ar-skbuff.c

Go to the documentation of this file.

/* ar-skbuff.c: socket buffer destruction handling
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

/*
 * set up for the ACK at the end of the receive phase when we discard the final
 * receive phase data packet
 * - called with softirqs disabled
 */
static void rxrpc_request_final_ACK(struct rxrpc_call *call)
{
    /* the call may be aborted before we have a chance to ACK it */
    write_lock(&call->state_lock);

    switch (call->state) {
    case RXRPC_CALL_CLIENT_RECV_REPLY:
        call->state = RXRPC_CALL_CLIENT_FINAL_ACK;
        _debug("request final ACK");

        /* get an extra ref on the call for the final-ACK generator to
         * release */
        rxrpc_get_call(call);
        set_bit(RXRPC_CALL_ACK_FINAL, &call->events);
        if (try_to_del_timer_sync(&call->ack_timer) >= 0)
            rxrpc_queue_call(call);
        break;

    case RXRPC_CALL_SERVER_RECV_REQUEST:
        call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
    default:
        break;
    }

    write_unlock(&call->state_lock);
}

/*
 * drop the bottom ACK off of the call ACK window and advance the window
 */
static void rxrpc_hard_ACK_data(struct rxrpc_call *call,
                struct rxrpc_skb_priv *sp)
{
    int loop;
    u32 seq;

    spin_lock_bh(&call->lock);

    _debug("hard ACK #%u", ntohl(sp->hdr.seq));

    for (loop = 0; loop < RXRPC_ACKR_WINDOW_ASZ; loop++) {
        call->ackr_window[loop] >>= 1;
        call->ackr_window[loop] |=
            call->ackr_window[loop + 1] << (BITS_PER_LONG - 1);
    }

    seq = ntohl(sp->hdr.seq);
    ASSERTCMP(seq, ==, call->rx_data_eaten + 1);
    call->rx_data_eaten = seq;

    if (call->ackr_win_top < UINT_MAX)
        call->ackr_win_top++;

    ASSERTIFCMP(call->state <= RXRPC_CALL_COMPLETE,
            call->rx_data_post, >=, call->rx_data_recv);
    ASSERTIFCMP(call->state <= RXRPC_CALL_COMPLETE,
            call->rx_data_recv, >=, call->rx_data_eaten);

    if (sp->hdr.flags & RXRPC_LAST_PACKET) {
        rxrpc_request_final_ACK(call);
    } else if (atomic_dec_and_test(&call->ackr_not_idle) &&
           test_and_clear_bit(RXRPC_CALL_TX_SOFT_ACK, &call->flags)) {
        _debug("send Rx idle ACK");
        __rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, sp->hdr.serial,
                    true);
    }

    spin_unlock_bh(&call->lock);
}

/*
 * destroy a packet that has an RxRPC control buffer
 * - advance the hard-ACK state of the parent call (done here in case something
 *   in the kernel bypasses recvmsg() and steals the packet directly off of the
 *   socket receive queue)
 */
void rxrpc_packet_destructor(struct sk_buff *skb)
{
    struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
    struct rxrpc_call *call = sp->call;

    _enter("%p{%p}", skb, call);

    if (call) {
        /* send the final ACK on a client call */
        if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
            rxrpc_hard_ACK_data(call, sp);
        rxrpc_put_call(call);
        sp->call = NULL;
    }

    if (skb->sk)
        sock_rfree(skb);
    _leave("");
}

void rxrpc_kernel_free_skb(struct sk_buff *skb)
{
    rxrpc_free_skb(skb);
}

EXPORT_SYMBOL(rxrpc_kernel_free_skb);