/*
 *  IUCV protocol stack for Linux on zSeries
 *
 *  Copyright IBM Corp. 2006, 2009
 *
 *  Author(s):  Jennifer Hunt <jenhunt@us.ibm.com>
 *              Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
 *  PM functions:
 *              Ursula Braun <ursula.braun@de.ibm.com>
 */

#define KMSG_COMPONENT "af_iucv"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/module.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/security.h>
#include <net/sock.h>
#include <asm/ebcdic.h>
#include <asm/cpcmd.h>
#include <linux/kmod.h>

#include <net/iucv/af_iucv.h>

#define VERSION "1.2"

static char iucv_userid[80];

static const struct proto_ops iucv_sock_ops;

static struct proto iucv_proto = {
        .name           = "AF_IUCV",
        .owner          = THIS_MODULE,
        .obj_size       = sizeof(struct iucv_sock),
};

static struct iucv_interface *pr_iucv;

/* special AF_IUCV IPRM messages */
static const u8 iprm_shutdown[8] =
        {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01};

#define TRGCLS_SIZE     (sizeof(((struct iucv_message *)0)->class))

#define __iucv_sock_wait(sk, condition, timeo, ret)                     \
do {                                                                    \
        DEFINE_WAIT(__wait);                                            \
        long __timeo = timeo;                                           \
        ret = 0;                                                        \
        prepare_to_wait(sk_sleep(sk), &__wait, TASK_INTERRUPTIBLE);     \
        while (!(condition)) {                                          \
                if (!__timeo) {                                         \
                        ret = -EAGAIN;                                  \
                        break;                                          \
                }                                                       \
                if (signal_pending(current)) {                          \
                        ret = sock_intr_errno(__timeo);                 \
                        break;                                          \
                }                                                       \
                release_sock(sk);                                       \
                __timeo = schedule_timeout(__timeo);                    \
                lock_sock(sk);                                          \
                ret = sock_error(sk);                                   \
                if (ret)                                                \
                        break;                                          \
        }                                                               \
        finish_wait(sk_sleep(sk), &__wait);                             \
} while (0)

#define iucv_sock_wait(sk, condition, timeo)                            \
({                                                                      \
        int __ret = 0;                                                  \
        if (!(condition))                                               \
                __iucv_sock_wait(sk, condition, timeo, __ret);          \
        __ret;                                                          \
})

static void iucv_sock_kill(struct sock *sk);
static void iucv_sock_close(struct sock *sk);
static void iucv_sever_path(struct sock *, int);

static int afiucv_hs_rcv(struct sk_buff *skb, struct net_device *dev,
        struct packet_type *pt, struct net_device *orig_dev);
static int afiucv_hs_send(struct iucv_message *imsg, struct sock *sock,
                   struct sk_buff *skb, u8 flags);
static void afiucv_hs_callback_txnotify(struct sk_buff *, enum iucv_tx_notify);

/* Call Back functions */
static void iucv_callback_rx(struct iucv_path *, struct iucv_message *);
static void iucv_callback_txdone(struct iucv_path *, struct iucv_message *);
static void iucv_callback_connack(struct iucv_path *, u8 *);
static int iucv_callback_connreq(struct iucv_path *, u8 *, u8 *);
static void iucv_callback_connrej(struct iucv_path *, u8 *);
static void iucv_callback_shutdown(struct iucv_path *, u8 *);

static struct iucv_sock_list iucv_sk_list = {
        .lock = __RW_LOCK_UNLOCKED(iucv_sk_list.lock),
        .autobind_name = ATOMIC_INIT(0)
};

static struct iucv_handler af_iucv_handler = {
        .path_pending     = iucv_callback_connreq,
        .path_complete    = iucv_callback_connack,
        .path_severed     = iucv_callback_connrej,
        .message_pending  = iucv_callback_rx,
        .message_complete = iucv_callback_txdone,
        .path_quiesced    = iucv_callback_shutdown,
};

static inline void high_nmcpy(unsigned char *dst, char *src)
{
       memcpy(dst, src, 8);
}

static inline void low_nmcpy(unsigned char *dst, char *src)
{
       memcpy(&dst[8], src, 8);
}

static int afiucv_pm_prepare(struct device *dev)
{
#ifdef CONFIG_PM_DEBUG
        printk(KERN_WARNING "afiucv_pm_prepare\n");
#endif
        return 0;
}

static void afiucv_pm_complete(struct device *dev)
{
#ifdef CONFIG_PM_DEBUG
        printk(KERN_WARNING "afiucv_pm_complete\n");
#endif
}

/**
 * afiucv_pm_freeze() - Freeze PM callback
 * @dev:        AFIUCV dummy device
 *
 * Sever all established IUCV communication pathes
 */
static int afiucv_pm_freeze(struct device *dev)
{
        struct iucv_sock *iucv;
        struct sock *sk;
        int err = 0;

#ifdef CONFIG_PM_DEBUG
        printk(KERN_WARNING "afiucv_pm_freeze\n");
#endif
        read_lock(&iucv_sk_list.lock);
        sk_for_each(sk, &iucv_sk_list.head) {
                iucv = iucv_sk(sk);
                switch (sk->sk_state) {
                case IUCV_DISCONN:
                case IUCV_CLOSING:
                case IUCV_CONNECTED:
                        iucv_sever_path(sk, 0);
                        break;
                case IUCV_OPEN:
                case IUCV_BOUND:
                case IUCV_LISTEN:
                case IUCV_CLOSED:
                default:
                        break;
                }
                skb_queue_purge(&iucv->send_skb_q);
                skb_queue_purge(&iucv->backlog_skb_q);
        }
        read_unlock(&iucv_sk_list.lock);
        return err;
}

/**
 * afiucv_pm_restore_thaw() - Thaw and restore PM callback
 * @dev:        AFIUCV dummy device
 *
 * socket clean up after freeze
 */
static int afiucv_pm_restore_thaw(struct device *dev)
{
        struct sock *sk;

#ifdef CONFIG_PM_DEBUG
        printk(KERN_WARNING "afiucv_pm_restore_thaw\n");
#endif
        read_lock(&iucv_sk_list.lock);
        sk_for_each(sk, &iucv_sk_list.head) {
                switch (sk->sk_state) {
                case IUCV_CONNECTED:
                        sk->sk_err = EPIPE;
                        sk->sk_state = IUCV_DISCONN;
                        sk->sk_state_change(sk);
                        break;
                case IUCV_DISCONN:
                case IUCV_CLOSING:
                case IUCV_LISTEN:
                case IUCV_BOUND:
                case IUCV_OPEN:
                default:
                        break;
                }
        }
        read_unlock(&iucv_sk_list.lock);
        return 0;
}

static const struct dev_pm_ops afiucv_pm_ops = {
        .prepare = afiucv_pm_prepare,
        .complete = afiucv_pm_complete,
        .freeze = afiucv_pm_freeze,
        .thaw = afiucv_pm_restore_thaw,
        .restore = afiucv_pm_restore_thaw,
};

static struct device_driver af_iucv_driver = {
        .owner = THIS_MODULE,
        .name = "afiucv",
        .bus  = NULL,
        .pm   = &afiucv_pm_ops,
};

/* dummy device used as trigger for PM functions */
static struct device *af_iucv_dev;

/**
 * iucv_msg_length() - Returns the length of an iucv message.
 * @msg:        Pointer to struct iucv_message, MUST NOT be NULL
 *
 * The function returns the length of the specified iucv message @msg of data
 * stored in a buffer and of data stored in the parameter list (PRMDATA).
 *
 * For IUCV_IPRMDATA, AF_IUCV uses the following convention to transport socket
 * data:
 *      PRMDATA[0..6]   socket data (max 7 bytes);
 *      PRMDATA[7]      socket data length value (len is 0xff - PRMDATA[7])
 *
 * The socket data length is computed by subtracting the socket data length
 * value from 0xFF.
 * If the socket data len is greater 7, then PRMDATA can be used for special
 * notifications (see iucv_sock_shutdown); and further,
 * if the socket data len is > 7, the function returns 8.
 *
 * Use this function to allocate socket buffers to store iucv message data.
 */
static inline size_t iucv_msg_length(struct iucv_message *msg)
{
        size_t datalen;

        if (msg->flags & IUCV_IPRMDATA) {
                datalen = 0xff - msg->rmmsg[7];
                return (datalen < 8) ? datalen : 8;
        }
        return msg->length;
}

/**
 * iucv_sock_in_state() - check for specific states
 * @sk:         sock structure
 * @state:      first iucv sk state
 * @state:      second iucv sk state
 *
 * Returns true if the socket in either in the first or second state.
 */
static int iucv_sock_in_state(struct sock *sk, int state, int state2)
{
        return (sk->sk_state == state || sk->sk_state == state2);
}

/**
 * iucv_below_msglim() - function to check if messages can be sent
 * @sk:         sock structure
 *
 * Returns true if the send queue length is lower than the message limit.
 * Always returns true if the socket is not connected (no iucv path for
 * checking the message limit).
 */
static inline int iucv_below_msglim(struct sock *sk)
{
        struct iucv_sock *iucv = iucv_sk(sk);

        if (sk->sk_state != IUCV_CONNECTED)
                return 1;
        if (iucv->transport == AF_IUCV_TRANS_IUCV)
                return (skb_queue_len(&iucv->send_skb_q) < iucv->path->msglim);
        else
                return ((atomic_read(&iucv->msg_sent) < iucv->msglimit_peer) &&
                        (atomic_read(&iucv->pendings) <= 0));
}

/**
 * iucv_sock_wake_msglim() - Wake up thread waiting on msg limit
 */
static void iucv_sock_wake_msglim(struct sock *sk)
{
        struct socket_wq *wq;

        rcu_read_lock();
        wq = rcu_dereference(sk->sk_wq);
        if (skwq_has_sleeper(wq))
                wake_up_interruptible_all(&wq->wait);
        sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
        rcu_read_unlock();
}

