Fix misspellings of "system", "controller", "interrupt" and "necessary".

[safe/jmp/linux-2.6] / net / iucv / iucv.c

/*
 * IUCV base infrastructure.
 *
 * Copyright 2001, 2006 IBM Deutschland Entwicklung GmbH, IBM Corporation
 * Author(s):
 *    Original source:
 *      Alan Altmark (Alan_Altmark@us.ibm.com)  Sept. 2000
 *      Xenia Tkatschow (xenia@us.ibm.com)
 *    2Gb awareness and general cleanup:
 *      Fritz Elfert (elfert@de.ibm.com, felfert@millenux.com)
 *    Rewritten for af_iucv:
 *      Martin Schwidefsky <schwidefsky@de.ibm.com>
 *
 * Documentation used:
 *    The original source
 *    CP Programming Service, IBM document # SC24-5760
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/spinlock.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/cpu.h>
#include <net/iucv/iucv.h>
#include <asm/atomic.h>
#include <asm/ebcdic.h>
#include <asm/io.h>
#include <asm/s390_ext.h>
#include <asm/s390_rdev.h>
#include <asm/smp.h>

/*
 * FLAGS:
 * All flags are defined in the field IPFLAGS1 of each function
 * and can be found in CP Programming Services.
 * IPSRCCLS - Indicates you have specified a source class.
 * IPTRGCLS - Indicates you have specified a target class.
 * IPFGPID  - Indicates you have specified a pathid.
 * IPFGMID  - Indicates you have specified a message ID.
 * IPNORPY  - Indicates a one-way message. No reply expected.
 * IPALL    - Indicates that all paths are affected.
 */
#define IUCV_IPSRCCLS   0x01
#define IUCV_IPTRGCLS   0x01
#define IUCV_IPFGPID    0x02
#define IUCV_IPFGMID    0x04
#define IUCV_IPNORPY    0x10
#define IUCV_IPALL      0x80

static int iucv_bus_match(struct device *dev, struct device_driver *drv)
{
        return 0;
}

struct bus_type iucv_bus = {
        .name = "iucv",
        .match = iucv_bus_match,
};
EXPORT_SYMBOL(iucv_bus);

struct device *iucv_root;
EXPORT_SYMBOL(iucv_root);

static int iucv_available;

/* General IUCV interrupt structure */
struct iucv_irq_data {
        u16 ippathid;
        u8  ipflags1;
        u8  iptype;
        u32 res2[8];
};

struct iucv_irq_list {
        struct list_head list;
        struct iucv_irq_data data;
};

static struct iucv_irq_data *iucv_irq_data;
static cpumask_t iucv_buffer_cpumask = CPU_MASK_NONE;
static cpumask_t iucv_irq_cpumask = CPU_MASK_NONE;

/*
 * Queue of interrupt buffers lock for delivery via the tasklet
 * (fast but can't call smp_call_function).
 */
static LIST_HEAD(iucv_task_queue);

/*
 * The tasklet for fast delivery of iucv interrupts.
 */
static void iucv_tasklet_fn(unsigned long);
static DECLARE_TASKLET(iucv_tasklet, iucv_tasklet_fn,0);

/*
 * Queue of interrupt buffers for delivery via a work queue
 * (slower but can call smp_call_function).
 */
static LIST_HEAD(iucv_work_queue);

/*
 * The work element to deliver path pending interrupts.
 */
static void iucv_work_fn(struct work_struct *work);
static DECLARE_WORK(iucv_work, iucv_work_fn);

/*
 * Spinlock protecting task and work queue.
 */
static DEFINE_SPINLOCK(iucv_queue_lock);

enum iucv_command_codes {
        IUCV_QUERY = 0,
        IUCV_RETRIEVE_BUFFER = 2,
        IUCV_SEND = 4,
        IUCV_RECEIVE = 5,
        IUCV_REPLY = 6,
        IUCV_REJECT = 8,
        IUCV_PURGE = 9,
        IUCV_ACCEPT = 10,
        IUCV_CONNECT = 11,
        IUCV_DECLARE_BUFFER = 12,
        IUCV_QUIESCE = 13,
        IUCV_RESUME = 14,
        IUCV_SEVER = 15,
        IUCV_SETMASK = 16,
};

/*
 * Error messages that are used with the iucv_sever function. They get
 * converted to EBCDIC.
 */
static char iucv_error_no_listener[16] = "NO LISTENER";
static char iucv_error_no_memory[16] = "NO MEMORY";
static char iucv_error_pathid[16] = "INVALID PATHID";

/*
 * iucv_handler_list: List of registered handlers.
 */
static LIST_HEAD(iucv_handler_list);

/*
 * iucv_path_table: an array of iucv_path structures.
 */
static struct iucv_path **iucv_path_table;
static unsigned long iucv_max_pathid;

/*
 * iucv_lock: spinlock protecting iucv_handler_list and iucv_pathid_table
 */
static DEFINE_SPINLOCK(iucv_table_lock);

/*
 * iucv_active_cpu: contains the number of the cpu executing the tasklet
 * or the work handler. Needed for iucv_path_sever called from tasklet.
 */
static int iucv_active_cpu = -1;

/*
 * Mutex and wait queue for iucv_register/iucv_unregister.
 */
static DEFINE_MUTEX(iucv_register_mutex);

/*
 * Counter for number of non-smp capable handlers.
 */
static int iucv_nonsmp_handler;

/*
 * IUCV control data structure. Used by iucv_path_accept, iucv_path_connect,
 * iucv_path_quiesce and iucv_path_sever.
 */
struct iucv_cmd_control {
        u16 ippathid;
        u8  ipflags1;
        u8  iprcode;
        u16 ipmsglim;
        u16 res1;
        u8  ipvmid[8];
        u8  ipuser[16];
        u8  iptarget[8];
} __attribute__ ((packed,aligned(8)));

/*
 * Data in parameter list iucv structure. Used by iucv_message_send,
 * iucv_message_send2way and iucv_message_reply.
 */
struct iucv_cmd_dpl {
        u16 ippathid;
        u8  ipflags1;
        u8  iprcode;
        u32 ipmsgid;
        u32 iptrgcls;
        u8  iprmmsg[8];
        u32 ipsrccls;
        u32 ipmsgtag;
        u32 ipbfadr2;
        u32 ipbfln2f;
        u32 res;
} __attribute__ ((packed,aligned(8)));

/*
 * Data in buffer iucv structure. Used by iucv_message_receive,
 * iucv_message_reject, iucv_message_send, iucv_message_send2way
 * and iucv_declare_cpu.
 */
struct iucv_cmd_db {
        u16 ippathid;
        u8  ipflags1;
        u8  iprcode;
        u32 ipmsgid;
        u32 iptrgcls;
        u32 ipbfadr1;
        u32 ipbfln1f;
        u32 ipsrccls;
        u32 ipmsgtag;
        u32 ipbfadr2;
        u32 ipbfln2f;
        u32 res;
} __attribute__ ((packed,aligned(8)));

