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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148// SPDX-License-Identifier: GPL-2.0
//! A kernel mutex.//!//! This module allows Rust code to use the kernel's `struct mutex`.
/// 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/// number.#[macro_export]macro_rules! new_mutex { ($inner:expr $(, $name:literal)? $(,)?) => { $crate::sync::Mutex::new( $inner, $crate::optional_name!($($name)?), $crate::static_lock_class!()) };}pub use new_mutex;
/// A mutual exclusion primitive.////// Exposes the kernel's [`struct mutex`]. When multiple threads attempt to lock the same mutex,/// only one at a time is allowed to progress, the others will block (sleep) until the mutex is/// unlocked, at which point another thread will be allowed to wake up and make progress.////// Since it may block, [`Mutex`] needs to be used with care in atomic contexts.////// Instances of [`Mutex`] need a lock class and to be pinned. The recommended way to create such/// instances is with the [`pin_init`](pin_init::pin_init) and [`new_mutex`] macros.////// # Examples////// The following example shows how to declare, allocate and initialise a struct (`Example`) that/// contains an inner struct (`Inner`) that is protected by a mutex.////// ```/// use kernel::sync::{new_mutex, Mutex};////// struct Inner {/// a: u32,/// b: u32,/// }////// #[pin_data]/// struct Example {/// c: u32,/// #[pin]/// d: Mutex<Inner>,/// }////// impl Example {/// fn new() -> impl PinInit<Self> {/// pin_init!(Self {/// c: 10,/// d <- new_mutex!(Inner { a: 20, b: 30 }),/// })/// }/// }////// // Allocate a boxed `Example`./// let e = KBox::pin_init(Example::new(), GFP_KERNEL)?;/// assert_eq!(e.c, 10);/// assert_eq!(e.d.lock().a, 20);/// assert_eq!(e.d.lock().b, 30);/// # Ok::<(), Error>(())/// ```////// The following example shows how to use interior mutability to modify the contents of a struct/// protected by a mutex despite only having a shared reference:////// ```/// use kernel::sync::Mutex;////// struct Example {/// a: u32,/// b: u32,/// }////// fn example(m: &Mutex<Example>) {/// let mut guard = m.lock();/// guard.a += 10;/// guard.b += 20;/// }/// ```////// [`struct mutex`]: srctree/include/linux/mutex.hpub type Mutex<T> = super::Lock<T, MutexBackend>;
/// A [`Guard`] acquired from locking a [`Mutex`].////// This is simply a type alias for a [`Guard`] returned from locking a [`Mutex`]. It will unlock/// the [`Mutex`] upon being dropped.////// [`Guard`]: super::Guardpub type MutexGuard<'a, T> = super::Guard<'a, T, MutexBackend>;
/// A kernel `struct mutex` lock backend.pub struct MutexBackend;
// SAFETY: The underlying kernel `struct mutex` object ensures mutual exclusion.unsafe impl super::Backend for MutexBackend { type State = bindings::mutex; type GuardState = ();
#[inline] unsafe fn init( ptr: *mut Self::State, name: *const crate::ffi::c_char, key: *mut bindings::lock_class_key, ) { // SAFETY: The safety requirements ensure that `ptr` is valid for writes, and `name` and // `key` are valid for read indefinitely. unsafe { bindings::__mutex_init(ptr, name, key) } }
#[inline] unsafe fn lock(ptr: *mut Self::State) -> Self::GuardState { // SAFETY: The safety requirements of this function ensure that `ptr` points to valid // memory, and that it has been initialised before. unsafe { bindings::mutex_lock(ptr) }; }
#[inline] unsafe fn unlock(ptr: *mut Self::State, _guard_state: &Self::GuardState) { // SAFETY: The safety requirements of this function ensure that `ptr` is valid and that the // caller is the owner of the mutex. unsafe { bindings::mutex_unlock(ptr) }; }
#[inline] unsafe fn try_lock(ptr: *mut Self::State) -> Option<Self::GuardState> { // SAFETY: The `ptr` pointer is guaranteed to be valid and initialized before use. let result = unsafe { bindings::mutex_trylock(ptr) };
if result != 0 { Some(()) } else { None } }
#[inline] unsafe fn assert_is_held(ptr: *mut Self::State) { // SAFETY: The `ptr` pointer is guaranteed to be valid and initialized before use. unsafe { bindings::mutex_assert_is_held(ptr) } }}