten);
  81
  82        if (sp->hdr.flags & RXRPC_LAST_PACKET) {
  83                rxrpc_request_final_ACK(call);
  84        } else if (atomic_dec_and_test(&call->ackr_not_idle) &&
  85                   test_and_clear_bit(RXRPC_CALL_TX_SOFT_ACK, &call->flags)) {
  86                _debug("send Rx idle ACK");
  87                __rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, sp->hdr.serial,
  88                                    true);
  89        }
  90
  91        spin_unlock_bh(&call->lock);
  92}
  93
  94/*
  95 * destroy a packet that has an RxRPC control buffer
  96 * - advance the hard-ACK state of the parent call (done here in case something
  97 *   in the kernel bypasses recvmsg() and steals the packet directly off of the
  98 *   socket receive queue)
  99 */
 100void rxrpc_packet_destructor(struct sk_buff *skb)
 101{
 102        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 103        struct rxrpc_call *call = sp->call;
 104
 105        _enter("%p{%p}", skb, call);
 106
 107        if (call) {
 108                /* send the final ACK on a client call */
 109                if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
 110                        rxrpc_hard_ACK_data(call, sp);
 111                rxrpc_put_call(call);
 112                sp->call = NULL;
 113        }
 114
 115        if (skb->sk)
 116                sock_rfree(skb);
 117        _leave("");
 118}
 119
 120/**
 121 * rxrpc_kernel_free_skb - Free an RxRPC socket buffer
 122 * @skb: The socket buffer to be freed
 123 *
 124 * Let RxRPC free its own socket buffer, permitting it to maintain debug
 125 * accounting.
 126 */
 127void rxrpc_kernel_free_skb(struct sk_buff *skb)
 128{
 129        rxrpc_free_skb(skb);
 130}
 131
 132EXPORT_SYMBOL(rxrpc_kernel_free_skb);
 133
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