drivers/isdn/hysdn/hysdn_proclog.c - third_party/linux - Git at Google

 /* $Id: hysdn_proclog.c,v 1.9.6.3 2001/09/23 22:24:54 kai Exp $
  *
  * Linux driver for HYSDN cards, /proc/net filesystem log functions.
  *
  * Author    Werner Cornelius (werner@titro.de) for Hypercope GmbH
  * Copyright 1999 by Werner Cornelius (werner@titro.de)
  *
  * This software may be used and distributed according to the terms
  * of the GNU General Public License, incorporated herein by reference.
  *
  */

 #include <linux/module.h>
 #include <linux/poll.h>
 #include <linux/proc_fs.h>
 #include <linux/smp_lock.h>

 #include "hysdn_defs.h"

 /* the proc subdir for the interface is defined in the procconf module */
 extern struct proc_dir_entry *hysdn_proc_entry;

 static void put_log_buffer(hysdn_card * card, char *cp);

 /*************************************************/
 /* structure keeping ascii log for device output */
 /*************************************************/
 struct log_data {
 	struct log_data *next;
 	unsigned long usage_cnt;/* number of files still to work */
 	void *proc_ctrl;	/* pointer to own control procdata structure */
 	char log_start[2];	/* log string start (final len aligned by size) */
 };

 /**********************************************/
 /* structure holding proc entrys for one card */
 /**********************************************/
 struct procdata {
 	struct proc_dir_entry *log;	/* log entry */
 	char log_name[15];	/* log filename */
 	struct log_data *log_head, *log_tail;	/* head and tail for queue */
 	int if_used;		/* open count for interface */
 	int volatile del_lock;	/* lock for delete operations */
 	unsigned char logtmp[LOG_MAX_LINELEN];
 	wait_queue_head_t rd_queue;
 };


 /**********************************************/
 /* log function for cards error log interface */
 /**********************************************/
 void
 hysdn_card_errlog(hysdn_card * card, tErrLogEntry * logp, int maxsize)
 {
 	char buf[ERRLOG_TEXT_SIZE + 40];

 	sprintf(buf, "LOG 0x%08lX 0x%08lX : %s\n", logp->ulErrType, logp->ulErrSubtype, logp->ucText);
 	put_log_buffer(card, buf);	/* output the string */
 }				/* hysdn_card_errlog */

 /***************************************************/
 /* Log function using format specifiers for output */
 /***************************************************/
 void
 hysdn_addlog(hysdn_card * card, char *fmt,...)
 {
 	struct procdata *pd = card->proclog;
 	char *cp;
 	va_list args;

 	if (!pd)
 		return;		/* log structure non existent */

 	cp = pd->logtmp;
 	cp += sprintf(cp, "HYSDN: card %d ", card->myid);

 	va_start(args, fmt);
 	cp += vsprintf(cp, fmt, args);
 	va_end(args);
 	*cp++ = '\n';
 	*cp = 0;

 	if (card->debug_flags & DEB_OUT_SYSLOG)
 		printk(KERN_INFO "%s", pd->logtmp);
 	else
 		put_log_buffer(card, pd->logtmp);

 }				/* hysdn_addlog */

 /********************************************/
 /* put an log buffer into the log queue.    */
 /* This buffer will be kept until all files */
 /* opened for read got the contents.        */
 /* Flushes buffers not longer in use.       */
 /********************************************/
 static void
 put_log_buffer(hysdn_card * card, char *cp)
 {
 	struct log_data *ib;
 	struct procdata *pd = card->proclog;
 	int i;
 	unsigned long flags;

 	if (!pd)
 		return;
 	if (!cp)
 		return;
 	if (!*cp)
 		return;
 	if (pd->if_used <= 0)
 		return;		/* no open file for read */

