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 <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Signed-off-by: Tamir Duberstein <[email protected]>
Acked-by: Viresh Kumar <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Acked-by: Danilo Krummrich <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Added `.cast()` for `opp`. - Miguel ]
Signed-off-by: Miguel Ojeda <[email protected]>

In Rust 1.72.0, Clippy introduced the `ptr_cast_constness` lint [1]:

> Though `as` casts between raw pointers are not terrible,
> `pointer::cast_mut` and `pointer::cast_const` are safer because they
> cannot accidentally cast the pointer to another type.

There are only 3 affected sites:
- `*mut T as *const U as *mut U` becomes `(*mut T).cast()`.
- `&self as *const Self as *mut Self` becomes
  `core::ptr::from_ref(self).cast_mut()`.
- `*const T as *mut _` becommes `(*const T).cast_mut()`.

Apply these changes and enable the lint -- no functional change
intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_cast_constness [1]
Reviewed-by: Benno Lossin <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Signed-off-by: Tamir Duberstein <[email protected]>
Acked-by: Danilo Krummrich <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>

In Rust 1.66.0, Clippy introduced the `as_ptr_cast_mut` lint [1]:

> Since `as_ptr` takes a `&self`, the pointer won’t have write
> permissions unless interior mutability is used, making it unlikely
> that having it as a mutable pointer is correct.

There is only one affected callsite, and the change amounts to replacing
`as _` with `.cast_mut().cast()`. This doesn't change the semantics, but
is more descriptive of what's going on.

Apply this change and enable the lint -- no functional change intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#as_ptr_cast_mut [1]
Reviewed-by: Benno Lossin <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Signed-off-by: Tamir Duberstein <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Acked-by: Danilo Krummrich <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>

In Rust 1.63.0, Clippy introduced the `as_underscore` lint [1]:

> The conversion might include lossy conversion or a dangerous cast that
> might go undetected due to the type being inferred.
>
> The lint is allowed by default as using `_` is less wordy than always
> specifying the type.

Always specifying the type is especially helpful in function call
contexts where the inferred type may change at a distance. Specifying
the type also allows Clippy to spot more cases of `useless_conversion`.

The primary downside is the need to specify the type in trivial getters.
There are 4 such functions: 3 have become slightly less ergonomic, 1 was
revealed to be a `useless_conversion`.

While this doesn't eliminate unchecked `as` conversions, it makes such
conversions easier to scrutinize.  It also has the slight benefit of
removing a degree of freedom on which to bikeshed. Thus apply the
changes and enable the lint -- no functional change intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#as_underscore [1]
Reviewed-by: Benno Lossin <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Signed-off-by: Tamir Duberstein <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Acked-by: Danilo Krummrich <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Changed `isize` to `c_long`. - Miguel ]
Signed-off-by: Miguel Ojeda <[email protected]>

Before Rust 1.29.0, Clippy introduced the `cast_lossless` lint [1]:

> Rust’s `as` keyword will perform many kinds of conversions, including
> silently lossy conversions. Conversion functions such as `i32::from`
> will only perform lossless conversions. Using the conversion functions
> prevents conversions from becoming silently lossy if the input types
> ever change, and makes it clear for people reading the code that the
> conversion is lossless.

While this doesn't eliminate unchecked `as` conversions, it makes such
conversions easier to scrutinize.  It also has the slight benefit of
removing a degree of freedom on which to bikeshed. Thus apply the
changes and enable the lint -- no functional change intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#cast_lossless [1]
Suggested-by: Benno Lossin <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
Reviewed-by: Benno Lossin <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Signed-off-by: Tamir Duberstein <[email protected]>
Acked-by: FUJITA Tomonori <[email protected]>
Acked-by: Jocelyn Falempe <[email protected]>
Acked-by: Danilo Krummrich <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>

In Rust 1.78.0, Clippy introduced the `ref_as_ptr` lint [1]:

> Using `as` casts may result in silently changing mutability or type.

While this doesn't eliminate unchecked `as` conversions, it makes such
conversions easier to scrutinize.  It also has the slight benefit of
removing a degree of freedom on which to bikeshed. Thus apply the
changes and enable the lint -- no functional change intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#ref_as_ptr [1]
Suggested-by: Benno Lossin <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
Reviewed-by: Benno Lossin <[email protected]>
Reviewed-by: Boqun Feng <[email protected]>
Signed-off-by: Tamir Duberstein <[email protected]>
Acked-by: Danilo Krummrich <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>

Remove `use core::ffi::c_void`, which shadows `kernel::ffi::c_void`
brought in via `use crate::prelude::*`, to maintain consistency and
centralize the abstraction.

