usbcore: fix up device and power state tests

This patch (as734) rationalizes the various tests of device state and
power states.  There are duplications and mistaken tests in several
places.

Perhaps the most interesting challenge is where the hub driver tests to
see that all the child devices are suspended before allowing itself to
be suspended.  When CONFIG_USB_SUSPEND is set the test is
straightforward, since we expect that the children _will_ be suspended.
But when CONFIG_USB_SUSPEND isn't set, it's not so clear what should be
done.  The code compromises by checking the child's
power.power_state.event field.


Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 29 insertions, 61 deletions

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 92ecc4eb1e88..affbfb53eb5e 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -757,11 +757,13 @@ static int suspend_device(struct usb_device *udev, pm_message_t msg)
 	struct usb_device_driver	*udriver;
 	int				status = 0;
 
+	if (udev->state == USB_STATE_NOTATTACHED ||
+			udev->state == USB_STATE_SUSPENDED)
+		goto done;
+
 	if (udev->dev.driver == NULL)
 		goto done;
 	udriver = to_usb_device_driver(udev->dev.driver);
-	if (udev->dev.power.power_state.event == msg.event)
-		goto done;
 	status = udriver->suspend(udev, msg);
 
 done:
@@ -776,14 +778,13 @@ static int resume_device(struct usb_device *udev)
 	struct usb_device_driver	*udriver;
 	int				status = 0;
 
-	if (udev->dev.power.power_state.event == PM_EVENT_ON)
+	if (udev->state == USB_STATE_NOTATTACHED ||
+			udev->state != USB_STATE_SUSPENDED)
 		goto done;
 
 	if (udev->dev.driver == NULL)
 		goto done;
 	udriver = to_usb_device_driver(udev->dev.driver);
-	if (udev->state == USB_STATE_NOTATTACHED)
-		goto done;
 	status = udriver->resume(udev);
 
 done:
@@ -798,14 +799,14 @@ static int suspend_interface(struct usb_interface *intf, pm_message_t msg)
 	struct usb_driver	*driver;
 	int			status = 0;
 
-	if (intf->dev.driver == NULL)
+	/* with no hardware, USB interfaces only use FREEZE and ON states */
+	if (interface_to_usbdev(intf)->state == USB_STATE_NOTATTACHED ||
+			!is_active(intf))
 		goto done;
 
-	driver = to_usb_driver(intf->dev.driver);
-
-	/* with no hardware, USB interfaces only use FREEZE and ON states */
-	if (!is_active(intf))
+	if (intf->dev.driver == NULL)
 		goto done;
+	driver = to_usb_driver(intf->dev.driver);
 
 	if (driver->suspend && driver->resume) {
 		status = driver->suspend(intf, msg);
@@ -831,25 +832,16 @@ done:
 static int resume_interface(struct usb_interface *intf)
 {
 	struct usb_driver	*driver;
-	struct usb_device	*udev;
 	int			status = 0;
 
-	if (intf->dev.power.power_state.event == PM_EVENT_ON)
+	if (interface_to_usbdev(intf)->state == USB_STATE_NOTATTACHED ||
+			is_active(intf))
 		goto done;
 
 	if (intf->dev.driver == NULL)
 		goto done;
-
 	driver = to_usb_driver(intf->dev.driver);
 
-	udev = interface_to_usbdev(intf);
-	if (udev->state == USB_STATE_NOTATTACHED)
-		goto done;
-
-	/* if driver was suspended, it has a resume method;
-	 * however, sysfs can wrongly mark things as suspended
-	 * (on the "no suspend method" FIXME path above)
-	 */
 	if (driver->resume) {
 		status = driver->resume(intf);
 		if (status)
@@ -904,6 +896,12 @@ int usb_resume_both(struct usb_device *udev)
 	int			i;
 	struct usb_interface	*intf;
 