/**
 * afiucv_hs_send() - send a message through HiperSockets transport
 */
static int afiucv_hs_send(struct iucv_message *imsg, struct sock *sock,
                   struct sk_buff *skb, u8 flags)
{
        struct iucv_sock *iucv = iucv_sk(sock);
        struct af_iucv_trans_hdr *phs_hdr;
        struct sk_buff *nskb;
        int err, confirm_recv = 0;

        memset(skb->head, 0, ETH_HLEN);
        phs_hdr = (struct af_iucv_trans_hdr *)skb_push(skb,
                                        sizeof(struct af_iucv_trans_hdr));
        skb_reset_mac_header(skb);
        skb_reset_network_header(skb);
        skb_push(skb, ETH_HLEN);
        skb_reset_mac_header(skb);
        memset(phs_hdr, 0, sizeof(struct af_iucv_trans_hdr));

        phs_hdr->magic = ETH_P_AF_IUCV;
        phs_hdr->version = 1;
        phs_hdr->flags = flags;
        if (flags == AF_IUCV_FLAG_SYN)
                phs_hdr->window = iucv->msglimit;
        else if ((flags == AF_IUCV_FLAG_WIN) || !flags) {
                confirm_recv = atomic_read(&iucv->msg_recv);
                phs_hdr->window = confirm_recv;
                if (confirm_recv)
                        phs_hdr->flags = phs_hdr->flags | AF_IUCV_FLAG_WIN;
        }
        memcpy(phs_hdr->destUserID, iucv->dst_user_id, 8);
        memcpy(phs_hdr->destAppName, iucv->dst_name, 8);
        memcpy(phs_hdr->srcUserID, iucv->src_user_id, 8);
        memcpy(phs_hdr->srcAppName, iucv->src_name, 8);
        ASCEBC(phs_hdr->destUserID, sizeof(phs_hdr->destUserID));
        ASCEBC(phs_hdr->destAppName, sizeof(phs_hdr->destAppName));
        ASCEBC(phs_hdr->srcUserID, sizeof(phs_hdr->srcUserID));
        ASCEBC(phs_hdr->srcAppName, sizeof(phs_hdr->srcAppName));
        if (imsg)
                memcpy(&phs_hdr->iucv_hdr, imsg, sizeof(struct iucv_message));

        skb->dev = iucv->hs_dev;
        if (!skb->dev)
                return -ENODEV;
        if (!(skb->dev->flags & IFF_UP) || !netif_carrier_ok(skb->dev))
                return -ENETDOWN;
        if (skb->len > skb->dev->mtu) {
                if (sock->sk_type == SOCK_SEQPACKET)
                        return -EMSGSIZE;
                else
                        skb_trim(skb, skb->dev->mtu);
        }
        skb->protocol = ETH_P_AF_IUCV;
        nskb = skb_clone(skb, GFP_ATOMIC);
        if (!nskb)
                return -ENOMEM;
        skb_queue_tail(&iucv->send_skb_q, nskb);
        err = dev_queue_xmit(skb);
        if (net_xmit_eval(err)) {
                skb_unlink(nskb, &iucv->send_skb_q);
                kfree_skb(nskb);
        } else {
                atomic_sub(confirm_recv, &iucv->msg_recv);
                WARN_ON(atomic_read(&iucv->msg_recv) < 0);
        }
        return net_xmit_eval(err);
}

static struct sock *__iucv_get_sock_by_name(char *nm)
{
        struct sock *sk;

        sk_for_each(sk, &iucv_sk_list.head)
                if (!memcmp(&iucv_sk(sk)->src_name, nm, 8))
                        return sk;

        return NULL;
}

static void iucv_sock_destruct(struct sock *sk)
{
        skb_queue_purge(&sk->sk_receive_queue);
        skb_queue_purge(&sk->sk_error_queue);

        sk_mem_reclaim(sk);

        if (!sock_flag(sk, SOCK_DEAD)) {
                pr_err("Attempt to release alive iucv socket %p\n", sk);
                return;
        }

        WARN_ON(atomic_read(&sk->sk_rmem_alloc));
        WARN_ON(atomic_read(&sk->sk_wmem_alloc));
        WARN_ON(sk->sk_wmem_queued);
        WARN_ON(sk->sk_forward_alloc);
}

/* Cleanup Listen */
static void iucv_sock_cleanup_listen(struct sock *parent)
{
        struct sock *sk;

        /* Close non-accepted connections */
        while ((sk = iucv_accept_dequeue(parent, NULL))) {
                iucv_sock_close(sk);
                iucv_sock_kill(sk);
        }

        parent->sk_state = IUCV_CLOSED;
}

/* Kill socket (only if zapped and orphaned) */
static void iucv_sock_kill(struct sock *sk)
{
        if (!sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
                return;

        iucv_sock_unlink(&iucv_sk_list, sk);
        sock_set_flag(sk, SOCK_DEAD);
        sock_put(sk);
}

/* Terminate an IUCV path */
static void iucv_sever_path(struct sock *sk, int with_user_data)
{
        unsigned char user_data[16];
        struct iucv_sock *iucv = iucv_sk(sk);
        struct iucv_path *path = iucv->path;

        if (iucv->path) {
                iucv->path = NULL;
                if (with_user_data) {
                        low_nmcpy(user_data, iucv->src_name);
                        high_nmcpy(user_data, iucv->dst_name);
                        ASCEBC(user_data, sizeof(user_data));
                        pr_iucv->path_sever(path, user_data);
                } else
                        pr_iucv->path_sever(path, NULL);
                iucv_path_free(path);
        }
}

/* Send controlling flags through an IUCV socket for HIPER transport */
static int iucv_send_ctrl(struct sock *sk, u8 flags)
{
        int err = 0;
        int blen;
        struct sk_buff *skb;
        u8 shutdown = 0;

        blen = sizeof(struct af_iucv_trans_hdr) + ETH_HLEN;
        if (sk->sk_shutdown & SEND_SHUTDOWN) {
                /* controlling flags should be sent anyway */
                shutdown = sk->sk_shutdown;
                sk->sk_shutdown &= RCV_SHUTDOWN;
        }
        skb = sock_alloc_send_skb(sk, blen, 1, &err);
        if (skb) {
                skb_reserve(skb, blen);
                err = afiucv_hs_send(NULL, sk, skb, flags);
        }
        if (shutdown)
                sk->sk_shutdown = shutdown;
        return err;
}

/* Close an IUCV socket */
static void iucv_sock_close(struct sock *sk)
{
        struct iucv_sock *iucv = iucv_sk(sk);
        unsigned long timeo;
        int err = 0;

        lock_sock(sk);

        switch (sk->sk_state) {
        case IUCV_LISTEN:
                iucv_sock_cleanup_listen(sk);
                break;

        case IUCV_CONNECTED:
                if (iucv->transport == AF_IUCV_TRANS_HIPER) {
                        err = iucv_send_ctrl(sk, AF_IUCV_FLAG_FIN);
                        sk->sk_state = IUCV_DISCONN;
                        sk->sk_state_change(sk);
                }
        case IUCV_DISCONN:   /* fall through */
                sk->sk_state = IUCV_CLOSING;
                sk->sk_state_change(sk);

                if (!err && !skb_queue_empty(&iucv->send_skb_q)) {
                        if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime)
                                timeo = sk->sk_lingertime;
                        else
                                timeo = IUCV_DISCONN_TIMEOUT;
                        iucv_sock_wait(sk,
                                        iucv_sock_in_state(sk, IUCV_CLOSED, 0),
                                        timeo);
                }

        case IUCV_CLOSING:   /* fall through */
                sk->sk_state = IUCV_CLOSED;
                sk->sk_state_change(sk);

                sk->sk_err = ECONNRESET;
                sk->sk_state_change(sk);

                skb_queue_purge(&iucv->send_skb_q);
                skb_queue_purge(&iucv->backlog_skb_q);

        default:   /* fall through */
                iucv_sever_path(sk, 1);
        }

        if (iucv->hs_dev) {
                dev_put(iucv->hs_dev);
                iucv->hs_dev = NULL;
                sk->sk_bound_dev_if = 0;
        }

        /* mark socket for deletion by iucv_sock_kill() */
        sock_set_flag(sk, SOCK_ZAPPED);

        release_sock(sk);
}

static void iucv_sock_init(struct sock *sk, struct sock *parent)
{
        if (parent) {
                sk->sk_type = parent->sk_type;
                security_sk_clone(parent, sk);
        }
}

static struct sock *iucv_sock_alloc(struct socket *sock, int proto, gfp_t prio, int kern)
{
        struct sock *sk;
        struct iucv_sock *iucv;

        sk = sk_alloc(&init_net, PF_IUCV, prio, &iucv_proto, kern);
        if (!sk)
                return NULL;
        iucv = iucv_sk(sk);

        sock_init_data(sock, sk);
        INIT_LIST_HEAD(&iucv->accept_q);
        spin_lock_init(&iucv->accept_q_lock);
        skb_queue_head_init(&iucv->send_skb_q);
        INIT_LIST_HEAD(&iucv->message_q.list);
        spin_lock_init(&iucv->message_q.lock);
        skb_queue_head_init(&iucv->backlog_skb_q);
        iucv->send_tag = 0;
        atomic_set(&iucv->pendings, 0);
        iucv->flags = 0;
        iucv->msglimit = 0;
        atomic_set(&iucv->msg_sent, 0);
        atomic_set(&iucv->msg_recv, 0);
        iucv->path = NULL;
        iucv->sk_txnotify = afiucv_hs_callback_txnotify;
        memset(&iucv->src_user_id , 0, 32);
        if (pr_iucv)
                iucv->transport = AF_IUCV_TRANS_IUCV;
        else
                iucv->transport = AF_IUCV_TRANS_HIPER;

        sk->sk_destruct = iucv_sock_destruct;
        sk->sk_sndtimeo = IUCV_CONN_TIMEOUT;
        sk->sk_allocation = GFP_DMA;

        sock_reset_flag(sk, SOCK_ZAPPED);

        sk->sk_protocol = proto;
        sk->sk_state    = IUCV_OPEN;

        iucv_sock_link(&iucv_sk_list, sk);
        return sk;
}

/* Create an IUCV socket */
static int iucv_sock_create(struct net *net, struct socket *sock, int protocol,
                            int kern)
{
        struct sock *sk;

        if (protocol && protocol != PF_IUCV)
                return -EPROTONOSUPPORT;

        sock->state = SS_UNCONNECTED;

        switch (sock->type) {
        case SOCK_STREAM:
                sock->ops = &iucv_sock_ops;
                break;
        case SOCK_SEQPACKET:
                /* currently, proto ops can handle both sk types */
                sock->ops = &iucv_sock_ops;
                break;
        default:
                return -ESOCKTNOSUPPORT;
        }

        sk = iucv_sock_alloc(sock, protocol, GFP_KERNEL, kern);
        if (!sk)
                return -ENOMEM;