 	if (!(ib = kmalloc(sizeof(struct log_data) + strlen(cp), GFP_ATOMIC)))
 		 return;	/* no memory */
 	strcpy(ib->log_start, cp);	/* set output string */
 	ib->next = NULL;
 	ib->proc_ctrl = pd;	/* point to own control structure */
 	spin_lock_irqsave(&card->hysdn_lock, flags);
 	ib->usage_cnt = pd->if_used;
 	if (!pd->log_head)
 		pd->log_head = ib;	/* new head */
 	else
 		pd->log_tail->next = ib;	/* follows existing messages */
 	pd->log_tail = ib;	/* new tail */
 	i = pd->del_lock++;	/* get lock state */
 	spin_unlock_irqrestore(&card->hysdn_lock, flags);

 	/* delete old entrys */
 	if (!i)
 		while (pd->log_head->next) {
 			if ((pd->log_head->usage_cnt <= 0) &&
 			    (pd->log_head->next->usage_cnt <= 0)) {
 				ib = pd->log_head;
 				pd->log_head = pd->log_head->next;
 				kfree(ib);
 			} else
 				break;
 		}		/* pd->log_head->next */
 	pd->del_lock--;		/* release lock level */
 	wake_up_interruptible(&(pd->rd_queue));		/* announce new entry */
 }				/* put_log_buffer */


 /******************************/
 /* file operations and tables */
 /******************************/

 /****************************************/
 /* write log file -> set log level bits */
 /****************************************/
 static ssize_t
 hysdn_log_write(struct file *file, const char __user *buf, size_t count, loff_t * off)
 {
 	unsigned long u = 0;
 	int found = 0;
 	unsigned char *cp, valbuf[128];
 	long base = 10;
 	hysdn_card *card = (hysdn_card *) file->private_data;

 	if (count > (sizeof(valbuf) - 1))
 		count = sizeof(valbuf) - 1;	/* limit length */
 	if (copy_from_user(valbuf, buf, count))
 		return (-EFAULT);	/* copy failed */

 	valbuf[count] = 0;	/* terminating 0 */
 	cp = valbuf;
 	if ((count > 2) && (valbuf[0] == '0') && (valbuf[1] == 'x')) {
 		cp += 2;	/* pointer after hex modifier */
 		base = 16;
 	}
 	/* scan the input for debug flags */
 	while (*cp) {
 		if ((*cp >= '0') && (*cp <= '9')) {
 			found = 1;
 			u *= base;	/* adjust to next digit */
 			u += *cp++ - '0';
 			continue;
 		}
 		if (base != 16)
 			break;	/* end of number */

 		if ((*cp >= 'a') && (*cp <= 'f')) {
 			found = 1;
 			u *= base;	/* adjust to next digit */
 			u += *cp++ - 'a' + 10;
 			continue;
 		}
 		break;		/* terminated */
 	}

 	if (found) {
 		card->debug_flags = u;	/* remember debug flags */
 		hysdn_addlog(card, "debug set to 0x%lx", card->debug_flags);
 	}
 	return (count);
 }				/* hysdn_log_write */

 /******************/
 /* read log file */
 /******************/
 static ssize_t
 hysdn_log_read(struct file *file, char __user *buf, size_t count, loff_t * off)
 {
 	struct log_data *inf;
 	int len;
 	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 	struct procdata *pd = NULL;
 	hysdn_card *card;

 	if (!*((struct log_data **) file->private_data)) {
 		if (file->f_flags & O_NONBLOCK)
 			return (-EAGAIN);

 		/* sorry, but we need to search the card */
 		card = card_root;
 		while (card) {
 			pd = card->proclog;
 			if (pd->log == pde)
 				break;
 			card = card->next;	/* search next entry */
 		}
 		if (card)
 			interruptible_sleep_on(&(pd->rd_queue));
 		else
 			return (-EAGAIN);

 	}
 	if (!(inf = *((struct log_data **) file->private_data)))
 		return (0);

 	inf->usage_cnt--;	/* new usage count */
 	file->private_data = &inf->next;	/* next structure */
 	if ((len = strlen(inf->log_start)) <= count) {
 		if (copy_to_user(buf, inf->log_start, len))
 			return -EFAULT;
 		*off += len;
 		return (len);
 	}
 	return (0);
 }				/* hysdn_log_read */

