read/write file_operation problem

ashok449 · 02-28-2008, 07:40 AM

Dear All,

I have a character driver compiled successfully but giving problem while reading/writting oprations.

Here is the code

Code:

struct a_sample
{
        char *buffer;
 };


static ssize_t device_read(struct file *flip, char *buff,size_t length,loff_t *offset)
{

struct a_sample *dev = flip->private_data;


 if(copy_to_user (buff,dev->buffer,sizeof(dev->buffer)))
               return -EFAULT;

printk("read data-----> %s\n", buff);

return 100;
}



static ssize_t device_write (struct file *flip, const char *buff, size_t len, loff_t *off)
{  
struct a_sample *dev = flip->private_data;
 
        if(copy_from_user(dev->buffer,buff,len))
        {
                return -EFAULT;
        }


printk("written data is = %s\n", buff);

 return len;

}

mknod /dev/sampl1 c 243 0

Issues:
1. while writting echo "test" > /dev/sampl1 terminal was closed/exit
2. on reading showing error segmentation fault.

Thanks in advance ...

ashok449 · 02-29-2008, 03:28 AM

This Issue is closed, there was a problem in my structure and allocation of kernel memory.

Thanks ...