        iucv_sock_init(sk, NULL);

        return 0;
}

void iucv_sock_link(struct iucv_sock_list *l, struct sock *sk)
{
        write_lock_bh(&l->lock);
        sk_add_node(sk, &l->head);
        write_unlock_bh(&l->lock);
}

void iucv_sock_unlink(struct iucv_sock_list *l, struct sock *sk)
{
        write_lock_bh(&l->lock);
        sk_del_node_init(sk);
        write_unlock_bh(&l->lock);
}

void iucv_accept_enqueue(struct sock *parent, struct sock *sk)
{
        unsigned long flags;
        struct iucv_sock *par = iucv_sk(parent);

        sock_hold(sk);
        spin_lock_irqsave(&par->accept_q_lock, flags);
        list_add_tail(&iucv_sk(sk)->accept_q, &par->accept_q);
        spin_unlock_irqrestore(&par->accept_q_lock, flags);
        iucv_sk(sk)->parent = parent;
        sk_acceptq_added(parent);
}

void iucv_accept_unlink(struct sock *sk)
{
        unsigned long flags;
        struct iucv_sock *par = iucv_sk(iucv_sk(sk)->parent);

        spin_lock_irqsave(&par->accept_q_lock, flags);
        list_del_init(&iucv_sk(sk)->accept_q);
        spin_unlock_irqrestore(&par->accept_q_lock, flags);
        sk_acceptq_removed(iucv_sk(sk)->parent);
        iucv_sk(sk)->parent = NULL;
        sock_put(sk);
}

struct sock *iucv_accept_dequeue(struct sock *parent, struct socket *newsock)
{
        struct iucv_sock *isk, *n;
        struct sock *sk;

        list_for_each_entry_safe(isk, n, &iucv_sk(parent)->accept_q, accept_q) {
                sk = (struct sock *) isk;
                lock_sock(sk);

                if (sk->sk_state == IUCV_CLOSED) {
                        iucv_accept_unlink(sk);
                        release_sock(sk);
                        continue;
                }

                if (sk->sk_state == IUCV_CONNECTED ||
                    sk->sk_state == IUCV_DISCONN ||
                    !newsock) {
                        iucv_accept_unlink(sk);
                        if (newsock)
                                sock_graft(sk, newsock);

                        release_sock(sk);
                        return sk;
                }

                release_sock(sk);
        }
        return NULL;
}

static void __iucv_auto_name(struct iucv_sock *iucv)
{
        char name[12];

        sprintf(name, "%08x", atomic_inc_return(&iucv_sk_list.autobind_name));
        while (__iucv_get_sock_by_name(name)) {
                sprintf(name, "%08x",
                        atomic_inc_return(&iucv_sk_list.autobind_name));
        }
        memcpy(iucv->src_name, name, 8);
}

/* Bind an unbound socket */
static int iucv_sock_bind(struct socket *sock, struct sockaddr *addr,
                          int addr_len)
{
        struct sockaddr_iucv *sa = (struct sockaddr_iucv *) addr;
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv;
        int err = 0;
        struct net_device *dev;
        char uid[9];

        /* Verify the input sockaddr */
        if (!addr || addr->sa_family != AF_IUCV)
                return -EINVAL;

        if (addr_len < sizeof(struct sockaddr_iucv))
                return -EINVAL;

        lock_sock(sk);
        if (sk->sk_state != IUCV_OPEN) {
                err = -EBADFD;
                goto done;
        }

        write_lock_bh(&iucv_sk_list.lock);

        iucv = iucv_sk(sk);
        if (__iucv_get_sock_by_name(sa->siucv_name)) {
                err = -EADDRINUSE;
                goto done_unlock;
        }
        if (iucv->path)
                goto done_unlock;

        /* Bind the socket */
        if (pr_iucv)
                if (!memcmp(sa->siucv_user_id, iucv_userid, 8))
                        goto vm_bind; /* VM IUCV transport */

        /* try hiper transport */
        memcpy(uid, sa->siucv_user_id, sizeof(uid));
        ASCEBC(uid, 8);
        rcu_read_lock();
        for_each_netdev_rcu(&init_net, dev) {
                if (!memcmp(dev->perm_addr, uid, 8)) {
                        memcpy(iucv->src_user_id, sa->siucv_user_id, 8);
                        /* Check for unitialized siucv_name */
                        if (strncmp(sa->siucv_name, "        ", 8) == 0)
                                __iucv_auto_name(iucv);
                        else
                                memcpy(iucv->src_name, sa->siucv_name, 8);
                        sk->sk_bound_dev_if = dev->ifindex;
                        iucv->hs_dev = dev;
                        dev_hold(dev);
                        sk->sk_state = IUCV_BOUND;
                        iucv->transport = AF_IUCV_TRANS_HIPER;
                        if (!iucv->msglimit)
                                iucv->msglimit = IUCV_HIPER_MSGLIM_DEFAULT;
                        rcu_read_unlock();
                        goto done_unlock;
                }
        }
        rcu_read_unlock();
vm_bind:
        if (pr_iucv) {
                /* use local userid for backward compat */
                memcpy(iucv->src_name, sa->siucv_name, 8);
                memcpy(iucv->src_user_id, iucv_userid, 8);
                sk->sk_state = IUCV_BOUND;
                iucv->transport = AF_IUCV_TRANS_IUCV;
                if (!iucv->msglimit)
                        iucv->msglimit = IUCV_QUEUELEN_DEFAULT;
                goto done_unlock;
        }
        /* found no dev to bind */
        err = -ENODEV;
done_unlock:
        /* Release the socket list lock */
        write_unlock_bh(&iucv_sk_list.lock);
done:
        release_sock(sk);
        return err;
}

/* Automatically bind an unbound socket */
static int iucv_sock_autobind(struct sock *sk)
{
        struct iucv_sock *iucv = iucv_sk(sk);
        int err = 0;

        if (unlikely(!pr_iucv))
                return -EPROTO;

        memcpy(iucv->src_user_id, iucv_userid, 8);

        write_lock_bh(&iucv_sk_list.lock);
        __iucv_auto_name(iucv);
        write_unlock_bh(&iucv_sk_list.lock);

        if (!iucv->msglimit)
                iucv->msglimit = IUCV_QUEUELEN_DEFAULT;

        return err;
}

static int afiucv_path_connect(struct socket *sock, struct sockaddr *addr)
{
        struct sockaddr_iucv *sa = (struct sockaddr_iucv *) addr;
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv = iucv_sk(sk);
        unsigned char user_data[16];
        int err;

        high_nmcpy(user_data, sa->siucv_name);
        low_nmcpy(user_data, iucv->src_name);
        ASCEBC(user_data, sizeof(user_data));

        /* Create path. */
        iucv->path = iucv_path_alloc(iucv->msglimit,
                                     IUCV_IPRMDATA, GFP_KERNEL);
        if (!iucv->path) {
                err = -ENOMEM;
                goto done;
        }
        err = pr_iucv->path_connect(iucv->path, &af_iucv_handler,
                                    sa->siucv_user_id, NULL, user_data,
                                    sk);
        if (err) {
                iucv_path_free(iucv->path);
                iucv->path = NULL;
                switch (err) {
                case 0x0b:      /* Target communicator is not logged on */
                        err = -ENETUNREACH;
                        break;
                case 0x0d:      /* Max connections for this guest exceeded */
                case 0x0e:      /* Max connections for target guest exceeded */
                        err = -EAGAIN;
                        break;
                case 0x0f:      /* Missing IUCV authorization */
                        err = -EACCES;
                        break;
                default:
                        err = -ECONNREFUSED;
                        break;
                }
        }
done:
        return err;
}

/* Connect an unconnected socket */
static int iucv_sock_connect(struct socket *sock, struct sockaddr *addr,
                             int alen, int flags)
{
        struct sockaddr_iucv *sa = (struct sockaddr_iucv *) addr;
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv = iucv_sk(sk);
        int err;

        if (addr->sa_family != AF_IUCV || alen < sizeof(struct sockaddr_iucv))
                return -EINVAL;

        if (sk->sk_state != IUCV_OPEN && sk->sk_state != IUCV_BOUND)
                return -EBADFD;

        if (sk->sk_state == IUCV_OPEN &&
            iucv->transport == AF_IUCV_TRANS_HIPER)
                return -EBADFD; /* explicit bind required */

        if (sk->sk_type != SOCK_STREAM && sk->sk_type != SOCK_SEQPACKET)
                return -EINVAL;

        if (sk->sk_state == IUCV_OPEN) {
                err = iucv_sock_autobind(sk);
                if (unlikely(err))
                        return err;
        }

        lock_sock(sk);

        /* Set the destination information */
        memcpy(iucv->dst_user_id, sa->siucv_user_id, 8);
        memcpy(iucv->dst_name, sa->siucv_name, 8);

        if (iucv->transport == AF_IUCV_TRANS_HIPER)
                err = iucv_send_ctrl(sock->sk, AF_IUCV_FLAG_SYN);
        else
                err = afiucv_path_connect(sock, addr);
        if (err)
                goto done;

        if (sk->sk_state != IUCV_CONNECTED)
                err = iucv_sock_wait(sk, iucv_sock_in_state(sk, IUCV_CONNECTED,
                                                            IUCV_DISCONN),
                                     sock_sndtimeo(sk, flags & O_NONBLOCK));

        if (sk->sk_state == IUCV_DISCONN || sk->sk_state == IUCV_CLOSED)
                err = -ECONNREFUSED;

        if (err && iucv->transport == AF_IUCV_TRANS_IUCV)
                iucv_sever_path(sk, 0);

done:
        release_sock(sk);
        return err;
}

/* Move a socket into listening state. */
static int iucv_sock_listen(struct socket *sock, int backlog)
{
        struct sock *sk = sock->sk;
        int err;

        lock_sock(sk);

        err = -EINVAL;
        if (sk->sk_state != IUCV_BOUND)
                goto done;

        if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
                goto done;

        sk->sk_max_ack_backlog = backlog;
        sk->sk_ack_backlog = 0;
        sk->sk_state = IUCV_LISTEN;
        err = 0;

done:
        release_sock(sk);
        return err;
}

/* Accept a pending connection */
static int iucv_sock_accept(struct socket *sock, struct socket *newsock,
                            int flags)
{
        DECLARE_WAITQUEUE(wait, current);
        struct sock *sk = sock->sk, *nsk;
        long timeo;
        int err = 0;

        lock_sock_nested(sk, SINGLE_DEPTH_NESTING);

        if (sk->sk_state != IUCV_LISTEN) {
                err = -EBADFD;
                goto done;
        }

        timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);

