[PATCH] s390: z/VM log reader

Add an interface to read from the z/VM recording system services.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/s390/defconfig

@@ -222,6 +222,7 @@ CONFIG_S390_TAPE_BLOCK=y
 # S/390 tape hardware support
 #
 CONFIG_S390_TAPE_34XX=m
+# CONFIG_VMLOGRDR is not set
 
 #
 # Cryptographic devices

drivers/s390/Kconfig

@@ -176,6 +176,17 @@ config S390_TAPE_34XX
 	  tape subsystems and 100% compatibles.
 	  It is safe to say "Y" here.
 
+
+
+config VMLOGRDR
+	tristate "Support for the z/VM recording system services (VM only)"
+	depends on IUCV
+	help
+	  Select this option if you want to be able to receive records collected
+	  by the z/VM recording system services, eg. from *LOGREC, *ACCOUNT or
+	  *SYMPTOM.
+	  This driver depends on the IUCV support driver.
+
 endmenu
 
 menu "Cryptographic devices"

drivers/s390/char/Makefile

@@ -18,6 +18,7 @@ obj-$(CONFIG_SCLP_VT220_TTY) += sclp_vt220.o
 obj-$(CONFIG_SCLP_CPI) += sclp_cpi.o
 
 obj-$(CONFIG_ZVM_WATCHDOG) += vmwatchdog.o
+obj-$(CONFIG_VMLOGRDR) += vmlogrdr.o
 
 tape-$(CONFIG_S390_TAPE_BLOCK) += tape_block.o
 tape-$(CONFIG_PROC_FS) += tape_proc.o

drivers/s390/char/vmlogrdr.c

+/*
+ * 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);