[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, 3 deletions

diff --git a/drivers/media/video/gspca/sq905c.c b/drivers/media/video/gspca/sq905c.c
index ae783634712f..720c187f6ec7 100644
--- a/drivers/media/video/gspca/sq905c.c
+++ b/drivers/media/video/gspca/sq905c.c
@@ -150,7 +150,7 @@ static void sq905c_dostream(struct work_struct *work)
 		goto quit_stream;
 	}
 
-	while (gspca_dev->present && gspca_dev->streaming) {
+	while (!gspca_dev->frozen && gspca_dev->dev && gspca_dev->streaming) {
 		/* Request the header, which tells the size to download */
 		ret = usb_bulk_msg(gspca_dev->dev,
 				usb_rcvbulkpipe(gspca_dev->dev, 0x81),
@@ -169,7 +169,7 @@ static void sq905c_dostream(struct work_struct *work)
 		packet_type = FIRST_PACKET;
 		gspca_frame_add(gspca_dev, packet_type,
 				buffer, FRAME_HEADER_LEN);
-		while (bytes_left > 0 && gspca_dev->present) {
+		while (bytes_left > 0 && gspca_dev->dev) {
 			data_len = bytes_left > SQ905C_MAX_TRANSFER ?
 				SQ905C_MAX_TRANSFER : bytes_left;
 			ret = usb_bulk_msg(gspca_dev->dev,
@@ -191,7 +191,7 @@ static void sq905c_dostream(struct work_struct *work)
 		}
 	}
 quit_stream:
-	if (gspca_dev->present) {
+	if (gspca_dev->dev) {
 		mutex_lock(&gspca_dev->usb_lock);
 		sq905c_command(gspca_dev, SQ905C_CLEAR, 0);
 		mutex_unlock(&gspca_dev->usb_lock);