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 db1db4cfc62e4f94b5dc750b91798fc1953e2008..38034e2bdd885d01a2be44a3dfefeb369aead041 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", __func__);
 
-       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;
@@ -562,6 +560,7 @@ 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 8f891cbaf9abd497f990e5ae68eabb8d2ae99971..4a6583d95a8eb2cfc1f1427a920ab7a85d66c9ed 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