On Fri Oct 17, 2025 at 4:12 AM CEST, Alexandre Courbot wrote: > On Thu Oct 16, 2025 at 9:55 PM JST, Danilo Krummrich wrote: >> The driver model defines the lifetime of the private data stored in (and >> owned by) a bus device to be valid from when the driver is bound to a
>> device (i.e. from successful probe()) until the driver is unbound from >> the device. >> >> This is already taken care of by the Rust implementation of the driver >> model. However, we still ask drivers to return a Result<Pin<KBox<Self>>> >> from probe(). >> >> Unlike in C, where we do not have the concept of initializers, but >> rather deal with uninitialized memory, drivers can just return an >> impl PinInit<Self, Error> instead. >> >> This contributed to more clarity to the fact that a driver returns it's > > nit: s/it's/its > >> device private data in probe() and the Rust driver model owns the data, >> manages the lifetime and - considering the lifetime - provides (safe) >> accessors for the driver. >> >> Hence, let probe() functions return an impl PinInit<Self, Error> instead >> of Result<Pin<KBox<Self>>>. >> >> Signed-off-by: Danilo Krummrich <[email protected]> > > Short anecdote: I was curious about measuring the footprint impact of > pin initializers, so I did a `size vmlinux` before and after this patch > to compare the size of the `text` section. This patch removes exactly 60 > bytes of binary code, which I guess corresponds to the duplicated `KBox` > allocations that are now gone. It's great to confirm once again how Rust > abstractions are indeed zero-overhead! :) Thanks for the test! If you find that at any point they aren't, let me know, then we can fix that :) --- Cheers, Benno
