Re: [PATCH net-next v10 4/5] net: devmem: document NETDEV_A_DMABUF_AUTORELEASE netlink attribute

[Bobby Eshleman <bobbyeshleman@gmail.com>]

On Mon, Jan 26, 2026 at 07:43:59PM -0800, Jakub Kicinski wrote:
> On Mon, 26 Jan 2026 19:06:49 -0800 Bobby Eshleman wrote:
> > > > Then, if the dmabuf count encoding space is exhausted, the socket would
> > > > have to wait until the user returns all of the tokens from one of the
> > > > dmabufs and frees the ID (or err out is another option).
> > > > 
> > > > This wouldn't change adding a field to the socket, we'd have to add one
> > > > or two more for allocating the dmabuf ID and fetching the dmabuf with
> > > > it. But it does fix the single binding thing.  
> > > 
> > > I think the bigger problem (than space exhaustion) is that we'd also
> > > have some understanding of permissions. If an application guesses 
> > > the binding ID of another app it can mess up its buffers. ENOBUENO..  
> > 
> > I was thinking it would be per-socket, effectively:
> > 
> > sk->sk_devmem_info.bindings[binding_id_from_token(token)]
> > 
> > So sockets could only access those that they have already recv'd on.
> 
> Ah, missed that the array would be per socket. I guess it'd have to be
> reusing the token xarray otherwise we're taking up even more space in
> the socket struct? Dunno.

Yeah, unless we just want to break this all off into a malloc'd struct
we point to... or put into tcp_sock (not sure if either addresses the
unappealing bit of adding to struct sock)?