Commit dfddb244 authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
Browse files

[media] v4l2-fh: add v4l2_fh_is_singular 



Several drivers need to do something when the first filehandle is opened
or the last filehandle is closed. Most implement some use count mechanism,
but if they use v4l2_fh, then you can also just check if this is the only
filehandle for the device node. A simple helper function can do this.

Signed-off-by: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 73cb4206

drivers/media/video/v4l2-fh.c

+14 −0
Original line number Diff line number Diff line
@@ -109,3 +109,17 @@ int v4l2_fh_release(struct file *filp) 
	return 0;

}

EXPORT_SYMBOL_GPL(v4l2_fh_release);



int v4l2_fh_is_singular(struct v4l2_fh *fh)

{

	unsigned long flags;

	int is_singular;



	if (fh == NULL || fh->vdev == NULL)

		return 0;

	spin_lock_irqsave(&fh->vdev->fh_lock, flags);

	is_singular = list_is_singular(&fh->list);

	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);

	return is_singular;

}

EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);

include/media/v4l2-fh.h

+13 −0
Original line number Diff line number Diff line
@@ -77,5 +77,18 @@ void v4l2_fh_exit(struct v4l2_fh *fh); 
 * v4l2_fh struct) is NULL. This function always returns 0.

 */

int v4l2_fh_release(struct file *filp);

/*

 * Returns 1 if this filehandle is the only filehandle opened for the

 * associated video_device. If fh is NULL, then it returns 0.

 */

int v4l2_fh_is_singular(struct v4l2_fh *fh);

/*

 * Helper function with struct file as argument. If filp->private_data is

 * NULL, then it will return 0.

 */

static inline int v4l2_fh_is_singular_file(struct file *filp)

{

	return v4l2_fh_is_singular(filp->private_data);

}



#endif /* V4L2_EVENT_H */

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