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Date: Tue, 28 Jan 2003 20:56:33 -0800 (PST)
From: Dhruv Gami <dhruvgami@yahoo.com>
Subject: module programming blues
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Hello Everyone,

I am trying to develop a kernel module that will read
some user input (being given to a file) and perform
certain flag settings based on the information dumped
in the file.

After reading up on the basics of kernel programming
etc (im a newbie), i wrote a code that creates a
character device, and uses ioctl to read and write
from the file kept in user space.

I got sample code from The Linux Kernel Module
Programming Guide by Ori Pomerantz. In chapter 5, it
talks about talking to character devices.

I am able to compile the code, and insmod my module.
The problem is that the function device_open is not
being called on accessing it. It calls device_release
TWICE, and thus reduces  reference count by 2, taking
the count in negatives. That way im unable to rmmod
this module. 

Also, I am not able to figure out how to interact with
this module. If i cat something onto it, it goes into
an infinite loop echo'ing the file again n again.

If i do "/dev/char_dev < params" where /dev/char_dev
is the device i made using mknod(and giving major
number returned by my module), it gives an error
saying Permission Denied.

Can somebody tell me what i'm doing wrong ? Or give me
some pointers to text that can explain how things work
in a module. I dont know how control flows within a
module once init_module has been called.

Kindly CC replies to dhruvgami@yahoo.com as i am not
subscribed to the list.

thanks in advance
regards,
Gami

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