USB: make usbdevices export their device nodes instead of using a separate class

o The "real" usb-devices export now a device node which can
  populate /dev/bus/usb.

o The usb_device class is optional now and can be disabled in the
  kernel config. Major/minor of the "real" devices and class devices
  are the same.

o The environment of the usb-device event contains DEVNUM and BUSNUM to
  help udev and get rid of the ugly udev rule we need for the class
  devices.

o The usb-devices and usb-interfaces share the same bus, so I used
  the new "struct device_type" to let these devices identify
  themselves. This also removes the current logic of using a magic
  platform-pointer.
  The name of the device_type is also added to the environment
  which makes it easier to distinguish the different kinds of devices
  on the same subsystem.

  It looks like this:
    add@/devices/pci0000:00/0000:00:1d.1/usb2/2-1
    ACTION=add
    DEVPATH=/devices/pci0000:00/0000:00:1d.1/usb2/2-1
    SUBSYSTEM=usb
    SEQNUM=1533
    MAJOR=189
    MINOR=131
    DEVTYPE=usb_device
    PRODUCT=46d/c03e/2000
    TYPE=0/0/0
    BUSNUM=002
    DEVNUM=004

This udev rule works as a replacement for usb_device class devices:
  SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", \
    NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}", MODE="0644"

Updated patch, which needs the device_type patches in Greg's tree.

I also got a bugzilla assigned for this. :)
  https://bugzilla.novell.com/show_bug.cgi?id=250659


Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 24 insertions, 1 deletions

diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
index 2fc0f88a3d8..f493fb1eaa2 100644
--- a/drivers/usb/core/Kconfig
+++ b/drivers/usb/core/Kconfig
@@ -31,7 +31,30 @@ config USB_DEVICEFS
 	  For the format of the various /proc/bus/usb/ files, please read
 	  <file:Documentation/usb/proc_usb_info.txt>.
 
-	  Most users want to say Y here.
+	  Usbfs files can't handle Access Control Lists (ACL), which are the
+	  default way to grant access to USB devices for untrusted users of a
+	  desktop system. The usbfs functionality is replaced by real
+	  device-nodes managed by udev. These nodes live in /dev/bus/usb and
+	  are used by libusb.
+
+config USB_DEVICE_CLASS
+	bool "USB device class-devices (DEPRECATED)"
+	depends on USB
+	default n
+	---help---
+	  Userspace access to USB devices is granted by device-nodes exported
+	  directly from the usbdev in sysfs. Old versions of the driver
+	  core and udev needed additional class devices to export device nodes.
+
+	  These additional devices are difficult to handle in userspace, if
+	  information about USB interfaces must be available. One device contains
+	  the device node, the other device contains the interface data. Both
+	  devices are at the same level in sysfs (siblings) and one can't access
+	  the other. The device node created directly by the usbdev is the parent
+	  device of the interface and therefore easily accessible from the interface
+	  event.
+
+	  This option provides backward compatibility if needed.
 
 config USB_DYNAMIC_MINORS
 	bool "Dynamic USB minor allocation (EXPERIMENTAL)"