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>

2 files changed, 12 insertions, 12 deletions

diff --git a/drivers/media/video/usbvision/usbvision-core.c b/drivers/media/video/usbvision/usbvision-core.c
index 06e8e67da362..5a61ed728b35 100644
--- a/drivers/media/video/usbvision/usbvision-core.c
+++ b/drivers/media/video/usbvision/usbvision-core.c
@@ -2287,7 +2287,7 @@ static void usbvision_isocIrq(struct urb *urb, struct pt_regs *regs)
 
         /* Manage streaming interruption */
         if (usbvision->streaming == Stream_Interrupt) {
-                usbvision->streaming = Stream_Off;
+                usbvision->streaming = Stream_Idle;
                 if ((*f)) {
                         (*f)->grabstate = FrameState_Ready;
                         (*f)->scanstate = ScanState_Scanning;
@@ -3092,7 +3092,7 @@ static int usbvision_stream_interrupt(struct usb_usbvision *usbvision)
 
         usbvision->streaming = Stream_Interrupt;
         ret = wait_event_timeout(usbvision->wait_stream,
-                                 (usbvision->streaming == Stream_Off),
+                                 (usbvision->streaming == Stream_Idle),
                                  msecs_to_jiffies(USBVISION_NUMSBUF*USBVISION_URB_FRAMES));
         return ret;
 }
@@ -3579,7 +3579,7 @@ static int usbvision_init_isoc(struct usb_usbvision *usbvision)
                 }
         }
 
-        usbvision->streaming = Stream_On;
+        usbvision->streaming = Stream_Idle;
         PDEBUG(DBG_ISOC, "%s: streaming=1 usbvision->video_endp=$%02x", __FUNCTION__, usbvision->video_endp);
         return 0;
 }
@@ -3595,8 +3595,7 @@ static void usbvision_stop_isoc(struct usb_usbvision *usbvision)
 {
         int bufIdx, errCode, regValue;
 
-        // FIXME : removed the streaming==Stream_Off. This field has not the same signification than before !
-        if (usbvision->dev == NULL)
+        if ((usbvision->streaming == Stream_Off) || (usbvision->dev == NULL))
                 return;
 
         /* Unschedule all of the iso td's */
@@ -4292,7 +4291,7 @@ static int usbvision_v4l2_do_ioctl(struct inode *inode, struct file *file,
                                 return -EINVAL;
 
                         if (list_empty(&(usbvision->outqueue))) {
-                                if (usbvision->streaming == Stream_Off)
+                                if (usbvision->streaming == Stream_Idle)
                                         return -EINVAL;
                                 ret = wait_event_interruptible
                                         (usbvision->wait_frame,
@@ -5665,6 +5664,7 @@ static int __devinit usbvision_probe(struct usb_interface *intf, const struct us
         usbvision->isocPacketSize = 0;
         usbvision->usb_bandwidth = 0;
         usbvision->user = 0;
+        usbvision->streaming = Stream_Off;
 
         usbvision_register_video(usbvision);
         usbvision_configure_video(usbvision);
@@ -5713,13 +5713,12 @@ static void __devexit usbvision_disconnect(struct usb_interface *intf)
         usb_put_dev(usbvision->dev);
         usbvision->dev = NULL;  // USB device is no more
 
-        wake_up_interruptible(&usbvision->wait_frame);
-        wake_up_interruptible(&usbvision->wait_stream);
-
         up(&usbvision->lock);
 
         if (usbvision->user) {
                 info("%s: In use, disconnect pending", __FUNCTION__);
+                wake_up_interruptible(&usbvision->wait_frame);
+                wake_up_interruptible(&usbvision->wait_stream);
         }
         else {
                 usbvision_release(usbvision);
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 {