mos7720 update

this driver has an interesting way of handling ENOMEM: complain and ignore.
If you decide to live with allocation failures, you must

1. guard against URBs without corresponding buffers
2. complete allocation failures
3. always test entries for NULL before you follow the pointers

This patch does so.
Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/mos7720.c

@@ -333,6 +333,7 @@ static int mos7720_open(struct usb_serial_port *port, struct file * filp)
 	int response;
 	int port_number;
 	char data;
+	int allocated_urbs = 0;
 	int j;
 
 	serial = port->serial;
@@ -365,10 +366,16 @@ static int mos7720_open(struct usb_serial_port *port, struct file * filp)
 					       GFP_KERNEL);
 		if (!urb->transfer_buffer) {
 			err("%s-out of memory for urb buffers.", __FUNCTION__);
+			usb_free_urb(mos7720_port->write_urb_pool[j]);
+			mos7720_port->write_urb_pool[j] = NULL;
 			continue;
 		}
+		allocated_urbs++;
 	}
 
+	if (!allocated_urbs)
+		return -ENOMEM;
+
 	 /* Initialize MCS7720 -- Write Init values to corresponding Registers
 	  *
 	  * Register Index
@@ -526,7 +533,7 @@ static int mos7720_chars_in_buffer(struct usb_serial_port *port)
 	}
 
 	for (i = 0; i < NUM_URBS; ++i) {
-		if (mos7720_port->write_urb_pool[i]->status == -EINPROGRESS)
+		if (mos7720_port->write_urb_pool[i] && mos7720_port->write_urb_pool[i]->status == -EINPROGRESS)
 			chars += URB_TRANSFER_BUFFER_SIZE;
 	}
 	dbg("%s - returns %d", __FUNCTION__, chars);
@@ -629,7 +636,7 @@ static int mos7720_write_room(struct usb_serial_port *port)
 	}
 
 	for (i = 0; i < NUM_URBS; ++i) {
-		if (mos7720_port->write_urb_pool[i]->status != -EINPROGRESS)
+		if (mos7720_port->write_urb_pool[i] && mos7720_port->write_urb_pool[i]->status != -EINPROGRESS)
 			room += URB_TRANSFER_BUFFER_SIZE;
 	}
 
@@ -664,7 +671,7 @@ static int mos7720_write(struct usb_serial_port *port,
 	urb = NULL;
 
 	for (i = 0; i < NUM_URBS; ++i) {
-		if (mos7720_port->write_urb_pool[i]->status != -EINPROGRESS) {
+		if (mos7720_port->write_urb_pool[i] && mos7720_port->write_urb_pool[i]->status != -EINPROGRESS) {
 			urb = mos7720_port->write_urb_pool[i];
 			dbg("URB:%d",i);
 			break;