USB: serial: make minor allocation dynamic

This moves the allocation of minor device numbers from a static array to
be dynamic, using the idr interface.  This means that you could
potentially get "gaps" in a minor number range for a single USB serial
device with multiple ports, but all should still work properly.

We remove the 'minor' field from the usb_serial structure, as it no
longer makes any sense for it (use the field in the usb_serial_port
structure if you really want to know this number), and take the fact
that we were overloading a number in this field to determine if we had
initialized the minor numbers or not, and just use a flag variable
instead.

Note, we still have the limitation of 255 USB to serial devices in the
system, as that is all we are registering with the TTY layer at this
point in time.

Tested-by: Tobias Winter <tobias@linuxdingsda.de>
Reviewed-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 3fa68b615ac1..9254c80a1cf8 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -21,7 +21,6 @@
 
 #define SERIAL_TTY_MAJOR        188     /* Nice legal number now */
 #define SERIAL_TTY_MINORS       254     /* loads of devices :) */
-#define SERIAL_TTY_NO_MINOR     255     /* No minor was assigned */
 
 /* The maximum number of ports one device can grab at once */
 #define MAX_NUM_PORTS           8
@@ -142,7 +141,6 @@ static inline void usb_set_serial_port_data(struct usb_serial_port *port,
  * @dev: pointer to the struct usb_device for this device
  * @type: pointer to the struct usb_serial_driver for this device
  * @interface: pointer to the struct usb_interface for this device
- * @minor: the starting minor number for this device
  * @num_ports: the number of ports this device has
  * @num_interrupt_in: number of interrupt in endpoints we have
  * @num_interrupt_out: number of interrupt out endpoints we have
@@ -161,7 +159,7 @@ struct usb_serial {
         unsigned char                   disconnected:1;
         unsigned char                   suspending:1;
         unsigned char                   attached:1;
-        unsigned char                   minor;
+        unsigned char                   minors_reserved:1;
         unsigned char                   num_ports;
         unsigned char                   num_port_pointers;
         char                            num_interrupt_in;
@@ -321,7 +319,7 @@ static inline void usb_serial_console_disconnect(struct usb_serial *serial) {}
 #endif
 
 /* Functions needed by other parts of the usbserial core */
-extern struct usb_serial *usb_serial_get_by_index(unsigned int minor);
+extern struct usb_serial_port *usb_serial_port_get_by_minor(unsigned int minor);
 extern void usb_serial_put(struct usb_serial *serial);
 extern int usb_serial_generic_open(struct tty_struct *tty,
         struct usb_serial_port *port);