### Hi, my comments all begin with "###".
I am trying to run the following code
#define __KERNEL__ /* We're part of the kernel */
#define MODULE /* Not a permanent part, though. */
#include <linux/modversions.h>
#include <linux/param.h>
#include <asm/system.h>
#include <linux/errno.h>
#include <linux/ioctl.h>
#include <linux/tty.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/wrapper.h> /* header for unregister */
#include <linux/fs.h> /* file types */
#include <asm/io.h>
#include <linux/types.h> /* for ssize_t */
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <asm/errno.h>
#include <asm/unistd.h>
#include <sys/syscall.h>
#ifndef min
#define min(a,b) (((a) <(b)) ? (a) : (b))
#endif
#define SAMP_LEN 20
struct samp2_buf
{
char *buffer;
/*
char *buffer,*end;
int buffersize;
char *rp,*wp;
*/
};
static int samp2_open(struct inode *inode, struct file *file)
{
console_print(" Exiting open \n ");
return 0;
}
### What kernel version are you using?
### I get warnings (important ones) when I compile this
### on 2.4.18. You should get rid of those warnings.
### When did read/write file_operations have a first parameter
### of struct inode * ? They don't in 2.4.18 or back in 2.4.2.
### open() and release() do, but read() and write() don't.
### That alone would cause serious errors in those functions.
static int samp2_release(struct inode *inode, struct file *file)
{
//MOD_DEC_USE_COUNT;
console_print(" Exiting Release \n ");
return 0;
}
int samp2_read(struct inode *inode, struct file *fp, char *buff,int count)
{
### read(): wrong function parameters.
struct samp2_buf *dev = fp->private_data;
char *buf;
int len;
console_print("In read \n ");
if(copy_to_user (buff,dev->buffer,sizeof(dev->buffer)))
return -EFAULT;
//dev->buffer = "\0";
return sizeof(dev->buffer);
}
ssize_t samp2_write(struct inode *inode,struct file *fp,char *buf,ssize_t
count)
{
### write: wrong function parameters.
struct samp2_buf *dev = (struct samp2_buf *)fp ->private_data;
printk(KERN_CRIT "\n I AM IN WRITE ..............");
//dev->buffer = (unsigned char *)kmalloc(SAMP_LEN,GFP_KERNEL);
if(count > SAMP_LEN)
{
count = SAMP_LEN;
}
if(copy_from_user(dev->buffer,buf,count))
{
return -EFAULT;
}
dev->buffer[count] = '\0';
console_print("In write \n ");
printk(KERN_CRIT "\n I AM IN END of WRITE ..............");
return count;
}
static struct file_operations samp2_fops =
{
NULL, /* seek */
samp2_read,
samp2_write, /* write*/
NULL, /* readdir */
NULL, /* select */
NULL, /* ioctl */
NULL, /* mmap */
samp2_open, /* open */
NULL,
samp2_release, /* release */
NULL,
NULL,
};
### This struct file_operations doesn't match what's in
### my kernel source files. And you really should use the
### "field: value" initializer construct, as in:
### read: samp2_read,
### etc.
int init_module(void)
{
int ret;
ret = register_chrdev(84,"samp2",&samp2_fops);
if(ret == 0)
{
console_print("<0> Device registered <0>");
}
else
{
console_print(" Device not registered ");
}
return 0;
}
void cleanup_module(void)
{
if(MOD_IN_USE)
{
console_print(" Driver in use ");
return;
}
unregister_chrdev(84,"samp2");
console_print(" <0> Driver Unregistered <0> ");
}
I am compiling this code with
gcc -D__KERNEL__ -DMODULE -DMODVERSIONS -DLINUX
-I/usr/src/linux-2.4B/include -O6 -Wall -c samp.c
### kernel is usually compiled with "-O2", not -O6.
But when ever i run a sample test program on this the write and read
always return a -1.
### Why do you say that it's a copy_from_user() problem?
### Does the sample program print errno?
### Where is the sample program?
### ~Randy
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This archive was generated by hypermail 2b29 : Sun Apr 07 2002 - 22:00:18 EST