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| author | Hans Verkuil <hverkuil@xs4all.nl> | 2011-01-08 13:38:02 +0100 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2011-03-22 20:37:58 +0100 |
| commit | dfddb2441f39e8c0254504516be35b854addf6fa (patch) | |
| tree | 7fd4bade365e394e38aee0764adca945a5bf394d | |
| parent | [media] v4l2-fh: add v4l2_fh_open and v4l2_fh_release helper functions (diff) | |
| download | linux-dfddb2441f39e8c0254504516be35b854addf6fa.tar.xz linux-dfddb2441f39e8c0254504516be35b854addf6fa.zip | |
[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>
| -rw-r--r-- | drivers/media/video/v4l2-fh.c | 14 | ||||
| -rw-r--r-- | include/media/v4l2-fh.h | 13 |
2 files changed, 27 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); diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h index 5657881cd44e..0206aa55be24 100644 --- a/include/media/v4l2-fh.h +++ b/include/media/v4l2-fh.h @@ -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 */ |