/*
 * Purge message iucv structure. Used by iucv_message_purge.
 */
struct iucv_cmd_purge {
        u16 ippathid;
        u8  ipflags1;
        u8  iprcode;
        u32 ipmsgid;
        u8  ipaudit[3];
        u8  res1[5];
        u32 res2;
        u32 ipsrccls;
        u32 ipmsgtag;
        u32 res3[3];
} __attribute__ ((packed,aligned(8)));

/*
 * Set mask iucv structure. Used by iucv_enable_cpu.
 */
struct iucv_cmd_set_mask {
        u8  ipmask;
        u8  res1[2];
        u8  iprcode;
        u32 res2[9];
} __attribute__ ((packed,aligned(8)));

union iucv_param {
        struct iucv_cmd_control ctrl;
        struct iucv_cmd_dpl dpl;
        struct iucv_cmd_db db;
        struct iucv_cmd_purge purge;
        struct iucv_cmd_set_mask set_mask;
};

/*
 * Anchor for per-cpu IUCV command parameter block.
 */
static union iucv_param *iucv_param;

/**
 * iucv_call_b2f0
 * @code: identifier of IUCV call to CP.
 * @parm: pointer to a struct iucv_parm block
 *
 * Calls CP to execute IUCV commands.
 *
 * Returns the result of the CP IUCV call.
 */
static inline int iucv_call_b2f0(int command, union iucv_param *parm)
{
        register unsigned long reg0 asm ("0");
        register unsigned long reg1 asm ("1");
        int ccode;

        reg0 = command;
        reg1 = virt_to_phys(parm);
        asm volatile(
                "       .long 0xb2f01000\n"
                "       ipm     %0\n"
                "       srl     %0,28\n"
                : "=d" (ccode), "=m" (*parm), "+d" (reg0), "+a" (reg1)
                :  "m" (*parm) : "cc");
        return (ccode == 1) ? parm->ctrl.iprcode : ccode;
}

/**
 * iucv_query_maxconn
 *
 * Determines the maximum number of connections that may be established.
 *
 * Returns the maximum number of connections or -EPERM is IUCV is not
 * available.
 */
static int iucv_query_maxconn(void)
{
        register unsigned long reg0 asm ("0");
        register unsigned long reg1 asm ("1");
        void *param;
        int ccode;

        param = kzalloc(sizeof(union iucv_param), GFP_KERNEL|GFP_DMA);
        if (!param)
                return -ENOMEM;
        reg0 = IUCV_QUERY;
        reg1 = (unsigned long) param;
        asm volatile (
                "       .long   0xb2f01000\n"
                "       ipm     %0\n"
                "       srl     %0,28\n"
                : "=d" (ccode), "+d" (reg0), "+d" (reg1) : : "cc");
        if (ccode == 0)
                iucv_max_pathid = reg0;
        kfree(param);
        return ccode ? -EPERM : 0;
}

/**
 * iucv_allow_cpu
 * @data: unused
 *
 * Allow iucv interrupts on this cpu.
 */
static void iucv_allow_cpu(void *data)
{
        int cpu = smp_processor_id();
        union iucv_param *parm;

        /*
         * Enable all iucv interrupts.
         * ipmask contains bits for the different interrupts
         *      0x80 - Flag to allow nonpriority message pending interrupts
         *      0x40 - Flag to allow priority message pending interrupts
         *      0x20 - Flag to allow nonpriority message completion interrupts
         *      0x10 - Flag to allow priority message completion interrupts
         *      0x08 - Flag to allow IUCV control interrupts
         */
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        parm->set_mask.ipmask = 0xf8;
        iucv_call_b2f0(IUCV_SETMASK, parm);

        /* Set indication that iucv interrupts are allowed for this cpu. */
        cpu_set(cpu, iucv_irq_cpumask);
}

/**
 * iucv_block_cpu
 * @data: unused
 *
 * Block iucv interrupts on this cpu.
 */
static void iucv_block_cpu(void *data)
{
        int cpu = smp_processor_id();
        union iucv_param *parm;

        /* Disable all iucv interrupts. */
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        iucv_call_b2f0(IUCV_SETMASK, parm);

        /* Clear indication that iucv interrupts are allowed for this cpu. */
        cpu_clear(cpu, iucv_irq_cpumask);
}

/**
 * iucv_declare_cpu
 * @data: unused
 *
 * Declare a interrupt buffer on this cpu.
 */
static void iucv_declare_cpu(void *data)
{
        int cpu = smp_processor_id();
        union iucv_param *parm;
        int rc;

        if (cpu_isset(cpu, iucv_buffer_cpumask))
                return;

        /* Declare interrupt buffer. */
        parm = percpu_ptr(iucv_param, cpu);
        memset(parm, 0, sizeof(union iucv_param));
        parm->db.ipbfadr1 = virt_to_phys(percpu_ptr(iucv_irq_data, cpu));
        rc = iucv_call_b2f0(IUCV_DECLARE_BUFFER, parm);
        if (rc) {
                char *err = "Unknown";
                switch (rc) {
                case 0x03:
                        err = "Directory error";
                        break;
                case 0x0a:
                        err = "Invalid length";
                        break;
                case 0x13:
                        err = "Buffer already exists";
                        break;
                case 0x3e:
                        err = "Buffer overlap";
                        break;
                case 0x5c:
                        err = "Paging or storage error";
                        break;
                }
                printk(KERN_WARNING "iucv_register: iucv_declare_buffer "
                       "on cpu %i returned error 0x%02x (%s)\n", cpu, rc, err);
                return;
        }

        /* Set indication that an iucv buffer exists for this cpu. */
        cpu_set(cpu, iucv_buffer_cpumask);

        if (iucv_nonsmp_handler == 0 || cpus_empty(iucv_irq_cpumask))
                /* Enable iucv interrupts on this cpu. */
                iucv_allow_cpu(NULL);
        else
                /* Disable iucv interrupts on this cpu. */
                iucv_block_cpu(NULL);
}

/**
 * iucv_retrieve_cpu
 * @data: unused
 *
 * Retrieve interrupt buffer on this cpu.
 */
static void iucv_retrieve_cpu(void *data)
{
        int cpu = smp_processor_id();
        union iucv_param *parm;

        if (!cpu_isset(cpu, iucv_buffer_cpumask))
                return;

        /* Block iucv interrupts. */
        iucv_block_cpu(NULL);

        /* Retrieve interrupt buffer. */
        parm = percpu_ptr(iucv_param, cpu);
        iucv_call_b2f0(IUCV_RETRIEVE_BUFFER, parm);

