More additions to the Rust core. Importantly, this adds the pin-init
API, which will be used by other abstractions, such as the
synchronization ones added here too:
- pin-init API: a solution for the safe pinned initialization problem.
This allows to reduce the need for 'unsafe' code in the kernel when
dealing with data structures that require a stable address. Commit
90e53c5e70 ("rust: add pin-init API core") contains a nice
introduction -- here is an example of how it looks like:
#[pin_data]
struct Example {
#[pin]
value: Mutex<u32>,
#[pin]
value_changed: CondVar,
}
impl Example {
fn new() -> impl PinInit<Self> {
pin_init!(Self {
value <- new_mutex!(0),
value_changed <- new_condvar!(),
})
}
}
// In a `Box`.
let b = Box::pin_init(Example::new())?;
// In the stack.
stack_pin_init!(let s = Example::new());
- 'sync' module: new types 'LockClassKey' ('struct lock_class_key'),
'Lock', 'Guard', 'Mutex' ('struct mutex'), 'SpinLock'
('spinlock_t'), 'LockedBy' and 'CondVar' (uses 'wait_queue_head_t'),
plus macros such as 'static_lock_class!' and 'new_spinlock!'.
In particular, 'Lock' and 'Guard' are generic implementations that
contain code that is common to all locks. Then, different backends
(the new 'Backend' trait) are implemented and used to define types
like 'Mutex':
type Mutex<T> = Lock<T, MutexBackend>;
In addition, new methods 'assume_init()', 'init_with()' and
'pin_init_with()' for 'UniqueArc<MaybeUninit<T>>' and 'downcast()'
for 'Arc<dyn Any + Send + Sync>'; as well as 'Debug' and 'Display'
implementations for 'Arc' and 'UniqueArc'. Reduced stack usage of
'UniqueArc::try_new_uninit()', too.
- 'types' module: new trait 'AlwaysRefCounted' and new type 'ARef'
(an owned reference to an always-reference-counted object, meant to
be used in wrappers for C types that have their own ref counting
functions).
Moreover, new associated functions 'raw_get()' and 'ffi_init()'
for 'Opaque'.
- New 'task' module with a new type 'Task' ('struct task_struct'), and
a new macro 'current!' to safely get a reference to the current one.
- New 'ioctl' module with new '_IOC*' const functions (equivalent to
the C macros).
- New 'uapi' crate, intended to be accessible by drivers directly.
- 'macros' crate: new 'quote!' macro (similar to the one provided in
userspace by the 'quote' crate); and the 'module!' macro now allows
specifying multiple module aliases.
- 'error' module: new associated functions for the 'Error' type,
such as 'from_errno()' and new functions such as 'to_result()'.
- 'alloc' crate: more fallible 'Vec' methods: 'try_resize` and
'try_extend_from_slice' and the infrastructure (imported from
the Rust standard library) they need.
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Merge tag 'rust-6.4' of https://github.com/Rust-for-Linux/linux
Pull rust updates from Miguel Ojeda
"More additions to the Rust core. Importantly, this adds the pin-init
API, which will be used by other abstractions, such as the
synchronization ones added here too:
- pin-init API: a solution for the safe pinned initialization
problem.
This allows to reduce the need for 'unsafe' code in the kernel when
dealing with data structures that require a stable address. Commit
90e53c5e70 ("rust: add pin-init API core") contains a nice
introduction -- here is an example of how it looks like:
#[pin_data]
struct Example {
#[pin]
value: Mutex<u32>,
#[pin]
value_changed: CondVar,
}
impl Example {
fn new() -> impl PinInit<Self> {
pin_init!(Self {
value <- new_mutex!(0),
value_changed <- new_condvar!(),
})
}
}
// In a `Box`.
let b = Box::pin_init(Example::new())?;
// In the stack.
stack_pin_init!(let s = Example::new());
- 'sync' module:
New types 'LockClassKey' ('struct lock_class_key'), 'Lock',
'Guard', 'Mutex' ('struct mutex'), 'SpinLock' ('spinlock_t'),
'LockedBy' and 'CondVar' (uses 'wait_queue_head_t'), plus macros
such as 'static_lock_class!' and 'new_spinlock!'.
In particular, 'Lock' and 'Guard' are generic implementations that
contain code that is common to all locks. Then, different backends
(the new 'Backend' trait) are implemented and used to define types
like 'Mutex':
type Mutex<T> = Lock<T, MutexBackend>;
In addition, new methods 'assume_init()', 'init_with()' and
'pin_init_with()' for 'UniqueArc<MaybeUninit<T>>' and 'downcast()'
for 'Arc<dyn Any + Send + Sync>'; as well as 'Debug' and 'Display'
implementations for 'Arc' and 'UniqueArc'. Reduced stack usage of
'UniqueArc::try_new_uninit()', too.
- 'types' module:
New trait 'AlwaysRefCounted' and new type 'ARef' (an owned
reference to an always-reference-counted object, meant to be used
in wrappers for C types that have their own ref counting
functions).
Moreover, new associated functions 'raw_get()' and 'ffi_init()' for
'Opaque'.
- New 'task' module with a new type 'Task' ('struct task_struct'),
and a new macro 'current!' to safely get a reference to the current
one.
- New 'ioctl' module with new '_IOC*' const functions (equivalent to
the C macros).
- New 'uapi' crate, intended to be accessible by drivers directly.
- 'macros' crate: new 'quote!' macro (similar to the one provided in
userspace by the 'quote' crate); and the 'module!' macro now allows
specifying multiple module aliases.
- 'error' module:
New associated functions for the 'Error' type, such as
'from_errno()' and new functions such as 'to_result()'.
- 'alloc' crate:
More fallible 'Vec' methods: 'try_resize` and
'try_extend_from_slice' and the infrastructure (imported from the
Rust standard library) they need"
* tag 'rust-6.4' of https://github.com/Rust-for-Linux/linux: (44 commits)
rust: ioctl: Add ioctl number manipulation functions
rust: uapi: Add UAPI crate
rust: sync: introduce `CondVar`
rust: lock: add `Guard::do_unlocked`
rust: sync: introduce `LockedBy`
rust: introduce `current`
rust: add basic `Task`
rust: introduce `ARef`
rust: lock: introduce `SpinLock`
rust: lock: introduce `Mutex`
rust: sync: introduce `Lock` and `Guard`
rust: sync: introduce `LockClassKey`
MAINTAINERS: add Benno Lossin as Rust reviewer
rust: init: broaden the blanket impl of `Init`
rust: sync: add functions for initializing `UniqueArc<MaybeUninit<T>>`
rust: sync: reduce stack usage of `UniqueArc::try_new_uninit`
rust: types: add `Opaque::ffi_init`
rust: prelude: add `pin-init` API items to prelude
rust: init: add `Zeroable` trait and `init::zeroed` function
rust: init: add `stack_pin_init!` macro
...
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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