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Commit 5062cb70 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
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V4L/DVB (12724): v4l2-dev: add simple wrapper functions around the devnode numbers 



There are some subtle differences in the way the devnode numbers are
handled depending on whether the FIXED_MINOR_RANGES config option is
set. Add some simple wrapper functions to handle that correctly.

Signed-off-by: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 581644d9

drivers/media/video/v4l2-dev.c

+48 −5
Original line number Diff line number Diff line
@@ -68,6 +68,48 @@ static struct video_device *video_device[VIDEO_NUM_DEVICES]; 
static DEFINE_MUTEX(videodev_lock);

static DECLARE_BITMAP(devnode_nums[VFL_TYPE_MAX], VIDEO_NUM_DEVICES);



/* Device node utility functions */



/* Note: these utility functions all assume that vfl_type is in the range

   [0, VFL_TYPE_MAX-1]. */



#ifdef CONFIG_VIDEO_FIXED_MINOR_RANGES

/* Return the bitmap corresponding to vfl_type. */

static inline unsigned long *devnode_bits(int vfl_type)

{

	/* Any types not assigned to fixed minor ranges must be mapped to

	   one single bitmap for the purposes of finding a free node number

	   since all those unassigned types use the same minor range. */

	int idx = (vfl_type > VFL_TYPE_VTX) ? VFL_TYPE_MAX - 1 : vfl_type;



	return devnode_nums[idx];

}

#else

/* Return the bitmap corresponding to vfl_type. */

static inline unsigned long *devnode_bits(int vfl_type)

{

	return devnode_nums[vfl_type];

}

#endif



/* Mark device node number vdev->num as used */

static inline void devnode_set(struct video_device *vdev)

{

	set_bit(vdev->num, devnode_bits(vdev->vfl_type));

}



/* Mark device node number vdev->num as unused */

static inline void devnode_clear(struct video_device *vdev)

{

	clear_bit(vdev->num, devnode_bits(vdev->vfl_type));

}



/* Try to find a free device node number in the range [from, to> */

static inline int devnode_find(struct video_device *vdev, int from, int to)

{

	return find_next_zero_bit(devnode_bits(vdev->vfl_type), to, from);

}



struct video_device *video_device_alloc(void)

{

	return kzalloc(sizeof(struct video_device), GFP_KERNEL);
@@ -120,7 +162,7 @@ static void v4l2_device_release(struct device *cd) 
	vdev->cdev = NULL;



	/* Mark device node number as free */

	clear_bit(vdev->num, devnode_nums[vdev->vfl_type]);

	devnode_clear(vdev);



	mutex_unlock(&videodev_lock);
@@ -435,9 +477,9 @@ int video_register_device(struct video_device *vdev, int type, int nr) 


	/* Pick a device node number */

	mutex_lock(&videodev_lock);

	nr = find_next_zero_bit(devnode_nums[type], minor_cnt, nr == -1 ? 0 : nr);

	nr = devnode_find(vdev, nr == -1 ? 0 : nr, minor_cnt);

	if (nr == minor_cnt)

		nr = find_first_zero_bit(devnode_nums[type], minor_cnt);

		nr = devnode_find(vdev, 0, minor_cnt);

	if (nr == minor_cnt) {

		printk(KERN_ERR "could not get a free device node number\n");

		mutex_unlock(&videodev_lock);
@@ -460,7 +502,8 @@ int video_register_device(struct video_device *vdev, int type, int nr) 
#endif

	vdev->minor = i + minor_offset;

	vdev->num = nr;

	set_bit(nr, devnode_nums[type]);

	devnode_set(vdev);



	/* Should not happen since we thought this minor was free */

	WARN_ON(video_device[vdev->minor] != NULL);

	vdev->index = get_index(vdev);
@@ -514,7 +557,7 @@ cleanup: 
	mutex_lock(&videodev_lock);

	if (vdev->cdev)

		cdev_del(vdev->cdev);

	clear_bit(vdev->num, devnode_nums[type]);

	devnode_clear(vdev);

	mutex_unlock(&videodev_lock);

	/* Mark this video device as never having been registered. */

	vdev->minor = -1;