BUG: 'Unknown symbol in module' happens after reloading ehci-hcd module

BUG: 'Unknown symbol in module' happens after reloading ehci-hcd module

[Ming Lei]

Hi,

'Unknown symbol in module'  happens after the actions below:

         rmmod ehci-hcd
         modprobe ehci-hcd

kernel version: 2.6.35-rc6+gregkh tree+wireless tree

dmsg info:
[  689.025428] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[  689.025431] Warning! ehci_hcd should always be loaded before
uhci_hcd and ohci_hcd, not after
[  689.025434] ehci_hcd: block sizes: qh 104 qtd 96 itd 192 sitd 96

>From source code of ehci-hcd, seems debugfs_create_dir or usb_debug_root
in ehci_hcd_init is thought as unknown symbol mistakenly by kernel.

-- 
Lei Ming

Re: BUG: 'Unknown symbol in module' happens after reloading ehci-hcd module

[Ming Lei]

2010/7/28 Ming Lei <tom.leiming@gmail.com>:
> Hi,
>
> 'Unknown symbol in module'  happens after the actions below:
>
>         rmmod ehci-hcd
>         modprobe ehci-hcd
>

The issue is caused by returning failure of debugfs_create_dir, and
which may be fixed by replacing debugfs_remove with
debugfs_remove_recursive in ehci_hcd_cleanup.

Why does insmod show 'Unknown symbol in module'  when module .init
return -ENOENT?  The message does make us confused.

-- 
Lei Ming

Re: BUG: 'Unknown symbol in module' happens after reloading ehci-hcd module

[Greg KH]

On Wed, Jul 28, 2010 at 03:33:30PM +0800, Ming Lei wrote:
> 2010/7/28 Ming Lei <tom.leiming@gmail.com>:
> > Hi,
> >
> > 'Unknown symbol in module' ?happens after the actions below:
> >
> > ? ? ? ? rmmod ehci-hcd
> > ? ? ? ? modprobe ehci-hcd
> >
> 
> The issue is caused by returning failure of debugfs_create_dir, and
> which may be fixed by replacing debugfs_remove with
> debugfs_remove_recursive in ehci_hcd_cleanup.

Or we can properly clean up all of the files, right?

Care to send a patch to resolve this?

thanks,

greg k-h

Re: BUG: 'Unknown symbol in module' happens after reloading ehci-hcd module

[Ming Lei]

2010/7/28 Greg KH <greg@kroah.com>:
> On Wed, Jul 28, 2010 at 03:33:30PM +0800, Ming Lei wrote:
>> 2010/7/28 Ming Lei <tom.leiming@gmail.com>:
>> > Hi,
>> >
>> > 'Unknown symbol in module' ?happens after the actions below:
>> >
>> > ? ? ? ? rmmod ehci-hcd
>> > ? ? ? ? modprobe ehci-hcd
>> >
>>
>> The issue is caused by returning failure of debugfs_create_dir, and
>> which may be fixed by replacing debugfs_remove with
>> debugfs_remove_recursive in ehci_hcd_cleanup.
>
> Or we can properly clean up all of the files, right?
>
> Care to send a patch to resolve this?

Sent, follows the patch's title:

           USB: ehci: fix remove of ehci debugfs dir

thanks,

-- 
Lei Ming