/*
 *  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 <net/sock.h>
#include <asm/ebcdic.h>
#include <asm/cpcmd.h>
#include <linux/kmod.h>

#include <net/iucv/iucv.h>
#include <net/iucv/af_iucv.h>

#define VERSION "1.1"

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),
};

/* 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))

/* macros to set/get socket control buffer at correct offset */
#define CB_TAG(skb)     ((skb)->cb)             /* iucv message tag */
#define CB_TAG_LEN      (sizeof(((struct iucv_message *) 0)->tag))
#define CB_TRGCLS(skb)  ((skb)->cb + CB_TAG_LEN) /* iucv msg target class */
#define CB_TRGCLS_LEN   (TRGCLS_SIZE)

#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);

/* 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 ipuser[16]);
static int iucv_callback_connreq(struct iucv_path *, u8 ipvmid[8],
                                 u8 ipuser[16]);
static void iucv_callback_connrej(struct iucv_path *, u8 ipuser[16]);
static void iucv_callback_shutdown(struct iucv_path *, u8 ipuser[16]);

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;
        struct hlist_node *node;
        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, node, &iucv_sk_list.head) {
                iucv = iucv_sk(sk);
                skb_queue_purge(&iucv->send_skb_q);
                skb_queue_purge(&iucv->backlog_skb_q);
                switch (sk->sk_state) {
                case IUCV_SEVERED:
                case IUCV_DISCONN:
                case IUCV_CLOSING:
                case IUCV_CONNECTED:
                        if (iucv->path) {
                                err = iucv_path_sever(iucv->path, NULL);
                                iucv_path_free(iucv->path);
                                iucv->path = NULL;
                        }
                        break;
                case IUCV_OPEN:
                case IUCV_BOUND:
                case IUCV_LISTEN:
                case IUCV_CLOSED:
                default:
                        break;
                }
        }
        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 iucv_sock *iucv;
        struct sock *sk;
        struct hlist_node *node;

#ifdef CONFIG_PM_DEBUG
        printk(KERN_WARNING "afiucv_pm_restore_thaw\n");
#endif
        read_lock(&iucv_sk_list.lock);
        sk_for_each(sk, node, &iucv_sk_list.head) {
                iucv = iucv_sk(sk);
                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_SEVERED:
                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  = &iucv_bus,
        .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 substracting 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;
        return (skb_queue_len(&iucv->send_skb_q) < iucv->path->msglim);
}

/**
 * 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 (wq_has_sleeper(wq))
                wake_up_interruptible_all(&wq->wait);
        sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
        rcu_read_unlock();
}

/* Timers */
static void iucv_sock_timeout(unsigned long arg)
{
        struct sock *sk = (struct sock *)arg;

        bh_lock_sock(sk);
        sk->sk_err = ETIMEDOUT;
        sk->sk_state_change(sk);
        bh_unlock_sock(sk);

        iucv_sock_kill(sk);
        sock_put(sk);
}

static void iucv_sock_clear_timer(struct sock *sk)
{
        sk_stop_timer(sk, &sk->sk_timer);
}

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

        sk_for_each(sk, node, &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_write_queue);
}

/* 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);
}

/* Close an IUCV socket */
static void iucv_sock_close(struct sock *sk)
{
        unsigned char user_data[16];
        struct iucv_sock *iucv = iucv_sk(sk);
        int err;
        unsigned long timeo;

        iucv_sock_clear_timer(sk);
        lock_sock(sk);

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

        case IUCV_CONNECTED:
        case IUCV_DISCONN:
                err = 0;

                sk->sk_state = IUCV_CLOSING;
                sk->sk_state_change(sk);

                if (!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;
                        err = 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);

                if (iucv->path) {
                        low_nmcpy(user_data, iucv->src_name);
                        high_nmcpy(user_data, iucv->dst_name);
                        ASCEBC(user_data, sizeof(user_data));
                        err = iucv_path_sever(iucv->path, user_data);
                        iucv_path_free(iucv->path);
                        iucv->path = NULL;
                }