        /* Clear indication that an iucv buffer exists for this cpu. */
        cpu_clear(cpu, iucv_buffer_cpumask);
}

/**
 * iucv_setmask_smp
 *
 * Allow iucv interrupts on all cpus.
 */
static void iucv_setmask_mp(void)
{
        int cpu;

        preempt_disable();
        for_each_online_cpu(cpu)
                /* Enable all cpus with a declared buffer. */
                if (cpu_isset(cpu, iucv_buffer_cpumask) &&
                    !cpu_isset(cpu, iucv_irq_cpumask))
                        smp_call_function_single(cpu, iucv_allow_cpu,
                                                 NULL, 0, 1);
        preempt_enable();
}

/**
 * iucv_setmask_up
 *
 * Allow iucv interrupts on a single cpu.
 */
static void iucv_setmask_up(void)
{
        cpumask_t cpumask;
        int cpu;

        /* Disable all cpu but the first in cpu_irq_cpumask. */
        cpumask = iucv_irq_cpumask;
        cpu_clear(first_cpu(iucv_irq_cpumask), cpumask);
        for_each_cpu_mask(cpu, cpumask)
                smp_call_function_single(cpu, iucv_block_cpu, NULL, 0, 1);
}

/**
 * iucv_enable
 *
 * This function makes iucv ready for use. It allocates the pathid
 * table, declares an iucv interrupt buffer and enables the iucv
 * interrupts. Called when the first user has registered an iucv
 * handler.
 */
static int iucv_enable(void)
{
        size_t alloc_size;
        int cpu, rc;

        rc = -ENOMEM;
        alloc_size = iucv_max_pathid * sizeof(struct iucv_path);
        iucv_path_table = kzalloc(alloc_size, GFP_KERNEL);
        if (!iucv_path_table)
                goto out;
        /* Declare per cpu buffers. */
        rc = -EIO;
        preempt_disable();
        for_each_online_cpu(cpu)
                smp_call_function_single(cpu, iucv_declare_cpu, NULL, 0, 1);
        preempt_enable();
        if (cpus_empty(iucv_buffer_cpumask))
                /* No cpu could declare an iucv buffer. */
                goto out_path;
        return 0;

out_path:
        kfree(iucv_path_table);
out:
        return rc;
}

/**
 * iucv_disable
 *
 * This function shuts down iucv. It disables iucv interrupts, retrieves
 * the iucv interrupt buffer and frees the pathid table. Called after the
 * last user unregister its iucv handler.
 */
static void iucv_disable(void)
{
        on_each_cpu(iucv_retrieve_cpu, NULL, 0, 1);
        kfree(iucv_path_table);
}

static int __cpuinit iucv_cpu_notify(struct notifier_block *self,
                                     unsigned long action, void *hcpu)
{
        cpumask_t cpumask;
        long cpu = (long) hcpu;

        switch (action) {
        case CPU_UP_PREPARE:
        case CPU_UP_PREPARE_FROZEN:
                if (!percpu_populate(iucv_irq_data,
                                     sizeof(struct iucv_irq_data),
                                     GFP_KERNEL|GFP_DMA, cpu))
                        return NOTIFY_BAD;
                if (!percpu_populate(iucv_param, sizeof(union iucv_param),
                                     GFP_KERNEL|GFP_DMA, cpu)) {
                        percpu_depopulate(iucv_irq_data, cpu);
                        return NOTIFY_BAD;
                }
                break;
        case CPU_UP_CANCELED:
        case CPU_UP_CANCELED_FROZEN:
        case CPU_DEAD:
        case CPU_DEAD_FROZEN:
                percpu_depopulate(iucv_param, cpu);
                percpu_depopulate(iucv_irq_data, cpu);
                break;
        case CPU_ONLINE:
        case CPU_ONLINE_FROZEN:
        case CPU_DOWN_FAILED:
        case CPU_DOWN_FAILED_FROZEN:
                smp_call_function_single(cpu, iucv_declare_cpu, NULL, 0, 1);
                break;
        case CPU_DOWN_PREPARE:
        case CPU_DOWN_PREPARE_FROZEN:
                cpumask = iucv_buffer_cpumask;
                cpu_clear(cpu, cpumask);
                if (cpus_empty(cpumask))
                        /* Can't offline last IUCV enabled cpu. */
                        return NOTIFY_BAD;
                smp_call_function_single(cpu, iucv_retrieve_cpu, NULL, 0, 1);
                if (cpus_empty(iucv_irq_cpumask))
                        smp_call_function_single(first_cpu(iucv_buffer_cpumask),
                                                 iucv_allow_cpu, NULL, 0, 1);
                break;
        }
        return NOTIFY_OK;
}

static struct notifier_block __cpuinitdata iucv_cpu_notifier = {
        .notifier_call = iucv_cpu_notify,
};

/**
 * iucv_sever_pathid
 * @pathid: path identification number.
 * @userdata: 16-bytes of user data.
 *
 * Sever an iucv path to free up the pathid. Used internally.
 */
static int iucv_sever_pathid(u16 pathid, u8 userdata[16])
{
        union iucv_param *parm;

        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        if (userdata)
                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));
        parm->ctrl.ippathid = pathid;
        return iucv_call_b2f0(IUCV_SEVER, parm);
}

#ifdef CONFIG_SMP
/**
 * __iucv_cleanup_queue
 * @dummy: unused dummy argument
 *
 * Nop function called via smp_call_function to force work items from
 * pending external iucv interrupts to the work queue.
 */
static void __iucv_cleanup_queue(void *dummy)
{
}
#endif

/**
 * iucv_cleanup_queue
 *
 * Function called after a path has been severed to find all remaining
 * work items for the now stale pathid. The caller needs to hold the
 * iucv_table_lock.
 */
static void iucv_cleanup_queue(void)
{
        struct iucv_irq_list *p, *n;

        /*
         * When a path is severed, the pathid can be reused immediatly
         * on a iucv connect or a connection pending interrupt. Remove
         * all entries from the task queue that refer to a stale pathid
         * (iucv_path_table[ix] == NULL). Only then do the iucv connect
         * or deliver the connection pending interrupt. To get all the
         * pending interrupts force them to the work queue by calling
         * an empty function on all cpus.
         */
        smp_call_function(__iucv_cleanup_queue, NULL, 0, 1);
        spin_lock_irq(&iucv_queue_lock);
        list_for_each_entry_safe(p, n, &iucv_task_queue, list) {
                /* Remove stale work items from the task queue. */
                if (iucv_path_table[p->data.ippathid] == NULL) {
                        list_del(&p->list);
                        kfree(p);
                }
        }
        spin_unlock_irq(&iucv_queue_lock);
}