        /* Wait for an incoming connection */
        add_wait_queue_exclusive(sk_sleep(sk), &wait);
        while (!(nsk = iucv_accept_dequeue(sk, newsock))) {
                set_current_state(TASK_INTERRUPTIBLE);
                if (!timeo) {
                        err = -EAGAIN;
                        break;
                }

                release_sock(sk);
                timeo = schedule_timeout(timeo);
                lock_sock_nested(sk, SINGLE_DEPTH_NESTING);

                if (sk->sk_state != IUCV_LISTEN) {
                        err = -EBADFD;
                        break;
                }

                if (signal_pending(current)) {
                        err = sock_intr_errno(timeo);
                        break;
                }
        }

        set_current_state(TASK_RUNNING);
        remove_wait_queue(sk_sleep(sk), &wait);

        if (err)
                goto done;

        newsock->state = SS_CONNECTED;

done:
        release_sock(sk);
        return err;
}

static int iucv_sock_getname(struct socket *sock, struct sockaddr *addr,
                             int *len, int peer)
{
        struct sockaddr_iucv *siucv = (struct sockaddr_iucv *) addr;
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv = iucv_sk(sk);

        addr->sa_family = AF_IUCV;
        *len = sizeof(struct sockaddr_iucv);

        if (peer) {
                memcpy(siucv->siucv_user_id, iucv->dst_user_id, 8);
                memcpy(siucv->siucv_name, iucv->dst_name, 8);
        } else {
                memcpy(siucv->siucv_user_id, iucv->src_user_id, 8);
                memcpy(siucv->siucv_name, iucv->src_name, 8);
        }
        memset(&siucv->siucv_port, 0, sizeof(siucv->siucv_port));
        memset(&siucv->siucv_addr, 0, sizeof(siucv->siucv_addr));
        memset(&siucv->siucv_nodeid, 0, sizeof(siucv->siucv_nodeid));

        return 0;
}

/**
 * iucv_send_iprm() - Send socket data in parameter list of an iucv message.
 * @path:       IUCV path
 * @msg:        Pointer to a struct iucv_message
 * @skb:        The socket data to send, skb->len MUST BE <= 7
 *
 * Send the socket data in the parameter list in the iucv message
 * (IUCV_IPRMDATA). The socket data is stored at index 0 to 6 in the parameter
 * list and the socket data len at index 7 (last byte).
 * See also iucv_msg_length().
 *
 * Returns the error code from the iucv_message_send() call.
 */
static int iucv_send_iprm(struct iucv_path *path, struct iucv_message *msg,
                          struct sk_buff *skb)
{
        u8 prmdata[8];

        memcpy(prmdata, (void *) skb->data, skb->len);
        prmdata[7] = 0xff - (u8) skb->len;
        return pr_iucv->message_send(path, msg, IUCV_IPRMDATA, 0,
                                 (void *) prmdata, 8);
}

static int iucv_sock_sendmsg(struct socket *sock, struct msghdr *msg,
                             size_t len)
{
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv = iucv_sk(sk);
        size_t headroom = 0;
        size_t linear;
        struct sk_buff *skb;
        struct iucv_message txmsg = {0};
        struct cmsghdr *cmsg;
        int cmsg_done;
        long timeo;
        char user_id[9];
        char appl_id[9];
        int err;
        int noblock = msg->msg_flags & MSG_DONTWAIT;

        err = sock_error(sk);
        if (err)
                return err;

        if (msg->msg_flags & MSG_OOB)
                return -EOPNOTSUPP;

        /* SOCK_SEQPACKET: we do not support segmented records */
        if (sk->sk_type == SOCK_SEQPACKET && !(msg->msg_flags & MSG_EOR))
                return -EOPNOTSUPP;

        lock_sock(sk);

        if (sk->sk_shutdown & SEND_SHUTDOWN) {
                err = -EPIPE;
                goto out;
        }

        /* Return if the socket is not in connected state */
        if (sk->sk_state != IUCV_CONNECTED) {
                err = -ENOTCONN;
                goto out;
        }

        /* initialize defaults */
        cmsg_done   = 0;        /* check for duplicate headers */
        txmsg.class = 0;

        /* iterate over control messages */
        for_each_cmsghdr(cmsg, msg) {
                if (!CMSG_OK(msg, cmsg)) {
                        err = -EINVAL;
                        goto out;
                }

                if (cmsg->cmsg_level != SOL_IUCV)
                        continue;

                if (cmsg->cmsg_type & cmsg_done) {
                        err = -EINVAL;
                        goto out;
                }
                cmsg_done |= cmsg->cmsg_type;

                switch (cmsg->cmsg_type) {
                case SCM_IUCV_TRGCLS:
                        if (cmsg->cmsg_len != CMSG_LEN(TRGCLS_SIZE)) {
                                err = -EINVAL;
                                goto out;
                        }

                        /* set iucv message target class */
                        memcpy(&txmsg.class,
                                (void *) CMSG_DATA(cmsg), TRGCLS_SIZE);

                        break;

                default:
                        err = -EINVAL;
                        goto out;
                }
        }

        /* allocate one skb for each iucv message:
         * this is fine for SOCK_SEQPACKET (unless we want to support
         * segmented records using the MSG_EOR flag), but
         * for SOCK_STREAM we might want to improve it in future */
        if (iucv->transport == AF_IUCV_TRANS_HIPER) {
                headroom = sizeof(struct af_iucv_trans_hdr) + ETH_HLEN;
                linear = len;
        } else {
                if (len < PAGE_SIZE) {
                        linear = len;
                } else {
                        /* In nonlinear "classic" iucv skb,
                         * reserve space for iucv_array
                         */
                        headroom = sizeof(struct iucv_array) *
                                   (MAX_SKB_FRAGS + 1);
                        linear = PAGE_SIZE - headroom;
                }
        }
        skb = sock_alloc_send_pskb(sk, headroom + linear, len - linear,
                                   noblock, &err, 0);
        if (!skb)
                goto out;
        if (headroom)
                skb_reserve(skb, headroom);
        skb_put(skb, linear);
        skb->len = len;
        skb->data_len = len - linear;
        err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, len);
        if (err)
                goto fail;

        /* wait if outstanding messages for iucv path has reached */
        timeo = sock_sndtimeo(sk, noblock);
        err = iucv_sock_wait(sk, iucv_below_msglim(sk), timeo);
        if (err)
                goto fail;

        /* return -ECONNRESET if the socket is no longer connected */
        if (sk->sk_state != IUCV_CONNECTED) {
                err = -ECONNRESET;
                goto fail;
        }

        /* increment and save iucv message tag for msg_completion cbk */
        txmsg.tag = iucv->send_tag++;
        IUCV_SKB_CB(skb)->tag = txmsg.tag;

        if (iucv->transport == AF_IUCV_TRANS_HIPER) {
                atomic_inc(&iucv->msg_sent);
                err = afiucv_hs_send(&txmsg, sk, skb, 0);
                if (err) {
                        atomic_dec(&iucv->msg_sent);
                        goto fail;
                }
        } else { /* Classic VM IUCV transport */
                skb_queue_tail(&iucv->send_skb_q, skb);

                if (((iucv->path->flags & IUCV_IPRMDATA) & iucv->flags) &&
                    skb->len <= 7) {
                        err = iucv_send_iprm(iucv->path, &txmsg, skb);

                        /* on success: there is no message_complete callback */
                        /* for an IPRMDATA msg; remove skb from send queue   */
                        if (err == 0) {
                                skb_unlink(skb, &iucv->send_skb_q);
                                kfree_skb(skb);
                        }

                        /* this error should never happen since the     */
                        /* IUCV_IPRMDATA path flag is set... sever path */
                        if (err == 0x15) {
                                pr_iucv->path_sever(iucv->path, NULL);
                                skb_unlink(skb, &iucv->send_skb_q);
                                err = -EPIPE;
                                goto fail;
                        }
                } else if (skb_is_nonlinear(skb)) {
                        struct iucv_array *iba = (struct iucv_array *)skb->head;
                        int i;

                        /* skip iucv_array lying in the headroom */
                        iba[0].address = (u32)(addr_t)skb->data;
                        iba[0].length = (u32)skb_headlen(skb);
                        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
                                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

                                iba[i + 1].address =
                                        (u32)(addr_t)skb_frag_address(frag);
                                iba[i + 1].length = (u32)skb_frag_size(frag);
                        }
                        err = pr_iucv->message_send(iucv->path, &txmsg,
                                                    IUCV_IPBUFLST, 0,
                                                    (void *)iba, skb->len);
                } else { /* non-IPRM Linear skb */
                        err = pr_iucv->message_send(iucv->path, &txmsg,
                                        0, 0, (void *)skb->data, skb->len);
                }
                if (err) {
                        if (err == 3) {
                                user_id[8] = 0;
                                memcpy(user_id, iucv->dst_user_id, 8);
                                appl_id[8] = 0;
                                memcpy(appl_id, iucv->dst_name, 8);
                                pr_err(
                "Application %s on z/VM guest %s exceeds message limit\n",
                                        appl_id, user_id);
                                err = -EAGAIN;
                        } else {
                                err = -EPIPE;
                        }
                        skb_unlink(skb, &iucv->send_skb_q);
                        goto fail;
                }
        }

        release_sock(sk);
        return len;

fail:
        kfree_skb(skb);
out:
        release_sock(sk);
        return err;
}

static struct sk_buff *alloc_iucv_recv_skb(unsigned long len)
{
        size_t headroom, linear;
        struct sk_buff *skb;
        int err;

        if (len < PAGE_SIZE) {
                headroom = 0;
                linear = len;
        } else {
                headroom = sizeof(struct iucv_array) * (MAX_SKB_FRAGS + 1);
                linear = PAGE_SIZE - headroom;
        }
        skb = alloc_skb_with_frags(headroom + linear, len - linear,
                                   0, &err, GFP_ATOMIC | GFP_DMA);
        WARN_ONCE(!skb,
                  "alloc of recv iucv skb len=%lu failed with errcode=%d\n",
                  len, err);
        if (skb) {
                if (headroom)
                        skb_reserve(skb, headroom);
                skb_put(skb, linear);
                skb->len = len;
                skb->data_len = len - linear;
        }
        return skb;
}

