signaling.c

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/* net/atm/signaling.c - ATM signaling */

/* Written 1995-2000 by Werner Almesberger, EPFL LRC/ICA */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s: " fmt, __func__

#include <linux/errno.h>    /* error codes */
#include <linux/kernel.h>   /* printk */
#include <linux/skbuff.h>
#include <linux/wait.h>
#include <linux/sched.h>    /* jiffies and HZ */
#include <linux/atm.h>      /* ATM stuff */
#include <linux/atmsap.h>
#include <linux/atmsvc.h>
#include <linux/atmdev.h>
#include <linux/bitops.h>
#include <linux/slab.h>

#include "resources.h"
#include "signaling.h"

#undef WAIT_FOR_DEMON       /* #define this if system calls on SVC sockets
                   should block until the demon runs.
                   Danger: may cause nasty hangs if the demon
                   crashes. */

struct atm_vcc *sigd = NULL;
#ifdef WAIT_FOR_DEMON
static DECLARE_WAIT_QUEUE_HEAD(sigd_sleep);
#endif

static void sigd_put_skb(struct sk_buff *skb)
{
#ifdef WAIT_FOR_DEMON
    DECLARE_WAITQUEUE(wait, current);

    add_wait_queue(&sigd_sleep, &wait);
    while (!sigd) {
        set_current_state(TASK_UNINTERRUPTIBLE);
        pr_debug("atmsvc: waiting for signaling daemon...\n");
        schedule();
    }
    current->state = TASK_RUNNING;
    remove_wait_queue(&sigd_sleep, &wait);
#else
    if (!sigd) {
        pr_debug("atmsvc: no signaling daemon\n");
        kfree_skb(skb);
        return;
    }
#endif
    atm_force_charge(sigd, skb->truesize);
    skb_queue_tail(&sk_atm(sigd)->sk_receive_queue, skb);
    sk_atm(sigd)->sk_data_ready(sk_atm(sigd), skb->len);
}

static void modify_qos(struct atm_vcc *vcc, struct atmsvc_msg *msg)
{
    struct sk_buff *skb;

    if (test_bit(ATM_VF_RELEASED, &vcc->flags) ||
        !test_bit(ATM_VF_READY, &vcc->flags))
        return;
    msg->type = as_error;
    if (!vcc->dev->ops->change_qos)
        msg->reply = -EOPNOTSUPP;
    else {
        /* should lock VCC */
        msg->reply = vcc->dev->ops->change_qos(vcc, &msg->qos,
                               msg->reply);
        if (!msg->reply)
            msg->type = as_okay;
    }
    /*
     * Should probably just turn around the old skb. But the, the buffer
     * space accounting needs to follow the change too. Maybe later.
     */
    while (!(skb = alloc_skb(sizeof(struct atmsvc_msg), GFP_KERNEL)))
        schedule();
    *(struct atmsvc_msg *)skb_put(skb, sizeof(struct atmsvc_msg)) = *msg;
    sigd_put_skb(skb);
}

static int sigd_send(struct atm_vcc *vcc, struct sk_buff *skb)
{
    struct atmsvc_msg *msg;
    struct atm_vcc *session_vcc;
    struct sock *sk;

    msg = (struct atmsvc_msg *) skb->data;
    atomic_sub(skb->truesize, &sk_atm(vcc)->sk_wmem_alloc);
    vcc = *(struct atm_vcc **) &msg->vcc;
    pr_debug("%d (0x%lx)\n", (int)msg->type, (unsigned long)vcc);
    sk = sk_atm(vcc);

    switch (msg->type) {
    case as_okay:
        sk->sk_err = -msg->reply;
        clear_bit(ATM_VF_WAITING, &vcc->flags);
        if (!*vcc->local.sas_addr.prv && !*vcc->local.sas_addr.pub) {
            vcc->local.sas_family = AF_ATMSVC;
            memcpy(vcc->local.sas_addr.prv,
                   msg->local.sas_addr.prv, ATM_ESA_LEN);
            memcpy(vcc->local.sas_addr.pub,
                   msg->local.sas_addr.pub, ATM_E164_LEN + 1);
        }
        session_vcc = vcc->session ? vcc->session : vcc;
        if (session_vcc->vpi || session_vcc->vci)
            break;
        session_vcc->itf = msg->pvc.sap_addr.itf;
        session_vcc->vpi = msg->pvc.sap_addr.vpi;
        session_vcc->vci = msg->pvc.sap_addr.vci;
        if (session_vcc->vpi || session_vcc->vci)
            session_vcc->qos = msg->qos;
        break;
    case as_error:
        clear_bit(ATM_VF_REGIS, &vcc->flags);
        clear_bit(ATM_VF_READY, &vcc->flags);
        sk->sk_err = -msg->reply;
        clear_bit(ATM_VF_WAITING, &vcc->flags);
        break;
    case as_indicate:
        vcc = *(struct atm_vcc **)&msg->listen_vcc;
        sk = sk_atm(vcc);
        pr_debug("as_indicate!!!\n");
        lock_sock(sk);
        if (sk_acceptq_is_full(sk)) {
            sigd_enq(NULL, as_reject, vcc, NULL, NULL);
            dev_kfree_skb(skb);
            goto as_indicate_complete;
        }
        sk->sk_ack_backlog++;
        skb_queue_tail(&sk->sk_receive_queue, skb);
        pr_debug("waking sk_sleep(sk) 0x%p\n", sk_sleep(sk));
        sk->sk_state_change(sk);
as_indicate_complete:
        release_sock(sk);
        return 0;
    case as_close:
        set_bit(ATM_VF_RELEASED, &vcc->flags);
        vcc_release_async(vcc, msg->reply);
        goto out;
    case as_modify:
        modify_qos(vcc, msg);
        break;
    case as_addparty:
    case as_dropparty:
        sk->sk_err_soft = msg->reply;
                    /* < 0 failure, otherwise ep_ref */
        clear_bit(ATM_VF_WAITING, &vcc->flags);
        break;
    default:
        pr_alert("bad message type %d\n", (int)msg->type);
        return -EINVAL;
    }
    sk->sk_state_change(sk);
out:
    dev_kfree_skb(skb);
    return 0;
}

