linux-stable.git/rust/kernel/alloc.rs, branch v6.13.7

rust: alloc: update module comment of alloc.rs

2024-10-15T21:10:32+00:00

Before we remove Rust's alloc crate, rewrite the module comment in
alloc.rs to avoid a rustdoc warning.

Besides that, the module comment in alloc.rs isn't correct anymore,
we're no longer extending Rust's alloc crate.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-28-dakr@kernel.org
Signed-off-by: Miguel Ojeda

rust: alloc: implement `Cmalloc` in module allocator_test

2024-10-15T21:10:32+00:00

So far the kernel's `Box` and `Vec` types can't be used by userspace
test cases, since all users of those types (e.g. `CString`) use kernel
allocators for instantiation.

In order to allow userspace test cases to make use of such types as
well, implement the `Cmalloc` allocator within the allocator_test module
and type alias all kernel allocators to `Cmalloc`. The `Cmalloc`
allocator uses libc's `realloc()` function as allocator backend.

Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-26-dakr@kernel.org
[ Removed the temporary `allow(dead_code)` as discussed in the list and
  fixed typo, added backticks. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: alloc: implement `contains` for `Flags`

2024-10-15T21:10:32+00:00

Provide a simple helper function to check whether given flags do
contain one or multiple other flags.

This is used by a subsequent patch implementing the Cmalloc `Allocator`
to check for __GFP_ZERO.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-25-dakr@kernel.org
Signed-off-by: Miguel Ojeda

rust: alloc: remove `VecExt` extension

2024-10-15T21:10:32+00:00

Now that all existing `Vec` users were moved to the kernel `Vec` type,
remove the `VecExt` extension.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-21-dakr@kernel.org
Signed-off-by: Miguel Ojeda

rust: alloc: implement `IntoIterator` for `Vec`

2024-10-15T21:10:32+00:00

Implement `IntoIterator` for `Vec`, `Vec`'s `IntoIter` type, as well as
`Iterator` for `IntoIter`.

`Vec::into_iter` disassembles the `Vec` into its raw parts; additionally,
`IntoIter` keeps track of a separate pointer, which is incremented
correspondingly as the iterator advances, while the length, or the count
of elements, is decremented.

This also means that `IntoIter` takes the ownership of the backing
buffer and is responsible to drop the remaining elements and free the
backing buffer, if it's dropped.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-18-dakr@kernel.org
[ Fixed typos. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: alloc: implement kernel `Vec` type

2024-10-15T21:10:32+00:00

`Vec` provides a contiguous growable array type with contents allocated
with the kernel's allocators (e.g. `Kmalloc`, `Vmalloc` or `KVmalloc`).

In contrast to Rust's stdlib `Vec` type, the kernel `Vec` type considers
the kernel's GFP flags for all appropriate functions, always reports
allocation failures through `Result<_, AllocError>` and remains
independent from unstable features.

[ This patch starts using a new unstable feature, `inline_const`, but
  it was stabilized in Rust 1.79.0, i.e. the next version after the
  minimum one, thus it will not be an issue. - Miguel ]

Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-17-dakr@kernel.org
[ Cleaned `rustdoc` unescaped backtick warning, added a couple more
  backticks elsewhere, fixed typos, sorted `feature`s, rewrapped
  documentation lines. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: alloc: introduce `ArrayLayout`

2024-10-15T20:56:59+00:00

When allocating memory for arrays using allocators, the `Layout::array`
function is typically used. It returns a result, since the given size
might be too big. However, `Vec` and its iterators store their allocated
capacity and thus they already did check that the size is not too big.

The `ArrayLayout` type provides this exact behavior, as it can be
infallibly converted into a `Layout`. Instead of a `usize` capacity,
`Vec` and other similar array-storing types can use `ArrayLayout`
instead.

Reviewed-by: Gary Guo 
Signed-off-by: Benno Lossin 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-16-dakr@kernel.org
[ Formatted a few comments. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: alloc: remove extension of std's `Box`

2024-10-15T20:56:59+00:00

Now that all existing `Box` users were moved to the kernel `Box` type,
remove the `BoxExt` extension and all other related extensions.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-14-dakr@kernel.org
Signed-off-by: Miguel Ojeda

rust: alloc: implement kernel `Box`

2024-10-15T20:56:59+00:00

`Box` provides the simplest way to allocate memory for a generic type
with one of the kernel's allocators, e.g. `Kmalloc`, `Vmalloc` or
`KVmalloc`.

In contrast to Rust's `Box` type, the kernel `Box` type considers the
kernel's GFP flags for all appropriate functions, always reports
allocation failures through `Result<_, AllocError>` and remains
independent from unstable features.

Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-12-dakr@kernel.org
[ Added backticks, fixed typos. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: alloc: add __GFP_NOWARN to `Flags`

2024-10-15T20:56:59+00:00

Some test cases in subsequent patches provoke allocation failures. Add
`__GFP_NOWARN` to enable test cases to silence unpleasant warnings.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-11-dakr@kernel.org
Signed-off-by: Miguel Ojeda