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authorHans Verkuil <hverkuil@xs4all.nl>2011-01-08 09:38:02 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-03-22 16:37:58 -0300
commitdfddb2441f39e8c0254504516be35b854addf6fa (patch)
tree7fd4bade365e394e38aee0764adca945a5bf394d /drivers
parent73cb42068cff419e72456940c713ceb5efa68c2a (diff)
[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 <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/media/video/v4l2-fh.c14
1 files changed, 14 insertions, 0 deletions
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);