Re: Flaw in the driver-model implementation of attributes

[Greg KH <greg@kroah.com>]

On Mon, Jun 16, 2003 at 05:29:00PM -0400, Alan Stern wrote:
> On Mon, 16 Jun 2003, Patrick Mochel wrote:
> 
> > > This doesn't provide any really good place to put device attributes that 
> > > are owned by the driver.  They can't go in
> > > 	/sysfs/class/pcmcia_socket/pcmcia_socket0/device/...
> > > because the driver doesn't own the device.  They can't go in
> > > 	/sysfs/class/pcmcia_socket/pcmcia_socket0/driver/...
> > > because they aren't attributes of the _driver_, they're attributes of the 
> > > _device_.  And they certainly aren't class attributes.
> > > 
> > > So where would you put them?  You'd have to create another subdirectory of
> > > 	/sysfs/class/pcmcia_socket/pcmcia_socket0/
> > > owned by the driver.  No really good name for this subdirectory spings 
> > > to mind, and it's still kind of awkward.  But doable.
> > 
> > What is wrong with putting them in 
> > 
> > /sysfs/class/pcmcia_socket/pcmcia_socket0/
> > 
> > ? The driver owns that object. And, if it is device-specific feature, then 
> > it is likely related to what class the device belongs to, and is therefore 
> > relevant for that directory.
> 
> Are you sure?  Suppose a pcmcia disk drive is plugged in to that socket.  
> Why is a disk driver going to name its object "pcmcia_socket0"?  It must
> be the pcmcia socket driver that owns the object, not the disk driver.  So 
> then where does the disk driver put the disk-related attributes?  Don't 
> say in /sys/class/pcmcia_socket/pcmcia_socket0/device/, because the driver 
> doesn't own that object either.

All disk info is in the /sys/block directory, does that work for you?

> Anyway, in my case it's a USB device.  At the moment /sys/class/usb
> doesn't contain anything AFAICT, although no doubt that can be changed.

It will contain things if you have a device that uses the USB major
plugged in.

> Greg, what is the current organization of directories for USB buses and 
> devices?  Would it make sense to let each driver register its devices as
> /sys/class/usb/bus#/dev#/ ?  Would that better be done under /sys/bus/usb 
> ?  Or is something else already there?  Or should the usb-storage driver, 
> for example, create its own class?

I think the scsi core will create you a directory that you can use that
will have the proper lifetime that you are looking for.  If not, I can
look into doing something else for some of the other USB devices that
are not using the USB major.

thanks,

greg k-h