 /******************/
 /* open log file */
 /******************/
 static int
 hysdn_log_open(struct inode *ino, struct file *filep)
 {
 	hysdn_card *card;
 	struct procdata *pd = NULL;
 	unsigned long flags;

 	lock_kernel();
 	card = card_root;
 	while (card) {
 		pd = card->proclog;
 		if (pd->log == PDE(ino))
 			break;
 		card = card->next;	/* search next entry */
 	}
 	if (!card) {
 		unlock_kernel();
 		return (-ENODEV);	/* device is unknown/invalid */
 	}
 	filep->private_data = card;	/* remember our own card */

 	if ((filep->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_WRITE) {
 		/* write only access -> write log level only */
 	} else if ((filep->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {

 		/* read access -> log/debug read */
 		spin_lock_irqsave(&card->hysdn_lock, flags);
 		pd->if_used++;
 		if (pd->log_head)
 			filep->private_data = &pd->log_tail->next;
 		else
 			filep->private_data = &pd->log_head;
 		spin_unlock_irqrestore(&card->hysdn_lock, flags);
 	} else {		/* simultaneous read/write access forbidden ! */
 		unlock_kernel();
 		return (-EPERM);	/* no permission this time */
 	}
 	unlock_kernel();
 	return nonseekable_open(ino, filep);
 }				/* hysdn_log_open */

 /*******************************************************************************/
 /* close a cardlog file. If the file has been opened for exclusive write it is */
 /* assumed as pof data input and the pof loader is noticed about.              */
 /* Otherwise file is handled as log output. In this case the interface usage   */
 /* count is decremented and all buffers are noticed of closing. If this file   */
 /* was the last one to be closed, all buffers are freed.                       */
 /*******************************************************************************/
 static int
 hysdn_log_close(struct inode *ino, struct file *filep)
 {
 	struct log_data *inf;
 	struct procdata *pd;
 	hysdn_card *card;
 	int retval = 0;

 	lock_kernel();
 	if ((filep->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_WRITE) {
 		/* write only access -> write debug level written */
 		retval = 0;	/* success */
 	} else {
 		/* read access -> log/debug read, mark one further file as closed */

 		pd = NULL;
 		inf = *((struct log_data **) filep->private_data);	/* get first log entry */
 		if (inf)
 			pd = (struct procdata *) inf->proc_ctrl;	/* still entries there */
 		else {
 			/* no info available -> search card */
 			card = card_root;
 			while (card) {
 				pd = card->proclog;
 				if (pd->log == PDE(ino))
 					break;
 				card = card->next;	/* search next entry */
 			}
 			if (card)
 				pd = card->proclog;	/* pointer to procfs log */
 		}
 		if (pd)
 			pd->if_used--;	/* decrement interface usage count by one */

 		while (inf) {
 			inf->usage_cnt--;	/* decrement usage count for buffers */
 			inf = inf->next;
 		}

 		if (pd)
 			if (pd->if_used <= 0)	/* delete buffers if last file closed */
 				while (pd->log_head) {
 					inf = pd->log_head;
 					pd->log_head = pd->log_head->next;
 					kfree(inf);
 				}
 	}			/* read access */
 	unlock_kernel();

 	return (retval);
 }				/* hysdn_log_close */

 /*************************************************/
 /* select/poll routine to be able using select() */
 /*************************************************/
 static unsigned int
 hysdn_log_poll(struct file *file, poll_table * wait)
 {
 	unsigned int mask = 0;
 	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 	hysdn_card *card;
 	struct procdata *pd = NULL;

 	if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_WRITE)
 		return (mask);	/* no polling for write supported */