/* iucv_process_message() - Receive a single outstanding IUCV message
 *
 * Locking: must be called with message_q.lock held
 */
static void iucv_process_message(struct sock *sk, struct sk_buff *skb,
                                 struct iucv_path *path,
                                 struct iucv_message *msg)
{
        int rc;
        unsigned int len;

        len = iucv_msg_length(msg);

        /* store msg target class in the second 4 bytes of skb ctrl buffer */
        /* Note: the first 4 bytes are reserved for msg tag */
        IUCV_SKB_CB(skb)->class = msg->class;

        /* check for special IPRM messages (e.g. iucv_sock_shutdown) */
        if ((msg->flags & IUCV_IPRMDATA) && len > 7) {
                if (memcmp(msg->rmmsg, iprm_shutdown, 8) == 0) {
                        skb->data = NULL;
                        skb->len = 0;
                }
        } else {
                if (skb_is_nonlinear(skb)) {
                        struct iucv_array *iba = (struct iucv_array *)skb->head;
                        int i;

                        iba[0].address = (u32)(addr_t)skb->data;
                        iba[0].length = (u32)skb_headlen(skb);
                        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
                                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

                                iba[i + 1].address =
                                        (u32)(addr_t)skb_frag_address(frag);
                                iba[i + 1].length = (u32)skb_frag_size(frag);
                        }
                        rc = pr_iucv->message_receive(path, msg,
                                              IUCV_IPBUFLST,
                                              (void *)iba, len, NULL);
                } else {
                        rc = pr_iucv->message_receive(path, msg,
                                              msg->flags & IUCV_IPRMDATA,
                                              skb->data, len, NULL);
                }
                if (rc) {
                        kfree_skb(skb);
                        return;
                }
                WARN_ON_ONCE(skb->len != len);
        }

        IUCV_SKB_CB(skb)->offset = 0;
        if (sk_filter(sk, skb)) {
                atomic_inc(&sk->sk_drops);      /* skb rejected by filter */
                kfree_skb(skb);
                return;
        }
        if (__sock_queue_rcv_skb(sk, skb))      /* handle rcv queue full */
                skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, skb);
}

/* iucv_process_message_q() - Process outstanding IUCV messages
 *
 * Locking: must be called with message_q.lock held
 */
static void iucv_process_message_q(struct sock *sk)
{
        struct iucv_sock *iucv = iucv_sk(sk);
        struct sk_buff *skb;
        struct sock_msg_q *p, *n;

        list_for_each_entry_safe(p, n, &iucv->message_q.list, list) {
                skb = alloc_iucv_recv_skb(iucv_msg_length(&p->msg));
                if (!skb)
                        break;
                iucv_process_message(sk, skb, p->path, &p->msg);
                list_del(&p->list);
                kfree(p);
                if (!skb_queue_empty(&iucv->backlog_skb_q))
                        break;
        }
}

static int iucv_sock_recvmsg(struct socket *sock, struct msghdr *msg,
                             size_t len, int flags)
{
        int noblock = flags & MSG_DONTWAIT;
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv = iucv_sk(sk);
        unsigned int copied, rlen;
        struct sk_buff *skb, *rskb, *cskb;
        int err = 0;
        u32 offset;

        if ((sk->sk_state == IUCV_DISCONN) &&
            skb_queue_empty(&iucv->backlog_skb_q) &&
            skb_queue_empty(&sk->sk_receive_queue) &&
            list_empty(&iucv->message_q.list))
                return 0;

        if (flags & (MSG_OOB))
                return -EOPNOTSUPP;

        /* receive/dequeue next skb:
         * the function understands MSG_PEEK and, thus, does not dequeue skb */
        skb = skb_recv_datagram(sk, flags, noblock, &err);
        if (!skb) {
                if (sk->sk_shutdown & RCV_SHUTDOWN)
                        return 0;
                return err;
        }

        offset = IUCV_SKB_CB(skb)->offset;
        rlen   = skb->len - offset;             /* real length of skb */
        copied = min_t(unsigned int, rlen, len);
        if (!rlen)
                sk->sk_shutdown = sk->sk_shutdown | RCV_SHUTDOWN;

        cskb = skb;
        if (skb_copy_datagram_msg(cskb, offset, msg, copied)) {
                if (!(flags & MSG_PEEK))
                        skb_queue_head(&sk->sk_receive_queue, skb);
                return -EFAULT;
        }

        /* SOCK_SEQPACKET: set MSG_TRUNC if recv buf size is too small */
        if (sk->sk_type == SOCK_SEQPACKET) {
                if (copied < rlen)
                        msg->msg_flags |= MSG_TRUNC;
                /* each iucv message contains a complete record */
                msg->msg_flags |= MSG_EOR;
        }

        /* create control message to store iucv msg target class:
         * get the trgcls from the control buffer of the skb due to
         * fragmentation of original iucv message. */
        err = put_cmsg(msg, SOL_IUCV, SCM_IUCV_TRGCLS,
                       sizeof(IUCV_SKB_CB(skb)->class),
                       (void *)&IUCV_SKB_CB(skb)->class);
        if (err) {
                if (!(flags & MSG_PEEK))
                        skb_queue_head(&sk->sk_receive_queue, skb);
                return err;
        }

        /* Mark read part of skb as used */
        if (!(flags & MSG_PEEK)) {

                /* SOCK_STREAM: re-queue skb if it contains unreceived data */
                if (sk->sk_type == SOCK_STREAM) {
                        if (copied < rlen) {
                                IUCV_SKB_CB(skb)->offset = offset + copied;
                                skb_queue_head(&sk->sk_receive_queue, skb);
                                goto done;
                        }
                }

                kfree_skb(skb);
                if (iucv->transport == AF_IUCV_TRANS_HIPER) {
                        atomic_inc(&iucv->msg_recv);
                        if (atomic_read(&iucv->msg_recv) > iucv->msglimit) {
                                WARN_ON(1);
                                iucv_sock_close(sk);
                                return -EFAULT;
                        }
                }

                /* Queue backlog skbs */
                spin_lock_bh(&iucv->message_q.lock);
                rskb = skb_dequeue(&iucv->backlog_skb_q);
                while (rskb) {
                        IUCV_SKB_CB(rskb)->offset = 0;
                        if (__sock_queue_rcv_skb(sk, rskb)) {
                                /* handle rcv queue full */
                                skb_queue_head(&iucv->backlog_skb_q,
                                                rskb);
                                break;
                        }
                        rskb = skb_dequeue(&iucv->backlog_skb_q);
                }
                if (skb_queue_empty(&iucv->backlog_skb_q)) {
                        if (!list_empty(&iucv->message_q.list))
                                iucv_process_message_q(sk);
                        if (atomic_read(&iucv->msg_recv) >=
                                                        iucv->msglimit / 2) {
                                err = iucv_send_ctrl(sk, AF_IUCV_FLAG_WIN);
                                if (err) {
                                        sk->sk_state = IUCV_DISCONN;
                                        sk->sk_state_change(sk);
                                }
                        }
                }
                spin_unlock_bh(&iucv->message_q.lock);
        }

done:
        /* SOCK_SEQPACKET: return real length if MSG_TRUNC is set */
        if (sk->sk_type == SOCK_SEQPACKET && (flags & MSG_TRUNC))
                copied = rlen;

        return copied;
}

static inline unsigned int iucv_accept_poll(struct sock *parent)
{
        struct iucv_sock *isk, *n;
        struct sock *sk;

        list_for_each_entry_safe(isk, n, &iucv_sk(parent)->accept_q, accept_q) {
                sk = (struct sock *) isk;

                if (sk->sk_state == IUCV_CONNECTED)
                        return POLLIN | POLLRDNORM;
        }

        return 0;
}

unsigned int iucv_sock_poll(struct file *file, struct socket *sock,
                            poll_table *wait)
{
        struct sock *sk = sock->sk;
        unsigned int mask = 0;

        sock_poll_wait(file, sk_sleep(sk), wait);

        if (sk->sk_state == IUCV_LISTEN)
                return iucv_accept_poll(sk);

        if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
                mask |= POLLERR |
                        (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0);

        if (sk->sk_shutdown & RCV_SHUTDOWN)
                mask |= POLLRDHUP;

        if (sk->sk_shutdown == SHUTDOWN_MASK)
                mask |= POLLHUP;

        if (!skb_queue_empty(&sk->sk_receive_queue) ||
            (sk->sk_shutdown & RCV_SHUTDOWN))
                mask |= POLLIN | POLLRDNORM;

        if (sk->sk_state == IUCV_CLOSED)
                mask |= POLLHUP;

        if (sk->sk_state == IUCV_DISCONN)
                mask |= POLLIN;

        if (sock_writeable(sk) && iucv_below_msglim(sk))
                mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
        else
                sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);

        return mask;
}

static int iucv_sock_shutdown(struct socket *sock, int how)
{
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv = iucv_sk(sk);
        struct iucv_message txmsg;
        int err = 0;

        how++;

        if ((how & ~SHUTDOWN_MASK) || !how)
                return -EINVAL;

        lock_sock(sk);
        switch (sk->sk_state) {
        case IUCV_LISTEN:
        case IUCV_DISCONN:
        case IUCV_CLOSING:
        case IUCV_CLOSED:
                err = -ENOTCONN;
                goto fail;
        default:
                break;
        }

        if (how == SEND_SHUTDOWN || how == SHUTDOWN_MASK) {
                if (iucv->transport == AF_IUCV_TRANS_IUCV) {
                        txmsg.class = 0;
                        txmsg.tag = 0;
                        err = pr_iucv->message_send(iucv->path, &txmsg,
                                IUCV_IPRMDATA, 0, (void *) iprm_shutdown, 8);
                        if (err) {
                                switch (err) {
                                case 1:
                                        err = -ENOTCONN;
                                        break;
                                case 2:
                                        err = -ECONNRESET;
                                        break;
                                default:
                                        err = -ENOTCONN;
                                        break;
                                }
                        }
                } else
                        iucv_send_ctrl(sk, AF_IUCV_FLAG_SHT);
        }

        sk->sk_shutdown |= how;
        if (how == RCV_SHUTDOWN || how == SHUTDOWN_MASK) {
                if ((iucv->transport == AF_IUCV_TRANS_IUCV) &&
                    iucv->path) {
                        err = pr_iucv->path_quiesce(iucv->path, NULL);
                        if (err)
                                err = -ENOTCONN;
/*                      skb_queue_purge(&sk->sk_receive_queue); */
                }
                skb_queue_purge(&sk->sk_receive_queue);
        }