+	/* Can't resume if the parent is suspended */
+	if (udev->parent && udev->parent->state == USB_STATE_SUSPENDED) {
+		dev_warn(&udev->dev, "can't resume; parent is suspended\n");
+		return -EHOSTUNREACH;
+	}
+
 	status = resume_device(udev);
 	if (status == 0 && udev->actconfig) {
 		for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
diff --git a/drivers/usb/core/generic.c b/drivers/usb/core/generic.c
index b6dacd7551d2..5358e656477c 100644
--- a/drivers/usb/core/generic.c
+++ b/drivers/usb/core/generic.c
@@ -195,9 +195,6 @@ static int generic_suspend(struct usb_device *udev, pm_message_t msg)
 
 static int generic_resume(struct usb_device *udev)
 {
-	if (udev->state == USB_STATE_NOTATTACHED)
-		return 0;
-
 	return usb_port_resume(udev);
 }
 
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 7af53db4d76f..a310c7cede99 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1556,26 +1556,6 @@ static int __usb_port_suspend (struct usb_device *udev, int port1)
 	if (port1 < 0)
 		return port1;
 
-	if (udev->state == USB_STATE_SUSPENDED
-			|| udev->state == USB_STATE_NOTATTACHED) {
-		return 0;
-	}
-
-	/* all interfaces must already be suspended */
-	if (udev->actconfig) {
-		int	i;
-
-		for (i = 0; i < udev->actconfig->desc.bNumInterfaces; i++) {
-			struct usb_interface	*intf;
-
-			intf = udev->actconfig->interface[i];
-			if (is_active(intf)) {
-				dev_dbg(&intf->dev, "nyet suspended\n");
-				return -EBUSY;
-			}
-		}
-	}
-
 	/* we change the device's upstream USB link,
 	 * but root hubs have no upstream USB link.
 	 */
@@ -1614,8 +1594,6 @@ static int __usb_port_suspend (struct usb_device *udev, int port1)
 int usb_port_suspend(struct usb_device *udev)
 {
 #ifdef	CONFIG_USB_SUSPEND
-	if (udev->state == USB_STATE_NOTATTACHED)
-		return -ENODEV;
 	return __usb_port_suspend(udev, udev->portnum);
 #else
 	return 0;
@@ -1761,24 +1739,17 @@ hub_port_resume(struct usb_hub *hub, int port1, struct usb_device *udev)
  */
 int usb_port_resume(struct usb_device *udev)
 {
-	int	status;
-
-	if (udev->state == USB_STATE_NOTATTACHED)
-		return -ENODEV;
+	int	status = 0;
 
 	/* we change the device's upstream USB link,
 	 * but root hubs have no upstream USB link.
 	 */
 	if (udev->parent) {
 #ifdef	CONFIG_USB_SUSPEND
-		if (udev->state == USB_STATE_SUSPENDED) {
-			// NOTE swsusp may bork us, device state being wrong...
-			// NOTE this fails if parent is also suspended...
-			status = hub_port_resume(hdev_to_hub(udev->parent),
-					udev->portnum, udev);
-		} else
+		// NOTE this fails if parent is also suspended...
+		status = hub_port_resume(hdev_to_hub(udev->parent),
+				udev->portnum, udev);
 #endif
-			status = 0;
 	} else
 		status = finish_port_resume(udev);
 	if (status < 0)
@@ -1821,12 +1792,14 @@ static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
 		struct usb_device	*udev;
 
 		udev = hdev->children [port1-1];
-		if (udev && (udev->dev.power.power_state.event
-					== PM_EVENT_ON
+		if (udev && msg.event == PM_EVENT_SUSPEND &&
 #ifdef	CONFIG_USB_SUSPEND
-				|| udev->state != USB_STATE_SUSPENDED
+				udev->state != USB_STATE_SUSPENDED
+#else
+				udev->dev.power.power_state.event
+					== PM_EVENT_ON
 #endif
-				)) {
+				) {
 			dev_dbg(&intf->dev, "port %d nyet suspended\n", port1);
 			return -EBUSY;
 		}