This commit was manufactured by cvs2svn to create branch 'vserver'.
[linux-2.6.git] / drivers / s390 / char / vmlogrdr.c
diff --git a/drivers/s390/char/vmlogrdr.c b/drivers/s390/char/vmlogrdr.c
new file mode 100644 (file)
index 0000000..88694e7
--- /dev/null
@@ -0,0 +1,920 @@
+/*
+ * drivers/s390/char/vmlogrdr.c
+ *     character device driver for reading z/VM system service records
+ *
+ *
+ *     Copyright (C) 2004 IBM Corporation
+ *     character device driver for reading z/VM system service records,
+ *     Version 1.0
+ *     Author(s): Xenia Tkatschow <xenia@us.ibm.com>
+ *                Stefan Weinhuber <wein@de.ibm.com>
+ *
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <asm/atomic.h>
+#include <asm/uaccess.h>
+#include <asm/cpcmd.h>
+#include <asm/debug.h>
+#include <asm/ebcdic.h>
+#include "../net/iucv.h"
+#include <linux/kmod.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/string.h>
+
+
+
+MODULE_AUTHOR
+       ("(C) 2004 IBM Corporation by Xenia Tkatschow (xenia@us.ibm.com)\n"
+        "                            Stefan Weinhuber (wein@de.ibm.com)");
+MODULE_DESCRIPTION ("Character device driver for reading z/VM "
+                   "system service records.");
+MODULE_LICENSE("GPL");
+
+
+/*
+ * The size of the buffer for iucv data transfer is one page,
+ * but in addition to the data we read from iucv we also
+ * place an integer and some characters into that buffer,
+ * so the maximum size for record data is a little less then
+ * one page.
+ */
+#define NET_BUFFER_SIZE        (PAGE_SIZE - sizeof(int) - sizeof(FENCE))
+
+/*
+ * The elements that are concurrently accessed by bottom halves are
+ * connection_established, iucv_path_severed, local_interrupt_buffer
+ * and receive_ready. The first three can be protected by
+ * priv_lock.  receive_ready is atomic, so it can be incremented and
+ * decremented without holding a lock.
+ * The variable dev_in_use needs to be protected by the lock, since
+ * it's a flag used by open to make sure that the device is opened only
+ * by one user at the same time.
+ */
+struct vmlogrdr_priv_t {
+       char system_service[8];
+       char internal_name[8];
+       char recording_name[8];
+       u16 pathid;
+       int connection_established;
+       int iucv_path_severed;
+       iucv_MessagePending local_interrupt_buffer;
+       atomic_t receive_ready;
+       iucv_handle_t iucv_handle;
+       int minor_num;
+       char * buffer;
+       char * current_position;
+       int remaining;
+       ulong residual_length;
+       int buffer_free;
+       int dev_in_use; /* 1: already opened, 0: not opened*/
+       spinlock_t priv_lock;
+       struct device  *device;
+       struct class_device  *class_device;
+       int autorecording;
+       int autopurge;
+};
+
+
+/*
+ * File operation structure for vmlogrdr devices
+ */
+static int vmlogrdr_open(struct inode *, struct file *);
+static int vmlogrdr_release(struct inode *, struct file *);
+static ssize_t vmlogrdr_read (struct file *filp, char *data, size_t count,
+                              loff_t * ppos);
+
+static struct file_operations vmlogrdr_fops = {
+       .owner   = THIS_MODULE,
+       .open    = vmlogrdr_open,
+       .release = vmlogrdr_release,
+       .read    = vmlogrdr_read,
+};
+
+
+static u8 iucvMagic[16] = {
+       0xF0, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
+       0xF0, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40
+};
+
+
+static u8 mask[] = {
+       0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+       0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+       0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+       0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
+};
+
+
+static u8 iucv_host[8] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
+
+
+static void
+vmlogrdr_iucv_ConnectionComplete(iucv_ConnectionComplete *eib, void *pgm_data);
+static void
+vmlogrdr_iucv_ConnectionSevered(iucv_ConnectionSevered *eib, void *pgm_data);
+static void
+vmlogrdr_iucv_MessagePending(iucv_MessagePending *eib, void *pgm_data);
+
+
+static iucv_interrupt_ops_t vmlogrdr_iucvops = {
+       .ConnectionComplete = vmlogrdr_iucv_ConnectionComplete,
+       .ConnectionSevered  = vmlogrdr_iucv_ConnectionSevered,
+       .MessagePending     = vmlogrdr_iucv_MessagePending,
+};
+
+
+DECLARE_WAIT_QUEUE_HEAD(conn_wait_queue);
+DECLARE_WAIT_QUEUE_HEAD(read_wait_queue);
+
+/*
