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authorHans Verkuil <hverkuil@xs4all.nl>2011-03-12 06:37:19 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-03-22 16:38:05 -0300
commitbedf8bcf6b4f90a6e31add3721a2e71877289381 (patch)
tree855560191d12dc9f21db59fca801c67f036b5167
parenta64bb4b7111e063154f97ff64dab03144cdfb5d9 (diff)
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[media] v4l2-device: add kref and a release function
The video_device struct has proper ref counting and its release function will be called when the last user releases it. But no such support was available for struct v4l2_device. This made it hard to determine when a USB driver can release the device if it has multiple device nodes. With one device node it is easy of course, since when the device node is released, the whole device can be released. This patch adds refcounting to v4l2_device. When registering device nodes the v4l2_device refcount will be increased, when releasing device nodes it will be decreased. The (optional) release function will be called when the last device node was released. Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
-rw-r--r--drivers/media/video/v4l2-dev.c10
-rw-r--r--drivers/media/video/v4l2-device.c16
-rw-r--r--include/media/v4l2-device.h11
3 files changed, 37 insertions, 0 deletions
diff --git a/drivers/media/video/v4l2-dev.c b/drivers/media/video/v4l2-dev.c
index 6b1ef85..1898099 100644
--- a/drivers/media/video/v4l2-dev.c
+++ b/drivers/media/video/v4l2-dev.c
@@ -143,6 +143,7 @@ static inline void video_put(struct video_device *vdev)
static void v4l2_device_release(struct device *cd)
{
struct video_device *vdev = to_video_device(cd);
+ struct v4l2_device *v4l2_dev = vdev->v4l2_dev;
mutex_lock(&videodev_lock);
if (video_device[vdev->minor] != vdev) {
@@ -169,6 +170,10 @@ static void v4l2_device_release(struct device *cd)
/* Release video_device and perform other
cleanups as needed. */
vdev->release(vdev);
+
+ /* Decrease v4l2_device refcount */
+ if (v4l2_dev)
+ v4l2_device_put(v4l2_dev);
}
static struct class video_class = {
@@ -676,6 +681,11 @@ int __video_register_device(struct video_device *vdev, int type, int nr,
if (nr != -1 && nr != vdev->num && warn_if_nr_in_use)
printk(KERN_WARNING "%s: requested %s%d, got %s\n", __func__,
name_base, nr, video_device_node_name(vdev));
+
+ /* Increase v4l2_device refcount */
+ if (vdev->v4l2_dev)
+ v4l2_device_get(vdev->v4l2_dev);
+
#if defined(CONFIG_MEDIA_CONTROLLER)
/* Part 5: Register the entity. */
if (vdev->v4l2_dev && vdev->v4l2_dev->mdev) {
diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index fd7a445..5aeaf87 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -37,6 +37,7 @@ int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
spin_lock_init(&v4l2_dev->lock);
mutex_init(&v4l2_dev->ioctl_lock);
v4l2_prio_init(&v4l2_dev->prio);
+ kref_init(&v4l2_dev->ref);
v4l2_dev->dev = dev;
if (dev == NULL) {
/* If dev == NULL, then name must be filled in by the caller */
@@ -54,6 +55,21 @@ int v4l2_device_register(struct device *dev, struct v4l2_device *v4l2_dev)
}
EXPORT_SYMBOL_GPL(v4l2_device_register);
+static void v4l2_device_release(struct kref *ref)
+{
+ struct v4l2_device *v4l2_dev =
+ container_of(ref, struct v4l2_device, ref);
+
+ if (v4l2_dev->release)
+ v4l2_dev->release(v4l2_dev);
+}
+
+int v4l2_device_put(struct v4l2_device *v4l2_dev)
+{
+ return kref_put(&v4l2_dev->ref, v4l2_device_release);
+}
+EXPORT_SYMBOL_GPL(v4l2_device_put);
+
int v4l2_device_set_name(struct v4l2_device *v4l2_dev, const char *basename,
atomic_t *instance)
{
diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h
index 3b72328..bd102cf 100644
--- a/include/media/v4l2-device.h
+++ b/include/media/v4l2-device.h
@@ -60,8 +60,19 @@ struct v4l2_device {
struct v4l2_prio_state prio;
/* BKL replacement mutex. Temporary solution only. */
struct mutex ioctl_lock;
+ /* Keep track of the references to this struct. */
+ struct kref ref;
+ /* Release function that is called when the ref count goes to 0. */
+ void (*release)(struct v4l2_device *v4l2_dev);
};
+static inline void v4l2_device_get(struct v4l2_device *v4l2_dev)
+{
+ kref_get(&v4l2_dev->ref);
+}
+
+int v4l2_device_put(struct v4l2_device *v4l2_dev);
+
/* Initialize v4l2_dev and make dev->driver_data point to v4l2_dev.
dev may be NULL in rare cases (ISA devices). In that case you
must fill in the v4l2_dev->name field before calling this function. */