V4L/DVB (4928): Usbvision_v4l2 robustness on disconnect

This patch corrects 2 bugs (causes kernel oops) that occur when
unplugging the peripheral whereas nobody has opened it yet :
- do not call usbvision_stop_isoc if usbvision_init_isoc has not been called
- do not call wakeup_interruptible on waitqueues that did not have been
initialized with init_waitqueue_head

Signed-off-by: Thierry MERLE <thierry.merle@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/media/video/usbvision/usbvision.h b/drivers/media/video/usbvision/usbvision.h
index 870c0cc81d84..ef83a5c4d2fd 100644
--- a/drivers/media/video/usbvision/usbvision.h
+++ b/drivers/media/video/usbvision/usbvision.h
@@ -227,9 +227,10 @@ enum FrameState {
 
 /* stream states */
 enum StreamState {
-        Stream_Off,
-        Stream_Interrupt,
-        Stream_On,
+        Stream_Off,             /* Driver streaming is completely OFF */
+        Stream_Idle,            /* Driver streaming is ready to be put ON by the application */
+        Stream_Interrupt,       /* Driver streaming must be interrupted */
+        Stream_On,              /* Driver streaming is put ON by the application */
 };
 
 enum IsocState {