root/net/rxrpc/ar-local.c

DEFINITIONS

1. rxrpc_alloc_local
2. rxrpc_create_local
3. rxrpc_lookup_local
4. rxrpc_put_local
5. rxrpc_destroy_local
6. rxrpc_destroy_all_locals

/* AF_RXRPC local endpoint management
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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"

static LIST_HEAD(rxrpc_locals);
DEFINE_RWLOCK(rxrpc_local_lock);
static DECLARE_RWSEM(rxrpc_local_sem);
static DECLARE_WAIT_QUEUE_HEAD(rxrpc_local_wq);

static void rxrpc_destroy_local(struct work_struct *work);

/*
 * allocate a new local
 */
static
struct rxrpc_local *rxrpc_alloc_local(struct sockaddr_rxrpc *srx)
{
        struct rxrpc_local *local;

        local = kzalloc(sizeof(struct rxrpc_local), GFP_KERNEL);
        if (local) {
                INIT_WORK(&local->destroyer, &rxrpc_destroy_local);
                INIT_WORK(&local->acceptor, &rxrpc_accept_incoming_calls);
                INIT_WORK(&local->rejecter, &rxrpc_reject_packets);
                INIT_LIST_HEAD(&local->services);
                INIT_LIST_HEAD(&local->link);
                init_rwsem(&local->defrag_sem);
                skb_queue_head_init(&local->accept_queue);
                skb_queue_head_init(&local->reject_queue);
                spin_lock_init(&local->lock);
                rwlock_init(&local->services_lock);
                atomic_set(&local->usage, 1);
                local->debug_id = atomic_inc_return(&rxrpc_debug_id);
                memcpy(&local->srx, srx, sizeof(*srx));
        }

        _leave(" = %p", local);
        return local;
}

/*
 * create the local socket
 * - must be called with rxrpc_local_sem writelocked
 */
static int rxrpc_create_local(struct rxrpc_local *local)
{
        struct sock *sock;
        int ret, opt;

        _enter("%p{%d}", local, local->srx.transport_type);

        /* create a socket to represent the local endpoint */
        ret = sock_create_kern(PF_INET, local->srx.transport_type, IPPROTO_UDP,
                               &local->socket);
        if (ret < 0) {
                _leave(" = %d [socket]", ret);
                return ret;
        }

        /* if a local address was supplied then bind it */
        if (local->srx.transport_len > sizeof(sa_family_t)) {
                _debug("bind");
                ret = kernel_bind(local->socket,
                                  (struct sockaddr *) &local->srx.transport,
                                  local->srx.transport_len);
                if (ret < 0) {
                        _debug("bind failed");
                        goto error;
                }
        }

        /* we want to receive ICMP errors */
        opt = 1;
        ret = kernel_setsockopt(local->socket, SOL_IP, IP_RECVERR,
                                (char *) &opt, sizeof(opt));
        if (ret < 0) {
                _debug("setsockopt failed");
                goto error;
        }

        /* we want to set the don't fragment bit */
        opt = IP_PMTUDISC_DO;
        ret = kernel_setsockopt(local->socket, SOL_IP, IP_MTU_DISCOVER,
                                (char *) &opt, sizeof(opt));
        if (ret < 0) {
                _debug("setsockopt failed");
                goto error;
        }

        write_lock_bh(&rxrpc_local_lock);
        list_add(&local->link, &rxrpc_locals);
        write_unlock_bh(&rxrpc_local_lock);

        /* set the socket up */
        sock = local->socket->sk;
        sock->sk_user_data      = local;
        sock->sk_data_ready     = rxrpc_data_ready;
        sock->sk_error_report   = rxrpc_UDP_error_report;
        _leave(" = 0");
        return 0;

error:
        kernel_sock_shutdown(local->socket, SHUT_RDWR);
        local->socket->sk->sk_user_data = NULL;
        sock_release(local->socket);
        local->socket = NULL;

        _leave(" = %d", ret);
        return ret;
}

/*
 * create a new local endpoint using the specified UDP address
 */
struct rxrpc_local *rxrpc_lookup_local(struct sockaddr_rxrpc *srx)
{
        struct rxrpc_local *local;
        int ret;

        _enter("{%d,%u,%u.%u.%u.%u+%hu}",
               srx->transport_type,
               srx->transport.family,
               NIPQUAD(srx->transport.sin.sin_addr),
               ntohs(srx->transport.sin.sin_port));

        down_write(&rxrpc_local_sem);