/**
 * iucv_register:
 * @handler: address of iucv handler structure
 * @smp: != 0 indicates that the handler can deal with out of order messages
 *
 * Registers a driver with IUCV.
 *
 * Returns 0 on success, -ENOMEM if the memory allocation for the pathid
 * table failed, or -EIO if IUCV_DECLARE_BUFFER failed on all cpus.
 */
int iucv_register(struct iucv_handler *handler, int smp)
{
        int rc;

        if (!iucv_available)
                return -ENOSYS;
        mutex_lock(&iucv_register_mutex);
        if (!smp)
                iucv_nonsmp_handler++;
        if (list_empty(&iucv_handler_list)) {
                rc = iucv_enable();
                if (rc)
                        goto out_mutex;
        } else if (!smp && iucv_nonsmp_handler == 1)
                iucv_setmask_up();
        INIT_LIST_HEAD(&handler->paths);

        spin_lock_irq(&iucv_table_lock);
        list_add_tail(&handler->list, &iucv_handler_list);
        spin_unlock_irq(&iucv_table_lock);
        rc = 0;
out_mutex:
        mutex_unlock(&iucv_register_mutex);
        return rc;
}
EXPORT_SYMBOL(iucv_register);

/**
 * iucv_unregister
 * @handler:  address of iucv handler structure
 * @smp: != 0 indicates that the handler can deal with out of order messages
 *
 * Unregister driver from IUCV.
 */
void iucv_unregister(struct iucv_handler *handler, int smp)
{
        struct iucv_path *p, *n;

        mutex_lock(&iucv_register_mutex);
        spin_lock_bh(&iucv_table_lock);
        /* Remove handler from the iucv_handler_list. */
        list_del_init(&handler->list);
        /* Sever all pathids still refering to the handler. */
        list_for_each_entry_safe(p, n, &handler->paths, list) {
                iucv_sever_pathid(p->pathid, NULL);
                iucv_path_table[p->pathid] = NULL;
                list_del(&p->list);
                iucv_path_free(p);
        }
        spin_unlock_bh(&iucv_table_lock);
        if (!smp)
                iucv_nonsmp_handler--;
        if (list_empty(&iucv_handler_list))
                iucv_disable();
        else if (!smp && iucv_nonsmp_handler == 0)
                iucv_setmask_mp();
        mutex_unlock(&iucv_register_mutex);
}
EXPORT_SYMBOL(iucv_unregister);

/**
 * iucv_path_accept
 * @path: address of iucv path structure
 * @handler: address of iucv handler structure
 * @userdata: 16 bytes of data reflected to the communication partner
 * @private: private data passed to interrupt handlers for this path
 *
 * This function is issued after the user received a connection pending
 * external interrupt and now wishes to complete the IUCV communication path.
 *
 * Returns the result of the CP IUCV call.
 */
int iucv_path_accept(struct iucv_path *path, struct iucv_handler *handler,
                     u8 userdata[16], void *private)
{
        union iucv_param *parm;
        int rc;

        local_bh_disable();
        /* Prepare parameter block. */
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        parm->ctrl.ippathid = path->pathid;
        parm->ctrl.ipmsglim = path->msglim;
        if (userdata)
                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));
        parm->ctrl.ipflags1 = path->flags;

        rc = iucv_call_b2f0(IUCV_ACCEPT, parm);
        if (!rc) {
                path->private = private;
                path->msglim = parm->ctrl.ipmsglim;
                path->flags = parm->ctrl.ipflags1;
        }
        local_bh_enable();
        return rc;
}
EXPORT_SYMBOL(iucv_path_accept);

/**
 * iucv_path_connect
 * @path: address of iucv path structure
 * @handler: address of iucv handler structure
 * @userid: 8-byte user identification
 * @system: 8-byte target system identification
 * @userdata: 16 bytes of data reflected to the communication partner
 * @private: private data passed to interrupt handlers for this path
 *
 * This function establishes an IUCV path. Although the connect may complete
 * successfully, you are not able to use the path until you receive an IUCV
 * Connection Complete external interrupt.
 *
 * Returns the result of the CP IUCV call.
 */
int iucv_path_connect(struct iucv_path *path, struct iucv_handler *handler,
                      u8 userid[8], u8 system[8], u8 userdata[16],
                      void *private)
{
        union iucv_param *parm;
        int rc;

        BUG_ON(in_atomic());
        spin_lock_bh(&iucv_table_lock);
        iucv_cleanup_queue();
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        parm->ctrl.ipmsglim = path->msglim;
        parm->ctrl.ipflags1 = path->flags;
        if (userid) {
                memcpy(parm->ctrl.ipvmid, userid, sizeof(parm->ctrl.ipvmid));
                ASCEBC(parm->ctrl.ipvmid, sizeof(parm->ctrl.ipvmid));
                EBC_TOUPPER(parm->ctrl.ipvmid, sizeof(parm->ctrl.ipvmid));
        }
        if (system) {
                memcpy(parm->ctrl.iptarget, system,
                       sizeof(parm->ctrl.iptarget));
                ASCEBC(parm->ctrl.iptarget, sizeof(parm->ctrl.iptarget));
                EBC_TOUPPER(parm->ctrl.iptarget, sizeof(parm->ctrl.iptarget));
        }
        if (userdata)
                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));

        rc = iucv_call_b2f0(IUCV_CONNECT, parm);
        if (!rc) {
                if (parm->ctrl.ippathid < iucv_max_pathid) {
                        path->pathid = parm->ctrl.ippathid;
                        path->msglim = parm->ctrl.ipmsglim;
                        path->flags = parm->ctrl.ipflags1;
                        path->handler = handler;
                        path->private = private;
                        list_add_tail(&path->list, &handler->paths);
                        iucv_path_table[path->pathid] = path;
                } else {
                        iucv_sever_pathid(parm->ctrl.ippathid,
                                          iucv_error_pathid);
                        rc = -EIO;
                }
        }
        spin_unlock_bh(&iucv_table_lock);
        return rc;
}
EXPORT_SYMBOL(iucv_path_connect);

/**
 * iucv_path_quiesce:
 * @path: address of iucv path structure
 * @userdata: 16 bytes of data reflected to the communication partner
 *
 * This function temporarily suspends incoming messages on an IUCV path.
 * You can later reactivate the path by invoking the iucv_resume function.
 *
 * Returns the result from the CP IUCV call.
 */
int iucv_path_quiesce(struct iucv_path *path, u8 userdata[16])
{
        union iucv_param *parm;
        int rc;

        local_bh_disable();
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        if (userdata)
                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));
        parm->ctrl.ippathid = path->pathid;
        rc = iucv_call_b2f0(IUCV_QUIESCE, parm);
        local_bh_enable();
        return rc;
}
EXPORT_SYMBOL(iucv_path_quiesce);