Since `kernel::ffi::c_void` is a straightforward re-export of
`core::ffi::c_void`, both are functionally equivalent. However, using
`kernel::ffi::c_void` improves consistency across the kernel's Rust code
and provides a unified reference point in case the definition ever needs
to change, even if such a change is unlikely.

Reviewed-by: Benno Lossin <[email protected]>
Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089/topic/x/near/520452733
Signed-off-by: Jesung Yang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>

Using `unwrap()` in kernel doctests can cause panics on error and may
give newcomers the mistaken impression that panicking is acceptable
in kernel code.

Replace all `.unwrap()` calls in `kernel::list`
examples with `.ok_or(EINVAL)?` so that errors are properly propagated.

Suggested-by: Miguel Ojeda <[email protected]>
Link: Rust-for-Linux#1164
Reviewed-by: Benno Lossin <[email protected]>
Signed-off-by: Albin Babu Varghese <[email protected]>
Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Danilo Krummrich <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <[email protected]>

Commit 38559da ("rust: module: introduce `authors` key") introduced
a new `authors` key to support multiple module authors, while keeping
the old `author` key for backward compatibility.

Now that most in-tree modules have migrated to `authors`, remove:
1. The deprecated `author` key support from the module macro
2. Legacy `author` entries from remaining modules

Signed-off-by: Guilherme Giacomo Simoes <[email protected]>
Acked-by: Andreas Hindborg <[email protected]>
Reviewed-by: Benno Lossin <[email protected]>
Acked-by: Danilo Krummrich <[email protected]>
Acked-by: Viresh Kumar <[email protected]>
Acked-by: Greg Kroah-Hartman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <[email protected]>

Use a consistent `# Examples` heading in rustdoc across the codebase.

Some modules previously used `## Examples` (even when they should be
available as top-level headers), while others used `# Example`, which
deviates from the preferred `# Examples` style.

Suggested-by: Miguel Ojeda <[email protected]>
Signed-off-by: Viresh Kumar <[email protected]>
Acked-by: Benno Lossin <[email protected]>
Link: https://lore.kernel.org/r/ddd5ce0ac20c99a72a4f1e4322d3de3911056922.1749545815.git.viresh.kumar@linaro.org
Signed-off-by: Miguel Ojeda <[email protected]>

Removed reference to internal variables in the comment of `IoMem`
This avoids using private variable names in public documentation.

Suggested-by: Miguel Ojeda <[email protected]>
Link: Rust-for-Linux#1167
Signed-off-by: Sai Vishnu M <[email protected]>
Reviewed-by: Benno Lossin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Reworded title and adjusted tags. - Miguel ]
Signed-off-by: Miguel Ojeda <[email protected]>

In Rust Binder I need to be able to determine whether a red/black tree
is empty. Thus, add a method for that operation to replace

	rbtree.iter().next().is_none()

This is terrible, so add a method for this purpose. We do not add a
RBTree::len method because computing the number of elements requires
iterating the entire tree, but checking whether it is empty can be done
cheaply.

Signed-off-by: Alice Ryhl <[email protected]>
Reviewed-by: Benno Lossin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Adjusted title. - Miguel ]
Signed-off-by: Miguel Ojeda <[email protected]>

When a reference appears in a function argument, the reference is
assumed to be valid for the entire duration of that function call; this
is called a stack protector [1]. Because of that, custom pointer types
whose destructor may invalidate the pointee (i.e. they are more similar
to Box<T> than &T) cannot internally use a reference, and must instead
use a raw pointer.

This issue is something that is often missed during unsafe review. For
examples, see [2] and [3]. To ensure that people don't try to simplify
RevocableGuard by changing the raw pointer to a reference, add a comment
to that effect.

Link: https://perso.crans.org/vanille/treebor/protectors.html [1]
Link: https://users.rust-lang.org/t/unsafe-code-review-semi-owning-weak-rwlock-t-guard/95706 [2]
Link: https://lore.kernel.org/all/[email protected]/ [3]
Signed-off-by: Alice Ryhl <[email protected]>
Reviewed-by: Benno Lossin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[ Adjusted title. - Miguel ]
Signed-off-by: Miguel Ojeda <[email protected]>

Implement `Borrow<T>` and `BorrowMut<T>` for `UniqueArc<T>`, and
`Borrow<T>` for `Arc<T>`. This allows these containers to be used in
generic APIs asking for types implementing those traits. `T` and `&mut
T` also implement those traits allowing users to use either owned,
shared or borrowed values.

`ForeignOwnable` makes a call to its own `borrow` method which must be
disambiguated.

Reviewed-by: Alice Ryhl <[email protected]>
Reviewed-by: Benno Lossin <[email protected]>
Signed-off-by: Alexandre Courbot <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Miguel Ojeda <[email protected]>