V4L/DVB (9690): gspca: Lock the subdrivers via module_get/put.

The previous subdriver protection against rmmod was done via the
file operations table in the device descriptor. On device disconnection
while streaming, the device structure was freed at close time, and the
module_put still used the module name in the freed area.
Now, explicit module get/put are done on open and close.

Signed-off-by: Jean-Francois Moine <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/video/gspca/gspca.c

···
 		ret = -EBUSY;
 		goto out;
 	}
+
+	/* protect the subdriver against rmmod */
+	if (!try_module_get(gspca_dev->module)) {
+		ret = -ENODEV;
+		goto out;
+	}
+
 	gspca_dev->users++;
 
 	/* one more user */
···
 		gspca_dev->memory = GSPCA_MEMORY_NO;
 	}
 	file->private_data = NULL;
+	module_put(gspca_dev->module);
 	mutex_unlock(&gspca_dev->queue_lock);
 
 	PDEBUG(D_STREAM, "close done");
···
 	/* init video stuff */
 	memcpy(&gspca_dev->vdev, &gspca_template, sizeof gspca_template);
 	gspca_dev->vdev.parent = &dev->dev;
-	memcpy(&gspca_dev->fops, &dev_fops, sizeof gspca_dev->fops);
-	gspca_dev->vdev.fops = &gspca_dev->fops;
-	gspca_dev->fops.owner = module;		/* module protection */
+	gspca_dev->vdev.fops = &dev_fops;
+	gspca_dev->module = module;
 	gspca_dev->present = 1;
 	ret = video_register_device(&gspca_dev->vdev,
 				  VFL_TYPE_GRABBER,

drivers/media/video/gspca/gspca.h

···
 
 struct gspca_dev {
 	struct video_device vdev;	/* !! must be the first item */
-	struct file_operations fops;
+	struct module *module;		/* subdriver handling the device */
 	struct usb_device *dev;
 	struct kref kref;
 	struct file *capt_file;		/* file doing video capture */