mirror of https://github.com/torvalds/linux.git
53 lines
1.3 KiB
Rust
53 lines
1.3 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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//! RCU support.
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//!
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//! C header: [`include/linux/rcupdate.h`](srctree/include/linux/rcupdate.h)
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use crate::{bindings, types::NotThreadSafe};
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/// Evidence that the RCU read side lock is held on the current thread/CPU.
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///
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/// The type is explicitly not `Send` because this property is per-thread/CPU.
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///
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/// # Invariants
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///
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/// The RCU read side lock is actually held while instances of this guard exist.
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pub struct Guard(NotThreadSafe);
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impl Guard {
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/// Acquires the RCU read side lock and returns a guard.
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#[inline]
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pub fn new() -> Self {
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// SAFETY: An FFI call with no additional requirements.
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unsafe { bindings::rcu_read_lock() };
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// INVARIANT: The RCU read side lock was just acquired above.
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Self(NotThreadSafe)
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}
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/// Explicitly releases the RCU read side lock.
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#[inline]
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pub fn unlock(self) {}
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}
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impl Default for Guard {
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#[inline]
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fn default() -> Self {
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Self::new()
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}
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}
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impl Drop for Guard {
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#[inline]
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fn drop(&mut self) {
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// SAFETY: By the type invariants, the RCU read side is locked, so it is ok to unlock it.
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unsafe { bindings::rcu_read_unlock() };
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}
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}
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/// Acquires the RCU read side lock.
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#[inline]
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pub fn read_lock() -> Guard {
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Guard::new()
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}
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