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author | Wedson Almeida Filho <walmeida@microsoft.com> | 2023-04-19 14:44:26 -0300 |
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committer | Miguel Ojeda <ojeda@kernel.org> | 2023-04-22 00:20:00 +0200 |
commit | c6d917a498bfef603f41bfc4d31e9699bb2909fc (patch) | |
tree | f710485f3aaadc20ffd4437fcd9aa2016462116f /rust | |
parent | 6d20d629c6d8575be98eeebe49a16fb2d7b32350 (diff) | |
download | linux-c6d917a498bfef603f41bfc4d31e9699bb2909fc.tar.gz linux-c6d917a498bfef603f41bfc4d31e9699bb2909fc.tar.bz2 linux-c6d917a498bfef603f41bfc4d31e9699bb2909fc.zip |
rust: lock: introduce `SpinLock`
This is the `spinlock_t` lock backend and allows Rust code to use the
kernel spinlock idiomatically.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20230419174426.132207-1-wedsonaf@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'rust')
-rw-r--r-- | rust/helpers.c | 24 | ||||
-rw-r--r-- | rust/kernel/sync.rs | 2 | ||||
-rw-r--r-- | rust/kernel/sync/lock.rs | 1 | ||||
-rw-r--r-- | rust/kernel/sync/lock/spinlock.rs | 116 |
4 files changed, 142 insertions, 1 deletions
diff --git a/rust/helpers.c b/rust/helpers.c index 86af099d2d66..446e3cfdb935 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -23,6 +23,7 @@ #include <linux/err.h> #include <linux/refcount.h> #include <linux/mutex.h> +#include <linux/spinlock.h> __noreturn void rust_helper_BUG(void) { @@ -36,6 +37,29 @@ void rust_helper_mutex_lock(struct mutex *lock) } EXPORT_SYMBOL_GPL(rust_helper_mutex_lock); +void rust_helper___spin_lock_init(spinlock_t *lock, const char *name, + struct lock_class_key *key) +{ +#ifdef CONFIG_DEBUG_SPINLOCK + __raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG); +#else + spin_lock_init(lock); +#endif +} +EXPORT_SYMBOL_GPL(rust_helper___spin_lock_init); + +void rust_helper_spin_lock(spinlock_t *lock) +{ + spin_lock(lock); +} +EXPORT_SYMBOL_GPL(rust_helper_spin_lock); + +void rust_helper_spin_unlock(spinlock_t *lock) +{ + spin_unlock(lock); +} +EXPORT_SYMBOL_GPL(rust_helper_spin_unlock); + refcount_t rust_helper_REFCOUNT_INIT(int n) { return (refcount_t)REFCOUNT_INIT(n); diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 693f0b7f4e4f..c997ff7e951e 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -11,7 +11,7 @@ mod arc; pub mod lock; pub use arc::{Arc, ArcBorrow, UniqueArc}; -pub use lock::mutex::Mutex; +pub use lock::{mutex::Mutex, spinlock::SpinLock}; /// Represents a lockdep class. It's a wrapper around C's `lock_class_key`. #[repr(transparent)] diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index 2ea512a8dfab..3c166e08f3d4 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -11,6 +11,7 @@ use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned}; use macros::pin_data; pub mod mutex; +pub mod spinlock; /// The "backend" of a lock. /// diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs new file mode 100644 index 000000000000..a52d20fc9755 --- /dev/null +++ b/rust/kernel/sync/lock/spinlock.rs @@ -0,0 +1,116 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! A kernel spinlock. +//! +//! This module allows Rust code to use the kernel's `spinlock_t`. + +use crate::bindings; + +/// 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!()) + }; +} + +/// 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`](crate::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::{init::InPlaceInit, init::PinInit, new_spinlock, pin_init, sync::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 = Box::pin_init(Example::new())?; +/// assert_eq!(e.c, 10); +/// assert_eq!(e.d.lock().a, 20); +/// assert_eq!(e.d.lock().b, 30); +/// ``` +/// +/// 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`]: ../../../../include/linux/spinlock.h +pub type SpinLock<T> = super::Lock<T, SpinLockBackend>; + +/// A kernel `spinlock_t` lock backend. +pub struct SpinLockBackend; + +// SAFETY: The underlying kernel `spinlock_t` object ensures mutual exclusion. +unsafe impl super::Backend for SpinLockBackend { + type State = bindings::spinlock_t; + type GuardState = (); + + unsafe fn init( + ptr: *mut Self::State, + name: *const core::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) } + } + + 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) } + } + + 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::spin_unlock(ptr) } + } +} |