On Thu, Apr 17, 2025 at 12:48 PM Boqun Feng <boqun.f...@gmail.com> wrote:
>
> On Wed, Apr 16, 2025 at 01:36:05PM -0400, Tamir Duberstein wrote:
> > In Rust 1.51.0, Clippy introduced the `ptr_as_ptr` lint [1]:
> >
> > > Though `as` casts between raw pointers are not terrible,
> > > `pointer::cast` is safer because it cannot accidentally change the
> > > pointer's mutability, nor cast the pointer to other types like `usize`.
> >
> > There are a few classes of changes required:
> > - Modules generated by bindgen are marked
> > `#[allow(clippy::ptr_as_ptr)]`.
> > - Inferred casts (` as _`) are replaced with `.cast()`.
> > - Ascribed casts (` as *... T`) are replaced with `.cast::<T>()`.
> > - Multistep casts from references (` as *const _ as *const T`) are
> > replaced with `core::ptr::from_ref(&x).cast()` with or without `::<T>`
> > according to the previous rules. The `core::ptr::from_ref` call is
> > required because `(x as *const _).cast::<T>()` results in inference
> > failure.
> > - Native literal C strings are replaced with `c_str!().as_char_ptr()`.
> > - `*mut *mut T as _` is replaced with `let *mut *const T = (*mut *mut
> > T)`.cast();` since pointer to pointer can be confusing.
> >
> > Apply these changes and enable the lint -- no functional change
> > intended.
> >
> > Link: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_as_ptr
> > [1]
> > Reviewed-by: Benno Lossin <benno.los...@proton.me>
> > Signed-off-by: Tamir Duberstein <tam...@gmail.com>
>
> Reviewed-by: Boqun Feng <boqun.f...@gmail.com>
Thanks!
> A few nits below though...
>
> > ---
> > Makefile | 1 +
> > rust/bindings/lib.rs | 1 +
> > rust/kernel/alloc/allocator_test.rs | 2 +-
> > rust/kernel/alloc/kvec.rs | 4 ++--
> > rust/kernel/device.rs | 4 ++--
> > rust/kernel/devres.rs | 2 +-
> > rust/kernel/dma.rs | 4 ++--
> > rust/kernel/error.rs | 2 +-
> > rust/kernel/firmware.rs | 3 ++-
> > rust/kernel/fs/file.rs | 2 +-
> > rust/kernel/kunit.rs | 11 +++++++----
> > rust/kernel/list/impl_list_item_mod.rs | 2 +-
> > rust/kernel/pci.rs | 2 +-
> > rust/kernel/platform.rs | 4 +++-
> > rust/kernel/print.rs | 6 +++---
> > rust/kernel/seq_file.rs | 2 +-
> > rust/kernel/str.rs | 2 +-
> > rust/kernel/sync/poll.rs | 2 +-
> > rust/kernel/time/hrtimer/pin.rs | 2 +-
> > rust/kernel/time/hrtimer/pin_mut.rs | 2 +-
> > rust/kernel/workqueue.rs | 10 +++++-----
> > rust/uapi/lib.rs | 1 +
> > 22 files changed, 40 insertions(+), 31 deletions(-)
> >
> [...]
> > diff --git a/rust/kernel/list/impl_list_item_mod.rs
> > b/rust/kernel/list/impl_list_item_mod.rs
> > index a0438537cee1..1f9498c1458f 100644
> > --- a/rust/kernel/list/impl_list_item_mod.rs
> > +++ b/rust/kernel/list/impl_list_item_mod.rs
> > @@ -34,7 +34,7 @@ pub unsafe trait HasListLinks<const ID: u64 = 0> {
> > unsafe fn raw_get_list_links(ptr: *mut Self) -> *mut ListLinks<ID> {
> > // SAFETY: The caller promises that the pointer is valid. The
> > implementer promises that the
> > // `OFFSET` constant is correct.
> > - unsafe { (ptr as *mut u8).add(Self::OFFSET) as *mut ListLinks<ID> }
> > + unsafe { ptr.cast::<u8>().add(Self::OFFSET).cast() }
>
> I think we better do:
>
> unsafe { ptr.byte_add(Self::OFFSET).cast() }
>
> here, similar for a few instances below. Maybe in a follow-up patch?
> byte_add() is way more clear about what is done here.
This code is deleted in
https://lore.kernel.org/all/20250409-list-no-offset-v2-4-0bab7e3c9...@gmail.com/,
which could also use a review!
Cheers.
Tamir
