[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, 3 insertions, 2 deletions

diff --git a/drivers/media/video/gspca/zc3xx.c b/drivers/media/video/gspca/zc3xx.c
index 7d9a4f1be9d..8f21bae46ef 100644
--- a/drivers/media/video/gspca/zc3xx.c
+++ b/drivers/media/video/gspca/zc3xx.c
@@ -6093,7 +6093,8 @@ static void transfer_update(struct work_struct *work)
 		/* get the transfer status */
 		/* the bit 0 of the bridge register 11 indicates overflow */
 		mutex_lock(&gspca_dev->usb_lock);
-		if (!gspca_dev->present || !gspca_dev->streaming)
+		if (gspca_dev->frozen || !gspca_dev->dev ||
+					 !gspca_dev->streaming)
 			goto err;
 		reg11 = reg_r(gspca_dev, 0x0011);
 		if (gspca_dev->usb_err < 0
@@ -6949,7 +6950,7 @@ static void sd_stop0(struct gspca_dev *gspca_dev)
 		mutex_lock(&gspca_dev->usb_lock);
 		sd->work_thread = NULL;
 	}
-	if (!gspca_dev->present)
+	if (!gspca_dev->dev)
 		return;
 	send_unknown(gspca_dev, sd->sensor);
 }