        /* Wake up anyone sleeping in poll */
        sk->sk_state_change(sk);

fail:
        release_sock(sk);
        return err;
}

static int iucv_sock_release(struct socket *sock)
{
        struct sock *sk = sock->sk;
        int err = 0;

        if (!sk)
                return 0;

        iucv_sock_close(sk);

        sock_orphan(sk);
        iucv_sock_kill(sk);
        return err;
}

/* getsockopt and setsockopt */
static int iucv_sock_setsockopt(struct socket *sock, int level, int optname,
                                char __user *optval, unsigned int optlen)
{
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv = iucv_sk(sk);
        int val;
        int rc;

        if (level != SOL_IUCV)
                return -ENOPROTOOPT;

        if (optlen < sizeof(int))
                return -EINVAL;

        if (get_user(val, (int __user *) optval))
                return -EFAULT;

        rc = 0;

        lock_sock(sk);
        switch (optname) {
        case SO_IPRMDATA_MSG:
                if (val)
                        iucv->flags |= IUCV_IPRMDATA;
                else
                        iucv->flags &= ~IUCV_IPRMDATA;
                break;
        case SO_MSGLIMIT:
                switch (sk->sk_state) {
                case IUCV_OPEN:
                case IUCV_BOUND:
                        if (val < 1 || val > (u16)(~0))
                                rc = -EINVAL;
                        else
                                iucv->msglimit = val;
                        break;
                default:
                        rc = -EINVAL;
                        break;
                }
                break;
        default:
                rc = -ENOPROTOOPT;
                break;
        }
        release_sock(sk);

        return rc;
}

static int iucv_sock_getsockopt(struct socket *sock, int level, int optname,
                                char __user *optval, int __user *optlen)
{
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv = iucv_sk(sk);
        unsigned int val;
        int len;

        if (level != SOL_IUCV)
                return -ENOPROTOOPT;

        if (get_user(len, optlen))
                return -EFAULT;

        if (len < 0)
                return -EINVAL;

        len = min_t(unsigned int, len, sizeof(int));

        switch (optname) {
        case SO_IPRMDATA_MSG:
                val = (iucv->flags & IUCV_IPRMDATA) ? 1 : 0;
                break;
        case SO_MSGLIMIT:
                lock_sock(sk);
                val = (iucv->path != NULL) ? iucv->path->msglim /* connected */
                                           : iucv->msglimit;    /* default */
                release_sock(sk);
                break;
        case SO_MSGSIZE:
                if (sk->sk_state == IUCV_OPEN)
                        return -EBADFD;
                val = (iucv->hs_dev) ? iucv->hs_dev->mtu -
                                sizeof(struct af_iucv_trans_hdr) - ETH_HLEN :
                                0x7fffffff;
                break;
        default:
                return -ENOPROTOOPT;
        }

        if (put_user(len, optlen))
                return -EFAULT;
        if (copy_to_user(optval, &val, len))
                return -EFAULT;

        return 0;
}


/* Callback wrappers - called from iucv base support */
static int iucv_callback_connreq(struct iucv_path *path,
                                 u8 ipvmid[8], u8 ipuser[16])
{
        unsigned char user_data[16];
        unsigned char nuser_data[16];
        unsigned char src_name[8];
        struct sock *sk, *nsk;
        struct iucv_sock *iucv, *niucv;
        int err;

        memcpy(src_name, ipuser, 8);
        EBCASC(src_name, 8);
        /* Find out if this path belongs to af_iucv. */
        read_lock(&iucv_sk_list.lock);
        iucv = NULL;
        sk = NULL;
        sk_for_each(sk, &iucv_sk_list.head)
                if (sk->sk_state == IUCV_LISTEN &&
                    !memcmp(&iucv_sk(sk)->src_name, src_name, 8)) {
                        /*
                         * Found a listening socket with
                         * src_name == ipuser[0-7].
                         */
                        iucv = iucv_sk(sk);
                        break;
                }
        read_unlock(&iucv_sk_list.lock);
        if (!iucv)
                /* No socket found, not one of our paths. */
                return -EINVAL;

        bh_lock_sock(sk);

        /* Check if parent socket is listening */
        low_nmcpy(user_data, iucv->src_name);
        high_nmcpy(user_data, iucv->dst_name);
        ASCEBC(user_data, sizeof(user_data));
        if (sk->sk_state != IUCV_LISTEN) {
                err = pr_iucv->path_sever(path, user_data);
                iucv_path_free(path);
                goto fail;
        }

        /* Check for backlog size */
        if (sk_acceptq_is_full(sk)) {
                err = pr_iucv->path_sever(path, user_data);
                iucv_path_free(path);
                goto fail;
        }

        /* Create the new socket */
        nsk = iucv_sock_alloc(NULL, sk->sk_type, GFP_ATOMIC, 0);
        if (!nsk) {
                err = pr_iucv->path_sever(path, user_data);
                iucv_path_free(path);
                goto fail;
        }

        niucv = iucv_sk(nsk);
        iucv_sock_init(nsk, sk);

        /* Set the new iucv_sock */
        memcpy(niucv->dst_name, ipuser + 8, 8);
        EBCASC(niucv->dst_name, 8);
        memcpy(niucv->dst_user_id, ipvmid, 8);
        memcpy(niucv->src_name, iucv->src_name, 8);
        memcpy(niucv->src_user_id, iucv->src_user_id, 8);
        niucv->path = path;

        /* Call iucv_accept */
        high_nmcpy(nuser_data, ipuser + 8);
        memcpy(nuser_data + 8, niucv->src_name, 8);
        ASCEBC(nuser_data + 8, 8);

        /* set message limit for path based on msglimit of accepting socket */
        niucv->msglimit = iucv->msglimit;
        path->msglim = iucv->msglimit;
        err = pr_iucv->path_accept(path, &af_iucv_handler, nuser_data, nsk);
        if (err) {
                iucv_sever_path(nsk, 1);
                iucv_sock_kill(nsk);
                goto fail;
        }

        iucv_accept_enqueue(sk, nsk);

        /* Wake up accept */
        nsk->sk_state = IUCV_CONNECTED;
        sk->sk_data_ready(sk);
        err = 0;
fail:
        bh_unlock_sock(sk);
        return 0;
}

static void iucv_callback_connack(struct iucv_path *path, u8 ipuser[16])
{
        struct sock *sk = path->private;

        sk->sk_state = IUCV_CONNECTED;
        sk->sk_state_change(sk);
}

static void iucv_callback_rx(struct iucv_path *path, struct iucv_message *msg)
{
        struct sock *sk = path->private;
        struct iucv_sock *iucv = iucv_sk(sk);
        struct sk_buff *skb;
        struct sock_msg_q *save_msg;
        int len;

        if (sk->sk_shutdown & RCV_SHUTDOWN) {
                pr_iucv->message_reject(path, msg);
                return;
        }

        spin_lock(&iucv->message_q.lock);

        if (!list_empty(&iucv->message_q.list) ||
            !skb_queue_empty(&iucv->backlog_skb_q))
                goto save_message;

        len = atomic_read(&sk->sk_rmem_alloc);
        len += SKB_TRUESIZE(iucv_msg_length(msg));
        if (len > sk->sk_rcvbuf)
                goto save_message;

        skb = alloc_iucv_recv_skb(iucv_msg_length(msg));
        if (!skb)
                goto save_message;

        iucv_process_message(sk, skb, path, msg);
        goto out_unlock;

save_message:
        save_msg = kzalloc(sizeof(struct sock_msg_q), GFP_ATOMIC | GFP_DMA);
        if (!save_msg)
                goto out_unlock;
        save_msg->path = path;
        save_msg->msg = *msg;

        list_add_tail(&save_msg->list, &iucv->message_q.list);

out_unlock:
        spin_unlock(&iucv->message_q.lock);
}

static void iucv_callback_txdone(struct iucv_path *path,
                                 struct iucv_message *msg)
{
        struct sock *sk = path->private;
        struct sk_buff *this = NULL;
        struct sk_buff_head *list = &iucv_sk(sk)->send_skb_q;
        struct sk_buff *list_skb = list->next;
        unsigned long flags;

        bh_lock_sock(sk);
        if (!skb_queue_empty(list)) {
                spin_lock_irqsave(&list->lock, flags);

                while (list_skb != (struct sk_buff *)list) {
                        if (msg->tag == IUCV_SKB_CB(list_skb)->tag) {
                                this = list_skb;
                                break;
                        }
                        list_skb = list_skb->next;
                }
                if (this)
                        __skb_unlink(this, list);

                spin_unlock_irqrestore(&list->lock, flags);

                if (this) {
                        kfree_skb(this);
                        /* wake up any process waiting for sending */
                        iucv_sock_wake_msglim(sk);
                }
        }

        if (sk->sk_state == IUCV_CLOSING) {
                if (skb_queue_empty(&iucv_sk(sk)->send_skb_q)) {
                        sk->sk_state = IUCV_CLOSED;
                        sk->sk_state_change(sk);
                }
        }
        bh_unlock_sock(sk);

}

static void iucv_callback_connrej(struct iucv_path *path, u8 ipuser[16])
{
        struct sock *sk = path->private;

        if (sk->sk_state == IUCV_CLOSED)
                return;

        bh_lock_sock(sk);
        iucv_sever_path(sk, 1);
        sk->sk_state = IUCV_DISCONN;

        sk->sk_state_change(sk);
        bh_unlock_sock(sk);
}

/* called if the other communication side shuts down its RECV direction;
 * in turn, the callback sets SEND_SHUTDOWN to disable sending of data.
 */
static void iucv_callback_shutdown(struct iucv_path *path, u8 ipuser[16])
{
        struct sock *sk = path->private;

        bh_lock_sock(sk);
        if (sk->sk_state != IUCV_CLOSED) {
                sk->sk_shutdown |= SEND_SHUTDOWN;
                sk->sk_state_change(sk);
        }
        bh_unlock_sock(sk);
}

/***************** HiperSockets transport callbacks ********************/
static void afiucv_swap_src_dest(struct sk_buff *skb)
{
        struct af_iucv_trans_hdr *trans_hdr =
                                (struct af_iucv_trans_hdr *)skb->data;
        char tmpID[8];
        char tmpName[8];

