Hi Adil,
On Wed, Oct 6, 2010 at 5:30 AM, Adil Mujeeb <mujeeb.adil@xxxxxxxxx> wrote:
> Hi list,
>
> I am trying to create a dummy module for learning purpose. For “hello
> world” example, everything goes fine. But when I tried to add
> register_filesystem and unregister_filesystem call the behavior is
> unexpected. I am not able to unload my module.
>
> My module has single file named rkfs_mod.c:
>
> [adil@tom kernel]$ cat rkfs_mod.c
> #include <linux/module.h>
> #include <linux/fs.h>
>
> static struct super_block *rkfs_get_sb(struct file_system_type *fs_type,
> int flags, char *dev_name, void *raw_data)
> {
> printk("get_sb call\n");
> return NULL;
> }
>
> static void rkfs_kill_sb(struct super_block *s)
> {
> printk("kill sb \n");
> return;
> }
>
> static struct file_system_type rkfs = {
> name: "rkfs_mod",
> get_sb: rkfs_get_sb,
> kill_sb: rkfs_kill_sb,
> owner: THIS_MODULE
> };
>
> int init_module(void) {
> int err;
> printk("Registering the filesystem\n");
> err = register_filesystem( &rkfs );
> return err;
> }
>
> void exit_module(void){
> printk("Unregisterign the filesystem\n");
> unregister_filesystem(&rkfs);
> }
> [adil@tom kernel]$
>
> My Makefile contents:
>
> [adil@tom kernel]$ cat Makefile
> obj-m += rkfs_mod.o
> all:
> make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
> clean :
> make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
> [adil@tom kernel]$
>
> [adil@tom kernel]$ uname -a
> Linux tom.HCLTECH 2.6.30 #1 SMP Thu Dec 17 16:45:24 IST 2009 i686 i686
> i386 GNU/Linux
> [adil@tom kernel]$
>
> Module loading is successful but unloading fails.
>
> [root@tom linux-2.6.30]# /sbin/lsmod | grep rkfs
> rkfs_mod 1452 0 [permanent]
The [permanent] tag indicates that the module has no module_exit, and
thus can't be unloaded.
--
Dave Hylands
Shuswap, BC, Canada
http://www.DaveHylands.com/
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