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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147// SPDX-License-Identifier: GPL-2.0
//! A kernel spinlock.//!//! This module allows Rust code to use the kernel's `spinlock_t`.
/// 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/// number.#[macro_export]macro_rules! new_spinlock { ($inner:expr $(, $name:literal)? $(,)?) => { $crate::sync::SpinLock::new( $inner, $crate::optional_name!($($name)?), $crate::static_lock_class!()) };}pub use new_spinlock;
/// A spinlock.////// Exposes the kernel's [`spinlock_t`]. When multiple CPUs attempt to lock the same spinlock, only/// one at a time is allowed to progress, the others will block (spinning) until the spinlock is/// unlocked, at which point another CPU will be allowed to make progress.////// Instances of [`SpinLock`] 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_spinlock`] 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 spinlock.////// ```/// use kernel::sync::{new_spinlock, SpinLock};////// struct Inner {/// a: u32,/// b: u32,/// }////// #[pin_data]/// struct Example {/// c: u32,/// #[pin]/// d: SpinLock<Inner>,/// }////// impl Example {/// fn new() -> impl PinInit<Self> {/// pin_init!(Self {/// c: 10,/// d <- new_spinlock!(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 spinlock despite only having a shared reference:////// ```/// use kernel::sync::SpinLock;////// struct Example {/// a: u32,/// b: u32,/// }////// fn example(m: &SpinLock<Example>) {/// let mut guard = m.lock();/// guard.a += 10;/// guard.b += 20;/// }/// ```////// [`spinlock_t`]: srctree/include/linux/spinlock.hpub type SpinLock<T> = super::Lock<T, SpinLockBackend>;
/// A kernel `spinlock_t` lock backend.pub struct SpinLockBackend;
/// A [`Guard`] acquired from locking a [`SpinLock`].////// This is simply a type alias for a [`Guard`] returned from locking a [`SpinLock`]. It will unlock/// the [`SpinLock`] upon being dropped.////// [`Guard`]: super::Guardpub type SpinLockGuard<'a, T> = super::Guard<'a, T, SpinLockBackend>;
// SAFETY: The underlying kernel `spinlock_t` object ensures mutual exclusion. `relock` uses the// default implementation that always calls the same locking method.unsafe impl super::Backend for SpinLockBackend { type State = bindings::spinlock_t; 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::__spin_lock_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::spin_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 spinlock. unsafe { bindings::spin_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::spin_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::spin_assert_is_held(ptr) } }}