[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>
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@ -109,3 +109,17 @@ int v4l2_fh_release(struct file *filp)
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return 0;
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return 0;
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}
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}
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EXPORT_SYMBOL_GPL(v4l2_fh_release);
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EXPORT_SYMBOL_GPL(v4l2_fh_release);
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int v4l2_fh_is_singular(struct v4l2_fh *fh)
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{
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unsigned long flags;
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int is_singular;
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if (fh == NULL || fh->vdev == NULL)
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return 0;
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spin_lock_irqsave(&fh->vdev->fh_lock, flags);
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is_singular = list_is_singular(&fh->list);
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spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
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return is_singular;
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}
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EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);
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@ -77,5 +77,18 @@ void v4l2_fh_exit(struct v4l2_fh *fh);
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* v4l2_fh struct) is NULL. This function always returns 0.
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* v4l2_fh struct) is NULL. This function always returns 0.
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*/
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*/
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int v4l2_fh_release(struct file *filp);
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int v4l2_fh_release(struct file *filp);
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/*
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* Returns 1 if this filehandle is the only filehandle opened for the
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* associated video_device. If fh is NULL, then it returns 0.
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*/
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int v4l2_fh_is_singular(struct v4l2_fh *fh);
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/*
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* Helper function with struct file as argument. If filp->private_data is
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* NULL, then it will return 0.
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*/
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static inline int v4l2_fh_is_singular_file(struct file *filp)
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{
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return v4l2_fh_is_singular(filp->private_data);
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}
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#endif /* V4L2_EVENT_H */
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#endif /* V4L2_EVENT_H */
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