usb: core: Fix USB 3.0 devices lost in NOTATTACHED state after a hub port reset

commit fb6d1f7d upstream.

Fix USB 3.0 devices lost in NOTATTACHED state after a hub port reset.

Dissolve the function hub_port_finish_reset() completely and divide the
actions to be taken into those which need to be done after each reset
attempt and those which need to be done after the full procedure is
complete, and place them in the appropriate places in hub_port_reset().
Also, remove an unneeded forward declaration of hub_port_reset().

Verbose Problem Description:

USB 3.0 devices may be "lost for good" during a hub port reset.
This makes Linux unable to boot from USB 3.0 devices in certain
constellations of host controllers and devices, because the USB device is
lost during initialization, preventing the rootfs from being mounted.

The underlying problem is that in the affected constellations, during the
processing inside hub_port_reset(), the hub link state goes from 0 to
SS.inactive after the initial reset, and back to 0 again only after the
following "warm" reset.

However, hub_port_finish_reset() is called after each reset attempt and
sets the state the connected USB device based on the "preliminary" status
of the hot reset to USB_STATE_NOTATTACHED due to SS.inactive, yet when
the following warm reset is complete and hub_port_finish_reset() is
called again, its call to set the device to USB_STATE_DEFAULT is blocked
by usb_set_device_state() which does not allow taking USB devices out of
USB_STATE_NOTATTACHED state.

Thanks to Alan Stern for guiding me to the proper solution and how to
submit it.

Link: http://lkml.kernel.org/r/trinity-25981484-72a9-4d46-bf17-9c1cf9301a31-1432073240136%20()%203capp-gmx-bs27Signed-off-by: Robert Schlabbach <robert_s@gmx.net>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/usb/core/hub.c

@@ -2608,9 +2608,6 @@ static bool use_new_scheme(struct usb_device *udev, int retry)
 	return USE_NEW_SCHEME(retry);
 }
 
-static int hub_port_reset(struct usb_hub *hub, int port1,
-			struct usb_device *udev, unsigned int delay, bool warm);
-
 /* Is a USB 3.0 port in the Inactive or Compliance Mode state?
  * Port worm reset is required to recover
  */
@@ -2691,44 +2688,6 @@ static int hub_port_wait_reset(struct usb_hub *hub, int port1,
 	return 0;
 }
 
-static void hub_port_finish_reset(struct usb_hub *hub, int port1,
-			struct usb_device *udev, int *status)
-{
-	switch (*status) {
-	case 0:
-		/* TRSTRCY = 10 ms; plus some extra */
-		msleep(10 + 40);
-		if (udev) {
-			struct usb_hcd *hcd = bus_to_hcd(udev->bus);
-
-			update_devnum(udev, 0);
-			/* The xHC may think the device is already reset,
-			 * so ignore the status.
-			 */
-			if (hcd->driver->reset_device)
-				hcd->driver->reset_device(hcd, udev);
-		}
-		/* FALL THROUGH */
-	case -ENOTCONN:
-	case -ENODEV:
-		usb_clear_port_feature(hub->hdev,
-				port1, USB_PORT_FEAT_C_RESET);
-		if (hub_is_superspeed(hub->hdev)) {
-			usb_clear_port_feature(hub->hdev, port1,
-					USB_PORT_FEAT_C_BH_PORT_RESET);
-			usb_clear_port_feature(hub->hdev, port1,
-					USB_PORT_FEAT_C_PORT_LINK_STATE);
-			usb_clear_port_feature(hub->hdev, port1,
-					USB_PORT_FEAT_C_CONNECTION);
-		}
-		if (udev)
-			usb_set_device_state(udev, *status
-					? USB_STATE_NOTATTACHED
-					: USB_STATE_DEFAULT);
-		break;
-	}
-}
-
 /* Handle port reset and port warm(BH) reset (for USB3 protocol ports) */
 static int hub_port_reset(struct usb_hub *hub, int port1,
 			struct usb_device *udev, unsigned int delay, bool warm)
@@ -2752,13 +2711,9 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
 		 * If the caller hasn't explicitly requested a warm reset,
 		 * double check and see if one is needed.
 		 */
-		status = hub_port_status(hub, port1,
-					&portstatus, &portchange);
-		if (status < 0)
-			goto done;
-
-		if (hub_port_warm_reset_required(hub, portstatus))
-			warm = true;
+		if (hub_port_status(hub, port1, &portstatus, &portchange) == 0)
+			if (hub_port_warm_reset_required(hub, portstatus))
+				warm = true;
 	}
 
 	/* Reset the port */
@@ -2783,11 +2738,19 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
 
 		/* Check for disconnect or reset */
 		if (status == 0 || status == -ENOTCONN || status == -ENODEV) {
-			hub_port_finish_reset(hub, port1, udev, &status);
+			usb_clear_port_feature(hub->hdev, port1,
+					USB_PORT_FEAT_C_RESET);
 
 			if (!hub_is_superspeed(hub->hdev))
 				goto done;
 
+			usb_clear_port_feature(hub->hdev, port1,
+					USB_PORT_FEAT_C_BH_PORT_RESET);
+			usb_clear_port_feature(hub->hdev, port1,
+					USB_PORT_FEAT_C_PORT_LINK_STATE);
+			usb_clear_port_feature(hub->hdev, port1,
+					USB_PORT_FEAT_C_CONNECTION);
+
 			/*
 			 * If a USB 3.0 device migrates from reset to an error
 			 * state, re-issue the warm reset.
@@ -2819,6 +2782,26 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
 	dev_err(&port_dev->dev, "Cannot enable. Maybe the USB cable is bad?\n");
 
 done:
+	if (status == 0) {
+		/* TRSTRCY = 10 ms; plus some extra */
+		msleep(10 + 40);
+		if (udev) {
+			struct usb_hcd *hcd = bus_to_hcd(udev->bus);
+
+			update_devnum(udev, 0);
+			/* The xHC may think the device is already reset,
+			 * so ignore the status.
+			 */
+			if (hcd->driver->reset_device)
+				hcd->driver->reset_device(hcd, udev);
+
+			usb_set_device_state(udev, USB_STATE_DEFAULT);
+		}
+	} else {
+		if (udev)
+			usb_set_device_state(udev, USB_STATE_NOTATTACHED);
+	}
+
 	if (!hub_is_superspeed(hub->hdev))
 		up_read(&ehci_cf_port_reset_rwsem);