 	/* we need to search the card */
 	card = card_root;
 	while (card) {
 		pd = card->proclog;
 		if (pd->log == pde)
 			break;
 		card = card->next;	/* search next entry */
 	}
 	if (!card)
 		return (mask);	/* card not found */

 	poll_wait(file, &(pd->rd_queue), wait);

 	if (*((struct log_data **) file->private_data))
 		mask |= POLLIN | POLLRDNORM;

 	return mask;
 }				/* hysdn_log_poll */

 /**************************************************/
 /* table for log filesystem functions defined above. */
 /**************************************************/
 static const struct file_operations log_fops =
 {
 	.llseek         = no_llseek,
 	.read           = hysdn_log_read,
 	.write          = hysdn_log_write,
 	.poll           = hysdn_log_poll,
 	.open           = hysdn_log_open,
 	.release        = hysdn_log_close,
 };


 /***********************************************************************************/
 /* hysdn_proclog_init is called when the module is loaded after creating the cards */
 /* conf files.                                                                     */
 /***********************************************************************************/
 int
 hysdn_proclog_init(hysdn_card * card)
 {
 	struct procdata *pd;

 	/* create a cardlog proc entry */

 	if ((pd = kzalloc(sizeof(struct procdata), GFP_KERNEL)) != NULL) {
 		sprintf(pd->log_name, "%s%d", PROC_LOG_BASENAME, card->myid);
 		if ((pd->log = create_proc_entry(pd->log_name, S_IFREG | S_IRUGO | S_IWUSR, hysdn_proc_entry)) != NULL) {
 		        pd->log->proc_fops = &log_fops;
 		        pd->log->owner = THIS_MODULE;
 		}

 		init_waitqueue_head(&(pd->rd_queue));

 		card->proclog = (void *) pd;	/* remember procfs structure */
 	}
 	return (0);
 }				/* hysdn_proclog_init */

 /************************************************************************************/
 /* hysdn_proclog_release is called when the module is unloaded and before the cards */
 /* conf file is released                                                            */
 /* The module counter is assumed to be 0 !                                          */
 /************************************************************************************/
 void
 hysdn_proclog_release(hysdn_card * card)
 {
 	struct procdata *pd;

 	if ((pd = (struct procdata *) card->proclog) != NULL) {
 		if (pd->log)
 			remove_proc_entry(pd->log_name, hysdn_proc_entry);
 		kfree(pd);	/* release memory */
 		card->proclog = NULL;
 	}
 }				/* hysdn_proclog_release */
	/* $Id: hysdn_proclog.c,v 1.9.6.3 2001/09/23 22:24:54 kai Exp $
	*
	* Linux driver for HYSDN cards, /proc/net filesystem log functions.
	*
	* Author Werner Cornelius (werner@titro.de) for Hypercope GmbH
	* Copyright 1999 by Werner Cornelius (werner@titro.de)
	*
	* This software may be used and distributed according to the terms
	* of the GNU General Public License, incorporated herein by reference.
	*
	*/

	#include <linux/module.h>
	#include <linux/poll.h>
	#include <linux/proc_fs.h>
	#include <linux/smp_lock.h>

	#include "hysdn_defs.h"

	/* the proc subdir for the interface is defined in the procconf module */
	extern struct proc_dir_entry *hysdn_proc_entry;

	static void put_log_buffer(hysdn_card * card, char *cp);

	/*************************************************/
	/* structure keeping ascii log for device output */
	/*************************************************/
	struct log_data {
	struct log_data *next;
	unsigned long usage_cnt;/* number of files still to work */
	void proc_ctrl; / pointer to own control procdata structure */
	char log_start[2]; /* log string start (final len aligned by size) */
	};

	/**********************************************/
	/* structure holding proc entrys for one card */
	/**********************************************/
	struct procdata {
	struct proc_dir_entry log; / log entry */
	char log_name[15]; /* log filename */
	struct log_data log_head, log_tail; /* head and tail for queue */
	int if_used; /* open count for interface */
	int volatile del_lock; /* lock for delete operations */
	unsigned char logtmp[LOG_MAX_LINELEN];
	wait_queue_head_t rd_queue;
	};


