[Linux-uvc-devel] [PATCH] device open counter

[Alexandre B. <di...@fr...>]

Hello,

I wrote a quick patch to prevent device open more than once. This will prevent 
kernel crash with the current driver.

--- uvc/uvcvideo.c	2006-01-28 04:39:39.000000000 +0100
+++ uvc2/uvcvideo.c	2006-01-28 04:30:48.000000000 +0100
@@ -295,6 +295,7 @@
 };
 
 struct uvc_video_device {
+	int count;
 	struct uvc_device *dev;
 	struct video_device *vdev;
 
@@ -1543,6 +1544,7 @@
 
 	video->streaming->cur_format = format;
 	video->streaming->cur_frame = frame;
+	video->count = 0;
 
 	return 0;
 }
@@ -1868,13 +1870,24 @@
 	video = video_get_drvdata(vdev);
 
 	if (video->dev->state & UVC_DEV_DISCONNECTED) {
+		uvc_printk(KERN_DEBUG, "uvc_v4l2_open failed: disconnected\n");
 		up(&dev_sem);
 		return -ENODEV;
 	}
 
+	if (video->count > 0) {
+		uvc_printk(KERN_DEBUG, "uvc_v4l2_open failed: count = %u\n", video->count);
+		up(&dev_sem);
+		return -EBUSY;
+	}
+
+	video->count++;
+
 	kref_get(&video->dev->kref);
 	up(&dev_sem);
 
+	uvc_printk(KERN_DEBUG, "uvc_v4l2_open done\n");
+
 	return 0;
 }
 
@@ -1891,7 +1904,11 @@
 		uvc_printk(KERN_DEBUG, "uvc_v4l2_release: Unable to free buffers.\n");
 	up(&video->queue.lock);
 
+	down(&dev_sem);
 	kref_put(&video->dev->kref, uvc_delete);
+	video->count--;
+	up(&dev_sem);
+
 	uvc_printk(KERN_DEBUG, "< uvc_v4l2_release\n");
 	return 0;
 }

-- 
Alexandre