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

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

        default:
                /* nothing to do here */
                break;
        }

        /* 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;
}

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

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

        sock_init_data(sock, sk);
        INIT_LIST_HEAD(&iucv_sk(sk)->accept_q);
        spin_lock_init(&iucv_sk(sk)->accept_q_lock);
        skb_queue_head_init(&iucv_sk(sk)->send_skb_q);
        INIT_LIST_HEAD(&iucv_sk(sk)->message_q.list);
        spin_lock_init(&iucv_sk(sk)->message_q.lock);
        skb_queue_head_init(&iucv_sk(sk)->backlog_skb_q);
        iucv_sk(sk)->send_tag = 0;
        iucv_sk(sk)->flags = 0;
        iucv_sk(sk)->msglimit = IUCV_QUEUELEN_DEFAULT;
        iucv_sk(sk)->path = NULL;
        memset(&iucv_sk(sk)->src_user_id , 0, 32);

        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;

        setup_timer(&sk->sk_timer, iucv_sock_timeout, (unsigned long)sk);

        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);
        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_SEVERED ||
                    sk->sk_state == IUCV_DISCONN ||     /* due to PM restore */
                    !newsock) {
                        iucv_accept_unlink(sk);
                        if (newsock)
                                sock_graft(sk, newsock);

                        if (sk->sk_state == IUCV_SEVERED)
                                sk->sk_state = IUCV_DISCONN;

                        release_sock(sk);
                        return sk;
                }

                release_sock(sk);
        }
        return NULL;
}

/* 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;

        /* Verify the input sockaddr */
        if (!addr || addr->sa_family != AF_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) {
                err = 0;
                goto done_unlock;
        }

        /* Bind the socket */
        memcpy(iucv->src_name, sa->siucv_name, 8);

        /* Copy the user id */
        memcpy(iucv->src_user_id, iucv_userid, 8);
        sk->sk_state = IUCV_BOUND;
        err = 0;

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);
        char query_buffer[80];
        char name[12];
        int err = 0;

        /* Set the userid and name */
        cpcmd("QUERY USERID", query_buffer, sizeof(query_buffer), &err);
        if (unlikely(err))
                return -EPROTO;

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

        write_lock_bh(&iucv_sk_list.lock);

        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));
        }

        write_unlock_bh(&iucv_sk_list.lock);

        memcpy(&iucv->src_name, name, 8);

        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;
        unsigned char user_data[16];
        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_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_sk(sk)->dst_user_id, sa->siucv_user_id, 8);
        memcpy(iucv_sk(sk)->dst_name, sa->siucv_name, 8);

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

        iucv = iucv_sk(sk);
        /* Create path. */
        iucv->path = iucv_path_alloc(iucv->msglimit,
                                     IUCV_IPRMDATA, GFP_KERNEL);
        if (!iucv->path) {
                err = -ENOMEM;
                goto done;
        }
        err = 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;
                }
                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) {
                err = -ECONNREFUSED;
        }

        if (err) {
                iucv_path_sever(iucv->path, NULL);
                iucv_path_free(iucv->path);
                iucv->path = NULL;
        }

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;

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

        if (peer) {
                memcpy(siucv->siucv_user_id, iucv_sk(sk)->dst_user_id, 8);
                memcpy(siucv->siucv_name, &iucv_sk(sk)->dst_name, 8);
        } else {
                memcpy(siucv->siucv_user_id, iucv_sk(sk)->src_user_id, 8);
                memcpy(siucv->siucv_name, iucv_sk(sk)->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 iucv_message_send(path, msg, IUCV_IPRMDATA, 0,
                                 (void *) prmdata, 8);
}

static int iucv_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
                             struct msghdr *msg, size_t len)
{
        struct sock *sk = sock->sk;
        struct iucv_sock *iucv = iucv_sk(sk);
        struct sk_buff *skb;
        struct iucv_message txmsg;
        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 (cmsg = CMSG_FIRSTHDR(msg); cmsg;
                cmsg = CMSG_NXTHDR(msg, cmsg)) {

                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;
                        break;
                }
        }