+ * pointer to system service private structure
+ * minor number 0 --> logrec
+ * minor number 1 --> account
+ * minor number 2 --> symptom
+ */
+
+static struct vmlogrdr_priv_t sys_ser[] = {
+       { .system_service = "*LOGREC ",
+         .internal_name  = "logrec",
+         .recording_name = "EREP",
+         .minor_num      = 0,
+         .buffer_free    = 1,
+         .priv_lock      = SPIN_LOCK_UNLOCKED,
+         .autorecording  = 1,
+         .autopurge      = 1,
+       },
+       { .system_service = "*ACCOUNT",
+         .internal_name  = "account",
+         .recording_name = "ACCOUNT",
+         .minor_num      = 1,
+         .buffer_free    = 1,
+         .priv_lock      = SPIN_LOCK_UNLOCKED,
+         .autorecording  = 1,
+         .autopurge      = 1,
+       },
+       { .system_service = "*SYMPTOM",
+         .internal_name  = "symptom",
+         .recording_name = "SYMPTOM",
+         .minor_num      = 2,
+         .buffer_free    = 1,
+         .priv_lock      = SPIN_LOCK_UNLOCKED,
+         .autorecording  = 1,
+         .autopurge      = 1,
+       }
+};
+
+#define MAXMINOR  (sizeof(sys_ser)/sizeof(struct vmlogrdr_priv_t))
+
+static char FENCE[] = {"EOR"};
+static int vmlogrdr_major = 0;
+static struct cdev  *vmlogrdr_cdev = NULL;
+static int recording_class_AB;
+
+
+static void
+vmlogrdr_iucv_ConnectionComplete (iucv_ConnectionComplete * eib,
+                                  void * pgm_data)
+{
+       struct vmlogrdr_priv_t * logptr = pgm_data;
+       spin_lock(&logptr->priv_lock);
+       logptr->connection_established = 1;
+       spin_unlock(&logptr->priv_lock);
+       wake_up(&conn_wait_queue);
+       return;
+}
+
+
+static void
+vmlogrdr_iucv_ConnectionSevered (iucv_ConnectionSevered * eib, void * pgm_data)
+{
+       u8 reason = (u8) eib->ipuser[8];
+       struct vmlogrdr_priv_t * logptr = pgm_data;
+
+       printk (KERN_ERR "vmlogrdr: connection severed with"
+               " reason %i\n", reason);
+
+       spin_lock(&logptr->priv_lock);
+       logptr->connection_established = 0;
+       logptr->iucv_path_severed = 1;
+       spin_unlock(&logptr->priv_lock);
+
+       wake_up(&conn_wait_queue);
+       /* just in case we're sleeping waiting for a record */
+       wake_up_interruptible(&read_wait_queue);
+}
+
+
+static void
+vmlogrdr_iucv_MessagePending (iucv_MessagePending * eib, void * pgm_data)
+{
+       struct vmlogrdr_priv_t * logptr = pgm_data;
+
+       /*
+        * This function is the bottom half so it should be quick.
+        * Copy the external interrupt data into our local eib and increment
+        * the usage count
+        */
+       spin_lock(&logptr->priv_lock);
+       memcpy(&(logptr->local_interrupt_buffer), eib, sizeof(*eib));
+       atomic_inc(&logptr->receive_ready);
+       spin_unlock(&logptr->priv_lock);
+       wake_up_interruptible(&read_wait_queue);
+}
+
+
+static int
+vmlogrdr_get_recording_class_AB(void) {
+       char cp_command[]="QUERY COMMAND RECORDING ";
+       char cp_response[80];
+       char *tail;
+       int len,i;
+
+       printk (KERN_DEBUG "vmlogrdr: query command: %s\n", cp_command);
+       cpcmd(cp_command, cp_response, sizeof(cp_response));
+       printk (KERN_DEBUG "vmlogrdr: response: %s", cp_response);
+       len = strnlen(cp_response,sizeof(cp_response));
+       // now the parsing
+       tail=strnchr(cp_response,len,'=');
+       if (!tail)
+               return 0;
+       tail++;
+       if (!strncmp("ANY",tail,3))
+               return 1;
+       if (!strncmp("NONE",tail,4))
+               return 0;
+       /*
+        * expect comma separated list of classes here, if one of them
+        * is A or B return 1 otherwise 0
+        */
+        for (i=tail-cp_response; i<len; i++)
+               if ( cp_response[i]=='A' || cp_response[i]=='B' )
+                       return 1;
+       return 0;
+}
+
+
+static int
+vmlogrdr_recording(struct vmlogrdr_priv_t * logptr, int action, int purge) {
+
+       char cp_command[80];
+       char cp_response[160];
+       char *onoff, *qid_string;
+
+       memset(cp_command, 0x00, sizeof(cp_command));
+       memset(cp_response, 0x00, sizeof(cp_response));
+
+        onoff = ((action == 1) ? "ON" : "OFF");
+       qid_string = ((recording_class_AB == 1) ? " QID * " : "");
+
+        /*
+        * The recording commands needs to be called with option QID
+        * for guests that have previlege classes A or B.
