vmlogrdr.c

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/*
 * drivers/s390/char/vmlogrdr.c
 *	character device driver for reading z/VM system service records
 *
 *
 *	Copyright 2004 IBM Corporation
 *	character device driver for reading z/VM system service records,
 *	Version 1.0
 *	Author(s): Xenia Tkatschow <[e-mail]>
 *		   Stefan Weinhuber <[e-mail]>
 *
 */
#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/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 ([e-mail])\n"
	 "                            Stefan Weinhuber ([e-mail])");
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];
	struct iucv_path *path;
	int connection_established;
	int iucv_path_severed;
	struct iucv_message local_interrupt_buffer;
	atomic_t receive_ready;
	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 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 __user *data,
			      size_t count, loff_t * ppos);

static const struct file_operations vmlogrdr_fops = {
	.owner   = THIS_MODULE,
	.open    = vmlogrdr_open,
	.release = vmlogrdr_release,
	.read    = vmlogrdr_read,
};


static void vmlogrdr_iucv_path_complete(struct iucv_path *, u8 ipuser[16]);
static void vmlogrdr_iucv_path_severed(struct iucv_path *, u8 ipuser[16]);
static void vmlogrdr_iucv_message_pending(struct iucv_path *,
					  struct iucv_message *);


static struct iucv_handler vmlogrdr_iucv_handler = {
	.path_complete	 = vmlogrdr_iucv_path_complete,
	.path_severed	 = vmlogrdr_iucv_path_severed,
	.message_pending = vmlogrdr_iucv_message_pending,
};


static DECLARE_WAIT_QUEUE_HEAD(conn_wait_queue);
static 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(sys_ser[0].priv_lock),
	  .autorecording  = 1,
	  .autopurge      = 1,
	},
	{ .system_service = "*ACCOUNT",
	  .internal_name  = "account",
	  .recording_name = "ACCOUNT",
	  .minor_num      = 1,
	  .buffer_free    = 1,
	  .priv_lock	  = __SPIN_LOCK_UNLOCKED(sys_ser[1].priv_lock),
	  .autorecording  = 1,
	  .autopurge      = 1,
	},
	{ .system_service = "*SYMPTOM",
	  .internal_name  = "symptom",
	  .recording_name = "SYMPTOM",
	  .minor_num      = 2,
	  .buffer_free    = 1,
	  .priv_lock	  = __SPIN_LOCK_UNLOCKED(sys_ser[2].priv_lock),
	  .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_path_complete(struct iucv_path *path, u8 ipuser[16])
{
	struct vmlogrdr_priv_t * logptr = path->private;

	spin_lock(&logptr->priv_lock);
	logptr->connection_established = 1;
	spin_unlock(&logptr->priv_lock);
	wake_up(&conn_wait_queue);
}


static void vmlogrdr_iucv_path_severed(struct iucv_path *path, u8 ipuser[16])
{
	struct vmlogrdr_priv_t * logptr = path->private;
	u8 reason = (u8) ipuser[8];

	printk (KERN_ERR "vmlogrdr: connection severed with"
		" reason %i\n", reason);

	iucv_path_sever(path, NULL);
	kfree(path);
	logptr->path = NULL;

	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_message_pending(struct iucv_path *path,
					  struct iucv_message *msg)
{
	struct vmlogrdr_priv_t * logptr = path->private;

	/*
	 * 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, msg, sizeof(*msg));
	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), NULL);
	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), NULL);
		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), NULL);
	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];

	/*
	 * 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;
	}
	logptr->dev_in_use = 1;
	logptr->connection_established = 0;
	logptr->iucv_path_severed = 0;
	atomic_set(&logptr->receive_ready, 0);
	logptr->buffer_free = 1;
	spin_unlock_bh(&logptr->priv_lock);

	/* set the file options */
	filp->private_data = logptr;
	filp->f_op = &vmlogrdr_fops;

	/* start recording for this service*/
	if (logptr->autorecording) {
		ret = vmlogrdr_recording(logptr,1,logptr->autopurge);
		if (ret)
			printk (KERN_WARNING "vmlogrdr: failed to start "
				"recording automatically\n");
	}

	/* create connection to the system service */
	logptr->path = iucv_path_alloc(10, 0, GFP_KERNEL);
	if (!logptr->path)
		goto out_dev;
	connect_rc = iucv_path_connect(logptr->path, &vmlogrdr_iucv_handler,
				       logptr->system_service, NULL, NULL,
				       logptr);
	if (connect_rc) {
		printk (KERN_ERR "vmlogrdr: iucv connection to %s "
			"failed with rc %i \n", logptr->system_service,
			connect_rc);
		goto out_path;
	}

	/* 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 out_record;
 	return nonseekable_open(inode, filp);

out_record:
	if (logptr->autorecording)
		vmlogrdr_recording(logptr,0,logptr->autopurge);
out_path:
	kfree(logptr->path);	/* kfree(NULL) is ok. */
	logptr->path = NULL;
out_dev:
	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_path_sever(logptr->path, NULL);
	kfree(logptr->path);
	logptr->path = 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.length;
			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_message_receive(priv->path,
					  &priv->local_interrupt_buffer,
					  0, buffer, iucv_data_count,
					  &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)