[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, 2 insertions, 2 deletions

diff --git a/drivers/media/video/gspca/vicam.c b/drivers/media/video/gspca/vicam.c
index e48ec4db6da4..432d6cd99cd6 100644
--- a/drivers/media/video/gspca/vicam.c
+++ b/drivers/media/video/gspca/vicam.c
@@ -225,7 +225,7 @@ static void vicam_dostream(struct work_struct *work)
 		goto exit;
 	}
 
-	while (gspca_dev->present && gspca_dev->streaming) {
+	while (!gspca_dev->frozen && gspca_dev->dev && gspca_dev->streaming) {
 		ret = vicam_read_frame(gspca_dev, buffer, frame_sz);
 		if (ret < 0)
 			break;
@@ -327,7 +327,7 @@ static void sd_stop0(struct gspca_dev *gspca_dev)
 	dev->work_thread = NULL;
 	mutex_lock(&gspca_dev->usb_lock);
 
-	if (gspca_dev->present)
+	if (gspca_dev->dev)
 		vicam_set_camera_power(gspca_dev, 0);
 }