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>

9 files changed, 183 insertions, 115 deletions

diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
index 2fc0f88a3d86..f493fb1eaa27 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)"
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index fc3545ddb06e..e023f3d56248 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -57,7 +57,6 @@
 
 #define USB_MAXBUS                      64
 #define USB_DEVICE_MAX                  USB_MAXBUS * 128
-static struct class *usb_device_class;
 
 /* Mutual exclusion for removal, open, and release */
 DEFINE_MUTEX(usbfs_mutex);
@@ -514,22 +513,25 @@ static int check_ctrlrecip(struct dev_state *ps, unsigned int requesttype, unsig
         return ret;
 }
 
-static struct usb_device *usbdev_lookup_minor(int minor)
+static int __match_minor(struct device *dev, void *data)
 {
-        struct device *device;
-        struct usb_device *udev = NULL;
+        int minor = *((int *)data);
 
-        down(&usb_device_class->sem);
-        list_for_each_entry(device, &usb_device_class->devices, node) {
-                if (device->devt == MKDEV(USB_DEVICE_MAJOR, minor)) {
-                        udev = device->platform_data;
-                        break;
-                }
-        }
-        up(&usb_device_class->sem);
+        if (dev->devt == MKDEV(USB_DEVICE_MAJOR, minor))
+                return 1;
+        return 0;
+}
 
-        return udev;
-};
+static struct usb_device *usbdev_lookup_by_minor(int minor)
+{
+        struct device *dev;
+
+        dev = bus_find_device(&usb_bus_type, NULL, &minor, __match_minor);
+        if (!dev)
+                return NULL;
+        put_device(dev);
+        return container_of(dev, struct usb_device, dev);
+}
 
 /*
  * file operations
@@ -548,11 +550,14 @@ static int usbdev_open(struct inode *inode, struct file *file)
                 goto out;
 
         ret = -ENOENT;
-        /* check if we are called from a real node or usbfs */
+        /* usbdev device-node */
         if (imajor(inode) == USB_DEVICE_MAJOR)
-                dev = usbdev_lookup_minor(iminor(inode));
+                dev = usbdev_lookup_by_minor(iminor(inode));
+#ifdef CONFIG_USB_DEVICEFS
+        /* procfs file */
         if (!dev)
                 dev = inode->i_private;
+#endif
         if (!dev)
                 goto out;
         ret = usb_autoresume_device(dev);
@@ -1570,7 +1575,7 @@ static unsigned int usbdev_poll(struct file *file, struct poll_table_struct *wai
         return mask;
 }
 
-const struct file_operations usbfs_device_file_operations = {
+const struct file_operations usbdev_file_operations = {
         .llseek =       usbdev_lseek,
         .read =         usbdev_read,
         .poll =         usbdev_poll,
@@ -1579,50 +1584,53 @@ const struct file_operations usbfs_device_file_operations = {
         .release =      usbdev_release,
 };
 
-static int usbdev_add(struct usb_device *dev)
+#ifdef CONFIG_USB_DEVICE_CLASS
+static struct class *usb_classdev_class;
+
+static int usb_classdev_add(struct usb_device *dev)
 {
         int minor = ((dev->bus->busnum-1) * 128) + (dev->devnum-1);
 
-        dev->usbfs_dev = device_create(usb_device_class, &dev->dev,
+        dev->usb_classdev = device_create(usb_classdev_class, &dev->dev,
                                 MKDEV(USB_DEVICE_MAJOR, minor),
                                 "usbdev%d.%d", dev->bus->busnum, dev->devnum);
-        if (IS_ERR(dev->usbfs_dev))
-                return PTR_ERR(dev->usbfs_dev);
+        if (IS_ERR(dev->usb_classdev))
+                return PTR_ERR(dev->usb_classdev);
 
-        dev->usbfs_dev->platform_data = dev;
         return 0;
 }
 
-static void usbdev_remove(struct usb_device *dev)
+static void usb_classdev_remove(struct usb_device *dev)
 {
-        device_unregister(dev->usbfs_dev);
+        device_unregister(dev->usb_classdev);
 }
 
-static int usbdev_notify(struct notifier_block *self, unsigned long action,
-                         void *dev)
+static int usb_classdev_notify(struct notifier_block *self,
+                               unsigned long action, void *dev)
 {
         switch (action) {
         case USB_DEVICE_ADD:
-                if (usbdev_add(dev))
+                if (usb_classdev_add(dev))
                         return NOTIFY_BAD;
                 break;
         case USB_DEVICE_REMOVE:
-                usbdev_remove(dev);
+                usb_classdev_remove(dev);
                 break;
         }