        ASCEBC(trans_hdr->destUserID, sizeof(trans_hdr->destUserID));
        ASCEBC(trans_hdr->destAppName, sizeof(trans_hdr->destAppName));
        ASCEBC(trans_hdr->srcUserID, sizeof(trans_hdr->srcUserID));
        ASCEBC(trans_hdr->srcAppName, sizeof(trans_hdr->srcAppName));
        memcpy(tmpID, trans_hdr->srcUserID, 8);
        memcpy(tmpName, trans_hdr->srcAppName, 8);
        memcpy(trans_hdr->srcUserID, trans_hdr->destUserID, 8);
        memcpy(trans_hdr->srcAppName, trans_hdr->destAppName, 8);
        memcpy(trans_hdr->destUserID, tmpID, 8);
        memcpy(trans_hdr->destAppName, tmpName, 8);
        skb_push(skb, ETH_HLEN);
        memset(skb->data, 0, ETH_HLEN);
}

/**
 * afiucv_hs_callback_syn - react on received SYN
 **/
static int afiucv_hs_callback_syn(struct sock *sk, struct sk_buff *skb)
{
        struct sock *nsk;
        struct iucv_sock *iucv, *niucv;
        struct af_iucv_trans_hdr *trans_hdr;
        int err;

        iucv = iucv_sk(sk);
        trans_hdr = (struct af_iucv_trans_hdr *)skb->data;
        if (!iucv) {
                /* no sock - connection refused */
                afiucv_swap_src_dest(skb);
                trans_hdr->flags = AF_IUCV_FLAG_SYN | AF_IUCV_FLAG_FIN;
                err = dev_queue_xmit(skb);
                goto out;
        }

        nsk = iucv_sock_alloc(NULL, sk->sk_type, GFP_ATOMIC, 0);
        bh_lock_sock(sk);
        if ((sk->sk_state != IUCV_LISTEN) ||
            sk_acceptq_is_full(sk) ||
            !nsk) {
                /* error on server socket - connection refused */
                afiucv_swap_src_dest(skb);
                trans_hdr->flags = AF_IUCV_FLAG_SYN | AF_IUCV_FLAG_FIN;
                err = dev_queue_xmit(skb);
                iucv_sock_kill(nsk);
                bh_unlock_sock(sk);
                goto out;
        }

        niucv = iucv_sk(nsk);
        iucv_sock_init(nsk, sk);
        niucv->transport = AF_IUCV_TRANS_HIPER;
        niucv->msglimit = iucv->msglimit;
        if (!trans_hdr->window)
                niucv->msglimit_peer = IUCV_HIPER_MSGLIM_DEFAULT;
        else
                niucv->msglimit_peer = trans_hdr->window;
        memcpy(niucv->dst_name, trans_hdr->srcAppName, 8);

        memcpy(niucv->dst_user_id, trans_hdr->srcUserID, 8);
        memcpy(niucv->src_name, iucv->src_name, 8);
        memcpy(niucv->src_user_id, iucv->src_user_id, 8);
        nsk->sk_bound_dev_if = sk->sk_bound_dev_if;
        niucv->hs_dev = iucv->hs_dev;
        dev_hold(niucv->hs_dev);
        afiucv_swap_src_dest(skb);
        trans_hdr->flags = AF_IUCV_FLAG_SYN | AF_IUCV_FLAG_ACK;
        trans_hdr->window = niucv->msglimit;
        /* if receiver acks the xmit connection is established */
        err = dev_queue_xmit(skb);
        if (!err) {
                iucv_accept_enqueue(sk, nsk);
                nsk->sk_state = IUCV_CONNECTED;
                sk->sk_data_ready(sk);
        } else
                iucv_sock_kill(nsk);
        bh_unlock_sock(sk);

out:
        return NET_RX_SUCCESS;
}

/**
 * afiucv_hs_callback_synack() - react on received SYN-ACK
 **/
static int afiucv_hs_callback_synack(struct sock *sk, struct sk_buff *skb)
{
        struct iucv_sock *iucv = iucv_sk(sk);
        struct af_iucv_trans_hdr *trans_hdr =
                                        (struct af_iucv_trans_hdr *)skb->data;

        if (!iucv)
                goto out;
        if (sk->sk_state != IUCV_BOUND)
                goto out;
        bh_lock_sock(sk);
        iucv->msglimit_peer = trans_hdr->window;
        sk->sk_state = IUCV_CONNECTED;
        sk->sk_state_change(sk);
        bh_unlock_sock(sk);
out:
        kfree_skb(skb);
        return NET_RX_SUCCESS;
}

/**
 * afiucv_hs_callback_synfin() - react on received SYN_FIN
 **/
static int afiucv_hs_callback_synfin(struct sock *sk, struct sk_buff *skb)
{
        struct iucv_sock *iucv = iucv_sk(sk);

        if (!iucv)
                goto out;
        if (sk->sk_state != IUCV_BOUND)
                goto out;
        bh_lock_sock(sk);
        sk->sk_state = IUCV_DISCONN;
        sk->sk_state_change(sk);
        bh_unlock_sock(sk);
out:
        kfree_skb(skb);
        return NET_RX_SUCCESS;
}

/**
 * afiucv_hs_callback_fin() - react on received FIN
 **/
static int afiucv_hs_callback_fin(struct sock *sk, struct sk_buff *skb)
{
        struct iucv_sock *iucv = iucv_sk(sk);

        /* other end of connection closed */
        if (!iucv)
                goto out;
        bh_lock_sock(sk);
        if (sk->sk_state == IUCV_CONNECTED) {
                sk->sk_state = IUCV_DISCONN;
                sk->sk_state_change(sk);
        }
        bh_unlock_sock(sk);
out:
        kfree_skb(skb);
        return NET_RX_SUCCESS;
}

/**
 * afiucv_hs_callback_win() - react on received WIN
 **/
static int afiucv_hs_callback_win(struct sock *sk, struct sk_buff *skb)
{
        struct iucv_sock *iucv = iucv_sk(sk);
        struct af_iucv_trans_hdr *trans_hdr =
                                        (struct af_iucv_trans_hdr *)skb->data;

        if (!iucv)
                return NET_RX_SUCCESS;

        if (sk->sk_state != IUCV_CONNECTED)
                return NET_RX_SUCCESS;

        atomic_sub(trans_hdr->window, &iucv->msg_sent);
        iucv_sock_wake_msglim(sk);
        return NET_RX_SUCCESS;
}

/**
 * afiucv_hs_callback_rx() - react on received data
 **/
static int afiucv_hs_callback_rx(struct sock *sk, struct sk_buff *skb)
{
        struct iucv_sock *iucv = iucv_sk(sk);

        if (!iucv) {
                kfree_skb(skb);
                return NET_RX_SUCCESS;
        }

        if (sk->sk_state != IUCV_CONNECTED) {
                kfree_skb(skb);
                return NET_RX_SUCCESS;
        }

        if (sk->sk_shutdown & RCV_SHUTDOWN) {
                kfree_skb(skb);
                return NET_RX_SUCCESS;
        }

        /* write stuff from iucv_msg to skb cb */
        skb_pull(skb, sizeof(struct af_iucv_trans_hdr));
        skb_reset_transport_header(skb);
        skb_reset_network_header(skb);
        IUCV_SKB_CB(skb)->offset = 0;
        if (sk_filter(sk, skb)) {
                atomic_inc(&sk->sk_drops);      /* skb rejected by filter */
                kfree_skb(skb);
                return NET_RX_SUCCESS;
        }

        spin_lock(&iucv->message_q.lock);
        if (skb_queue_empty(&iucv->backlog_skb_q)) {
                if (__sock_queue_rcv_skb(sk, skb))
                        /* handle rcv queue full */
                        skb_queue_tail(&iucv->backlog_skb_q, skb);
        } else
                skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, skb);
        spin_unlock(&iucv->message_q.lock);
        return NET_RX_SUCCESS;
}

/**
 * afiucv_hs_rcv() - base function for arriving data through HiperSockets
 *                   transport
 *                   called from netif RX softirq
 **/
static int afiucv_hs_rcv(struct sk_buff *skb, struct net_device *dev,
        struct packet_type *pt, struct net_device *orig_dev)
{
        struct sock *sk;
        struct iucv_sock *iucv;
        struct af_iucv_trans_hdr *trans_hdr;
        char nullstring[8];
        int err = 0;

        if (skb->len < (ETH_HLEN + sizeof(struct af_iucv_trans_hdr))) {
                WARN_ONCE(1, "AF_IUCV too short skb, len=%d, min=%d",
                          (int)skb->len,
                          (int)(ETH_HLEN + sizeof(struct af_iucv_trans_hdr)));
                kfree_skb(skb);
                return NET_RX_SUCCESS;
        }
        if (skb_headlen(skb) < (ETH_HLEN + sizeof(struct af_iucv_trans_hdr)))
                if (skb_linearize(skb)) {
                        WARN_ONCE(1, "AF_IUCV skb_linearize failed, len=%d",
                                  (int)skb->len);
                        kfree_skb(skb);
                        return NET_RX_SUCCESS;
                }
        skb_pull(skb, ETH_HLEN);
        trans_hdr = (struct af_iucv_trans_hdr *)skb->data;
        EBCASC(trans_hdr->destAppName, sizeof(trans_hdr->destAppName));
        EBCASC(trans_hdr->destUserID, sizeof(trans_hdr->destUserID));
        EBCASC(trans_hdr->srcAppName, sizeof(trans_hdr->srcAppName));
        EBCASC(trans_hdr->srcUserID, sizeof(trans_hdr->srcUserID));
        memset(nullstring, 0, sizeof(nullstring));
        iucv = NULL;
        sk = NULL;
        read_lock(&iucv_sk_list.lock);
        sk_for_each(sk, &iucv_sk_list.head) {
                if (trans_hdr->flags == AF_IUCV_FLAG_SYN) {
                        if ((!memcmp(&iucv_sk(sk)->src_name,
                                     trans_hdr->destAppName, 8)) &&
                            (!memcmp(&iucv_sk(sk)->src_user_id,
                                     trans_hdr->destUserID, 8)) &&
                            (!memcmp(&iucv_sk(sk)->dst_name, nullstring, 8)) &&
                            (!memcmp(&iucv_sk(sk)->dst_user_id,
                                     nullstring, 8))) {
                                iucv = iucv_sk(sk);
                                break;
                        }
                } else {
                        if ((!memcmp(&iucv_sk(sk)->src_name,
                                     trans_hdr->destAppName, 8)) &&
                            (!memcmp(&iucv_sk(sk)->src_user_id,
                                     trans_hdr->destUserID, 8)) &&
                            (!memcmp(&iucv_sk(sk)->dst_name,
                                     trans_hdr->srcAppName, 8)) &&
                            (!memcmp(&iucv_sk(sk)->dst_user_id,
                                     trans_hdr->srcUserID, 8))) {
                                iucv = iucv_sk(sk);
                                break;
                        }
                }
        }
        read_unlock(&iucv_sk_list.lock);
        if (!iucv)
                sk = NULL;

