On Sun, Apr 13, 2025 at 07:36:55PM +0200, Danilo Krummrich wrote: > Currently, we do not ensure that APIs that require a bound device instance can > only be called with a bound device. > > Examples of such APIs are Devres, dma::CoherentAllocation and > pci::Device::iomap_region(). > > This patch series introduces the "Bound" device context such that we can ensure > to only ever pass a bound device to APIs that require this precondition. > > In order to get there, we need some prerequisites: > > (1) Implement macros to consistently derive Deref implementations for the > different device contexts. For instance, Device<Core> can be dereferenced to > Device<Bound>, since all device references we get from "core" bus callbacks > are guaranteed to be from a bound device. Device<Bound> can always be > dereferenced to Device (i.e. Device<Normal>), since the "Normal" device > context has no specific requirements. > > (2) Implement device context support for the generic Device type. Some APIs such > as Devres and dma::CoherentAllocation work with generic devices. > > (3) Preserve device context generics in bus specific device' AsRef > implementation, such that we can derive the device context when converting > from a bus specific device reference to a generic device reference. > > With this, Devres::new(), for instance, can take a &Device<Bound> argument and > hence ensure that it can't be called with a Device reference that is not > guaranteed to be bound to a driver. > > A branch containing the patches can be found in [1]. > > [1] https://web.git.kernel.org/pub/scm/linux/kernel/git/dakr/linux.git/log/?h=rust/device-bound With the following changes, applied to driver-core/topic/device-context, thanks! * Add missing `::` prefix in macros. * Fix typos pointed out by Bjorn. - Danilo