/**
 * iucv_path_resume:
 * @path: address of iucv path structure
 * @userdata: 16 bytes of data reflected to the communication partner
 *
 * This function resumes incoming messages on an IUCV path that has
 * been stopped with iucv_path_quiesce.
 *
 * Returns the result from the CP IUCV call.
 */
int iucv_path_resume(struct iucv_path *path, u8 userdata[16])
{
        union iucv_param *parm;
        int rc;

        local_bh_disable();
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        if (userdata)
                memcpy(parm->ctrl.ipuser, userdata, sizeof(parm->ctrl.ipuser));
        parm->ctrl.ippathid = path->pathid;
        rc = iucv_call_b2f0(IUCV_RESUME, parm);
        local_bh_enable();
        return rc;
}

/**
 * iucv_path_sever
 * @path: address of iucv path structure
 * @userdata: 16 bytes of data reflected to the communication partner
 *
 * This function terminates an IUCV path.
 *
 * Returns the result from the CP IUCV call.
 */
int iucv_path_sever(struct iucv_path *path, u8 userdata[16])
{
        int rc;

        preempt_disable();
        if (iucv_active_cpu != smp_processor_id())
                spin_lock_bh(&iucv_table_lock);
        rc = iucv_sever_pathid(path->pathid, userdata);
        if (!rc) {
                iucv_path_table[path->pathid] = NULL;
                list_del_init(&path->list);
        }
        if (iucv_active_cpu != smp_processor_id())
                spin_unlock_bh(&iucv_table_lock);
        preempt_enable();
        return rc;
}
EXPORT_SYMBOL(iucv_path_sever);

/**
 * iucv_message_purge
 * @path: address of iucv path structure
 * @msg: address of iucv msg structure
 * @srccls: source class of message
 *
 * Cancels a message you have sent.
 *
 * Returns the result from the CP IUCV call.
 */
int iucv_message_purge(struct iucv_path *path, struct iucv_message *msg,
                       u32 srccls)
{
        union iucv_param *parm;
        int rc;

        local_bh_disable();
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        parm->purge.ippathid = path->pathid;
        parm->purge.ipmsgid = msg->id;
        parm->purge.ipsrccls = srccls;
        parm->purge.ipflags1 = IUCV_IPSRCCLS | IUCV_IPFGMID | IUCV_IPFGPID;
        rc = iucv_call_b2f0(IUCV_PURGE, parm);
        if (!rc) {
                msg->audit = (*(u32 *) &parm->purge.ipaudit) >> 8;
                msg->tag = parm->purge.ipmsgtag;
        }
        local_bh_enable();
        return rc;
}
EXPORT_SYMBOL(iucv_message_purge);

/**
 * iucv_message_receive
 * @path: address of iucv path structure
 * @msg: address of iucv msg structure
 * @flags: how the message is received (IUCV_IPBUFLST)
 * @buffer: address of data buffer or address of struct iucv_array
 * @size: length of data buffer
 * @residual:
 *
 * This function receives messages that are being sent to you over
 * established paths. This function will deal with RMDATA messages
 * embedded in struct iucv_message as well.
 *
 * Returns the result from the CP IUCV call.
 */
int iucv_message_receive(struct iucv_path *path, struct iucv_message *msg,
                         u8 flags, void *buffer, size_t size, size_t *residual)
{
        union iucv_param *parm;
        struct iucv_array *array;
        u8 *rmmsg;
        size_t copy;
        int rc;

        if (msg->flags & IUCV_IPRMDATA) {
                /*
                 * Message is 8 bytes long and has been stored to the
                 * message descriptor itself.
                 */
                rc = (size < 8) ? 5 : 0;
                if (residual)
                        *residual = abs(size - 8);
                rmmsg = msg->rmmsg;
                if (flags & IUCV_IPBUFLST) {
                        /* Copy to struct iucv_array. */
                        size = (size < 8) ? size : 8;
                        for (array = buffer; size > 0; array++) {
                                copy = min_t(size_t, size, array->length);
                                memcpy((u8 *)(addr_t) array->address,
                                       rmmsg, copy);
                                rmmsg += copy;
                                size -= copy;
                        }
                } else {
                        /* Copy to direct buffer. */
                        memcpy(buffer, rmmsg, min_t(size_t, size, 8));
                }
                return 0;
        }

        local_bh_disable();
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        parm->db.ipbfadr1 = (u32)(addr_t) buffer;
        parm->db.ipbfln1f = (u32) size;
        parm->db.ipmsgid = msg->id;
        parm->db.ippathid = path->pathid;
        parm->db.iptrgcls = msg->class;
        parm->db.ipflags1 = (flags | IUCV_IPFGPID |
                             IUCV_IPFGMID | IUCV_IPTRGCLS);
        rc = iucv_call_b2f0(IUCV_RECEIVE, parm);
        if (!rc || rc == 5) {
                msg->flags = parm->db.ipflags1;
                if (residual)
                        *residual = parm->db.ipbfln1f;
        }
        local_bh_enable();
        return rc;
}
EXPORT_SYMBOL(iucv_message_receive);

/**
 * iucv_message_reject
 * @path: address of iucv path structure
 * @msg: address of iucv msg structure
 *
 * The reject function refuses a specified message. Between the time you
 * are notified of a message and the time that you complete the message,
 * the message may be rejected.
 *
 * Returns the result from the CP IUCV call.
 */
int iucv_message_reject(struct iucv_path *path, struct iucv_message *msg)
{
        union iucv_param *parm;
        int rc;

        local_bh_disable();
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        parm->db.ippathid = path->pathid;
        parm->db.ipmsgid = msg->id;
        parm->db.iptrgcls = msg->class;
        parm->db.ipflags1 = (IUCV_IPTRGCLS | IUCV_IPFGMID | IUCV_IPFGPID);
        rc = iucv_call_b2f0(IUCV_REJECT, parm);
        local_bh_enable();
        return rc;
}
EXPORT_SYMBOL(iucv_message_reject);

/**
 * iucv_message_reply
 * @path: address of iucv path structure
 * @msg: address of iucv msg structure
 * @flags: how the reply is sent (IUCV_IPRMDATA, IUCV_IPPRTY, IUCV_IPBUFLST)
 * @reply: address of reply data buffer or address of struct iucv_array
 * @size: length of reply data buffer
 *
 * This function responds to the two-way messages that you receive. You
 * must identify completely the message to which you wish to reply. ie,
 * pathid, msgid, and trgcls. Prmmsg signifies the data is moved into
 * the parameter list.
 *
 * Returns the result from the CP IUCV call.
 */
int iucv_message_reply(struct iucv_path *path, struct iucv_message *msg,
                       u8 flags, void *reply, size_t size)
{
        union iucv_param *parm;
        int rc;

        local_bh_disable();
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        if (flags & IUCV_IPRMDATA) {
                parm->dpl.ippathid = path->pathid;
                parm->dpl.ipflags1 = flags;
                parm->dpl.ipmsgid = msg->id;
                parm->dpl.iptrgcls = msg->class;
                memcpy(parm->dpl.iprmmsg, reply, min_t(size_t, size, 8));
        } else {
                parm->db.ipbfadr1 = (u32)(addr_t) reply;
                parm->db.ipbfln1f = (u32) size;
                parm->db.ippathid = path->pathid;
                parm->db.ipflags1 = flags;
                parm->db.ipmsgid = msg->id;
                parm->db.iptrgcls = msg->class;
        }
        rc = iucv_call_b2f0(IUCV_REPLY, parm);
        local_bh_enable();
        return rc;
}
EXPORT_SYMBOL(iucv_message_reply);

