USB: usbcore get rid of the timer in usb_start_wait_urb()

This patch uses completion timeout instead of a timer to implement
a timeout when submitting an URB in usb_start_wait_urb().

It also fixes a small issue. With the previous code, if no timeout
happened and the URB's status was set to ECONNRESET value, the code
assumed wrongly that a timeout had occured.
Signed-off-by: Franck Bui-Huu <vagabon.xyz@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/message.c

@@ -23,59 +23,44 @@ static void usb_api_blocking_completion(struct urb *urb, struct pt_regs *regs)
 }
 
 
-static void timeout_kill(unsigned long data)
-{
-	struct urb	*urb = (struct urb *) data;
-
-	usb_unlink_urb(urb);
-}
-
-// Starts urb and waits for completion or timeout
-// note that this call is NOT interruptible, while
-// many device driver i/o requests should be interruptible
-static int usb_start_wait_urb(struct urb *urb, int timeout, int* actual_length)
+/*
+ * Starts urb and waits for completion or timeout. Note that this call
+ * is NOT interruptible. Many device driver i/o requests should be
+ * interruptible and therefore these drivers should implement their
+ * own interruptible routines.
+ */
+static int usb_start_wait_urb(struct urb *urb, int timeout, int *actual_length)
 { 
 	struct completion done;
-	struct timer_list	timer;
+	unsigned long expire;
 	int status;
 
 	init_completion(&done); 	
 	urb->context = &done;
 	urb->actual_length = 0;
 	status = usb_submit_urb(urb, GFP_NOIO);
+	if (unlikely(status))
+		goto out;
+
+	expire = timeout ? msecs_to_jiffies(timeout) : MAX_SCHEDULE_TIMEOUT;
+	if (!wait_for_completion_timeout(&done, expire)) {
 
-	if (status == 0) {
-		if (timeout > 0) {
-			init_timer(&timer);
-			timer.expires = jiffies + msecs_to_jiffies(timeout);
-			timer.data = (unsigned long)urb;
-			timer.function = timeout_kill;
-			/* grr.  timeout _should_ include submit delays. */
-			add_timer(&timer);
-		}
-		wait_for_completion(&done);
-		status = urb->status;
-		/* note:  HCDs return ETIMEDOUT for other reasons too */
-		if (status == -ECONNRESET) {
 		dev_dbg(&urb->dev->dev,
 			"%s timed out on ep%d%s len=%d/%d\n",
 			current->comm,
 			usb_pipeendpoint(urb->pipe),
 			usb_pipein(urb->pipe) ? "in" : "out",
 			urb->actual_length,
-				urb->transfer_buffer_length
-				);
-			if (urb->actual_length > 0)
-				status = 0;
-			else
-				status = -ETIMEDOUT;
-		}
-		if (timeout > 0)
-			del_timer_sync(&timer);
-	}
+			urb->transfer_buffer_length);
 
+		usb_kill_urb(urb);
+		status = urb->status == -ENOENT ? -ETIMEDOUT : urb->status;
+	} else
+		status = urb->status;
+out:
 	if (actual_length)
 		*actual_length = urb->actual_length;
+
 	usb_free_urb(urb);
 	return status;
 }