[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, 11 insertions, 5 deletions

diff --git a/drivers/media/video/gspca/gspca.c b/drivers/media/video/gspca/gspca.c
index 7669f27238c..a14c8f71d48 100644
--- a/drivers/media/video/gspca/gspca.c
+++ b/drivers/media/video/gspca/gspca.c
@@ -2499,8 +2499,11 @@ int gspca_suspend(struct usb_interface *intf, pm_message_t message)
 	destroy_urbs(gspca_dev);
 	gspca_input_destroy_urb(gspca_dev);
 	gspca_set_alt0(gspca_dev);
-	if (gspca_dev->sd_desc->stop0)
+	if (gspca_dev->sd_desc->stop0) {
+		mutex_lock(&gspca_dev->usb_lock);
 		gspca_dev->sd_desc->stop0(gspca_dev);
+		mutex_unlock(&gspca_dev->usb_lock);
+	}
 	return 0;
 }
 EXPORT_SYMBOL(gspca_suspend);
@@ -2508,7 +2511,7 @@ EXPORT_SYMBOL(gspca_suspend);
 int gspca_resume(struct usb_interface *intf)
 {
 	struct gspca_dev *gspca_dev = usb_get_intfdata(intf);
-	int streaming;
+	int streaming, ret = 0;
 
 	gspca_dev->frozen = 0;
 	gspca_dev->sd_desc->init(gspca_dev);
@@ -2521,9 +2524,12 @@ int gspca_resume(struct usb_interface *intf)
 	streaming = gspca_dev->streaming;
 	gspca_dev->streaming = 0;
 	v4l2_ctrl_handler_setup(gspca_dev->vdev.ctrl_handler);
-	if (streaming)
-		return gspca_init_transfer(gspca_dev);
-	return 0;
+	if (streaming) {
+		mutex_lock(&gspca_dev->queue_lock);
+		ret = gspca_init_transfer(gspca_dev);
+		mutex_unlock(&gspca_dev->queue_lock);
+	}
+	return ret;
 }
 EXPORT_SYMBOL(gspca_resume);
 #endif