rust: kernel: remove redundant imports

Rust's `unused_imports` lint covers both unused and redundant imports.
In the upcoming 1.78.0, the lint detects more cases of redundant imports
[1], e.g.:

error: the item `bindings` is imported redundantly
--> rust/kernel/print.rs:38:9
|
38 | use crate::bindings;
| ^^^^^^^^^^^^^^^ the item `bindings` is already defined by prelude

Most cases are `use crate::bindings`, plus a few other items like `Box`.
Thus clean them up.

Note that, in the `bindings` case, the message "defined by prelude"
above means the extern prelude, i.e. the `--extern` flags we pass.

Link: https://github.com/rust-lang/rust/pull/117772 [1]
Reviewed-by: Alice Ryhl <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Miguel Ojeda <[e-mail]>

rust/kernel/alloc.rs

···
 /// These are meant to be used in functions that can allocate memory.
 pub mod flags {
     use super::Flags;
-    use crate::bindings;
 
     /// Zeroes out the allocated memory.
     ///

rust/kernel/alloc/allocator.rs

···
 use core::alloc::{GlobalAlloc, Layout};
 use core::ptr;
 
-use crate::bindings;
-
 struct KernelAllocator;
 
 /// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment.

rust/kernel/alloc/box_ext.rs

···
 use super::{AllocError, Flags};
 use alloc::boxed::Box;
 use core::mem::MaybeUninit;
-use core::result::Result;
 
 /// Extensions to [`Box`].
 pub trait BoxExt<T>: Sized {

rust/kernel/alloc/vec_ext.rs

···
 
 use super::{AllocError, Flags};
 use alloc::vec::Vec;
-use core::result::Result;
 
 /// Extensions to [`Vec`].
 pub trait VecExt<T>: Sized {

rust/kernel/error.rs

···
 
 use alloc::alloc::LayoutError;
 
-use core::convert::From;
 use core::fmt;
 use core::num::TryFromIntError;
 use core::str::Utf8Error;

rust/kernel/net/phy.rs

···
 //!
 //! C headers: [`include/linux/phy.h`](srctree/include/linux/phy.h).
 
-use crate::{bindings, error::*, prelude::*, str::CStr, types::Opaque};
+use crate::{error::*, prelude::*, types::Opaque};
 
 use core::marker::PhantomData;
 

rust/kernel/print.rs

···
 
 use crate::str::RawFormatter;
 
-#[cfg(CONFIG_PRINTK)]
-use crate::bindings;
-
 // Called from `vsprintf` with format specifier `%pA`.
 #[no_mangle]
 unsafe extern "C" fn rust_fmt_argument(
···
 /// Public but hidden since it should only be used from public macros.
 #[doc(hidden)]
 pub mod format_strings {
-    use crate::bindings;
-
     /// The length we copy from the `KERN_*` kernel prefixes.
     const LENGTH_PREFIX: usize = 2;
 

rust/kernel/str.rs

···
 use core::fmt::{self, Write};
 use core::ops::{self, Deref, DerefMut, Index};
 
-use crate::{
-    bindings,
-    error::{code::*, Error},
-};
+use crate::error::{code::*, Error};
 
 /// Byte string without UTF-8 validity guarantee.
 #[repr(transparent)]

rust/kernel/sync/arc.rs

···
 
 use crate::{
     alloc::{box_ext::BoxExt, AllocError, Flags},
-    bindings,
     error::{self, Error},
     init::{self, InPlaceInit, Init, PinInit},
     try_init,

rust/kernel/sync/condvar.rs

···
 
 use super::{lock::Backend, lock::Guard, LockClassKey};
 use crate::{
-    bindings,
     init::PinInit,
     pin_init,
     str::CStr,

rust/kernel/sync/lock.rs

···
 //! spinlocks, raw spinlocks) to be provided with minimal effort.
 
 use super::LockClassKey;
-use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque, types::ScopeGuard};
+use crate::{init::PinInit, pin_init, str::CStr, types::Opaque, types::ScopeGuard};
 use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned};
 use macros::pin_data;
 

rust/kernel/sync/lock/mutex.rs

···
 //!
 //! This module allows Rust code to use the kernel's `struct mutex`.
 
-use crate::bindings;
-
 /// Creates a [`Mutex`] initialiser with the given name and a newly-created lock class.
 ///
 /// It uses the name if one is given, otherwise it generates one based on the file name and line

rust/kernel/sync/lock/spinlock.rs

···
 //!
 //! This module allows Rust code to use the kernel's `spinlock_t`.
 
-use crate::bindings;
-
 /// Creates a [`SpinLock`] initialiser with the given name and a newly-created lock class.
 ///
 /// It uses the name if one is given, otherwise it generates one based on the file name and line

rust/kernel/task.rs

···
 //!
 //! C header: [`include/linux/sched.h`](srctree/include/linux/sched.h).
 
-use crate::{bindings, types::Opaque};
+use crate::types::Opaque;
 use core::{
     ffi::{c_int, c_long, c_uint},
     marker::PhantomData,

rust/kernel/workqueue.rs

···
 //! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h)
 
 use crate::alloc::{AllocError, Flags};
-use crate::{bindings, prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
-use alloc::boxed::Box;
+use crate::{prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
 use core::marker::PhantomData;
-use core::pin::Pin;
 
 /// Creates a [`Work`] initialiser with the given name and a newly-created lock class.
 #[macro_export]