projects/linux·blob assoc-array-fixes-v2 · refs

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1// SPDX-License-Identifier: GPL-2.0
2
3//! Synchronisation primitives.
4//!
5//! This module contains the kernel APIs related to synchronisation that have been ported or
6//! wrapped for usage by Rust code in the kernel.
7
8use crate::prelude::*;
9use crate::types::Opaque;
10use pin_init;
11
12mod arc;
13pub mod aref;
14pub mod atomic;
15pub mod barrier;
16pub mod completion;
17mod condvar;
18pub mod lock;
19mod locked_by;
20pub mod poll;
21pub mod rcu;
22mod refcount;
23mod set_once;
24pub mod srcu;
25
26pub use arc::{Arc, ArcBorrow, UniqueArc};
27pub use completion::Completion;
28pub use condvar::{new_condvar, CondVar, CondVarTimeoutResult};
29pub use lock::global::{global_lock, GlobalGuard, GlobalLock, GlobalLockBackend, GlobalLockedBy};
30pub use lock::mutex::{new_mutex, Mutex, MutexGuard};
31pub use lock::spinlock::{
32 new_spinlock,
33 new_spinlock_irq,
34 SpinLock,
35 SpinLockGuard,
36 SpinLockIrq,
37 SpinLockIrqGuard, //
38};
39pub use locked_by::LockedBy;
40pub use refcount::Refcount;
41pub use set_once::SetOnce;
42pub use srcu::Srcu;
43
44/// Represents a lockdep class.
45///
46/// Wraps the kernel's `struct lock_class_key`.
47#[repr(transparent)]
48#[pin_data(PinnedDrop)]
49pub struct LockClassKey {
50 #[pin]
51 inner: Opaque<bindings::lock_class_key>,
52}
53
54// SAFETY: Unregistering a lock class key from a different thread than where it was registered is
55// allowed.
56unsafe impl Send for LockClassKey {}
57
58// SAFETY: `bindings::lock_class_key` is designed to be used concurrently from multiple threads and
59// provides its own synchronization.
60unsafe impl Sync for LockClassKey {}
61
62impl LockClassKey {
63 /// Initializes a statically allocated lock class key.
64 ///
65 /// This is usually used indirectly through the [`static_lock_class!`] macro. See its
66 /// documentation for more information.
67 ///
68 /// # Safety
69 ///
70 /// * Before using the returned value, it must be pinned in a static memory location.
71 /// * The destructor must never run on the returned `LockClassKey`.
72 pub const unsafe fn new_static() -> Self {
73 LockClassKey {
74 inner: Opaque::uninit(),
75 }
76 }
77
78 /// Initializes a dynamically allocated lock class key.
79 ///
80 /// In the common case of using a statically allocated lock class key, the
81 /// [`static_lock_class!`] macro should be used instead.
82 ///
83 /// # Examples
84 ///
85 /// ```
86 /// use kernel::alloc::KBox;
87 /// use kernel::types::ForeignOwnable;
88 /// use kernel::sync::{LockClassKey, SpinLock};
89 /// use pin_init::stack_pin_init;
90 ///
91 /// let key = KBox::pin_init(LockClassKey::new_dynamic(), GFP_KERNEL)?;
92 /// let key_ptr = key.into_foreign();
93 ///
94 /// {
95 /// stack_pin_init!(let num: SpinLock<u32> = SpinLock::new(
96 /// 0,
97 /// c"my_spinlock",
98 /// // SAFETY: `key_ptr` is returned by the above `into_foreign()`, whose
99 /// // `from_foreign()` has not yet been called.
100 /// unsafe { <Pin<KBox<LockClassKey>> as ForeignOwnable>::borrow(key_ptr) }
101 /// ));
102 /// }
103 ///
104 /// // SAFETY: We dropped `num`, the only use of the key, so the result of the previous
105 /// // `borrow` has also been dropped. Thus, it's safe to use from_foreign.
106 /// unsafe { drop(<Pin<KBox<LockClassKey>> as ForeignOwnable>::from_foreign(key_ptr)) };
107 /// # Ok::<(), Error>(())
108 /// ```
109 pub fn new_dynamic() -> impl PinInit<Self> {
110 pin_init!(Self {
111 // SAFETY: lockdep_register_key expects an uninitialized block of memory
112 inner <- Opaque::ffi_init(|slot| unsafe { bindings::lockdep_register_key(slot) })
113 })
114 }
115
116 /// Returns a raw pointer to the inner C struct.
117 ///
118 /// It is up to the caller to use the raw pointer correctly.
119 pub fn as_ptr(&self) -> *mut bindings::lock_class_key {
120 self.inner.get()
121 }
122}
123
124#[pinned_drop]
125impl PinnedDrop for LockClassKey {
126 fn drop(self: Pin<&mut Self>) {
127 // SAFETY: `self.as_ptr()` was registered with lockdep and `self` is pinned, so the address
128 // hasn't changed. Thus, it's safe to pass it to unregister.
129 unsafe { bindings::lockdep_unregister_key(self.as_ptr()) }
130 }
131}
132
133/// Defines a new static lock class and returns a pointer to it.
134///
135/// # Examples
136///
137/// ```
138/// use kernel::sync::{static_lock_class, Arc, SpinLock};
139///
140/// fn new_locked_int() -> Result<Arc<SpinLock<u32>>> {
141/// Arc::pin_init(SpinLock::new(
142/// 42,
143/// c"new_locked_int",
144/// static_lock_class!(),
145/// ), GFP_KERNEL)
146/// }
147/// ```
148#[macro_export]
149macro_rules! static_lock_class {
150 () => {{
151 static CLASS: $crate::sync::LockClassKey =
152 // SAFETY: The returned `LockClassKey` is stored in static memory and we pin it. Drop
153 // never runs on a static global.
154 unsafe { $crate::sync::LockClassKey::new_static() };
155 $crate::prelude::Pin::static_ref(&CLASS)
156 }};
157}
158pub use static_lock_class;
159
160/// Returns the given string, if one is provided, otherwise generates one based on the source code
161/// location.
162#[doc(hidden)]
163#[macro_export]
164macro_rules! optional_name {
165 () => {
166 $crate::c_str!(::core::concat!(::core::file!(), ":", ::core::line!()))
167 };
168 ($name:literal) => {
169 $crate::c_str!($name)
170 };
171}