From 1abdeeb1d566f74bc5b3e68447d91c8c37d47942 Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.de>
Date: Mon, 7 May 2007 12:09:33 +0200
Subject: [PATCH] USB: generic usb serial to new buffering scheme

the generic driver also had its own buffering.

Signed-off-by: Oliver Neukum <oneukum@suse.de_
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 drivers/usb/serial/generic.c | 69 ++++++++++++++++++------------------
 1 file changed, 34 insertions(+), 35 deletions(-)

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index b90ef3f70f..b09bed4b77 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -281,45 +281,54 @@ int usb_serial_generic_chars_in_buffer (struct usb_serial_port *port)
 	return (chars);
 }
 
-/* Push data to tty layer and resubmit the bulk read URB */
-static void flush_and_resubmit_read_urb (struct usb_serial_port *port)
+
+static void resubmit_read_urb(struct usb_serial_port *port, gfp_t mem_flags)
 {
-	struct usb_serial *serial = port->serial;
 	struct urb *urb = port->read_urb;
-	struct tty_struct *tty = port->tty;
+	struct usb_serial *serial = port->serial;
 	int result;
 
-	/* Push data to tty */
-	if (tty && urb->actual_length) {
-		tty_buffer_request_room(tty, urb->actual_length);
-		tty_insert_flip_string(tty, urb->transfer_buffer, urb->actual_length);
-	  	tty_flip_buffer_push(tty); /* is this allowed from an URB callback ? */
-	}
-
 	/* Continue reading from device */
-	usb_fill_bulk_urb (port->read_urb, serial->dev,
+	usb_fill_bulk_urb (urb, serial->dev,
 			   usb_rcvbulkpipe (serial->dev,
 				   	    port->bulk_in_endpointAddress),
-			   port->read_urb->transfer_buffer,
-			   port->read_urb->transfer_buffer_length,
+			   urb->transfer_buffer,
+			   urb->transfer_buffer_length,
 			   ((serial->type->read_bulk_callback) ? 
 			     serial->type->read_bulk_callback : 
 			     usb_serial_generic_read_bulk_callback), port);
-	result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
+	result = usb_submit_urb(urb, mem_flags);
 	if (result)
 		dev_err(&port->dev, "%s - failed resubmitting read urb, error %d\n", __FUNCTION__, result);
 }
 
+/* Push data to tty layer and resubmit the bulk read URB */
+static void flush_and_resubmit_read_urb (struct usb_serial_port *port)
+{
+	struct urb *urb = port->read_urb;
+	struct tty_struct *tty = port->tty;
+	int room;
+
+	/* Push data to tty */
+	if (tty && urb->actual_length) {
+		room = tty_buffer_request_room(tty, urb->actual_length);
+		if (room) {
+			tty_insert_flip_string(tty, urb->transfer_buffer, room);
+			tty_flip_buffer_push(tty); /* is this allowed from an URB callback ? */
+		}
+	}
+
+	resubmit_read_urb(port, GFP_ATOMIC);
+}
+
 void usb_serial_generic_read_bulk_callback (struct urb *urb)
 {
 	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
 	unsigned char *data = urb->transfer_buffer;
-	int is_throttled;
-	unsigned long flags;
 
 	dbg("%s - port %d", __FUNCTION__, port->number);
 
-	if (urb->status) {
+	if (unlikely(urb->status != 0)) {
 		dbg("%s - nonzero read bulk status received: %d", __FUNCTION__, urb->status);
 		return;
 	}
@@ -327,21 +336,11 @@ void usb_serial_generic_read_bulk_callback (struct urb *urb)
 	usb_serial_debug_data(debug, &port->dev, __FUNCTION__, urb->actual_length, data);
 
 	/* Throttle the device if requested by tty */
-	if (urb->actual_length) {
-		spin_lock_irqsave(&port->lock, flags);
-		is_throttled = port->throttled = port->throttle_req;
-		spin_unlock_irqrestore(&port->lock, flags);
-		if (is_throttled) {
-			/* Let the received data linger in the read URB;
-			 * usb_serial_generic_unthrottle() will pick it
-			 * up later. */
-			dbg("%s - throttling device", __FUNCTION__);
-			return;
-		}
-	}
-
-	/* Handle data and continue reading from device */
-	flush_and_resubmit_read_urb(port);
+	spin_lock(&port->lock);
+	if (!(port->throttled = port->throttle_req))
+		/* Handle data and continue reading from device */
+		flush_and_resubmit_read_urb(port);
+	spin_unlock(&port->lock);
 }
 EXPORT_SYMBOL_GPL(usb_serial_generic_read_bulk_callback);
 
@@ -388,8 +387,8 @@ void usb_serial_generic_unthrottle (struct usb_serial_port *port)
 	spin_unlock_irqrestore(&port->lock, flags);
 
 	if (was_throttled) {
-		/* Handle pending data and resume reading from device */
-		flush_and_resubmit_read_urb(port);
+		/* Resume reading from device */
+		resubmit_read_urb(port, GFP_KERNEL);
 	}
 }
 
-- 
2.39.2