[patch]unbalanced calls to post_reset() from usb_reset_device()

[Oliver Neukum <oliver@xxxxxxxxxx>]

Greg,

here's one for the next merge window. It fixes an obscure logic
bug that strikes only few drivers in an unlikely error case.

	Regards
		Oliver

Signed-off-by: Oliver Neukum <oliver@xxxxxxxxxx>

--

commit 092d62009be992df7d6ba6c7c6acb91ca58567b5
Author: Oliver Neukum <oliver@xxxxxxxxxx>
Date:   Wed Nov 25 10:22:20 2009 +0100

    usb:fix unbalanced calls to post_reset() in usb_reset_device()
    
    usb_reset_device() can mean drivers are disconnected or reconnected
    for such drivers post_reset() must not be called. Therefore do the
    post_reset() and the probing in two passes

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 5ce8391..b326ccc 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3652,16 +3652,17 @@ int usb_reset_device(struct usb_device *udev)
 	int i;
 	struct usb_host_config *config = udev->actconfig;
 
-	if (udev->state == USB_STATE_NOTATTACHED ||
-			udev->state == USB_STATE_SUSPENDED) {
+	/* Prevent autosuspend during the reset */
+	ret = usb_autoresume_device(udev);
+	if (ret < 0)
+		return ret;
+
+	if (udev->state == USB_STATE_NOTATTACHED) {
 		dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
 				udev->state);
 		return -EINVAL;
 	}
 
-	/* Prevent autosuspend during the reset */
-	usb_autoresume_device(udev);
-
 	if (config) {
 		for (i = 0; i < config->desc.bNumInterfaces; ++i) {
 			struct usb_interface *cintf = config->interface[i];
@@ -3687,17 +3688,23 @@ int usb_reset_device(struct usb_device *udev)
 		for (i = config->desc.bNumInterfaces - 1; i >= 0; --i) {
 			struct usb_interface *cintf = config->interface[i];
 			struct usb_driver *drv;
-			int rebind = cintf->needs_binding;
 
-			if (!rebind && cintf->dev.driver) {
+			if (!cintf->needs_binding && cintf->dev.driver) {
 				drv = to_usb_driver(cintf->dev.driver);
-				if (drv->post_reset)
-					rebind = (drv->post_reset)(cintf);
-				else if (cintf->condition ==
-						USB_INTERFACE_BOUND)
-					rebind = 1;
+				cintf->needs_binding = (drv->post_reset)(cintf)
+					? 1 : 0;
 			}
-			if (ret == 0 && rebind)
+		}
+		
+		/*
+		 * Don't rebind until after all the post_reset() calls
+		 * so that a newly bound driver does not get an unbalanced
+		 * call to post_reset()
+		 */
+		for (i = config->desc.bNumInterfaces - 1; i >= 0; --i){
+			struct usb_interface *cintf = config->interface[i];
+
+			if (ret == 0 && cintf->needs_binding)
 				usb_rebind_intf(cintf);
 		}
 	}

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