void sigd_enq2(struct atm_vcc *vcc, enum atmsvc_msg_type type,
           struct atm_vcc *listen_vcc, const struct sockaddr_atmpvc *pvc,
           const struct sockaddr_atmsvc *svc, const struct atm_qos *qos,
           int reply)
{
    struct sk_buff *skb;
    struct atmsvc_msg *msg;
    static unsigned int session = 0;

    pr_debug("%d (0x%p)\n", (int)type, vcc);
    while (!(skb = alloc_skb(sizeof(struct atmsvc_msg), GFP_KERNEL)))
        schedule();
    msg = (struct atmsvc_msg *)skb_put(skb, sizeof(struct atmsvc_msg));
    memset(msg, 0, sizeof(*msg));
    msg->type = type;
    *(struct atm_vcc **) &msg->vcc = vcc;
    *(struct atm_vcc **) &msg->listen_vcc = listen_vcc;
    msg->reply = reply;
    if (qos)
        msg->qos = *qos;
    if (vcc)
        msg->sap = vcc->sap;
    if (svc)
        msg->svc = *svc;
    if (vcc)
        msg->local = vcc->local;
    if (pvc)
        msg->pvc = *pvc;
    if (vcc) {
        if (type == as_connect && test_bit(ATM_VF_SESSION, &vcc->flags))
            msg->session = ++session;
            /* every new pmp connect gets the next session number */
    }
    sigd_put_skb(skb);
    if (vcc)
        set_bit(ATM_VF_REGIS, &vcc->flags);
}

void sigd_enq(struct atm_vcc *vcc, enum atmsvc_msg_type type,
          struct atm_vcc *listen_vcc, const struct sockaddr_atmpvc *pvc,
          const struct sockaddr_atmsvc *svc)
{
    sigd_enq2(vcc, type, listen_vcc, pvc, svc, vcc ? &vcc->qos : NULL, 0);
    /* other ISP applications may use "reply" */
}

static void purge_vcc(struct atm_vcc *vcc)
{
    if (sk_atm(vcc)->sk_family == PF_ATMSVC &&
        !test_bit(ATM_VF_META, &vcc->flags)) {
        set_bit(ATM_VF_RELEASED, &vcc->flags);
        clear_bit(ATM_VF_REGIS, &vcc->flags);
        vcc_release_async(vcc, -EUNATCH);
    }
}

static void sigd_close(struct atm_vcc *vcc)
{
    struct hlist_node *node;
    struct sock *s;
    int i;

    pr_debug("\n");
    sigd = NULL;
    if (skb_peek(&sk_atm(vcc)->sk_receive_queue))
        pr_err("closing with requests pending\n");
    skb_queue_purge(&sk_atm(vcc)->sk_receive_queue);

    read_lock(&vcc_sklist_lock);
    for (i = 0; i < VCC_HTABLE_SIZE; ++i) {
        struct hlist_head *head = &vcc_hash[i];

        sk_for_each(s, node, head) {
            vcc = atm_sk(s);

            purge_vcc(vcc);
        }
    }
    read_unlock(&vcc_sklist_lock);
}

static struct atmdev_ops sigd_dev_ops = {
    .close = sigd_close,
    .send = sigd_send
};

static struct atm_dev sigd_dev = {
    .ops =      &sigd_dev_ops,
    .type =     "sig",
    .number =   999,
    .lock =     __SPIN_LOCK_UNLOCKED(sigd_dev.lock)
};

int sigd_attach(struct atm_vcc *vcc)
{
    if (sigd)
        return -EADDRINUSE;
    pr_debug("\n");
    sigd = vcc;
    vcc->dev = &sigd_dev;
    vcc_insert_socket(sk_atm(vcc));
    set_bit(ATM_VF_META, &vcc->flags);
    set_bit(ATM_VF_READY, &vcc->flags);
#ifdef WAIT_FOR_DEMON
    wake_up(&sigd_sleep);
#endif
    return 0;
}