[media] pwc: Allow dqbuf / read to complete while waiting for controls

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/pwc/pwc.h b/drivers/media/video/pwc/pwc.h
index 601a549..e02dbf7 100644
--- a/drivers/media/video/pwc/pwc.h
+++ b/drivers/media/video/pwc/pwc.h
@@ -200,6 +200,9 @@
 
 	/* Pointer to our usb_device, may be NULL after unplug */
 	struct usb_device *udev;
+	/* Protects the setting of udev to NULL by our disconnect handler */
+	struct mutex udevlock;
+
 	/* type of cam (645, 646, 675, 680, 690, 720, 730, 740, 750) */
 	int type;
 	int release;		/* release number */