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>

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 8c2d531..b157c48 100644 (file)
--- 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;
 }

diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 09a3e6a..655341d 100644 (file)
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -17,7 +17,8 @@
 #include <linux/mutex.h>
 
 #define SERIAL_TTY_MAJOR       188     /* Nice legal number now */
-#define SERIAL_TTY_MINORS      255     /* loads of devices :) */
+#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