[media] gspca: Fix locking issues related to suspend/resume

There are two bugs here: first the calls to stop0 (in gspca_suspend) and
gspca_init_transfer (in gspca_resume) need to be called with the usb_lock held.
That's true for the other places they are called and it is what subdrivers
expect. Quite a few will unlock the usb_lock in stop0 while waiting for a
worker thread to finish, and if usb_lock isn't held then that can cause a
kernel oops.

The other problem is that a worker thread needs to detect that it has to
halt due to a suspend. Otherwise it will just go on looping. So add tests
against gspca_dev->frozen in the worker threads that need it.

Hdg, 2 minor changes:
1) The finepix device is ok with stopping reading a frame halfway through,
   so add frozen checks in all places where we also check if we're still
   streaming
2) Use gspca_dev->dev instead of gspca_dev->present to check for disconnect
   in all touched drivers. I plan to do this everywhere in the future, and
   most relevant lines in the touched drivers are already modified by this
   patch.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/media/video/gspca/finepix.c b/drivers/media/video/gspca/finepix.c
index 0107513cd72..d0befe98109 100644
--- a/drivers/media/video/gspca/finepix.c
+++ b/drivers/media/video/gspca/finepix.c
@@ -94,7 +94,7 @@ static void dostream(struct work_struct *work)
 
 	/* loop reading a frame */
 again:
-	while (gspca_dev->present && gspca_dev->streaming) {
+	while (!gspca_dev->frozen && gspca_dev->dev && gspca_dev->streaming) {
 
 		/* request a frame */
 		mutex_lock(&gspca_dev->usb_lock);
@@ -102,7 +102,8 @@ again:
 		mutex_unlock(&gspca_dev->usb_lock);
 		if (ret < 0)
 			break;
-		if (!gspca_dev->present || !gspca_dev->streaming)
+		if (gspca_dev->frozen || !gspca_dev->dev ||
+					 !gspca_dev->streaming)
 			break;
 
 		/* the frame comes in parts */
@@ -117,7 +118,8 @@ again:
 				 * error. Just restart. */
 				goto again;
 			}
-			if (!gspca_dev->present || !gspca_dev->streaming)
+			if (gspca_dev->frozen || !gspca_dev->dev ||
+						 !gspca_dev->streaming)
 				goto out;
 			if (len < FPIX_MAX_TRANSFER ||
 				(data[len - 2] == 0xff &&