+        * Purging has to be done as separate step, because recording
+        * can't be switched on as long as records are on the queue.
+        * Doing both at the same time doesn't work.
+        */
+
+       if (purge) {
+               snprintf(cp_command, sizeof(cp_command),
+                        "RECORDING %s PURGE %s",
+                        logptr->recording_name,
+                        qid_string);
+
+               printk (KERN_DEBUG "vmlogrdr: recording command: %s\n",
+                       cp_command);
+               cpcmd(cp_command, cp_response, sizeof(cp_response));
+               printk (KERN_DEBUG "vmlogrdr: recording response: %s",
+                       cp_response);
+       }
+
+       memset(cp_command, 0x00, sizeof(cp_command));
+       memset(cp_response, 0x00, sizeof(cp_response));
+       snprintf(cp_command, sizeof(cp_command), "RECORDING %s %s %s",
+               logptr->recording_name,
+               onoff,
+               qid_string);
+
+       printk (KERN_DEBUG "vmlogrdr: recording command: %s\n", cp_command);
+       cpcmd(cp_command, cp_response, sizeof(cp_response));
+       printk (KERN_DEBUG "vmlogrdr: recording response: %s",
+               cp_response);
+       /* The recording command will usually answer with 'Command complete'
+        * on success, but when the specific service was never connected
+        * before then there might be an additional informational message
+        * 'HCPCRC8072I Recording entry not found' before the
+         * 'Command complete'. So I use strstr rather then the strncmp.
+        */
+       if (strstr(cp_response,"Command complete"))
+               return 0;
+       else
+               return -EIO;
+
+}
+
+
+static int
+vmlogrdr_open (struct inode *inode, struct file *filp)
+{
+       int dev_num = 0;
+       struct vmlogrdr_priv_t * logptr = NULL;
+       int connect_rc = 0;
+       int ret;
+
+       dev_num = iminor(inode);
+       if (dev_num > MAXMINOR)
+               return -ENODEV;
+
+       logptr = &sys_ser[dev_num];
+       if (logptr == NULL)
+               return -ENODEV;
+
+       /*
+        * only allow for blocking reads to be open
+        */
+       if (filp->f_flags & O_NONBLOCK)
+               return -ENOSYS;
+
+       /* Besure this device hasn't already been opened */
+       spin_lock_bh(&logptr->priv_lock);
+       if (logptr->dev_in_use) {
+               spin_unlock_bh(&logptr->priv_lock);
+               return -EBUSY;
+       } else {
+               logptr->dev_in_use = 1;
+               spin_unlock_bh(&logptr->priv_lock);
+       }
+
+       atomic_set(&logptr->receive_ready, 0);
+       logptr->buffer_free = 1;
+
+       /* set the file options */
+       filp->private_data = logptr;
+       filp->f_op = &vmlogrdr_fops;
+
+       /* start recording for this service*/
+       ret=0;
+       if (logptr->autorecording)
+               ret = vmlogrdr_recording(logptr,1,logptr->autopurge);
+       if (ret)
+               printk (KERN_WARNING "vmlogrdr: failed to start "
+                       "recording automatically\n");
+
+       /* Register with iucv driver */
+       logptr->iucv_handle = iucv_register_program(iucvMagic,
+                       logptr->system_service, mask, &vmlogrdr_iucvops,
+                       logptr);
+
+       if (logptr->iucv_handle == NULL) {
+               printk (KERN_ERR "vmlogrdr: failed to register with"
+                       "iucv driver\n");
+               goto not_registered;
+       }
+
+       /* create connection to the system service */
+       spin_lock_bh(&logptr->priv_lock);
+       logptr->connection_established = 0;
+       logptr->iucv_path_severed = 0;
+       spin_unlock_bh(&logptr->priv_lock);
+
+       connect_rc = iucv_connect (&(logptr->pathid), 10, iucvMagic,
+                                       logptr->system_service, iucv_host, 0,
+                                       NULL, NULL,
+                                       logptr->iucv_handle, NULL);
+       if (connect_rc) {
+               printk (KERN_ERR "vmlogrdr: iucv connection to %s "
+                       "failed with rc %i \n", logptr->system_service,
+                       connect_rc);
+               goto not_connected;
+       }
+
+       /* We've issued the connect and now we must wait for a
+        * ConnectionComplete or ConnectinSevered Interrupt
+        * before we can continue to process.
