USB: cdc-wdm: reset handling according to new requirements

This patch
- ensures no IO takes place during resets
- reports resets to user space

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

drivers/usb/class/cdc-wdm.c

@@ -542,6 +542,8 @@ static int wdm_open(struct inode *inode, struct file *file)
 
 	mutex_lock(&desc->lock);
 	if (!desc->count++) {
+		desc->werr = 0;
+		desc->rerr = 0;
 		rv = usb_submit_urb(desc->validity, GFP_KERNEL);
 		if (rv < 0) {
 			desc->count--;
@@ -853,6 +855,18 @@ static int wdm_pre_reset(struct usb_interface *intf)
 	struct wdm_device *desc = usb_get_intfdata(intf);
 
 	mutex_lock(&desc->lock);
+	kill_urbs(desc);
+
+	/*
+	 * we notify everybody using poll of
+	 * an exceptional situation
+	 * must be done before recovery lest a spontaneous
+	 * message from the device is lost
+	 */
+	spin_lock_irq(&desc->iuspin);
+	desc->rerr = -EINTR;
+	spin_unlock_irq(&desc->iuspin);
+	wake_up_all(&desc->wait);
 	return 0;
 }