From dfddb2441f39e8c0254504516be35b854addf6fa Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Sat, 8 Jan 2011 09:38:02 -0300 Subject: [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: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/v4l2-fh.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'drivers/media') diff --git a/drivers/media/video/v4l2-fh.c b/drivers/media/video/v4l2-fh.c index 27242e5ca431..543b3fe6784e 100644 --- a/drivers/media/video/v4l2-fh.c +++ b/drivers/media/video/v4l2-fh.c @@ -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); -- cgit v1.2.2