/**
 * iucv_message_send
 * @path: address of iucv path structure
 * @msg: address of iucv msg structure
 * @flags: how the message is sent (IUCV_IPRMDATA, IUCV_IPPRTY, IUCV_IPBUFLST)
 * @srccls: source class of message
 * @buffer: address of send buffer or address of struct iucv_array
 * @size: length of send buffer
 *
 * This function transmits data to another application. Data to be
 * transmitted is in a buffer and this is a one-way message and the
 * receiver will not reply to the message.
 *
 * Returns the result from the CP IUCV call.
 */
int iucv_message_send(struct iucv_path *path, struct iucv_message *msg,
                      u8 flags, u32 srccls, void *buffer, size_t size)
{
        union iucv_param *parm;
        int rc;

        local_bh_disable();
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        if (flags & IUCV_IPRMDATA) {
                /* Message of 8 bytes can be placed into the parameter list. */
                parm->dpl.ippathid = path->pathid;
                parm->dpl.ipflags1 = flags | IUCV_IPNORPY;
                parm->dpl.iptrgcls = msg->class;
                parm->dpl.ipsrccls = srccls;
                parm->dpl.ipmsgtag = msg->tag;
                memcpy(parm->dpl.iprmmsg, buffer, 8);
        } else {
                parm->db.ipbfadr1 = (u32)(addr_t) buffer;
                parm->db.ipbfln1f = (u32) size;
                parm->db.ippathid = path->pathid;
                parm->db.ipflags1 = flags | IUCV_IPNORPY;
                parm->db.iptrgcls = msg->class;
                parm->db.ipsrccls = srccls;
                parm->db.ipmsgtag = msg->tag;
        }
        rc = iucv_call_b2f0(IUCV_SEND, parm);
        if (!rc)
                msg->id = parm->db.ipmsgid;
        local_bh_enable();
        return rc;
}
EXPORT_SYMBOL(iucv_message_send);

/**
 * iucv_message_send2way
 * @path: address of iucv path structure
 * @msg: address of iucv msg structure
 * @flags: how the message is sent and the reply is received
 *         (IUCV_IPRMDATA, IUCV_IPBUFLST, IUCV_IPPRTY, IUCV_ANSLST)
 * @srccls: source class of message
 * @buffer: address of send buffer or address of struct iucv_array
 * @size: length of send buffer
 * @ansbuf: address of answer buffer or address of struct iucv_array
 * @asize: size of reply buffer
 *
 * This function transmits data to another application. Data to be
 * transmitted is in a buffer. The receiver of the send is expected to
 * reply to the message and a buffer is provided into which IUCV moves
 * the reply to this message.
 *
 * Returns the result from the CP IUCV call.
 */
int iucv_message_send2way(struct iucv_path *path, struct iucv_message *msg,
                          u8 flags, u32 srccls, void *buffer, size_t size,
                          void *answer, size_t asize, size_t *residual)
{
        union iucv_param *parm;
        int rc;

        local_bh_disable();
        parm = percpu_ptr(iucv_param, smp_processor_id());
        memset(parm, 0, sizeof(union iucv_param));
        if (flags & IUCV_IPRMDATA) {
                parm->dpl.ippathid = path->pathid;
                parm->dpl.ipflags1 = path->flags;       /* priority message */
                parm->dpl.iptrgcls = msg->class;
                parm->dpl.ipsrccls = srccls;
                parm->dpl.ipmsgtag = msg->tag;
                parm->dpl.ipbfadr2 = (u32)(addr_t) answer;
                parm->dpl.ipbfln2f = (u32) asize;
                memcpy(parm->dpl.iprmmsg, buffer, 8);
        } else {
                parm->db.ippathid = path->pathid;
                parm->db.ipflags1 = path->flags;        /* priority message */
                parm->db.iptrgcls = msg->class;
                parm->db.ipsrccls = srccls;
                parm->db.ipmsgtag = msg->tag;
                parm->db.ipbfadr1 = (u32)(addr_t) buffer;
                parm->db.ipbfln1f = (u32) size;
                parm->db.ipbfadr2 = (u32)(addr_t) answer;
                parm->db.ipbfln2f = (u32) asize;
        }
        rc = iucv_call_b2f0(IUCV_SEND, parm);
        if (!rc)
                msg->id = parm->db.ipmsgid;
        local_bh_enable();
        return rc;
}
EXPORT_SYMBOL(iucv_message_send2way);

/**
 * iucv_path_pending
 * @data: Pointer to external interrupt buffer
 *
 * Process connection pending work item. Called from tasklet while holding
 * iucv_table_lock.
 */
struct iucv_path_pending {
        u16 ippathid;
        u8  ipflags1;
        u8  iptype;
        u16 ipmsglim;
        u16 res1;
        u8  ipvmid[8];
        u8  ipuser[16];
        u32 res3;
        u8  ippollfg;
        u8  res4[3];
} __attribute__ ((packed));

static void iucv_path_pending(struct iucv_irq_data *data)
{
        struct iucv_path_pending *ipp = (void *) data;
        struct iucv_handler *handler;
        struct iucv_path *path;
        char *error;

        BUG_ON(iucv_path_table[ipp->ippathid]);
        /* New pathid, handler found. Create a new path struct. */
        error = iucv_error_no_memory;
        path = iucv_path_alloc(ipp->ipmsglim, ipp->ipflags1, GFP_ATOMIC);
        if (!path)
                goto out_sever;
        path->pathid = ipp->ippathid;
        iucv_path_table[path->pathid] = path;
        EBCASC(ipp->ipvmid, 8);

        /* Call registered handler until one is found that wants the path. */
        list_for_each_entry(handler, &iucv_handler_list, list) {
                if (!handler->path_pending)
                        continue;
                /*
                 * Add path to handler to allow a call to iucv_path_sever
                 * inside the path_pending function. If the handler returns
                 * an error remove the path from the handler again.
                 */
                list_add(&path->list, &handler->paths);
                path->handler = handler;
                if (!handler->path_pending(path, ipp->ipvmid, ipp->ipuser))
                        return;
                list_del(&path->list);
                path->handler = NULL;
        }
        /* No handler wanted the path. */
        iucv_path_table[path->pathid] = NULL;
        iucv_path_free(path);
        error = iucv_error_no_listener;
out_sever:
        iucv_sever_pathid(ipp->ippathid, error);
}

