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// SPDX-License-Identifier: GPL-2.0
use super::HasHrTimer;
use super::HrTimer;
use super::HrTimerCallback;
use super::HrTimerHandle;
use super::HrTimerPointer;
use super::RawHrTimerCallback;
use crate::sync::Arc;
use crate::sync::ArcBorrow;
use crate::time::Ktime;
/// A handle for an `Arc<HasHrTimer<T>>` returned by a call to
/// [`HrTimerPointer::start`].
pub struct ArcHrTimerHandle<T>
where
T: HasHrTimer<T>,
{
pub(crate) inner: Arc<T>,
}
// SAFETY: We implement drop below, and we cancel the timer in the drop
// implementation.
unsafe impl<T> HrTimerHandle for ArcHrTimerHandle<T>
where
T: HasHrTimer<T>,
{
fn cancel(&mut self) -> bool {
let self_ptr = Arc::as_ptr(&self.inner);
// SAFETY: As we obtained `self_ptr` from a valid reference above, it
// must point to a valid `T`.
let timer_ptr = unsafe { <T as HasHrTimer<T>>::raw_get_timer(self_ptr) };
// SAFETY: As `timer_ptr` points into `T` and `T` is valid, `timer_ptr`
// must point to a valid `HrTimer` instance.
unsafe { HrTimer::<T>::raw_cancel(timer_ptr) }
}
}
impl<T> Drop for ArcHrTimerHandle<T>
where
T: HasHrTimer<T>,
{
fn drop(&mut self) {
self.cancel();
}
}
impl<T> HrTimerPointer for Arc<T>
where
T: 'static,
T: Send + Sync,
T: HasHrTimer<T>,
T: for<'a> HrTimerCallback<Pointer<'a> = Self>,
{
type TimerHandle = ArcHrTimerHandle<T>;
fn start(self, expires: Ktime) -> ArcHrTimerHandle<T> {
// SAFETY:
// - We keep `self` alive by wrapping it in a handle below.
// - Since we generate the pointer passed to `start` from a valid
// reference, it is a valid pointer.
unsafe { T::start(Arc::as_ptr(&self), expires) };
ArcHrTimerHandle { inner: self }
}
}
impl<T> RawHrTimerCallback for Arc<T>
where
T: 'static,
T: HasHrTimer<T>,
T: for<'a> HrTimerCallback<Pointer<'a> = Self>,
{
type CallbackTarget<'a> = ArcBorrow<'a, T>;
unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart {
// `HrTimer` is `repr(C)`
let timer_ptr = ptr.cast::<super::HrTimer<T>>();
// SAFETY: By C API contract `ptr` is the pointer we passed when
// queuing the timer, so it is a `HrTimer<T>` embedded in a `T`.
let data_ptr = unsafe { T::timer_container_of(timer_ptr) };
// SAFETY:
// - `data_ptr` is derived form the pointer to the `T` that was used to
// queue the timer.
// - As per the safety requirements of the trait `HrTimerHandle`, the
// `ArcHrTimerHandle` associated with this timer is guaranteed to
// be alive until this method returns. That handle borrows the `T`
// behind `data_ptr` thus guaranteeing the validity of
// the `ArcBorrow` created below.
// - We own one refcount in the `ArcTimerHandle` associated with this
// timer, so it is not possible to get a `UniqueArc` to this
// allocation from other `Arc` clones.
let receiver = unsafe { ArcBorrow::from_raw(data_ptr) };
T::run(receiver).into_c()
}
}
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