V4L/DVB (9034): With the recent patch to v4l2 titled "v4l2: use register_chrdev_region

instead of register_chrdev", the internal reference count is no longer
necessary in order to free the internal stk_webcam struct. This patch
removes the reference counter from the stk_webcam struct and frees the
struct via the video_device release callback. It also fixes an
associated bug in stk_camera_probe which could result from
video_unregister_device being called before video_register_device.
Lastly, it simplifies access to the stk_webcam struct in several
places. This patch should apply cleanly against the "working" branch
of the v4l-dvb git repository.

This patch is identical to the patch I sent a couple of months back
titled "stk-webcam: Fix video_device handling" except that it has been
rebased against current modifications to stk-webcam and it no longer
depends on any other outstanding patches.

Acked-by: Jaime Velasco Juan <jsagarribay@gmail.com>
Signed-off-by: David Ellingsworth <david@identd.dyndns.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

2 files changed, 23 insertions, 63 deletions

diff --git a/drivers/media/video/stk-webcam.c b/drivers/media/video/stk-webcam.c
index 8dda5680094d..db69bc5556d6 100644
--- a/drivers/media/video/stk-webcam.c
+++ b/drivers/media/video/stk-webcam.c
@@ -65,22 +65,6 @@ static struct usb_device_id stkwebcam_table[] = {
 };
 MODULE_DEVICE_TABLE(usb, stkwebcam_table);
 
-static void stk_camera_cleanup(struct kref *kref)
-{
-        struct stk_camera *dev = to_stk_camera(kref);
-
-        STK_INFO("Syntek USB2.0 Camera release resources"
-                " video device /dev/video%d\n", dev->vdev.minor);
-        video_unregister_device(&dev->vdev);
-        video_set_drvdata(&dev->vdev, NULL);
-
-        if (dev->sio_bufs != NULL || dev->isobufs != NULL)
-                STK_ERROR("We are leaking memory\n");
-        usb_put_intf(dev->interface);
-        kfree(dev);
-}
-
-
 /*
  * Basic stuff
  */
@@ -694,8 +678,7 @@ static int v4l_stk_open(struct inode *inode, struct file *fp)
                 unlock_kernel();
                 return -ENXIO;
         }
-        fp->private_data = vdev;
-        kref_get(&dev->kref);
+        fp->private_data = dev;
         usb_autopm_get_interface(dev->interface);
         unlock_kernel();
 
@@ -704,23 +687,10 @@ static int v4l_stk_open(struct inode *inode, struct file *fp)
 
 static int v4l_stk_release(struct inode *inode, struct file *fp)
 {
-        struct stk_camera *dev;
-        struct video_device *vdev;
-
-        vdev = video_devdata(fp);
-        if (vdev == NULL) {
-                STK_ERROR("v4l_release called w/o video devdata\n");
-                return -EFAULT;
-        }
-        dev = vdev_to_camera(vdev);
-        if (dev == NULL) {
-                STK_ERROR("v4l_release called on removed device\n");
-                return -ENODEV;
-        }
+        struct stk_camera *dev = fp->private_data;
 
         if (dev->owner != fp) {
                 usb_autopm_put_interface(dev->interface);
-                kref_put(&dev->kref, stk_camera_cleanup);
                 return 0;
         }
 
@@ -731,7 +701,6 @@ static int v4l_stk_release(struct inode *inode, struct file *fp)
         dev->owner = NULL;
 
         usb_autopm_put_interface(dev->interface);
-        kref_put(&dev->kref, stk_camera_cleanup);
 
         return 0;
 }
@@ -742,14 +711,8 @@ static ssize_t v4l_stk_read(struct file *fp, char __user *buf,
         int i;
         int ret;
         unsigned long flags;
-        struct stk_camera *dev;
-        struct video_device *vdev;
         struct stk_sio_buffer *sbuf;
-
-        vdev = video_devdata(fp);
-        if (vdev == NULL)
-                return -EFAULT;
-        dev = vdev_to_camera(vdev);
+        struct stk_camera *dev = fp->private_data;
 
         if (dev == NULL)
                 return -EIO;
@@ -808,15 +771,8 @@ static ssize_t v4l_stk_read(struct file *fp, char __user *buf,
 
 static unsigned int v4l_stk_poll(struct file *fp, poll_table *wait)
 {
-        struct stk_camera *dev;
-        struct video_device *vdev;
-
-        vdev = video_devdata(fp);
-
-        if (vdev == NULL)
-                return -EFAULT;
+        struct stk_camera *dev = fp->private_data;
 
-        dev = vdev_to_camera(vdev);
         if (dev == NULL)
                 return -ENODEV;
 
