usb: core: port: do error out if usb_autopm_get_interface() fails

Reviewing a fresh portion of coverity defects in USB core
(specifically CID 1458999), Alan Stern noted below in [1]:

On Tue, Feb 25, 2020 at 02:39:23PM -0500, Alan Stern wrote:
 > A revised search finds line 997 in drivers/usb/core/hub.c and lines
 > 216, 269 in drivers/usb/core/port.c.  (I didn't try looking in any
 > other directories.)  AFAICT all three of these should check the
 > return value, although a error message in the kernel log probably
 > isn't needed.

Factor out the usb_port_runtime_{resume,suspend}() changes into a
standalone patch to allow conflict-free porting on top of stable v3.9+.

[1] https://lore.kernel.org/lkml/[email protected]

Fixes: 971fcd4 ("usb: add runtime pm support for usb port device")
Cc: [email protected] # v3.9+
Suggested-by: Alan Stern <[email protected]>
Signed-off-by: Eugeniu Rosca <[email protected]>
Acked-by: Alan Stern <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Eugeniu Rosca

drivers/usb/core/port.c

@@ -213,7 +213,10 @@ static int usb_port_runtime_resume(struct device *dev)
 	if (!port_dev->is_superspeed && peer)
 		pm_runtime_get_sync(&peer->dev);
 
-	usb_autopm_get_interface(intf);
+	retval = usb_autopm_get_interface(intf);
+	if (retval < 0)
+		return retval;
+
 	retval = usb_hub_set_port_power(hdev, hub, port1, true);
 	msleep(hub_power_on_good_delay(hub));
 	if (udev && !retval) {
@@ -266,7 +269,10 @@ static int usb_port_runtime_suspend(struct device *dev)
 	if (usb_port_block_power_off)
 		return -EBUSY;
 
-	usb_autopm_get_interface(intf);
+	retval = usb_autopm_get_interface(intf);
+	if (retval < 0)
+		return retval;
+
 	retval = usb_hub_set_port_power(hdev, hub, port1, false);
 	usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_CONNECTION);
 	if (!port_dev->is_superspeed)