        /* 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 */
        skb = sock_alloc_send_skb(sk, len, noblock, &err);
        if (!skb)
                goto out;
        if (memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len)) {
                err = -EFAULT;
                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++;
        memcpy(CB_TAG(skb), &txmsg.tag, CB_TAG_LEN);
        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) {
                        iucv_path_sever(iucv->path, NULL);
                        skb_unlink(skb, &iucv->send_skb_q);
                        err = -EPIPE;
                        goto fail;
                }
        } else
                err = 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;
}

/* iucv_fragment_skb() - Fragment a single IUCV message into multiple skb's
 *
 * Locking: must be called with message_q.lock held
 */
static int iucv_fragment_skb(struct sock *sk, struct sk_buff *skb, int len)
{
        int dataleft, size, copied = 0;
        struct sk_buff *nskb;

        dataleft = len;
        while (dataleft) {
                if (dataleft >= sk->sk_rcvbuf / 4)
                        size = sk->sk_rcvbuf / 4;
                else
                        size = dataleft;

                nskb = alloc_skb(size, GFP_ATOMIC | GFP_DMA);
                if (!nskb)
                        return -ENOMEM;

                /* copy target class to control buffer of new skb */
                memcpy(CB_TRGCLS(nskb), CB_TRGCLS(skb), CB_TRGCLS_LEN);

                /* copy data fragment */
                memcpy(nskb->data, skb->data + copied, size);
                copied += size;
                dataleft -= size;

                skb_reset_transport_header(nskb);
                skb_reset_network_header(nskb);
                nskb->len = size;

                skb_queue_tail(&iucv_sk(sk)->backlog_skb_q, nskb);
        }

        return 0;
}

/* 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 */
        memcpy(CB_TRGCLS(skb), &msg->class, CB_TRGCLS_LEN);

        /* 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 {
                rc = iucv_message_receive(path, msg, msg->flags & IUCV_IPRMDATA,
                                          skb->data, len, NULL);
                if (rc) {
                        kfree_skb(skb);
                        return;
                }
                /* we need to fragment iucv messages for SOCK_STREAM only;
                 * for SOCK_SEQPACKET, it is only relevant if we support
                 * record segmentation using MSG_EOR (see also recvmsg()) */
                if (sk->sk_type == SOCK_STREAM &&
                    skb->truesize >= sk->sk_rcvbuf / 4) {
                        rc = iucv_fragment_skb(sk, skb, len);
                        kfree_skb(skb);
                        skb = NULL;
                        if (rc) {
                                iucv_path_sever(path, NULL);
                                return;
                        }
                        skb = skb_dequeue(&iucv_sk(sk)->backlog_skb_q);
                } else {
                        skb_reset_transport_header(skb);
                        skb_reset_network_header(skb);
                        skb->len = len;
                }
        }

        if (sock_queue_rcv_skb(sk, skb))
                skb_queue_head(&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_skb(iucv_msg_length(&p->msg), GFP_ATOMIC | GFP_DMA);
                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 kiocb *iocb, 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;

        if ((sk->sk_state == IUCV_DISCONN || sk->sk_state == IUCV_SEVERED) &&
            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;
        }

        rlen   = skb->len;              /* real length of skb */
        copied = min_t(unsigned int, rlen, len);

        cskb = skb;
        if (memcpy_toiovec(msg->msg_iov, cskb->data, 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,
                        CB_TRGCLS_LEN, CB_TRGCLS(skb));
        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) {
                        skb_pull(skb, copied);
                        if (skb->len) {
                                skb_queue_head(&sk->sk_receive_queue, skb);
                                goto done;
                        }
                }

                kfree_skb(skb);

                /* Queue backlog skbs */
                spin_lock_bh(&iucv->message_q.lock);
                rskb = skb_dequeue(&iucv->backlog_skb_q);
                while (rskb) {
                        if (sock_queue_rcv_skb(sk, rskb)) {
                                skb_queue_head(&iucv->backlog_skb_q,
                                                rskb);
                                break;
                        } else {
                                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);
                }
                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;

