Re: lockdep whine in 2.6.26-rc2-mm1

[Greg KH <greg@kroah.com>]

On Tue, May 20, 2008 at 09:27:59AM +0800, Dave Young wrote:
> On Mon, May 19, 2008 at 6:23 PM, Matthew Wilcox <matthew@wil.cx> wrote:
> > On Mon, May 19, 2008 at 01:20:33PM +0800, Dave Young wrote:
> >> On Sat, May 17, 2008 at 6:14 PM, Dave Young <hidave.darkstar@gmail.com> wrote:
> >> > On 5/15/08, Matthew Wilcox <matthew@wil.cx> wrote:
> >> >> On Thu, May 15, 2008 at 05:01:01PM +0800, Dave Young wrote:
> >> >>> > The classes are different here, first sdev_class, then sg_sysfs_class
> >> >>
> >> >> Oh ... right.  I misread scsi_register_interface as
> >> >> class_register_interface.
> >> >>
> >> >>> Greg, what about using mutex_lock_nested to silence lockdep? They are
> >> >>> the only usage of class->mutex out of class.c
> >> >>
> >> >> I don't see how we prove that, for example, you can never take the
> >> >> sg_sysfs_class mutex and then take the sdev_class mutex.
> >> >
> >> > Sorry for my delay. AFAIK, there's no this kind of use.
> >
> > The question isn't whether there is or isn't this kind of use right now.
> > The question is whether there might be this kind of use in the future,
> > and if there is, whether we'd like lockdep to warn us.
> 
> In the future, IMHO, the class_interface should go away just as
> class_device. If that happened this problem would going away as well.

Patches gladly accepted to do this, but what you will end up with is
something just called a different name, yet doing the same
functionality, so you are back at square one :(

thanks,

greg k-h