+        */
+       wait_event(conn_wait_queue, (logptr->connection_established)
+                  || (logptr->iucv_path_severed));
+       if (logptr->iucv_path_severed) {
+               goto not_connected;
+       }
+
+       return 0;
+
+not_connected:
+       iucv_unregister_program(logptr->iucv_handle);
+       logptr->iucv_handle = NULL;
+not_registered:
+       if (logptr->autorecording)
+               vmlogrdr_recording(logptr,0,logptr->autopurge);
+       logptr->dev_in_use = 0;
+       return -EIO;
+
+
+}
+
+
+static int
+vmlogrdr_release (struct inode *inode, struct file *filp)
+{
+       int ret;
+
+       struct vmlogrdr_priv_t * logptr = filp->private_data;
+
+       iucv_unregister_program(logptr->iucv_handle);
+       logptr->iucv_handle = NULL;
+
+       if (logptr->autorecording) {
+               ret = vmlogrdr_recording(logptr,0,logptr->autopurge);
+               if (ret)
+                       printk (KERN_WARNING "vmlogrdr: failed to stop "
+                               "recording automatically\n");
+       }
+       logptr->dev_in_use = 0;
+
+       return 0;
+}
+
+
+static int
+vmlogrdr_receive_data(struct vmlogrdr_priv_t *priv) {
+       int rc, *temp;
+       /* we need to keep track of two data sizes here:
+        * The number of bytes we need to receive from iucv and
+        * the total number of bytes we actually write into the buffer.
+        */
+       int user_data_count, iucv_data_count;
+       char * buffer;
+
+       if (atomic_read(&priv->receive_ready)) {
+               spin_lock_bh(&priv->priv_lock);
+               if (priv->residual_length){
+                       /* receive second half of a record */
+                       iucv_data_count = priv->residual_length;
+                       user_data_count = 0;
+                       buffer = priv->buffer;
+               } else {
+                       /* receive a new record:
+                        * We need to return the total length of the record
+                         * + size of FENCE in the first 4 bytes of the buffer.
+                        */
+                       iucv_data_count =
+                               priv->local_interrupt_buffer.ln1msg2.ipbfln1f;
+                       user_data_count = sizeof(int);
+                       temp = (int*)priv->buffer;
+                       *temp= iucv_data_count + sizeof(FENCE);
+                       buffer = priv->buffer + sizeof(int);
+               }
+               /*
+                * If the record is bigger then our buffer, we receive only
+                * a part of it. We can get the rest later.
+                */
+               if (iucv_data_count > NET_BUFFER_SIZE)
+                       iucv_data_count = NET_BUFFER_SIZE;
+               rc = iucv_receive(priv->pathid,
+                                 priv->local_interrupt_buffer.ipmsgid,
+                                 priv->local_interrupt_buffer.iptrgcls,
+                                 buffer,
+                                 iucv_data_count,
+                                 NULL,
+                                 NULL,
+                                 &priv->residual_length);
+               spin_unlock_bh(&priv->priv_lock);
+               /* An rc of 5 indicates that the record was bigger then
+                * the buffer, which is OK for us. A 9 indicates that the
+                * record was purged befor we could receive it.