	/**********************************************/
	/* log function for cards error log interface */
	/**********************************************/
	void
	hysdn_card_errlog(hysdn_card * card, tErrLogEntry * logp, int maxsize)
	{
	char buf[ERRLOG_TEXT_SIZE + 40];

	sprintf(buf, "LOG 0x%08lX 0x%08lX : %s\n", logp->ulErrType, logp->ulErrSubtype, logp->ucText);
	put_log_buffer(card, buf); /* output the string */
	} /* hysdn_card_errlog */

	/***************************************************/
	/* Log function using format specifiers for output */
	/***************************************************/
	void
	hysdn_addlog(hysdn_card * card, char *fmt,...)
	{
	struct procdata *pd = card->proclog;
	char *cp;
	va_list args;

	if (!pd)
	return; /* log structure non existent */

	cp = pd->logtmp;
	cp += sprintf(cp, "HYSDN: card %d ", card->myid);

	va_start(args, fmt);
	cp += vsprintf(cp, fmt, args);
	va_end(args);
	*cp++ = '\n';
	*cp = 0;

	if (card->debug_flags & DEB_OUT_SYSLOG)
	printk(KERN_INFO "%s", pd->logtmp);
	else
	put_log_buffer(card, pd->logtmp);

	} /* hysdn_addlog */

	/********************************************/
	/* put an log buffer into the log queue. */
	/* This buffer will be kept until all files */
	/* opened for read got the contents. */
	/* Flushes buffers not longer in use. */
	/********************************************/
	static void
	put_log_buffer(hysdn_card * card, char *cp)
	{
	struct log_data *ib;
	struct procdata *pd = card->proclog;
	int i;
	unsigned long flags;

	if (!pd)
	return;
	if (!cp)
	return;
	if (!*cp)
	return;
	if (pd->if_used <= 0)
	return; /* no open file for read */

	if (!(ib = kmalloc(sizeof(struct log_data) + strlen(cp), GFP_ATOMIC)))
	return; /* no memory */
	strcpy(ib->log_start, cp); /* set output string */
	ib->next = NULL;
	ib->proc_ctrl = pd; /* point to own control structure */
	spin_lock_irqsave(&card->hysdn_lock, flags);
	ib->usage_cnt = pd->if_used;
	if (!pd->log_head)
	pd->log_head = ib; /* new head */
	else
	pd->log_tail->next = ib; /* follows existing messages */
	pd->log_tail = ib; /* new tail */
	i = pd->del_lock++; /* get lock state */
	spin_unlock_irqrestore(&card->hysdn_lock, flags);

	/* delete old entrys */
	if (!i)
	while (pd->log_head->next) {
	if ((pd->log_head->usage_cnt <= 0) &&
	(pd->log_head->next->usage_cnt <= 0)) {
	ib = pd->log_head;
	pd->log_head = pd->log_head->next;
	kfree(ib);
	} else
	break;
	} /* pd->log_head->next */
	pd->del_lock--; /* release lock level */
	wake_up_interruptible(&(pd->rd_queue)); /* announce new entry */
	} /* put_log_buffer */


	/******************************/
	/* file operations and tables */
	/******************************/

	/****************************************/
	/* write log file -> set log level bits */
	/****************************************/
	static ssize_t
	hysdn_log_write(struct file file, const char __user buf, size_t count, loff_t * off)
	{
	unsigned long u = 0;
	int found = 0;
	unsigned char *cp, valbuf[128];
	long base = 10;
	hysdn_card card = (hysdn_card ) file->private_data;

	if (count > (sizeof(valbuf) - 1))
	count = sizeof(valbuf) - 1; /* limit length */
	if (copy_from_user(valbuf, buf, count))
	return (-EFAULT); /* copy failed */

