Hi,
I am sorry, i need to make a small correction. I am returning 1 in open
when the segmentation faul occurs. If the return value is 0 it doesnt.
Sorry for the mistake.
On Fri, 9 Sep 2005, Vijay Ram Chitrapu (RCVIJAYD) wrote:
> Hi all,
> I have a query regarding the file descriptor obtained from the open
> call. I have written a dummy driver code which has open, ioclt and release
> file operations to it. In the open, i am returning 0. In the user space
> when i open the device , i get an fd as 3. When i perform an ioctl with
> the same fd to the device, a segmentation fault of NULL pointer derefence
> is thrown. I have tried return 1 in the open and everything worked well.
> Can anyone please tell me in what way is the return value of open related
> to the file descriptor.
> The code is below for reference..
>
> static struct file_operations this_fops = {
> open:this_open,
> ioctl:this_ioctl,
> release:this_release,
> };
>
> int this_open (struct inode *ino, struct file *fp)
> {
> printk("<1> in open");
> return 0;
> }
>
> int this_ioctl(struct inode * ino, struct file *fp, unsigned int cmd,
> unsigned long len)
> {
> printk("<1> in ioctl function);
> return 1;
> }
>
>
>
> Thanks In Advance
> Vijay Ram.C
>
>
>
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