+                */
+               if (rc == 5)
+                       rc = 0;
+               if (rc == 9)
+                       atomic_set(&priv->receive_ready, 0);
+       } else {
+               rc = 1;
+       }
+       if (!rc) {
+               priv->buffer_free = 0;
+               user_data_count += iucv_data_count;
+               priv->current_position = priv->buffer;
+               if (priv->residual_length == 0){
+                       /* the whole record has been captured,
+                        * now add the fence */
+                       atomic_dec(&priv->receive_ready);
+                       buffer = priv->buffer + user_data_count;
+                       memcpy(buffer, FENCE, sizeof(FENCE));
+                       user_data_count += sizeof(FENCE);
+               }
+               priv->remaining = user_data_count;
+       }
+
+       return rc;
+}
+
+
+static ssize_t
+vmlogrdr_read (struct file *filp, char *data, size_t count, loff_t * ppos)
+{
+       int rc;
+       struct vmlogrdr_priv_t * priv = filp->private_data;
+
+       while (priv->buffer_free) {
+               rc = vmlogrdr_receive_data(priv);
+               if (rc) {
+                       rc = wait_event_interruptible(read_wait_queue,
+                                       atomic_read(&priv->receive_ready));
+                       if (rc)
+                               return rc;
+               }
+       }
+       /* copy only up to end of record */
+       if (count > priv->remaining)
+               count = priv->remaining;
+
+       if (copy_to_user(data, priv->current_position, count))
+               return -EFAULT;
+
+       *ppos += count;
+       priv->current_position += count;
+       priv->remaining -= count;
+
+       /* if all data has been transferred, set buffer free */
+       if (priv->remaining == 0)
+               priv->buffer_free = 1;
+
+       return count;
+}
+
+static ssize_t
+vmlogrdr_autopurge_store(struct device * dev, const char * buf, size_t count) {
+       struct vmlogrdr_priv_t *priv = dev->driver_data;
+       ssize_t ret = count;
+
+       switch (buf[0]) {
+       case '0':
+               priv->autopurge=0;
+               break;
+       case '1':
+               priv->autopurge=1;
+               break;
+       default:
+               ret = -EINVAL;
+       }
+       return ret;
+}
+
+
+static ssize_t
+vmlogrdr_autopurge_show(struct device *dev, char *buf) {
+       struct vmlogrdr_priv_t *priv = dev->driver_data;
+       return sprintf(buf, "%u\n", priv->autopurge);
+}
+
+
+static DEVICE_ATTR(autopurge, 0644, vmlogrdr_autopurge_show,
+                  vmlogrdr_autopurge_store);
+
+
+static ssize_t
+vmlogrdr_purge_store(struct device * dev, const char * buf, size_t count) {
+
+       char cp_command[80];
+       char cp_response[80];
+       struct vmlogrdr_priv_t *priv = dev->driver_data;
+
+       if (buf[0] != '1')
+               return -EINVAL;
+
+       memset(cp_command, 0x00, sizeof(cp_command));
+       memset(cp_response, 0x00, sizeof(cp_response));
+
+        /*
+        * The recording command needs to be called with option QID
+        * for guests that have previlege classes A or B.
+        * Other guests will not recognize the command and we have to
+        * issue the same command without the QID parameter.
+        */
+
+       if (recording_class_AB)
+               snprintf(cp_command, sizeof(cp_command),
+                        "RECORDING %s PURGE QID * ",
+                        priv->recording_name);
+       else
+               snprintf(cp_command, sizeof(cp_command),
+                        "RECORDING %s PURGE ",
+                        priv->recording_name);
+
+       printk (KERN_DEBUG "vmlogrdr: recording command: %s\n", cp_command);
+       cpcmd(cp_command, cp_response, sizeof(cp_response));
+       printk (KERN_DEBUG "vmlogrdr: recording response: %s",
+               cp_response);
+
+       return count;
+}
+
+
+static DEVICE_ATTR(purge, 0200, NULL, vmlogrdr_purge_store);
+
+
+static ssize_t
+vmlogrdr_autorecording_store(struct device *dev, const char *buf,
+                            size_t count) {
