On Thu, Oct 23, 2025 at 06:20:02PM +0200, Danilo Krummrich wrote: > On Thu Oct 23, 2025 at 5:57 PM CEST, Jason Gunthorpe wrote: > > IMHO the rust code does it principally because the sync unregister > > life cycle model does not fit naturally into rust. > > That's not the case. > > In fact, we try to give as much "sync" guarantees as possible. For instance, > when a driver registers an IRQ the irq::Registration API enforces that the IRQ > is unregistered before the registering device is unbound. > > As a consequence, the IRQ callback can provide a &Device<Bound>, which acts > as a > "cookie" that proves that for this scope (IRQ callback) the device is > guaranteed > to be bound. > > With this "cookie" we can then directly access device resources (such as I/O > memory) that is within a Devres (and hence a Revocable) container directly, > *without* any locking. I.e. we can safely bypass the Revocable and hence its > overhead.
It is good news to hear it, but I think you are making the point I was trying to make. In rust if you have a Device<bound> and you skip the revocable locking, I'd argue that you don't need "revocable" at all, just enforcement of a Device<bound>. IOW the presence of revocable in rust, with all the locking, is because the sync life cycle model is not available. Sounds like the idea is that the sync model will be widely available and the revocable lock will rarely be used? Jason