	valbuf[count] = 0; /* terminating 0 */
	cp = valbuf;
	if ((count > 2) && (valbuf[0] == '0') && (valbuf[1] == 'x')) {
	cp += 2; /* pointer after hex modifier */
	base = 16;
	}
	/* scan the input for debug flags */
	while (*cp) {
	if ((cp >= '0') && (cp <= '9')) {
	found = 1;
	u = base; / adjust to next digit */
	u += *cp++ - '0';
	continue;
	}
	if (base != 16)
	break; /* end of number */

	if ((cp >= 'a') && (cp <= 'f')) {
	found = 1;
	u = base; / adjust to next digit */
	u += *cp++ - 'a' + 10;
	continue;
	}
	break; /* terminated */
	}

	if (found) {
	card->debug_flags = u; /* remember debug flags */
	hysdn_addlog(card, "debug set to 0x%lx", card->debug_flags);
	}
	return (count);
	} /* hysdn_log_write */

	/******************/
	/* read log file */
	/******************/
	static ssize_t
	hysdn_log_read(struct file file, char __user buf, size_t count, loff_t * off)
	{
	struct log_data *inf;
	int len;
	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	struct procdata *pd = NULL;
	hysdn_card *card;

	if (!((struct log_data *) file->private_data)) {
	if (file->f_flags & O_NONBLOCK)
	return (-EAGAIN);

	/* sorry, but we need to search the card */
	card = card_root;
	while (card) {
	pd = card->proclog;
	if (pd->log == pde)
	break;
	card = card->next; /* search next entry */
	}
	if (card)
	interruptible_sleep_on(&(pd->rd_queue));
	else
	return (-EAGAIN);

	}
	if (!(inf = ((struct log_data *) file->private_data)))
	return (0);

	inf->usage_cnt--; /* new usage count */
	file->private_data = &inf->next; /* next structure */
	if ((len = strlen(inf->log_start)) <= count) {
	if (copy_to_user(buf, inf->log_start, len))
	return -EFAULT;
	*off += len;
	return (len);
	}
	return (0);
	} /* hysdn_log_read */

	/******************/
	/* open log file */
	/******************/
	static int
	hysdn_log_open(struct inode ino, struct file filep)
	{
	hysdn_card *card;
	struct procdata *pd = NULL;
	unsigned long flags;

	lock_kernel();
	card = card_root;
	while (card) {
	pd = card->proclog;
	if (pd->log == PDE(ino))
	break;
	card = card->next; /* search next entry */
	}
	if (!card) {
	unlock_kernel();
	return (-ENODEV); /* device is unknown/invalid */
	}
	filep->private_data = card; /* remember our own card */

	if ((filep->f_mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_WRITE) {
	/* write only access -> write log level only */
	} else if ((filep->f_mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_READ) {

	/* read access -> log/debug read */
	spin_lock_irqsave(&card->hysdn_lock, flags);
	pd->if_used++;
	if (pd->log_head)
	filep->private_data = &pd->log_tail->next;
	else
	filep->private_data = &pd->log_head;
	spin_unlock_irqrestore(&card->hysdn_lock, flags);
	} else { /* simultaneous read/write access forbidden ! */
	unlock_kernel();
	return (-EPERM); /* no permission this time */
	}
	unlock_kernel();
	return nonseekable_open(ino, filep);
	} /* hysdn_log_open */

	/*******************************************************************************/
	/* close a cardlog file. If the file has been opened for exclusive write it is */
	/* assumed as pof data input and the pof loader is noticed about. */
	/* Otherwise file is handled as log output. In this case the interface usage */
	/* count is decremented and all buffers are noticed of closing. If this file */
	/* was the last one to be closed, all buffers are freed. */
	/*******************************************************************************/
	static int
	hysdn_log_close(struct inode ino, struct file filep)
	{
	struct log_data *inf;
	struct procdata *pd;
	hysdn_card *card;
	int retval = 0;