+       struct vmlogrdr_priv_t *priv = dev->driver_data;
+       ssize_t ret = count;
+
+       switch (buf[0]) {
+       case '0':
+               priv->autorecording=0;
+               break;
+       case '1':
+               priv->autorecording=1;
+               break;
+       default:
+               ret = -EINVAL;
+       }
+       return ret;
+}
+
+
+static ssize_t
+vmlogrdr_autorecording_show(struct device *dev, char *buf) {
+       struct vmlogrdr_priv_t *priv = dev->driver_data;
+       return sprintf(buf, "%u\n", priv->autorecording);
+}
+
+
+static DEVICE_ATTR(autorecording, 0644, vmlogrdr_autorecording_show,
+                  vmlogrdr_autorecording_store);
+
+
+static ssize_t
+vmlogrdr_recording_store(struct device * dev, const char * buf, size_t count) {
+
+       struct vmlogrdr_priv_t *priv = dev->driver_data;
+       ssize_t ret;
+
+       switch (buf[0]) {
+       case '0':
+               ret = vmlogrdr_recording(priv,0,0);
+               break;
+       case '1':
+               ret = vmlogrdr_recording(priv,1,0);
+               break;
+       default:
+               ret = -EINVAL;
+       }
+       if (ret)
+               return ret;
+       else
+               return count;
+
+}
+
+
+static DEVICE_ATTR(recording, 0200, NULL, vmlogrdr_recording_store);
+
+
+static ssize_t
+vmlogrdr_recording_status_show(struct device_driver *driver, char *buf) {
+
+       char cp_command[] = "QUERY RECORDING ";
+       int len;
+
+       cpcmd(cp_command, buf, 4096);
+       len = strlen(buf);
+       return len;
+}
+
+
+static DRIVER_ATTR(recording_status, 0444, vmlogrdr_recording_status_show,
+                  NULL);
+
+static struct attribute *vmlogrdr_attrs[] = {
+       &dev_attr_autopurge.attr,
+       &dev_attr_purge.attr,
+       &dev_attr_autorecording.attr,
+       &dev_attr_recording.attr,
+       NULL,
+};
+
+static struct attribute_group vmlogrdr_attr_group = {
+       .attrs = vmlogrdr_attrs,
+};
+
+static struct class_simple *vmlogrdr_class;
+static struct device_driver vmlogrdr_driver = {
+       .name = "vmlogrdr",
+       .bus  = &iucv_bus,
+};
+
+
+static int
+vmlogrdr_register_driver(void) {
+       int ret;
+
+       ret = driver_register(&vmlogrdr_driver);
+       if (ret) {
+               printk(KERN_ERR "vmlogrdr: failed to register driver.\n");
+               return ret;
+       }
+
+       ret = driver_create_file(&vmlogrdr_driver,
+                                &driver_attr_recording_status);
+       if (ret) {
+               printk(KERN_ERR "vmlogrdr: failed to add driver attribute.\n");
+               goto unregdriver;
+       }
+
+       vmlogrdr_class = class_simple_create(THIS_MODULE, "vmlogrdr");
+       if (IS_ERR(vmlogrdr_class)) {
+               printk(KERN_ERR "vmlogrdr: failed to create class.\n");
+               ret=PTR_ERR(vmlogrdr_class);
+               vmlogrdr_class=NULL;
+               goto unregattr;
+       }
+       return 0;
+
+unregattr:
+       driver_remove_file(&vmlogrdr_driver, &driver_attr_recording_status);
+unregdriver:
+       driver_unregister(&vmlogrdr_driver);
+       return ret;
+}
+
+
+static void
+vmlogrdr_unregister_driver(void) {
+       class_simple_destroy(vmlogrdr_class);
+       vmlogrdr_class = NULL;
+       driver_remove_file(&vmlogrdr_driver, &driver_attr_recording_status);
+       driver_unregister(&vmlogrdr_driver);
+       return;
+}
+
+
+static int
+vmlogrdr_register_device(struct vmlogrdr_priv_t *priv) {
+       struct device *dev;
+       int ret;
+
+       dev = kmalloc(sizeof(struct device), GFP_KERNEL);
+       if (dev) {
+               memset(dev, 0, sizeof(struct device));
+               snprintf(dev->bus_id, BUS_ID_SIZE, "%s",
+                        priv->internal_name);
+               dev->bus = &iucv_bus;
+               dev->parent = iucv_root;
+               dev->driver = &vmlogrdr_driver;
+               /*
+                * The release function could be called after the
+                * module has been unloaded. It's _only_ task is to
+                * free the struct. Therefore, we specify kfree()
+                * directly here. (Probably a little bit obfuscating
+                * but legitime ...).