        /* see if we have a suitable local local endpoint already */
        read_lock_bh(&rxrpc_local_lock);

        list_for_each_entry(local, &rxrpc_locals, link) {
                _debug("CMP {%d,%u,%u.%u.%u.%u+%hu}",
                       local->srx.transport_type,
                       local->srx.transport.family,
                       NIPQUAD(local->srx.transport.sin.sin_addr),
                       ntohs(local->srx.transport.sin.sin_port));

                if (local->srx.transport_type != srx->transport_type ||
                    local->srx.transport.family != srx->transport.family)
                        continue;

                switch (srx->transport.family) {
                case AF_INET:
                        if (local->srx.transport.sin.sin_port !=
                            srx->transport.sin.sin_port)
                                continue;
                        if (memcmp(&local->srx.transport.sin.sin_addr,
                                   &srx->transport.sin.sin_addr,
                                   sizeof(struct in_addr)) != 0)
                                continue;
                        goto found_local;

                default:
                        BUG();
                }
        }

        read_unlock_bh(&rxrpc_local_lock);

        /* we didn't find one, so we need to create one */
        local = rxrpc_alloc_local(srx);
        if (!local) {
                up_write(&rxrpc_local_sem);
                return ERR_PTR(-ENOMEM);
        }

        ret = rxrpc_create_local(local);
        if (ret < 0) {
                up_write(&rxrpc_local_sem);
                kfree(local);
                _leave(" = %d", ret);
                return ERR_PTR(ret);
        }

        up_write(&rxrpc_local_sem);

        _net("LOCAL new %d {%d,%u,%u.%u.%u.%u+%hu}",
             local->debug_id,
             local->srx.transport_type,
             local->srx.transport.family,
             NIPQUAD(local->srx.transport.sin.sin_addr),
             ntohs(local->srx.transport.sin.sin_port));

        _leave(" = %p [new]", local);
        return local;

found_local:
        rxrpc_get_local(local);
        read_unlock_bh(&rxrpc_local_lock);
        up_write(&rxrpc_local_sem);

        _net("LOCAL old %d {%d,%u,%u.%u.%u.%u+%hu}",
             local->debug_id,
             local->srx.transport_type,
             local->srx.transport.family,
             NIPQUAD(local->srx.transport.sin.sin_addr),
             ntohs(local->srx.transport.sin.sin_port));

        _leave(" = %p [reuse]", local);
        return local;
}

/*
 * release a local endpoint
 */
void rxrpc_put_local(struct rxrpc_local *local)
{
        _enter("%p{u=%d}", local, atomic_read(&local->usage));

        ASSERTCMP(atomic_read(&local->usage), >, 0);

        /* to prevent a race, the decrement and the dequeue must be effectively
         * atomic */
        write_lock_bh(&rxrpc_local_lock);
        if (unlikely(atomic_dec_and_test(&local->usage))) {
                _debug("destroy local");
                rxrpc_queue_work(&local->destroyer);
        }
        write_unlock_bh(&rxrpc_local_lock);
        _leave("");
}

/*
 * destroy a local endpoint
 */
static void rxrpc_destroy_local(struct work_struct *work)
{
        struct rxrpc_local *local =
                container_of(work, struct rxrpc_local, destroyer);

        _enter("%p{%d}", local, atomic_read(&local->usage));

        down_write(&rxrpc_local_sem);

        write_lock_bh(&rxrpc_local_lock);
        if (atomic_read(&local->usage) > 0) {
                write_unlock_bh(&rxrpc_local_lock);
                up_read(&rxrpc_local_sem);
                _leave(" [resurrected]");
                return;
        }

        list_del(&local->link);
        local->socket->sk->sk_user_data = NULL;
        write_unlock_bh(&rxrpc_local_lock);

        downgrade_write(&rxrpc_local_sem);

        ASSERT(list_empty(&local->services));
        ASSERT(!work_pending(&local->acceptor));
        ASSERT(!work_pending(&local->rejecter));

        /* finish cleaning up the local descriptor */
        rxrpc_purge_queue(&local->accept_queue);
        rxrpc_purge_queue(&local->reject_queue);
        kernel_sock_shutdown(local->socket, SHUT_RDWR);
        sock_release(local->socket);

        up_read(&rxrpc_local_sem);

        _net("DESTROY LOCAL %d", local->debug_id);
        kfree(local);

        if (list_empty(&rxrpc_locals))
                wake_up_all(&rxrpc_local_wq);

        _leave("");
}

/*
 * preemptively destroy all local local endpoint rather than waiting for
 * them to be destroyed
 */
void __exit rxrpc_destroy_all_locals(void)
{
        DECLARE_WAITQUEUE(myself,current);

        _enter("");

        /* we simply have to wait for them to go away */
        if (!list_empty(&rxrpc_locals)) {
                set_current_state(TASK_UNINTERRUPTIBLE);
                add_wait_queue(&rxrpc_local_wq, &myself);

                while (!list_empty(&rxrpc_locals)) {
                        schedule();
                        set_current_state(TASK_UNINTERRUPTIBLE);
                }

                remove_wait_queue(&rxrpc_local_wq, &myself);
                set_current_state(TASK_RUNNING);
        }

        _leave("");
}