usb-serial: don't release unregistered minors

This patch (as1121) fixes a bug in the USB serial core.  When a device
is unregistered, the core will give back its minors -- even if the
device hasn't been assigned any!

The patch reserves the highest minor value (255) to mean that no minor
was assigned.  It also removes some dead code and does a small style
fixup.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 4 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 8c2d531eedea..b157c48e8b78 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -122,9 +122,6 @@ static void return_serial(struct usb_serial *serial)
 
         dbg("%s", __func__);
 
-        if (serial == NULL)
-                return;
-
         for (i = 0; i < serial->num_ports; ++i)
                 serial_table[serial->minor + i] = NULL;
 }
@@ -142,7 +139,8 @@ static void destroy_serial(struct kref *kref)
         serial->type->shutdown(serial);
 
         /* return the minor range that this device had */
-        return_serial(serial);
+        if (serial->minor != SERIAL_TTY_NO_MINOR)
+                return_serial(serial);
 
         for (i = 0; i < serial->num_ports; ++i)
                 serial->port[i]->port.count = 0;
@@ -575,6 +573,7 @@ static struct usb_serial *create_serial(struct usb_device *dev,
         serial->interface = interface;
         kref_init(&serial->kref);
         mutex_init(&serial->disc_mutex);
+        serial->minor = SERIAL_TTY_NO_MINOR;
 
         return serial;
 }