@@ -854,16 +810,12 @@ static int v4l_stk_mmap(struct file *fp, struct vm_area_struct *vma)
         unsigned int i;
         int ret;
         unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
-        struct stk_camera *dev;
-        struct video_device *vdev;
+        struct stk_camera *dev = fp->private_data;
         struct stk_sio_buffer *sbuf = NULL;
 
         if (!(vma->vm_flags & VM_WRITE) || !(vma->vm_flags & VM_SHARED))
                 return -EINVAL;
 
-        vdev = video_devdata(fp);
-        dev = vdev_to_camera(vdev);
-
         for (i = 0; i < dev->n_sbufs; i++) {
                 if (dev->sio_bufs[i].v4lbuf.m.offset == offset) {
                         sbuf = dev->sio_bufs + i;
@@ -1359,6 +1311,12 @@ static const struct v4l2_ioctl_ops v4l_stk_ioctl_ops = {
 
 static void stk_v4l_dev_release(struct video_device *vd)
 {
+        struct stk_camera *dev = vdev_to_camera(vd);
+
+        if (dev->sio_bufs != NULL || dev->isobufs != NULL)
+                STK_ERROR("We are leaking memory\n");
+        usb_put_intf(dev->interface);
+        kfree(dev);
 }
 
 static struct video_device stk_v4l_data = {
@@ -1379,7 +1337,6 @@ static int stk_register_video_device(struct stk_camera *dev)
         dev->vdev = stk_v4l_data;
         dev->vdev.debug = debug;
         dev->vdev.parent = &dev->interface->dev;
-        video_set_drvdata(&dev->vdev, dev);
         err = video_register_device(&dev->vdev, VFL_TYPE_GRABBER, -1);
         if (err)
                 STK_ERROR("v4l registration failed\n");
@@ -1396,7 +1353,7 @@ static int stk_camera_probe(struct usb_interface *interface,
                 const struct usb_device_id *id)
 {
         int i;
-        int err;
+        int err = 0;
 
         struct stk_camera *dev = NULL;
         struct usb_device *udev = interface_to_usbdev(interface);
@@ -1409,7 +1366,6 @@ static int stk_camera_probe(struct usb_interface *interface,
                 return -ENOMEM;
         }
 
-        kref_init(&dev->kref);
         spin_lock_init(&dev->spinlock);
         init_waitqueue_head(&dev->wait_frame);
 
@@ -1442,8 +1398,8 @@ static int stk_camera_probe(struct usb_interface *interface,
         }
         if (!dev->isoc_ep) {
                 STK_ERROR("Could not find isoc-in endpoint");
-                kref_put(&dev->kref, stk_camera_cleanup);
-                return -ENODEV;
+                err = -ENODEV;
+                goto error;
         }
         dev->vsettings.brightness = 0x7fff;
         dev->vsettings.palette = V4L2_PIX_FMT_RGB565;
@@ -1457,14 +1413,17 @@ static int stk_camera_probe(struct usb_interface *interface,
 
         err = stk_register_video_device(dev);
         if (err) {
-                kref_put(&dev->kref, stk_camera_cleanup);
-                return err;
+                goto error;
         }
 
         stk_create_sysfs_files(&dev->vdev);
         usb_autopm_enable(dev->interface);
 
         return 0;
+
+error:
+        kfree(dev);
+        return err;
 }
 
 static void stk_camera_disconnect(struct usb_interface *interface)
@@ -1477,7 +1436,10 @@ static void stk_camera_disconnect(struct usb_interface *interface)
         wake_up_interruptible(&dev->wait_frame);
         stk_remove_sysfs_files(&dev->vdev);
 
-        kref_put(&dev->kref, stk_camera_cleanup);
+        STK_INFO("Syntek USB2.0 Camera release resources"
+                "video device /dev/video%d\n", dev->vdev.minor);
+
+        video_unregister_device(&dev->vdev);
 }
 
 #ifdef CONFIG_PM
diff --git a/drivers/media/video/stk-webcam.h b/drivers/media/video/stk-webcam.h
index df4dfefc5327..084a85bdd16e 100644
--- a/drivers/media/video/stk-webcam.h
+++ b/drivers/media/video/stk-webcam.h
@@ -99,7 +99,6 @@ struct stk_camera {
 
         u8 isoc_ep;
 
-        struct kref kref;
         /* Not sure if this is right */
         atomic_t urbs_used;
 
@@ -121,7 +120,6 @@ struct stk_camera {
         unsigned sequence;
 };
 
-#define to_stk_camera(d) container_of(d, struct stk_camera, kref)
 #define vdev_to_camera(d) container_of(d, struct stk_camera, vdev)
 
 void stk_camera_delete(struct kref *);