+                */
+               dev->release = (void (*)(struct device *))kfree;
+       } else
+               return -ENOMEM;
+       ret = device_register(dev);
+       if (ret)
+               return ret;
+
+       ret = sysfs_create_group(&dev->kobj, &vmlogrdr_attr_group);
+       if (ret) {
+               device_unregister(dev);
+               return ret;
+       }
+       priv->class_device = class_simple_device_add(
+                               vmlogrdr_class,
+                               MKDEV(vmlogrdr_major, priv->minor_num),
+                               dev,
+                               "%s", dev->bus_id );
+       if (IS_ERR(priv->class_device)) {
+               ret = PTR_ERR(priv->class_device);
+               priv->class_device=NULL;
+               sysfs_remove_group(&dev->kobj, &vmlogrdr_attr_group);
+               device_unregister(dev);
+               return ret;
+       }
+       dev->driver_data = priv;
+       priv->device = dev;
+       return 0;
+}
+
+
+static int
+vmlogrdr_unregister_device(struct vmlogrdr_priv_t *priv ) {
+       class_simple_device_remove(MKDEV(vmlogrdr_major, priv->minor_num));
+       if (priv->device != NULL) {
+               sysfs_remove_group(&priv->device->kobj, &vmlogrdr_attr_group);
+               device_unregister(priv->device);
+               priv->device=NULL;
+       }
+       return 0;
+}
+
+
+static int
+vmlogrdr_register_cdev(dev_t dev) {
+       int rc = 0;
+       vmlogrdr_cdev = cdev_alloc();
+       if (!vmlogrdr_cdev) {
+               return -ENOMEM;
+       }
+       vmlogrdr_cdev->owner = THIS_MODULE;
+       vmlogrdr_cdev->ops = &vmlogrdr_fops;
+       vmlogrdr_cdev->dev = dev;
+       rc = cdev_add(vmlogrdr_cdev, vmlogrdr_cdev->dev, MAXMINOR);
+       if (!rc)
+               return 0;
+
+       // cleanup: cdev is not fully registered, no cdev_del here!
+       kobject_put(&vmlogrdr_cdev->kobj);
+       vmlogrdr_cdev=NULL;
+       return rc;
+}
+
+
+static void
+vmlogrdr_cleanup(void) {
+        int i;
+       if (vmlogrdr_cdev) {
+               cdev_del(vmlogrdr_cdev);
+               vmlogrdr_cdev=NULL;
+       }
+       for (i=0; i < MAXMINOR; ++i ) {
+               vmlogrdr_unregister_device(&sys_ser[i]);
+               free_page((unsigned long)sys_ser[i].buffer);
+       }
+       vmlogrdr_unregister_driver();
+       if (vmlogrdr_major) {
+               unregister_chrdev_region(MKDEV(vmlogrdr_major, 0), MAXMINOR);
+               vmlogrdr_major=0;
+       }
+}
+
+
+static int
+vmlogrdr_init(void)
+{
+       int rc;
+       int i;
+       dev_t dev;
+
+       if (! MACHINE_IS_VM) {
+               printk (KERN_ERR "vmlogrdr: not running under VM, "
+                               "driver not loaded.\n");
+               return -ENODEV;
+       }
+
+        recording_class_AB = vmlogrdr_get_recording_class_AB();
+
+       rc = alloc_chrdev_region(&dev, 0, MAXMINOR, "vmlogrdr");
+       if (rc)
+               return rc;
+       vmlogrdr_major = MAJOR(dev);
+
+       rc=vmlogrdr_register_driver();
+       if (rc)
+               goto cleanup;
+
+       for (i=0; i < MAXMINOR; ++i ) {
+               sys_ser[i].buffer = (char *) get_zeroed_page(GFP_KERNEL);
+               if (!sys_ser[i].buffer) {
+                       rc = ENOMEM;
+                       break;
+               }
+               sys_ser[i].current_position = sys_ser[i].buffer;
+               rc=vmlogrdr_register_device(&sys_ser[i]);
+               if (rc)
+                       break;
+       }
+       if (rc)
+               goto cleanup;
+
+       rc = vmlogrdr_register_cdev(dev);
+       if (rc)
+               goto cleanup;
+       printk (KERN_INFO "vmlogrdr: driver loaded\n");
+       return 0;
+
+cleanup:
+       vmlogrdr_cleanup();
+       printk (KERN_ERR "vmlogrdr: driver not loaded.\n");
+       return rc;
+}
+
+
+static void
+vmlogrdr_exit(void)
+{
+       vmlogrdr_cleanup();
+       printk (KERN_INFO "vmlogrdr: driver unloaded\n");
+       return;
+}
+
+
+module_init(vmlogrdr_init);
+module_exit(vmlogrdr_exit);