Re: [PATCH 1/2] kernfs: add kernfs_ops.free operation to free resources tied to the file

Christian Brauner
2023-06-27T08:24:15Z

On Mon, Jun 26, 2023 at 10:31:49AM -1000, Tejun Heo wrote:
> On Mon, Jun 26, 2023 at 01:17:12PM -0700, Suren Baghdasaryan wrote:
> > diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
> > index 73f5c120def8..a7e404ff31bb 100644
> > --- a/include/linux/kernfs.h
> > +++ b/include/linux/kernfs.h
> > @@ -273,6 +273,11 @@ struct kernfs_ops {
> > */
> > int (*open)(struct kernfs_open_file *of);
> > void (*release)(struct kernfs_open_file *of);
> > + /*
> > + * Free resources tied to the lifecycle of the file, like a
> > + * waitqueue used for polling.
> > + */
> > + void (*free)(struct kernfs_open_file *of);
>
> I think this can use a bit more commenting - ie. explain that release may be
> called earlier than the actual freeing of the file and how that can lead to
> problems. Othre than that, looks fine to me.

It seems the more natural thing to do would be to introduce a ->drain()
operation and order it before ->release(), no?