USB: serial core should respect driver requirements

This patch (as997) fixes a bug in the USB serial core.  The core needs
to pay attention to drivers' requirements regarding the number and
type of endpoints a device has.

At the same time, the patch changes the NUM_DONT_CARE constant (which
is stored in a single-byte field) from -1 to a safer, unsigned value.
It also improves the kerneldoc for several fields in the
usb_serial_driver structure.

Finally, the patch replaces a list_for_each() with list_for_each_entry().

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

2 files changed, 35 insertions, 16 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 26e015c39a31..4b1bd7def4a5 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -662,16 +662,14 @@ exit:
 
 static struct usb_serial_driver *search_serial_device(struct usb_interface *iface)
 {
-        struct list_head *p;
         const struct usb_device_id *id;
-        struct usb_serial_driver *t;
+        struct usb_serial_driver *drv;
 
         /* Check if the usb id matches a known device */
-        list_for_each(p, &usb_serial_driver_list) {
-                t = list_entry(p, struct usb_serial_driver, driver_list);
-                id = get_iface_id(t, iface);
+        list_for_each_entry(drv, &usb_serial_driver_list, driver_list) {
+                id = get_iface_id(drv, iface);
                 if (id)
-                        return t;
+                        return drv;
         }
 
         return NULL;
@@ -811,9 +809,6 @@ int usb_serial_probe(struct usb_interface *interface,
         /* END HORRIBLE HACK FOR PL2303 */
 #endif
 
-        /* found all that we need */
-        dev_info(&interface->dev, "%s converter detected\n", type->description);
-
 #ifdef CONFIG_USB_SERIAL_GENERIC
         if (type == &usb_serial_generic_device) {
                 num_ports = num_bulk_out;
@@ -847,6 +842,24 @@ int usb_serial_probe(struct usb_interface *interface,
         serial->num_interrupt_in = num_interrupt_in;
         serial->num_interrupt_out = num_interrupt_out;
 
+        /* check that the device meets the driver's requirements */
+        if ((type->num_interrupt_in != NUM_DONT_CARE &&
+                                type->num_interrupt_in != num_interrupt_in)
+                        || (type->num_interrupt_out != NUM_DONT_CARE &&
+                                type->num_interrupt_out != num_interrupt_out)
+                        || (type->num_bulk_in != NUM_DONT_CARE &&
+                                type->num_bulk_in != num_bulk_in)
+                        || (type->num_bulk_out != NUM_DONT_CARE &&
+                                type->num_bulk_out != num_bulk_out)) {
+                dbg("wrong number of endpoints");
+                kfree(serial);
+                return -EIO;
+        }
+
+        /* found all that we need */
+        dev_info(&interface->dev, "%s converter detected\n",
+                        type->description);
+
         /* create our ports, we need as many as the max endpoints */
         /* we don't use num_ports here cauz some devices have more endpoint pairs than ports */
         max_endpoints = max(num_bulk_in, num_bulk_out);
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index e8b8928232c8..488ce128885c 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -141,7 +141,7 @@ struct usb_serial {
 };
 #define to_usb_serial(d) container_of(d, struct usb_serial, kref)
 
-#define NUM_DONT_CARE   (-1)
+#define NUM_DONT_CARE   99
 
 /* get and set the serial private data pointer helper functions */
 static inline void *usb_get_serial_data (struct usb_serial *serial)
@@ -160,12 +160,18 @@ static inline void usb_set_serial_data (struct usb_serial *serial, void *data)
  *      in the syslog messages when a device is inserted or removed.
  * @id_table: pointer to a list of usb_device_id structures that define all
  *      of the devices this structure can support.
- * @num_interrupt_in: the number of interrupt in endpoints this device will
- *      have.
- * @num_interrupt_out: the number of interrupt out endpoints this device will
- *      have.
- * @num_bulk_in: the number of bulk in endpoints this device will have.
- * @num_bulk_out: the number of bulk out endpoints this device will have.
+ * @num_interrupt_in: If a device doesn't have this many interrupt-in
+ *      endpoints, it won't be sent to the driver's attach() method.
+ *      (But it might still be sent to the probe() method.)
+ * @num_interrupt_out: If a device doesn't have this many interrupt-out
+ *      endpoints, it won't be sent to the driver's attach() method.
+ *      (But it might still be sent to the probe() method.)
+ * @num_bulk_in: If a device doesn't have this many bulk-in
+ *      endpoints, it won't be sent to the driver's attach() method.
+ *      (But it might still be sent to the probe() method.)
+ * @num_bulk_out: If a device doesn't have this many bulk-out
+ *      endpoints, it won't be sent to the driver's attach() method.
+ *      (But it might still be sent to the probe() method.)
  * @num_ports: the number of different ports this device will have.
  * @calc_num_ports: pointer to a function to determine how many ports this
  *      device has dynamically.  It will be called after the probe()