Re: Flaw in the driver-model implementation of attributes

From: Greg KH (
Date: Mon Jun 16 2003 - 18:36:51 EST

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.


greg k-h
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