	lock_kernel();
	if ((filep->f_mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_WRITE) {
	/* write only access -> write debug level written */
	retval = 0; /* success */
	} else {
	/* read access -> log/debug read, mark one further file as closed */

	pd = NULL;
	inf = ((struct log_data ) filep->private_data); / get first log entry */
	if (inf)
	pd = (struct procdata ) inf->proc_ctrl; / still entries there */
	else {
	/* no info available -> search card */
	card = card_root;
	while (card) {
	pd = card->proclog;
	if (pd->log == PDE(ino))
	break;
	card = card->next; /* search next entry */
	}
	if (card)
	pd = card->proclog; /* pointer to procfs log */
	}
	if (pd)
	pd->if_used--; /* decrement interface usage count by one */

	while (inf) {
	inf->usage_cnt--; /* decrement usage count for buffers */
	inf = inf->next;
	}

	if (pd)
	if (pd->if_used <= 0) /* delete buffers if last file closed */
	while (pd->log_head) {
	inf = pd->log_head;
	pd->log_head = pd->log_head->next;
	kfree(inf);
	}
	} /* read access */
	unlock_kernel();

	return (retval);
	} /* hysdn_log_close */

	/*************************************************/
	/* select/poll routine to be able using select() */
	/*************************************************/
	static unsigned int
	hysdn_log_poll(struct file file, poll_table wait)
	{
	unsigned int mask = 0;
	struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
	hysdn_card *card;
	struct procdata *pd = NULL;

	if ((file->f_mode & (FMODE_READ \| FMODE_WRITE)) == FMODE_WRITE)
	return (mask); /* no polling for write supported */

	/* we need to search the card */
	card = card_root;
	while (card) {
	pd = card->proclog;
	if (pd->log == pde)
	break;
	card = card->next; /* search next entry */
	}
	if (!card)
	return (mask); /* card not found */

	poll_wait(file, &(pd->rd_queue), wait);

	if (((struct log_data *) file->private_data))
	mask \|= POLLIN \| POLLRDNORM;

	return mask;
	} /* hysdn_log_poll */

	/**************************************************/
	/* table for log filesystem functions defined above. */
	/**************************************************/
	static const struct file_operations log_fops =
	{
	.llseek = no_llseek,
	.read = hysdn_log_read,
	.write = hysdn_log_write,
	.poll = hysdn_log_poll,
	.open = hysdn_log_open,
	.release = hysdn_log_close,
	};


	/***********************************************************************************/
	/* hysdn_proclog_init is called when the module is loaded after creating the cards */
	/* conf files. */
	/***********************************************************************************/
	int
	hysdn_proclog_init(hysdn_card * card)
	{
	struct procdata *pd;

	/* create a cardlog proc entry */

	if ((pd = kzalloc(sizeof(struct procdata), GFP_KERNEL)) != NULL) {
	sprintf(pd->log_name, "%s%d", PROC_LOG_BASENAME, card->myid);
	if ((pd->log = create_proc_entry(pd->log_name, S_IFREG \| S_IRUGO \| S_IWUSR, hysdn_proc_entry)) != NULL) {
	pd->log->proc_fops = &log_fops;
	pd->log->owner = THIS_MODULE;
	}

	init_waitqueue_head(&(pd->rd_queue));

	card->proclog = (void ) pd; / remember procfs structure */
	}
	return (0);
	} /* hysdn_proclog_init */

	/************************************************************************************/
	/* hysdn_proclog_release is called when the module is unloaded and before the cards */
	/* conf file is released */
	/* The module counter is assumed to be 0 ! */
	/************************************************************************************/
	void
	hysdn_proclog_release(hysdn_card * card)
	{
	struct procdata *pd;

	if ((pd = (struct procdata *) card->proclog) != NULL) {
	if (pd->log)
	remove_proc_entry(pd->log_name, hysdn_proc_entry);
	kfree(pd); /* release memory */
	card->proclog = NULL;
	}
	} /* hysdn_proclog_release */