From: Brandon Philips <bphilips@suse.de>
Date: Thu, 27 Sep 2007 23:55:17 +0000 (-0300)
Subject: V4L/DVB (6275): V4L: vivi.c remove the "resource" locking
X-Git-Tag: v2.6.24-rc1~1463^2~30
X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=ba32bd95d431525ad2ffac97cadf9ee40b63939e;p=linux-2.6-omap-h63xx.git

V4L/DVB (6275): V4L: vivi.c remove the "resource" locking

The "resource" locking in vivi isn't needed since
streamon/streamoff/read_stream do mutual exclusion using
q->reading/q->streaming.

Plus it is sort of broken:

a) res_locked() use in vivi_read() is racey.
b) res_free() calls mutex_lock twice causing streamoff to break

Signed-off-by: Brandon Philips <bphilips@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
---

diff --git a/drivers/media/video/vivi.c b/drivers/media/video/vivi.c
index cdef622f6b3..82755091648 100644
--- a/drivers/media/video/vivi.c
+++ b/drivers/media/video/vivi.c
@@ -170,7 +170,6 @@ struct vivi_dev {
 	int                        users;
 
 	/* various device info */
-	unsigned int               resources;
 	struct video_device        vfd;
 
 	struct vivi_dmaqueue       vidq;
@@ -726,40 +725,6 @@ static struct videobuf_queue_ops vivi_video_qops = {
 	.buf_release    = buffer_release,
 };
 
-/* ------------------------------------------------------------------
-	IOCTL handling
-   ------------------------------------------------------------------*/
-
-
-static int res_get(struct vivi_dev *dev, struct vivi_fh *fh)
-{
-	/* is it free? */
-	mutex_lock(&dev->lock);
-	if (dev->resources) {
-		/* no, someone else uses it */
-		mutex_unlock(&dev->lock);
-		return 0;
-	}
-	/* it's free, grab it */
-	dev->resources =1;
-	dprintk(1,"res: get\n");
-	mutex_unlock(&dev->lock);
-	return 1;
-}
-
-static int res_locked(struct vivi_dev *dev)
-{
-	return (dev->resources);
-}
-
-static void res_free(struct vivi_dev *dev, struct vivi_fh *fh)
-{
-	mutex_lock(&dev->lock);
-	dev->resources = 0;
-	dprintk(1,"res: put\n");
-	mutex_lock(&dev->lock);
-}
-
 /* ------------------------------------------------------------------
 	IOCTL vidioc handling
    ------------------------------------------------------------------*/
@@ -913,9 +878,7 @@ static int vidioc_streamon(struct file *file, void *priv, enum v4l2_buf_type i)
 	if (i != fh->type)
 		return -EINVAL;
 
-	if (!res_get(dev,fh))
-		return -EBUSY;
-	return (videobuf_streamon(&fh->vb_vidq));
+	return videobuf_streamon(&fh->vb_vidq);
 }
 
 static int vidioc_streamoff(struct file *file, void *priv, enum v4l2_buf_type i)
@@ -928,10 +891,7 @@ static int vidioc_streamoff(struct file *file, void *priv, enum v4l2_buf_type i)
 	if (i != fh->type)
 		return -EINVAL;
 
-	videobuf_streamoff(&fh->vb_vidq);
-	res_free(dev,fh);
-
-	return (0);
+	return videobuf_streamoff(&fh->vb_vidq);
 }
 
 static int vidioc_s_std (struct file *file, void *priv, v4l2_std_id *i)
@@ -1096,10 +1056,10 @@ static ssize_t
 vivi_read(struct file *file, char __user *data, size_t count, loff_t *ppos)
 {
 	struct vivi_fh        *fh = file->private_data;
+	struct vivi_dev        *dev = fh->dev;
+	struct videobuf_queue *q = &fh->vb_vidq;
 
 	if (fh->type==V4L2_BUF_TYPE_VIDEO_CAPTURE) {
-		if (res_locked(fh->dev))
-			return -EBUSY;
 		return videobuf_read_stream(&fh->vb_vidq, data, count, ppos, 0,
 					file->f_flags & O_NONBLOCK);
 	}