/**
 * iucv_path_complete
 * @data: Pointer to external interrupt buffer
 *
 * Process connection complete work item. Called from tasklet while holding
 * iucv_table_lock.
 */
struct iucv_path_complete {
        u16 ippathid;
        u8  ipflags1;
        u8  iptype;
        u16 ipmsglim;
        u16 res1;
        u8  res2[8];
        u8  ipuser[16];
        u32 res3;
        u8  ippollfg;
        u8  res4[3];
} __attribute__ ((packed));

static void iucv_path_complete(struct iucv_irq_data *data)
{
        struct iucv_path_complete *ipc = (void *) data;
        struct iucv_path *path = iucv_path_table[ipc->ippathid];

        if (path && path->handler && path->handler->path_complete)
                path->handler->path_complete(path, ipc->ipuser);
}

/**
 * iucv_path_severed
 * @data: Pointer to external interrupt buffer
 *
 * Process connection severed work item. Called from tasklet while holding
 * iucv_table_lock.
 */
struct iucv_path_severed {
        u16 ippathid;
        u8  res1;
        u8  iptype;
        u32 res2;
        u8  res3[8];
        u8  ipuser[16];
        u32 res4;
        u8  ippollfg;
        u8  res5[3];
} __attribute__ ((packed));

static void iucv_path_severed(struct iucv_irq_data *data)
{
        struct iucv_path_severed *ips = (void *) data;
        struct iucv_path *path = iucv_path_table[ips->ippathid];

        if (!path || !path->handler)    /* Already severed */
                return;
        if (path->handler->path_severed)
                path->handler->path_severed(path, ips->ipuser);
        else {
                iucv_sever_pathid(path->pathid, NULL);
                iucv_path_table[path->pathid] = NULL;
                list_del_init(&path->list);
                iucv_path_free(path);
        }
}

/**
 * iucv_path_quiesced
 * @data: Pointer to external interrupt buffer
 *
 * Process connection quiesced work item. Called from tasklet while holding
 * iucv_table_lock.
 */
struct iucv_path_quiesced {
        u16 ippathid;
        u8  res1;
        u8  iptype;
        u32 res2;
        u8  res3[8];
        u8  ipuser[16];
        u32 res4;
        u8  ippollfg;
        u8  res5[3];
} __attribute__ ((packed));

static void iucv_path_quiesced(struct iucv_irq_data *data)
{
        struct iucv_path_quiesced *ipq = (void *) data;
        struct iucv_path *path = iucv_path_table[ipq->ippathid];

        if (path && path->handler && path->handler->path_quiesced)
                path->handler->path_quiesced(path, ipq->ipuser);
}

/**
 * iucv_path_resumed
 * @data: Pointer to external interrupt buffer
 *
 * Process connection resumed work item. Called from tasklet while holding
 * iucv_table_lock.
 */
struct iucv_path_resumed {
        u16 ippathid;
        u8  res1;
        u8  iptype;
        u32 res2;
        u8  res3[8];
        u8  ipuser[16];
        u32 res4;
        u8  ippollfg;
        u8  res5[3];
} __attribute__ ((packed));

static void iucv_path_resumed(struct iucv_irq_data *data)
{
        struct iucv_path_resumed *ipr = (void *) data;
        struct iucv_path *path = iucv_path_table[ipr->ippathid];

        if (path && path->handler && path->handler->path_resumed)
                path->handler->path_resumed(path, ipr->ipuser);
}

/**
 * iucv_message_complete
 * @data: Pointer to external interrupt buffer
 *
 * Process message complete work item. Called from tasklet while holding
 * iucv_table_lock.
 */
struct iucv_message_complete {
        u16 ippathid;
        u8  ipflags1;
        u8  iptype;
        u32 ipmsgid;
        u32 ipaudit;
        u8  iprmmsg[8];
        u32 ipsrccls;
        u32 ipmsgtag;
        u32 res;
        u32 ipbfln2f;
        u8  ippollfg;
        u8  res2[3];
} __attribute__ ((packed));

static void iucv_message_complete(struct iucv_irq_data *data)
{
        struct iucv_message_complete *imc = (void *) data;
        struct iucv_path *path = iucv_path_table[imc->ippathid];
        struct iucv_message msg;

        if (path && path->handler && path->handler->message_complete) {
                msg.flags = imc->ipflags1;
                msg.id = imc->ipmsgid;
                msg.audit = imc->ipaudit;
                memcpy(msg.rmmsg, imc->iprmmsg, 8);
                msg.class = imc->ipsrccls;
                msg.tag = imc->ipmsgtag;
                msg.length = imc->ipbfln2f;
                path->handler->message_complete(path, &msg);
        }
}

/**
 * iucv_message_pending
 * @data: Pointer to external interrupt buffer
 *
 * Process message pending work item. Called from tasklet while holding
 * iucv_table_lock.
 */
struct iucv_message_pending {
        u16 ippathid;
        u8  ipflags1;
        u8  iptype;
        u32 ipmsgid;
        u32 iptrgcls;
        union {
                u32 iprmmsg1_u32;
                u8  iprmmsg1[4];
        } ln1msg1;
        union {
                u32 ipbfln1f;
                u8  iprmmsg2[4];
        } ln1msg2;
        u32 res1[3];
        u32 ipbfln2f;
        u8  ippollfg;
        u8  res2[3];
} __attribute__ ((packed));

static void iucv_message_pending(struct iucv_irq_data *data)
{
        struct iucv_message_pending *imp = (void *) data;
        struct iucv_path *path = iucv_path_table[imp->ippathid];
        struct iucv_message msg;

        if (path && path->handler && path->handler->message_pending) {
                msg.flags = imp->ipflags1;
                msg.id = imp->ipmsgid;
                msg.class = imp->iptrgcls;
                if (imp->ipflags1 & IUCV_IPRMDATA) {
                        memcpy(msg.rmmsg, imp->ln1msg1.iprmmsg1, 8);
                        msg.length = 8;
                } else
                        msg.length = imp->ln1msg2.ipbfln1f;
                msg.reply_size = imp->ipbfln2f;
                path->handler->message_pending(path, &msg);
        }
}