        /* no sock
        how should we send with no sock
        1) send without sock no send rc checking?
        2) introduce default sock to handle this cases

         SYN -> send SYN|ACK in good case, send SYN|FIN in bad case
         data -> send FIN
         SYN|ACK, SYN|FIN, FIN -> no action? */

        switch (trans_hdr->flags) {
        case AF_IUCV_FLAG_SYN:
                /* connect request */
                err = afiucv_hs_callback_syn(sk, skb);
                break;
        case (AF_IUCV_FLAG_SYN | AF_IUCV_FLAG_ACK):
                /* connect request confirmed */
                err = afiucv_hs_callback_synack(sk, skb);
                break;
        case (AF_IUCV_FLAG_SYN | AF_IUCV_FLAG_FIN):
                /* connect request refused */
                err = afiucv_hs_callback_synfin(sk, skb);
                break;
        case (AF_IUCV_FLAG_FIN):
                /* close request */
                err = afiucv_hs_callback_fin(sk, skb);
                break;
        case (AF_IUCV_FLAG_WIN):
                err = afiucv_hs_callback_win(sk, skb);
                if (skb->len == sizeof(struct af_iucv_trans_hdr)) {
                        kfree_skb(skb);
                        break;
                }
                /* fall through and receive non-zero length data */
        case (AF_IUCV_FLAG_SHT):
                /* shutdown request */
                /* fall through and receive zero length data */
        case 0:
                /* plain data frame */
                IUCV_SKB_CB(skb)->class = trans_hdr->iucv_hdr.class;
                err = afiucv_hs_callback_rx(sk, skb);
                break;
        default:
                ;
        }

        return err;
}

/**
 * afiucv_hs_callback_txnotify() - handle send notifcations from HiperSockets
 *                                 transport
 **/
static void afiucv_hs_callback_txnotify(struct sk_buff *skb,
                                        enum iucv_tx_notify n)
{
        struct sock *isk = skb->sk;
        struct sock *sk = NULL;
        struct iucv_sock *iucv = NULL;
        struct sk_buff_head *list;
        struct sk_buff *list_skb;
        struct sk_buff *nskb;
        unsigned long flags;

        read_lock_irqsave(&iucv_sk_list.lock, flags);
        sk_for_each(sk, &iucv_sk_list.head)
                if (sk == isk) {
                        iucv = iucv_sk(sk);
                        break;
                }
        read_unlock_irqrestore(&iucv_sk_list.lock, flags);

        if (!iucv || sock_flag(sk, SOCK_ZAPPED))
                return;

        list = &iucv->send_skb_q;
        spin_lock_irqsave(&list->lock, flags);
        if (skb_queue_empty(list))
                goto out_unlock;
        list_skb = list->next;
        nskb = list_skb->next;
        while (list_skb != (struct sk_buff *)list) {
                if (skb_shinfo(list_skb) == skb_shinfo(skb)) {
                        switch (n) {
                        case TX_NOTIFY_OK:
                                __skb_unlink(list_skb, list);
                                kfree_skb(list_skb);
                                iucv_sock_wake_msglim(sk);
                                break;
                        case TX_NOTIFY_PENDING:
                                atomic_inc(&iucv->pendings);
                                break;
                        case TX_NOTIFY_DELAYED_OK:
                                __skb_unlink(list_skb, list);
                                atomic_dec(&iucv->pendings);
                                if (atomic_read(&iucv->pendings) <= 0)
                                        iucv_sock_wake_msglim(sk);
                                kfree_skb(list_skb);
                                break;
                        case TX_NOTIFY_UNREACHABLE:
                        case TX_NOTIFY_DELAYED_UNREACHABLE:
                        case TX_NOTIFY_TPQFULL: /* not yet used */
                        case TX_NOTIFY_GENERALERROR:
                        case TX_NOTIFY_DELAYED_GENERALERROR:
                                __skb_unlink(list_skb, list);
                                kfree_skb(list_skb);
                                if (sk->sk_state == IUCV_CONNECTED) {
                                        sk->sk_state = IUCV_DISCONN;
                                        sk->sk_state_change(sk);
                                }
                                break;
                        }
                        break;
                }
                list_skb = nskb;
                nskb = nskb->next;
        }
out_unlock:
        spin_unlock_irqrestore(&list->lock, flags);

        if (sk->sk_state == IUCV_CLOSING) {
                if (skb_queue_empty(&iucv_sk(sk)->send_skb_q)) {
                        sk->sk_state = IUCV_CLOSED;
                        sk->sk_state_change(sk);
                }
        }

}

/*
 * afiucv_netdev_event: handle netdev notifier chain events
 */
static int afiucv_netdev_event(struct notifier_block *this,
                               unsigned long event, void *ptr)
{
        struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);
        struct sock *sk;
        struct iucv_sock *iucv;

        switch (event) {
        case NETDEV_REBOOT:
        case NETDEV_GOING_DOWN:
                sk_for_each(sk, &iucv_sk_list.head) {
                        iucv = iucv_sk(sk);
                        if ((iucv->hs_dev == event_dev) &&
                            (sk->sk_state == IUCV_CONNECTED)) {
                                if (event == NETDEV_GOING_DOWN)
                                        iucv_send_ctrl(sk, AF_IUCV_FLAG_FIN);
                                sk->sk_state = IUCV_DISCONN;
                                sk->sk_state_change(sk);
                        }
                }
                break;
        case NETDEV_DOWN:
        case NETDEV_UNREGISTER:
        default:
                break;
        }
        return NOTIFY_DONE;
}

static struct notifier_block afiucv_netdev_notifier = {
        .notifier_call = afiucv_netdev_event,
};

static const struct proto_ops iucv_sock_ops = {
        .family         = PF_IUCV,
        .owner          = THIS_MODULE,
        .release        = iucv_sock_release,
        .bind           = iucv_sock_bind,
        .connect        = iucv_sock_connect,
        .listen         = iucv_sock_listen,
        .accept         = iucv_sock_accept,
        .getname        = iucv_sock_getname,
        .sendmsg        = iucv_sock_sendmsg,
        .recvmsg        = iucv_sock_recvmsg,
        .poll           = iucv_sock_poll,
        .ioctl          = sock_no_ioctl,
        .mmap           = sock_no_mmap,
        .socketpair     = sock_no_socketpair,
        .shutdown       = iucv_sock_shutdown,
        .setsockopt     = iucv_sock_setsockopt,
        .getsockopt     = iucv_sock_getsockopt,
};

static const struct net_proto_family iucv_sock_family_ops = {
        .family = AF_IUCV,
        .owner  = THIS_MODULE,
        .create = iucv_sock_create,
};

static struct packet_type iucv_packet_type = {
        .type = cpu_to_be16(ETH_P_AF_IUCV),
        .func = afiucv_hs_rcv,
};

static int afiucv_iucv_init(void)
{
        int err;

        err = pr_iucv->iucv_register(&af_iucv_handler, 0);
        if (err)
                goto out;
        /* establish dummy device */
        af_iucv_driver.bus = pr_iucv->bus;
        err = driver_register(&af_iucv_driver);
        if (err)
                goto out_iucv;
        af_iucv_dev = kzalloc(sizeof(struct device), GFP_KERNEL);
        if (!af_iucv_dev) {
                err = -ENOMEM;
                goto out_driver;
        }
        dev_set_name(af_iucv_dev, "af_iucv");
        af_iucv_dev->bus = pr_iucv->bus;
        af_iucv_dev->parent = pr_iucv->root;
        af_iucv_dev->release = (void (*)(struct device *))kfree;
        af_iucv_dev->driver = &af_iucv_driver;
        err = device_register(af_iucv_dev);
        if (err)
                goto out_driver;
        return 0;

out_driver:
        driver_unregister(&af_iucv_driver);
out_iucv:
        pr_iucv->iucv_unregister(&af_iucv_handler, 0);
out:
        return err;
}

static int __init afiucv_init(void)
{
        int err;

        if (MACHINE_IS_VM) {
                cpcmd("QUERY USERID", iucv_userid, sizeof(iucv_userid), &err);
                if (unlikely(err)) {
                        WARN_ON(err);
                        err = -EPROTONOSUPPORT;
                        goto out;
                }

                pr_iucv = try_then_request_module(symbol_get(iucv_if), "iucv");
                if (!pr_iucv) {
                        printk(KERN_WARNING "iucv_if lookup failed\n");
                        memset(&iucv_userid, 0, sizeof(iucv_userid));
                }
        } else {
                memset(&iucv_userid, 0, sizeof(iucv_userid));
                pr_iucv = NULL;
        }

        err = proto_register(&iucv_proto, 0);
        if (err)
                goto out;
        err = sock_register(&iucv_sock_family_ops);
        if (err)
                goto out_proto;

        if (pr_iucv) {
                err = afiucv_iucv_init();
                if (err)
                        goto out_sock;
        } else
                register_netdevice_notifier(&afiucv_netdev_notifier);
        dev_add_pack(&iucv_packet_type);
        return 0;

out_sock:
        sock_unregister(PF_IUCV);
out_proto:
        proto_unregister(&iucv_proto);
out:
        if (pr_iucv)
                symbol_put(iucv_if);
        return err;
}

static void __exit afiucv_exit(void)
{
        if (pr_iucv) {
                device_unregister(af_iucv_dev);
                driver_unregister(&af_iucv_driver);
                pr_iucv->iucv_unregister(&af_iucv_handler, 0);
                symbol_put(iucv_if);
        } else
                unregister_netdevice_notifier(&afiucv_netdev_notifier);
        dev_remove_pack(&iucv_packet_type);
        sock_unregister(PF_IUCV);
        proto_unregister(&iucv_proto);
}

module_init(afiucv_init);
module_exit(afiucv_exit);

MODULE_AUTHOR("Jennifer Hunt <jenhunt@us.ibm.com>");
MODULE_DESCRIPTION("IUCV Sockets ver " VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");
MODULE_ALIAS_NETPROTO(PF_IUCV);