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git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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582523d9de
Allow pinned references to structs that contain a `HrTimer` node to be scheduled with the `hrtimer` subsystem. Acked-by: Frederic Weisbecker <frederic@kernel.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Lyude Paul <lyude@redhat.com> Reviewed-by: Benno Lossin <benno.lossin@proton.me> Link: https://lore.kernel.org/r/20250309-hrtimer-v3-v6-12-rc2-v12-7-73586e2bd5f1@kernel.org Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
105 lines
3.3 KiB
Rust
105 lines
3.3 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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use super::HasHrTimer;
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use super::HrTimer;
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use super::HrTimerCallback;
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use super::HrTimerHandle;
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use super::RawHrTimerCallback;
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use super::UnsafeHrTimerPointer;
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use crate::time::Ktime;
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use core::pin::Pin;
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/// A handle for a `Pin<&HasHrTimer>`. When the handle exists, the timer might be
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/// running.
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pub struct PinHrTimerHandle<'a, T>
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where
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T: HasHrTimer<T>,
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{
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pub(crate) inner: Pin<&'a T>,
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}
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// SAFETY: We cancel the timer when the handle is dropped. The implementation of
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// the `cancel` method will block if the timer handler is running.
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unsafe impl<'a, T> HrTimerHandle for PinHrTimerHandle<'a, T>
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where
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T: HasHrTimer<T>,
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{
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fn cancel(&mut self) -> bool {
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let self_ptr: *const T = self.inner.get_ref();
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// SAFETY: As we got `self_ptr` from a reference above, it must point to
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// a valid `T`.
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let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self_ptr) };
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// SAFETY: As `timer_ptr` is derived from a reference, it must point to
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// a valid and initialized `HrTimer`.
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unsafe { HrTimer::<T>::raw_cancel(timer_ptr) }
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}
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}
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impl<'a, T> Drop for PinHrTimerHandle<'a, T>
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where
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T: HasHrTimer<T>,
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{
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fn drop(&mut self) {
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self.cancel();
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}
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}
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// SAFETY: We capture the lifetime of `Self` when we create a `PinHrTimerHandle`,
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// so `Self` will outlive the handle.
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unsafe impl<'a, T> UnsafeHrTimerPointer for Pin<&'a T>
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where
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T: Send + Sync,
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T: HasHrTimer<T>,
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T: HrTimerCallback<Pointer<'a> = Self>,
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{
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type TimerHandle = PinHrTimerHandle<'a, T>;
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unsafe fn start(self, expires: Ktime) -> Self::TimerHandle {
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// Cast to pointer
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let self_ptr: *const T = self.get_ref();
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// SAFETY:
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// - As we derive `self_ptr` from a reference above, it must point to a
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// valid `T`.
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// - We keep `self` alive by wrapping it in a handle below.
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unsafe { T::start(self_ptr, expires) };
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PinHrTimerHandle { inner: self }
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}
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}
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impl<'a, T> RawHrTimerCallback for Pin<&'a T>
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where
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T: HasHrTimer<T>,
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T: HrTimerCallback<Pointer<'a> = Self>,
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{
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type CallbackTarget<'b> = Self;
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unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
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// `HrTimer` is `repr(C)`
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let timer_ptr = ptr as *mut HrTimer<T>;
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// SAFETY: By the safety requirement of this function, `timer_ptr`
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// points to a `HrTimer<T>` contained in an `T`.
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let receiver_ptr = unsafe { T::timer_container_of(timer_ptr) };
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// SAFETY:
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// - By the safety requirement of this function, `timer_ptr`
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// points to a `HrTimer<T>` contained in an `T`.
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// - As per the safety requirements of the trait `HrTimerHandle`, the
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// `PinHrTimerHandle` associated with this timer is guaranteed to
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// be alive until this method returns. That handle borrows the `T`
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// behind `receiver_ptr`, thus guaranteeing the validity of
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// the reference created below.
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let receiver_ref = unsafe { &*receiver_ptr };
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// SAFETY: `receiver_ref` only exists as pinned, so it is safe to pin it
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// here.
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let receiver_pin = unsafe { Pin::new_unchecked(receiver_ref) };
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T::run(receiver_pin).into_c()
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}
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}
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