/**
 * iucv_tasklet_fn:
 *
 * This tasklet loops over the queue of irq buffers created by
 * iucv_external_interrupt, calls the appropriate action handler
 * and then frees the buffer.
 */
static void iucv_tasklet_fn(unsigned long ignored)
{
        typedef void iucv_irq_fn(struct iucv_irq_data *);
        static iucv_irq_fn *irq_fn[] = {
                [0x02] = iucv_path_complete,
                [0x03] = iucv_path_severed,
                [0x04] = iucv_path_quiesced,
                [0x05] = iucv_path_resumed,
                [0x06] = iucv_message_complete,
                [0x07] = iucv_message_complete,
                [0x08] = iucv_message_pending,
                [0x09] = iucv_message_pending,
        };
        struct list_head task_queue = LIST_HEAD_INIT(task_queue);
        struct iucv_irq_list *p, *n;

        /* Serialize tasklet, iucv_path_sever and iucv_path_connect. */
        if (!spin_trylock(&iucv_table_lock)) {
                tasklet_schedule(&iucv_tasklet);
                return;
        }
        iucv_active_cpu = smp_processor_id();

        spin_lock_irq(&iucv_queue_lock);
        list_splice_init(&iucv_task_queue, &task_queue);
        spin_unlock_irq(&iucv_queue_lock);

        list_for_each_entry_safe(p, n, &task_queue, list) {
                list_del_init(&p->list);
                irq_fn[p->data.iptype](&p->data);
                kfree(p);
        }

        iucv_active_cpu = -1;
        spin_unlock(&iucv_table_lock);
}

/**
 * iucv_work_fn:
 *
 * This work function loops over the queue of path pending irq blocks
 * created by iucv_external_interrupt, calls the appropriate action
 * handler and then frees the buffer.
 */
static void iucv_work_fn(struct work_struct *work)
{
        typedef void iucv_irq_fn(struct iucv_irq_data *);
        struct list_head work_queue = LIST_HEAD_INIT(work_queue);
        struct iucv_irq_list *p, *n;

        /* Serialize tasklet, iucv_path_sever and iucv_path_connect. */
        spin_lock_bh(&iucv_table_lock);
        iucv_active_cpu = smp_processor_id();

        spin_lock_irq(&iucv_queue_lock);
        list_splice_init(&iucv_work_queue, &work_queue);
        spin_unlock_irq(&iucv_queue_lock);

        iucv_cleanup_queue();
        list_for_each_entry_safe(p, n, &work_queue, list) {
                list_del_init(&p->list);
                iucv_path_pending(&p->data);
                kfree(p);
        }

        iucv_active_cpu = -1;
        spin_unlock_bh(&iucv_table_lock);
}

/**
 * iucv_external_interrupt
 * @code: irq code
 *
 * Handles external interrupts coming in from CP.
 * Places the interrupt buffer on a queue and schedules iucv_tasklet_fn().
 */
static void iucv_external_interrupt(u16 code)
{
        struct iucv_irq_data *p;
        struct iucv_irq_list *work;

        p = percpu_ptr(iucv_irq_data, smp_processor_id());
        if (p->ippathid >= iucv_max_pathid) {
                printk(KERN_WARNING "iucv_do_int: Got interrupt with "
                       "pathid %d > max_connections (%ld)\n",
                       p->ippathid, iucv_max_pathid - 1);
                iucv_sever_pathid(p->ippathid, iucv_error_no_listener);
                return;
        }
        if (p->iptype  < 0x01 || p->iptype > 0x09) {
                printk(KERN_ERR "iucv_do_int: unknown iucv interrupt\n");
                return;
        }
        work = kmalloc(sizeof(struct iucv_irq_list), GFP_ATOMIC);
        if (!work) {
                printk(KERN_WARNING "iucv_external_interrupt: out of memory\n");
                return;
        }
        memcpy(&work->data, p, sizeof(work->data));
        spin_lock(&iucv_queue_lock);
        if (p->iptype == 0x01) {
                /* Path pending interrupt. */
                list_add_tail(&work->list, &iucv_work_queue);
                schedule_work(&iucv_work);
        } else {
                /* The other interrupts. */
                list_add_tail(&work->list, &iucv_task_queue);
                tasklet_schedule(&iucv_tasklet);
        }
        spin_unlock(&iucv_queue_lock);
}

/**
 * iucv_init
 *
 * Allocates and initializes various data structures.
 */
static int __init iucv_init(void)
{
        int rc;

        if (!MACHINE_IS_VM) {
                rc = -EPROTONOSUPPORT;
                goto out;
        }
        rc = iucv_query_maxconn();
        if (rc)
                goto out;
        rc = register_external_interrupt(0x4000, iucv_external_interrupt);
        if (rc)
                goto out;
        rc = bus_register(&iucv_bus);
        if (rc)
                goto out_int;
        iucv_root = s390_root_dev_register("iucv");
        if (IS_ERR(iucv_root)) {
                rc = PTR_ERR(iucv_root);
                goto out_bus;
        }
        /* Note: GFP_DMA used to get memory below 2G */
        iucv_irq_data = percpu_alloc(sizeof(struct iucv_irq_data),
                                     GFP_KERNEL|GFP_DMA);
        if (!iucv_irq_data) {
                rc = -ENOMEM;
                goto out_root;
        }
        /* Allocate parameter blocks. */
        iucv_param = percpu_alloc(sizeof(union iucv_param),
                                  GFP_KERNEL|GFP_DMA);
        if (!iucv_param) {
                rc = -ENOMEM;
                goto out_extint;
        }
        register_hotcpu_notifier(&iucv_cpu_notifier);
        ASCEBC(iucv_error_no_listener, 16);
        ASCEBC(iucv_error_no_memory, 16);
        ASCEBC(iucv_error_pathid, 16);
        iucv_available = 1;
        return 0;

out_extint:
        percpu_free(iucv_irq_data);
out_root:
        s390_root_dev_unregister(iucv_root);
out_bus:
        bus_unregister(&iucv_bus);
out_int:
        unregister_external_interrupt(0x4000, iucv_external_interrupt);
out:
        return rc;
}

/**
 * iucv_exit
 *
 * Frees everything allocated from iucv_init.
 */
static void __exit iucv_exit(void)
{
        struct iucv_irq_list *p, *n;

        spin_lock_irq(&iucv_queue_lock);
        list_for_each_entry_safe(p, n, &iucv_task_queue, list)
                kfree(p);
        list_for_each_entry_safe(p, n, &iucv_work_queue, list)
                kfree(p);
        spin_unlock_irq(&iucv_queue_lock);
        unregister_hotcpu_notifier(&iucv_cpu_notifier);
        percpu_free(iucv_param);
        percpu_free(iucv_irq_data);
        s390_root_dev_unregister(iucv_root);
        bus_unregister(&iucv_bus);
        unregister_external_interrupt(0x4000, iucv_external_interrupt);
}

subsys_initcall(iucv_init);
module_exit(iucv_exit);

MODULE_AUTHOR("(C) 2001 IBM Corp. by Fritz Elfert (felfert@millenux.com)");
MODULE_DESCRIPTION("Linux for S/390 IUCV lowlevel driver");
MODULE_LICENSE("GPL");