usb-serial: don't release unregistered minors

commit 0282b7f2a874e72c18fcd5a112ccf67f71ba7f5c upstream

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>
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 2138ba8aeb697b2e35ee04d5e62e6f008bdb0c47..ec7b96b655a163b23e903357e4a74e7035d3ca1d 100644 (file)
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -119,9 +119,6 @@ static void return_serial(struct usb_serial *serial)
 
        dbg("%s", __FUNCTION__);
 
-       if (serial == NULL)
-               return;
-
        for (i = 0; i < serial->num_ports; ++i) {
                serial_table[serial->minor + i] = NULL;
        }
@@ -140,7 +137,8 @@ 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]->open_count = 0;
@@ -635,6 +633,7 @@ 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 21b4a1c6f5851f9c92998694afd0171602af880b..e6f623de35ffc066767863d1e15f1e675a5cba1d 100644 (file)
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -18,7 +18,8 @@
 #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