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

Stanislav Fomichev
2026-01-22T04:07:13Z

On 01/21, Jakub Kicinski wrote:
> On Wed, 21 Jan 2026 19:25:27 -0800 Bobby Eshleman wrote:
> > > > That is correct, neither is true. If the two sockets share a binding the
> > > > kernel doesn't care which socket received the token or which one
> > > > returned it. No token <> socket association. There is no
> > > > queued-but-not-read race either. If any tokens are not returned, as long
> > > > as all of the binding references are eventually released and all sockets
> > > > that used the binding are closed, then all references will be accounted
> > > > for and everything cleaned up.
> > >
> > > Naming is hard, but I wonder whether the whole feature wouldn't be
> > > better referred to as something to do with global token accounting
> > > / management? AUTORELEASE makes sense but seems like focusing on one
> > > particular side effect.
> >
> > Good point. The only real use case for autorelease=on is for backwards
> > compatibility... so I thought maybe DEVMEM_A_DMABUF_COMPAT_TOKEN
> > or DEVMEM_A_DMABUF_COMPAT_DONTNEED would be clearer?
>
> Hm. Maybe let's return to naming once we have consensus on the uAPI.
>
> Does everyone think that pushing this via TCP socket opts still makes
> sense, even tho in practice the TCP socket is just how we find the
> binding?

I'm not a fan of the existing cmsg scheme, but we already have userspace
using it, so getting more performance out of it seems like an easy win?