Fix usb_serial_probe() problem introduced by the recent kfifo changes

The USB serial code was a new user of the kfifo API, and it was missed
when porting things to the new kfifo API.

Please make the write_fifo in place.  Here is my patch to fix the
regression and full ported version.
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Reported-and-tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/usb/serial/generic.c

@@ -276,7 +276,7 @@ static int usb_serial_generic_write_start(struct usb_serial_port *port)
 	if (port->write_urb_busy)
 		start_io = false;
 	else {
-		start_io = (kfifo_len(port->write_fifo) != 0);
+		start_io = (kfifo_len(&port->write_fifo) != 0);
 		port->write_urb_busy = start_io;
 	}
 	spin_unlock_irqrestore(&port->lock, flags);
@@ -285,7 +285,7 @@ static int usb_serial_generic_write_start(struct usb_serial_port *port)
 		return 0;
 
 	data = port->write_urb->transfer_buffer;
-	count = kfifo_out_locked(port->write_fifo, data, port->bulk_out_size, &port->lock);
+	count = kfifo_out_locked(&port->write_fifo, data, port->bulk_out_size, &port->lock);
 	usb_serial_debug_data(debug, &port->dev, __func__, count, data);
 
 	/* set up our urb */
@@ -345,7 +345,7 @@ int usb_serial_generic_write(struct tty_struct *tty,
 		return usb_serial_multi_urb_write(tty, port,
 						  buf, count);
 
-	count = kfifo_in_locked(port->write_fifo, buf, count, &port->lock);
+	count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);
 	result = usb_serial_generic_write_start(port);
 
 	if (result >= 0)
@@ -370,7 +370,7 @@ int usb_serial_generic_write_room(struct tty_struct *tty)
 				(serial->type->max_in_flight_urbs -
 				 port->urbs_in_flight);
 	} else if (serial->num_bulk_out)
-		room = port->write_fifo->size - kfifo_len(port->write_fifo);
+		room = kfifo_avail(&port->write_fifo);
 	spin_unlock_irqrestore(&port->lock, flags);
 
 	dbg("%s - returns %d", __func__, room);
@@ -391,7 +391,7 @@ int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
 		chars = port->tx_bytes_flight;
 		spin_unlock_irqrestore(&port->lock, flags);
 	} else if (serial->num_bulk_out)
-		chars = kfifo_len(port->write_fifo);
+		chars = kfifo_len(&port->write_fifo);
 
 	dbg("%s - returns %d", __func__, chars);
 	return chars;
@@ -507,7 +507,7 @@ void usb_serial_generic_write_bulk_callback(struct urb *urb)
 		if (status) {
 			dbg("%s - nonzero multi-urb write bulk status "
 				"received: %d", __func__, status);
-			kfifo_reset(port->write_fifo);
+			kfifo_reset_out(&port->write_fifo);
 		} else
 			usb_serial_generic_write_start(port);
 	}

drivers/usb/serial/usb-serial.c

@@ -595,8 +595,7 @@ static void port_release(struct device *dev)
 	usb_free_urb(port->write_urb);
 	usb_free_urb(port->interrupt_in_urb);
 	usb_free_urb(port->interrupt_out_urb);
-	if (!IS_ERR(port->write_fifo) && port->write_fifo)
-		kfifo_free(port->write_fifo);
+	kfifo_free(&port->write_fifo);
 	kfree(port->bulk_in_buffer);
 	kfree(port->bulk_out_buffer);
 	kfree(port->interrupt_in_buffer);
@@ -939,7 +938,7 @@ int usb_serial_probe(struct usb_interface *interface,
 			dev_err(&interface->dev, "No free urbs available\n");
 			goto probe_error;
 		}
-		if (kfifo_alloc(port->write_fifo, PAGE_SIZE, GFP_KERNEL))
+		if (kfifo_alloc(&port->write_fifo, PAGE_SIZE, GFP_KERNEL))
 			goto probe_error;
 		buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 		port->bulk_out_size = buffer_size;

include/linux/usb/serial.h

@@ -16,6 +16,7 @@
 #include <linux/kref.h>
 #include <linux/mutex.h>
 #include <linux/sysrq.h>
+#include <linux/kfifo.h>
 
 #define SERIAL_TTY_MAJOR	188	/* Nice legal number now */
 #define SERIAL_TTY_MINORS	254	/* loads of devices :) */
@@ -94,7 +95,7 @@ struct usb_serial_port {
 	unsigned char		*bulk_out_buffer;
 	int			bulk_out_size;
 	struct urb		*write_urb;
-	struct kfifo		*write_fifo;
+	struct kfifo		write_fifo;
 	int			write_urb_busy;
 	__u8			bulk_out_endpointAddress;