Re: [PATCH 2/2] rust: driver core: remove drvdata() and driver_type

[Alice Ryhl <aliceryhl@google.com>]

On Tue, Apr 28, 2026 at 12:09:41AM +0200, Danilo Krummrich wrote:
> When drvdata() was introduced in commit 6f61a2637abe ("rust: device:
> introduce Device::drvdata()"), its commit message already noted that a
> direct accessor to the driver's bus device private data is not commonly
> required -- bus callbacks provide access through &self, and other entry
> points (IRQs, workqueues, IOCTLs, etc.) carry their own private data.
> 
> The sole motivation for drvdata() was inter-driver interaction -- an
> auxiliary driver deriving the parent's bus device private data from the
> parent device.
> 
> However, drvdata() exposes the driver's bus device private data beyond
> the driver's own scope. This creates ordering constraints; for instance
> drvdata may not be set yet when the first caller of drvdata() can
> appear. It also forces the driver's bus device private data to outlive
> all registrations that access it, which causes unnecessary
> complications.
> 
> Private data should be private to the entity that issues it, i.e. bus
> device private data belongs to bus callbacks, class device private data
> to class callbacks, IRQ private data to the IRQ handler, etc.
> 
> With registration-private data now available through the auxiliary bus,
> there is no remaining user of drvdata(), thus remove it.
> 
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>