From bedf8bcf6b4f90a6e31add3721a2e71877289381 Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Sat, 12 Mar 2011 06:37:19 -0300 Subject: [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 Signed-off-by: Mauro Carvalho Chehab --- include/media/v4l2-device.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include') diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h index 3b723283da26..bd102cf509ac 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. */ -- cgit v1.2.2