Re: [PATCH v1 14/30] io_uring: add release callback for ring death

[Joanne Koong <joannelkoong@gmail.com>]

On Wed, Dec 3, 2025 at 2:25 PM Caleb Sander Mateos
<csander@purestorage.com> wrote:
>
> On Tue, Dec 2, 2025 at 4:36 PM Joanne Koong <joannelkoong@gmail.com> wrote:
> >
> > Allow registering a release callback on a ring context that will be
> > called when the ring is about to be destroyed.
> >
> > This is a preparatory patch for fuse. Fuse will be pinning buffers and
> > registering bvecs, which requires cleanup whenever a server
> > disconnects. It needs to know if the ring is alive when the server has
> > disconnected, to avoid double-freeing or accessing invalid memory.
> >
> > Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> > ---
> >  include/linux/io_uring.h       |  9 +++++++++
> >  include/linux/io_uring_types.h |  2 ++
> >  io_uring/io_uring.c            | 15 +++++++++++++++
> >  3 files changed, 26 insertions(+)
> >
> > diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
> > index 85fe4e6b275c..327fd8ac6e42 100644
> >
> > +void io_uring_set_release_callback(struct io_ring_ctx *ctx,
> > +                                  void (*release)(void *), void *priv,
> > +                                  unsigned int issue_flags)
> > +{
> > +       io_ring_submit_lock(ctx, issue_flags);
> > +
> > +       ctx->release = release;
> > +       ctx->priv = priv;
>
> Looks like this doesn't support the registration of multiple release
> callbacks. Should there be a WARN_ON() to that effect?

Great idea, I'll add that in for v2.

Thanks,
Joanne
>
> Best,
> Caleb