        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 || sk->sk_state == IUCV_SEVERED)
                mask |= POLLIN;

        if (sock_writeable(sk))
                mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
        else
                set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);

        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_DISCONN:
        case IUCV_CLOSING:
        case IUCV_SEVERED:
        case IUCV_CLOSED:
                err = -ENOTCONN;
                goto fail;

        default:
                sk->sk_shutdown |= how;
                break;
        }

        if (how == SEND_SHUTDOWN || how == SHUTDOWN_MASK) {
                txmsg.class = 0;
                txmsg.tag = 0;
                err = 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;
                        }
                }
        }

        if (how == RCV_SHUTDOWN || how == SHUTDOWN_MASK) {
                err = iucv_path_quiesce(iucv_sk(sk)->path, NULL);
                if (err)
                        err = -ENOTCONN;

                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);

        /* Unregister with IUCV base support */
        if (iucv_sk(sk)->path) {
                iucv_path_sever(iucv_sk(sk)->path, NULL);
                iucv_path_free(iucv_sk(sk)->path);
                iucv_sk(sk)->path = NULL;
        }

        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);
        int val, 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;
        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 hlist_node *node;
        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, node, &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 = iucv_path_sever(path, user_data);
                iucv_path_free(path);
                goto fail;
        }

        /* Check for backlog size */
        if (sk_acceptq_is_full(sk)) {
                err = 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);
        if (!nsk) {
                err = 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 = iucv_path_accept(path, &af_iucv_handler, nuser_data, nsk);
        if (err) {
                err = iucv_path_sever(path, user_data);
                iucv_path_free(path);
                iucv_sock_kill(nsk);
                goto fail;
        }

        iucv_accept_enqueue(sk, nsk);

        /* Wake up accept */
        nsk->sk_state = IUCV_CONNECTED;
        sk->sk_data_ready(sk, 1);
        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) {
                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 += iucv_msg_length(msg) + sizeof(struct sk_buff);
        if (len > sk->sk_rcvbuf)
                goto save_message;

        skb = alloc_skb(iucv_msg_length(msg), GFP_ATOMIC | GFP_DMA);
        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;

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

                while (list_skb != (struct sk_buff *)list) {
                        if (!memcmp(&msg->tag, CB_TAG(list_skb), CB_TAG_LEN)) {
                                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);
                }
        }
        BUG_ON(!this);

        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);
                }
        }

}

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

        if (!list_empty(&iucv_sk(sk)->accept_q))
                sk->sk_state = IUCV_SEVERED;
        else
                sk->sk_state = IUCV_DISCONN;

        sk->sk_state_change(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);
}

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 int __init afiucv_init(void)
{
        int err;

        if (!MACHINE_IS_VM) {
                pr_err("The af_iucv module cannot be loaded"
                       " without z/VM\n");
                err = -EPROTONOSUPPORT;
                goto out;
        }
        cpcmd("QUERY USERID", iucv_userid, sizeof(iucv_userid), &err);
        if (unlikely(err)) {
                WARN_ON(err);
                err = -EPROTONOSUPPORT;
                goto out;
        }

        err = iucv_register(&af_iucv_handler, 0);
        if (err)
                goto out;
        err = proto_register(&iucv_proto, 0);
        if (err)
                goto out_iucv;
        err = sock_register(&iucv_sock_family_ops);
        if (err)
                goto out_proto;
        /* establish dummy device */
        err = driver_register(&af_iucv_driver);
        if (err)
                goto out_sock;
        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 = &iucv_bus;
        af_iucv_dev->parent = 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_sock:
        sock_unregister(PF_IUCV);
out_proto:
        proto_unregister(&iucv_proto);
out_iucv:
        iucv_unregister(&af_iucv_handler, 0);
out:
        return err;
}

static void __exit afiucv_exit(void)
{
        device_unregister(af_iucv_dev);
        driver_unregister(&af_iucv_driver);
        sock_unregister(PF_IUCV);
        proto_unregister(&iucv_proto);
        iucv_unregister(&af_iucv_handler, 0);
}

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);