rust: alloc: use kernel::{fmt,prelude::fmt!}

Reduce coupling to implementation details of the formatting machinery by
avoiding direct use for `core`'s formatting traits and macros.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/kernel/alloc/kbox.rs

@@ -7,7 +7,6 @@
 use super::{AllocError, Allocator, Flags};
 use core::alloc::Layout;
 use core::borrow::{Borrow, BorrowMut};
-use core::fmt;
 use core::marker::PhantomData;
 use core::mem::ManuallyDrop;
 use core::mem::MaybeUninit;
@@ -17,6 +16,7 @@
 use core::result::Result;
 
 use crate::ffi::c_void;
+use crate::fmt;
 use crate::init::InPlaceInit;
 use crate::types::ForeignOwnable;
 use pin_init::{InPlaceWrite, Init, PinInit, ZeroableOption};

rust/kernel/alloc/kvec.rs

@@ -7,9 +7,9 @@
     layout::ArrayLayout,
     AllocError, Allocator, Box, Flags,
 };
+use crate::fmt;
 use core::{
     borrow::{Borrow, BorrowMut},
-    fmt,
     marker::PhantomData,
     mem::{ManuallyDrop, MaybeUninit},
     ops::Deref,

rust/kernel/alloc/kvec/errors.rs

@@ -2,7 +2,7 @@
 
 //! Errors for the [`Vec`] type.
 
-use core::fmt::{self, Debug, Formatter};
+use kernel::fmt::{self, Debug, Formatter};
 use kernel::prelude::*;
 
 /// Error type for [`Vec::push_within_capacity`].